GBE > Encyclopaedia > Code > Issues > Overheating > G#145

Overheating (Issue Paper)
Update 11


Slogan:           Build Light, Insulate Right, Solar Tight

Overheating before and after energy saving retrofit or future-facing adaptations

 

GBE Issue Paper: Overheating: Executive Summary

Many specialists in the UK have explored overheating in summer but none appear to have found the primary problem and not found the whole solution. Most of the proposals just fine tune the problem but do not solve it. Zero Carbon Hub and NHBC publications are missing the point too. DECC got close with the problem, but not the solution.

Just like the severe and continuous drip feed of storms on the West-country coast 2013-2014 leading to the battering of the coastal towns, closing of a railway line, flooding of the Somerset Levels, Severn estuary and eventually the Thames valley; the nub of the problem was not the congested rivers and drainage dykes, it was the 2 months of prolonged, heavy and incessant rainfall.

Summer overheating is down to the incessant sun heating of the buildings through the transparent surfaces, but more importantly through the opaque surfaces, roof and walls of lightweight construction.

This is exacerbated by the use of the familiar, cheap, but unfit-for-purpose, wrong thermal insulation materials that permits radiant heat to get in and then prevents conducted heat getting out. (Another greenhouse effect)

We used to teach about this issue in University in the 1970’s but the appropriate and competent materials were not available in the UK market place, so we could not engage with it;

In mainland Europe well away from the mild Atlantic weather, in more intensely urbanised settlements, more prevalence for summer overheating will have prompted action, the problem has been understood and they have developed the products to address it for over 30 years.

Today those right materials are in the UK market. The Greens have been bringing these products into the UK for 15-20 years and promoting their use.

However the UK market obsessed with fiduciary rules and making a profit; mainstream construction is not interested in investment, or in climate change, unless regulated or customer driven.

Customers do not understand overheating either, so the problem remains unresolved and the solution remains a green fringe benefit.

Stop the heat getting in and the other proposed solutions by ZCH and NHBC can work more successfully.

There are many other problems and solutions to be addressed.

Overheating in winter is often communal and district heating flow and return pipes inadequately insulated, under-floor heating in confined communal spaces; added to by cavity party walls acting as chimneys moving heat to other parts of buildings.

Passivhaus or EnerPHit designed housing and better specification, commissioning and optimisation of any residual insulated communal services could fix these.

Green Building Encyclopaedia (GBE) has a GBE Issue Paper on Overheating that goes into great detail on all the contributing factors. Its is currently 81 pages, on its 11 update, 235 topics, including:

  • Theory, practice, problems, solutions, case studies;
  • Bigger picture to small detail = top down and bottom up;
  • Heating, hot water, other sources, ventilation, insulation, solar shading, windows, door, rooflights, etc.

Start here to see all the pages so far related to Overheating.

http://greenbuildingencyclopaedia.uk/?p=2613

Straight to the Overheating Paper

http://greenbuildingencyclopaedia.uk/?p=145

 

P          Zero Carbon Hub’s view: Energy Efficiency and Air-Tightness

I have just skimmed through all the ZCH publications about overheating and have not found any evidence that they know the big problem let alone the big answer.

They have lots of clues about the obvious and smaller problems, but not the big one.

If their ambitions for Energy Experts are carried out with conventional know-how we will race faster into oblivion.

 

Quoting from: Overheating in Homes Drivers for Change

“In recent decades there has been a strong drive towards reducing heat loss in homes and winter heating costs by incorporating energy efficiency measures.

As a result, new-build dwellings are highly insulated and airtight and lose much less energy through the building fabric.

Millions of existing buildings have also been retrofitted with insulation and other energy efficiency measures.

Such measures are extremely beneficial in winter – helping to keep homes warm and to save energy – but could have unforeseen and unintended consequences in summer if not managed.

For example, insulation keeps homes warm in winter and helps keep them cooler in summer, but effects such as solar gain can cause an increase in internal temperatures which are potentially difficult to dissipate”.

 

GBE Comment:

“Unforeseen and unintended consequences”:

Solar heating through opaque fabric has been understood since the 1970s and taught at university and long forgotten by many, but not understood by Building Regulations and compliance design tools.

Unintended or not the Regulations focussed on conductivity and ignoring solar radiation resistance are causing overheating.

“If not managed”:

You cannot manage solar heat gains through opaque fabric very easily they are of such magnitude; opening windows, ventilation or shading at windows will not manage it.

“insulation…helps keep them cooler in summer”:

Wrong, the vast majority of insulation used in UK pitched or flat roofs will not help keep buildings cooler in summer.

They are the wrong materials with the wrong properties.

They will let the solar radiant heat in and prevent that heat getting out by conduction.

They are more likely to keep them hotter in summer.

“effects such as solar gains”:

Assuming they are referring to solar gains through glazed parts.

“Potentially difficult to dissipate”:

Ventilation will help remove ‘glazed part solar heat gains’ relatively easily, but added to ‘opaque part solar heat gains’ there is a lot less hope of success with ventilation until after the sun has set.

 

P          SOM Architect’s Post Occupancy Evaluation (POE) survey report

World FM reported on SOM Architect’s Post Occupancy Evaluation (POE) survey report, May 2015, including a recent survey of building occupants in many building use types.

The striking issue was that whilst almost all issues scored fairly well:

  • Thermal comfort was consistently the worst scoring topic of all,
  • With very low satisfaction rates.

See Also:

SOM Post Occupancy Evaluation (POE) survey report, May 2015

 

 

1.    OVERHEATING OF EXISTING BUILDINGS

 

Back to basics: Leap frog this at your peril.

You probably think you know what follows and you could leap frog it.
But beware there are quite a few bits you probably don’t know or haven’t joined up before.
They are essential to understand the later bits.

 

P          Understand the context first:

Before we talk about the after effects of energy saving retrofit measure let’s look at buildings in their raw state.
Overheating in summer:

  • Buildings that are potentially vulnerable:
    • Most houses, bungalows and chalets built in the UK have hot attic spaces, rooms in roofs or upper floor bedrooms
    • Top floor flats
    • Southerly single aspect flats or houses with limited scope for ventilation and escape from sun
    • Recently built homes
  • Other problems include communal stairs/lift cores and corridors serving flats, apartments and maisonettes.
    • Glazed walls to stairs lead to overheating from the sun, feeding heat to communal corridors, to flats.
  • Conservatories, porches and sunspaces

Passive ventilated offices connecting onto atrium that should help cool them but fail
Overheat in winter:

  • Communal heating plant rooms within blocks of flats inadequately insulated and heating flats around them
  • Communal areas of blocks of flats distributing inadequately insulated district or communal heating pipes.
  • Under-floor or other heating in communal corridors of blocks of flats that do not need heating.

Overheating all year round (including sunny days in winter)

  • Chilled storage warehouses with the wrong insulation: chillers work harder on sunny days.
  • Any retail shed construction building with the wrong insulation.
  • Industrial processes releasing heat and insufficient ventilation to remove it, reclaim it and reuse it.
  • Data centres releasing heat and insufficient ventilation to remove it, reclaim it and reuse it.
  • All offices under large span lightweight timber or steel framed lightweight roofs with the wrong insulation.
  • All buildings under large span lightweight timber or steel framed lightweight roofs with the wrong insulation.
  • Illegal growing of plants for recreational drugs in buildings using 24 hour artificial lighting for rapid plant growth generating excess heat (probably desirable in this case)

So it’s worth understanding what that is all about before we start thinking about the after effects of adding insulation.

 

P          Heat sources:

Sun light, Sun-lit building, Sunspaces, Sun-lit surroundings, People/Pets, Services for Living, Consequences

 

I           Quality of light:

Northern hemisphere

Daytime:

Daylight:

North light:

  • Cool, white or blue, non-directional

Overcast sky:

  • Grey or white, non-directional to faintly directional

Sunlight:

  • East light: warming, red, white or blue, directional, panning and rising
    • More in summer, less in winter
    • Cooler air temperatures
  • South light: hot, yellow, white or blue, directional, panning and peaking
    • Higher in summer, lower in winter
    • Warm air temperatures
  • West light: hot, red, white or blue, directional, panning and setting
    • More in summer, less in winter
    • Warmest air temperatures

Moonlight:

  • Inconsequential,

Night-time:

Moonlight:

  • Waxing and waning over month cycle from full moon to no moon to full moon

Cloudy or overcast sky:

  • Sodium street light orange (progressively whiter and darker), non-directional;

Clear sky:

  • Clear and white-blue, directional, panning and peaking,

 

I           Combined effects of Sun and Moon

Sun’s Solar Heat: drives the wind, its direction, heating or cooling effect of land and ocean masses and weather

Moon: drives the tides and the potential for cooling effect of ocean breezes

Sun and moon: dictate the normal and peak tides

 

I           Orientation:

There are at least three aspects to orientation:

 

I/P/S   Solar orientation of buildings:

‘All buildings face the sun’.

At some point during the day most buildings face the sun.

This is true of detached buildings but this is not always true of:

  • Back-to-back terraces where pairs of houses face opposite directions,
    • Somewhere between north-south and east-west.
    • South facing cannot escape from the sun
    • May have limited scope for ventilation cooling
  • 4 houses on each corner of a single block,
    • Each corner gets light from two directions but potentially from 270 degrees,
    • A southerly corner gets solar light/heat all day
    • A northerly corner may get summer morning sunrise and summer evening sunset and none during the rest of the day.
  • Skyscraper (Tower blocks) or ground scrapers (slab blocks) of flats with flats on only one side or another.
    • South facing cannot escape from the sun
    • May have limited scope for ventilation cooling
    • Like riverside, dockside, seaside towers many more flats are now designed to get a view of the water
      • Moving riser, stair, lifts, rubbish chutes and services cores towards the land
      • Planning the flats leading away from the core, facing the water
      • And 100% glazed to exploit the views at all times
    • Now towers are being designed so all flats get a southerly aspect, south-east to south-west
      • Moving riser, stair, lifts, rubbish chutes and services cores towards the north
      • Planning the flats leading away from the cores facing south-east, south or south-west
      • And 100% glazed to exploit the views at all times
      • Inevitably overheating and reliant upon being cooled by ventilation or worse air-conditioning

In some of these cases some properties will not see the sun ever and others will not escape it.

Exposed opaque (solid) parts either permit or prevent solar light/heat gains depending upon their materials and methods of construction.

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: Sustaining Towers

GBE CPD: Integer Tower Refurbishment

GBE CPD: Survey Test Analysis

GBE CPD: Refurbishment: Survey Test Analysis

GBE CPD: Zero Carbon Buildings

GBE Case Study: Architectural Competition: Isle of Dogs Mudchute site, Competition Brief Failure

 

P/S      Solar orientation of the windows, roof lights and glazed doors:

We are encouraged to:

  • Maximise the number and size of windows, roof lights and glazed doors on the south and south-west elevations of houses to maximise solar gain and
  • Minimise the number and size of windows on the north elevation of houses to minimise heat loss.

Exposed transparent (glazed) parts permit daylight and solar light/heat gains when they face in the right direction(s).

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: L10 Windows

GBE Products: L10 Windows, Rooflights, Roof windows, L20 Glazed Doors

GBE Robust Specification

By others:

Passivhaus Webinar: Passive House Windows for Mediterranean Climates ‪https://youtu.be/YHg4Pt1M5Tw  via ‪@YouTube via twitter @JMenendez

 

P/S      Solar orientation of the pitched roofs:

Depending upon the geometry of roofs, orientation of predominant ridges and larger slopes is important.

Roof plains include dormers, roof lights, roof windows and can also include solar panels.

Their orientation will determine the quality and amount of light entering the upper floor or attic through glazed parts.

Exposed opaque pitched roofs either permit or prevent solar light/heat gains depending upon their materials and methods.

Exposed transparent parts permit daylight, sunlight and solar light/heat gains depending upon the direction they face.

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: Pitched Roofs

 

P/S      Pitched roofs and solar reflection/absorption:

Pitched roofs are normally and most often mid to dark tone absorbing the sun and its heat, contributing to overheating of the attic space, room in roof, bedrooms or top floor flat below.

Pitched roofs tile and slates are:

  • Red (clay mid tone);
  • Many colours white, colours and black from manufacturers swatch (terracotta or glazed clay),
  • Green, blue, purple, grey, black (slate, mid tone to dark),
  • Yellow-brown (stone slate, pale to mid tone),
  • Black (recycled rubber tile mid tone to dark),
  • Black (fibre-cement dark reducing to grey),
  • Pale grey (old asbestos-cement),
  • Mid to dark tone, greys and colours (concrete),
  • Any colour from manufacturers swatch (thin metal profiled multi-tiles),

Thatch roof will start lighter yellow and end up mid tone grey and offers some solar radiation resistant thermal insulation.

Exceptionally roof tiles were glazed reflecting some of the sun’s heat and re-radiate the rest inwards.

Malleable metal claddings include:

  • Copper (dark brown turning to mid-pale green patina)
  • Copper (pre-patinated green-blue)
  • Lead with patination oil (grey lightening slightly)
  • Zinc (grey lightening slightly, or pre-patinated mid-pale grey)
  • Stainless steel (silver) (Highly reflective – potential glare, migraine or accidents)
  • Terne coated stainless steel (mid-tone grey)

Exceptionally: (highly reflective; potential glare, migraine or accidents)

  • Stainless steel oxidation layer (colour from manufacturers swatch)
  • ‘Gehry Tourist Attraction’ Platinum (silver or silver and colour)
  • ‘RVA Golden Banana’ Gilding metal? (gold)

Coated profiled metal cladding can be any colour you like from the manufacturers swatch:

  • But in the UK we more often choose:
    • Mid to pale tone grey or
    • Manufacturer’s logo colours.

Coated flat metal cladding can be any colour you like from the manufacturer’s swatch

  • But in the UK we more often choose:
    • RAL 9010 White (reflective and light coloured adding to albedo effect)
    • RAL 9006 Gatwick Grey (mid tone with or without reflective metallic grains)

Choosing white, lighter colours, lighter tone and low saturation colours potentially:

  • Improve albedo effect
  • Reflects more solar light/heat
  • Reduce heat gains

See Also:

GBE Lectures: Elements: (27.2) Pitched Roofs

Case Study: Self cooling roof: http://www.fastcoexist.com/3047090/with-this-self-cooling-roof-you-might-not-need-a-c?utmcontent=buffer8bbb4&utmmedium=social&utmsource=twitter.com&utmcampaign=buffer

GBE Checklist

GBE Jargon Buster

GBE Products:

  • H60-H69 Roof tiles, Roof slates,
  • H31 & H70-79 Metal roof claddings

GBE Robust Specification

 

P          Glass roof tiles

Twitter had a tweet about glass roof tiles available from Sweden asking “What would you do with all that free heat?”

  • The obvious answer is overheat.
  • So in the minds of ZCH the roof is now all glazing and so the roof will overheat as well as the rooms below.
  • But your roof was overheating already, despite the opaque tiles and slates.
  • Now you get the sunlight as well as the solar heat.

You need expensive kit to exploit it, capture it, store it, move it, use it.

  • And because the sun is most effective in the summer you need to store lots of the heat until winter.
  • And you attic will still overheat and the top floor rooms will too.
  • Could you add PV and ST or PVT panels at the ceiling?
  • Yes but all the roof timbers would be blocking the sunlight.
  • Better on top of the tiles or integrated in place of the tiles then.

A few years back at a TGR event a ST panel inventor presented a glass slate replacement

  • With ST panel paraphernalia below it,
  • Not sealed in but with a draughty space below,
  • All connected up serially,
  • It appeared to be a very ineffective proposal
  • He showed it covering whole roofs, but with a ragged margin at hips and valleys.

And what about the embodied energy and carbon of making glass tiles or slate replacements?

  • Bad news indeed.

Historically a glass or transparent roof tile would replace a tile or two

  • Allow beneficial daylight and sunlight into the attic.
  • Historically we would not have used roofing underlay, today we do,
  • So the view would be of battens and breather or wind tightness membranes covered in logos or fixing instructions not a pretty sight.
  • This tweet showed the whole roof glazed
  • I can’t see battens, no underlays and no structure.

So what would you do with all that glass roof tiling and no underlays?

  • With all that air passing through, the heat build up will be minimised
  • Show off your roof structure, cold water and heating top up tanks and insulation not pretty.
  • Show off your attic stored possessions, another not pretty site.
  • It’s a bit like leaving your company laptop with customer details database on the front seat of your car whilst shopping.
  • Invite roof entry burglars who could now enter your roof unhindered by membranes, break a few battens and their in.
  • Next your house, that’s if the hatch is not hooked or locked down, and if you’re attic is well insulated with conduction thermal insulation, probably entering via the plasterboard ceiling by accident.
  • Moonlight and streetlight through the glass tiles would make riffling through your possessions easy.
  • I remember reading about an epidemic of roof entry burglaries, probably not in the UK though.
  • At least burglars won’t be tempted to hide out long term in your roof space, they will get hot, tanned and shrivelled
  • But most likely they will be seen.
  • And what of your possessions (family heirlooms, photos, camping gear) won’t they just fade and degrade?

So it’s just another stupid idea then.

  • Now it’s been on twitter I wonder how many people will want to have them?
  • Twits!

I realise that the manufacturer has gone to great lengths to produce the tiles and want to sell a few

  • They probably have been making and selling them forever for those scattered roof lights I mentioned earlier.
  • But to their credit I can think of one or two applications.
  • Outdoor canopies to keep the rain off and let the sun through
    • so you can sun bathe in the rain, if you like stripy sun tans.
  • Conservatories, porches and entrance canopies:
    • if you won’t mind the sight of all the timbers and no membranes below
    • and a little wind blow rain getting through or around.
  • Sunspaces and greenhouses
    • But because they would be air leaky they may not be very effective for heat capture

What do they say any news coverage, good or bad, is good marketing.

 

P          Lightweight pitched roofs

Most pitched and mansard roofs will be made of:

  • Lightweight timber framed construction with lightweight insulation and lightweight linings
  • Lightweight metal framed construction with lightweight insulation and lightweight linings
  • The solar radiation heat will pass through lightweight roof, and ceilings with ease
  • Conductivity thermal insulation offers low protection from solar radiation heat
  • They offer no solar radiation resistant thermal insulation, only conductivity thermal insulation
  • The roof space reaches extremely high temperatures and the conductivity insulation tries to stop it passing into the floor below but is overwhelmed by the high temperatures
  • The heat that has transferred from the roof to the floors below can no longer escape because conductivity thermal insulation prevents it escaping.
  • And hotter attics offer no route out

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • G10, G20, Roof framing,
  • P10 Radiation resistant thermal insulation,
  • K10, K11, K13 Linings

GBE Robust Specification

 

P/S      Lightweight insulation in lightweight timber pitched roofs and lightweight pitched lining

It is commonplace (seen most times on Grand Design) for timber framed pitched roofs with sloping ceilings to be insulated with foamed plastic insulation for its thinness and high thermal conductivity insulation performance.

Foamed plastics:

  • Offer plenty of conductivity thermal performance but low solar radiation resistant thermal performance.
  • Are not ideal for pitched roof thermal insulation, they will let the heat in but won’t let it back out again.
  • Potentially drive any moisture entering construction via defective Vapour Barriers, through the structural timbers

Mineral wool:

  • Offers conductivity thermal performance but low solar radiation resistant thermal performance.
  • Are not ideal for pitched roof thermal insulation, they will let the heat in but won’t let it back out again.
  • Potentially drive any moisture entering construction via defective Vapour Barriers, into contact with structural timbers

Cellular glass:

  • Offer conductivity thermal performance and solar radiation resistant thermal performance.
  • Are ideal for pitched roof thermal insulation, they won’t let the heat in and won’t let it out.
  • Potentially drive any moisture entering construction via defective Vapour Barriers, through the structural timbers

Plant based fibre or flake:

  • Offer conductivity thermal performance and solar radiation resistant thermal performance.
  • Are ideal for pitched roof thermal insulation, they won’t let the heat in and won’t let it out.
  • Potentially absorbing any moisture entering construction via breathing moisture permeable airtightness layers, into the insulation fibres away from timbers and releases it when conditions are right.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • P10 Radiation resistant thermal insulation,
  • P14 breathing moisture permeable airtightness layer

GBE Robust Specification

 

P/S      New Build Pitched Roof Heel Trussed Rafters

At the eaves edges of pitched roofs the roof timber framing tapers to a triangle with say 100 mm vertical end at the supporting wall outer edge.

With UK Building Regulations requiring 200-300 mm of insulation it means the ceiling level conductivity thermal insulation will taper and reduce in thickness at the eaves edges of roofs.

Roof usually also need a 50 mm ventilation gap between eaves and attic, this may be achieved with an airtight wood based panel maintaining the air gap, so the insulation will be reduced further.

The result is a risk of greater heat loss through the ceiling, along the eaves at the most vulnerable position.

With bathrooms and bedrooms often at the external wall, this runs the risk of condensation and mould.

The solution is for new build pitched roof trusses to be designed with a ‘heel’ or vertical at the eaves, the height of the heel should correspond to the thickness of the conductivity thermal insulation on the ceiling.

If the roof is only insulated with conductivity thermal insulation then the upper floor rooms will overheat.

So the heel height should correspond to the thickness of solar radiation resistant and conductivity thermal insulation.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • G20 Heel Trussed Rafters,

GBE Robust Specification

 

S          Heavyweight pitched roofs

Far fewer pitched roofs are constructed with heavyweight construction

  • The British Library was made with:
    • Dense concrete frame supporting precast lightweight concrete panels stitched together with insitu dense concrete infill
    • On top of that 100 mm autoclaved aerated concrete blockwork was laid on its face on the sloping concrete roof
    • Followed by slate roofing.
  • This provides:
    • Heavy acoustic construction
    • Conductivity thermal insulation
    • Solar radiation resistant thermal insulation
    • Fire protection
    • Long life expectancy and durability to suit the 120-year design life.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • F10 Blockwork,
  • H62 Slate roofing

GBE Robust Specification

 

P          Lightweight New Upper Floor extension on Existing Roof

Developers regularly want to maximise profits on developments and so refurbishments of commercial or industrial buildings to residential or commercial will usually require extra floors added to the roof of the building.

T&C Planners will want the extra floors set back so as not to change the character and appearance of the existing buildings.

Setting it back will complicate the structural support and encourage the designers to introduce lightweight framing, lightweight insulation and lightweight claddings.

The top floors are often sold as the penthouse and sold for the highest prices, but will suffer the greatest overheating and probably get air conditioning fitted.

 

P          Lightweight Upper Floor Roof: New Build: Inland Revenue Nottingham

The Architects made the decision that they wanted a heavyweight brick plinth with heavy solar shading and a set back lightweight glazed and metal roof on aesthetic grounds.

The result is relatively sombre dark lower floors and bright and airy top floor.

The top floor also overheats.

 

S          New slogan

Just like ‘Build Tight, Ventilate Right’ a slogan that engages with building air-tight and purposeful ventilation.

The issues of overheating of lightweight construction could do with a slogan too.

Explanation: If you BUILD it LIGHT weight you must INSULATE it RIGHT to keep it SOLAR-TIGHT

Initially: BUILD LIGHT, INSULATE RIGHT, SOLAR TIGHT

Ultimately: BUILD LIGHT, SOLAR TIGHT

BrianSpecMan aka Brian Murphy 11th August 2015

See also:

GBE Jargon Buster: Build Light, Solar Tight

 

P/S      Shallow roofs and solar reflection/absorption:

Shallow roofs are normally and most often mid to dark tone absorbing the sun and its heat, contributing to overheating of the attic space, room in roof, bedrooms or top floor flat below.

Malleable metal roofing include:

  • Copper (dark brown turning to mid-pale green patina)
  • Copper (pre-patinated green-blue)
  • Lead with patination oil (grey lightening slightly)
  • Zinc (grey lightening slightly, or pre-patinated mid-pale grey)
  • Stainless steel (silver) (Highly reflective – potential glare)
  • Terne coated stainless steel (mid-tone grey)

Coated profiled metal roof cladding can be any colour you like from the manufacturers swatch:

  • But in the UK we more often choose:
    • Mid to pale tone grey or

Choosing white, lighter colours, lighter tone and low saturation colours potentially:

  • Improve albedo effect
  • Reflects more solar light/heat
  • Reduce heat gains

See Also:

GBE Lectures: Elements: (27.1) Flat Roofs

GBE CPD: Materials

 

P/S      Solar orientation and flat roofs:

With flat roofs there is a surface area for solar light/heat gain.

High parapets can offer some shading to the roof area,

In winter the sun will be at an acute (shallow) angle and parapets provide more shading.

In summer the sun will be at an obtuse (steep) angle and parapets provide less shading.

Flat roof plains can include roof lights, plant (mechanical and electrical equipment).

These roof plains can also include solar panels.

Exposed opaque flat roofs either permit or prevent solar light/heat gains depending upon their materials and methods.

Exposed transparent parts of flat roofs permit solar light/heat gains to the interior.

GBE Lectures: Elements: (27.1) Flat roofs

 

S          Flat roofs and solar reflection/absorption:

Flat roofs have traditionally been light coloured to reflect the sun and its heat, contributing to the albedo effect.

The light colouring of flat roofs was made with solar reflective white aggregate chippings on built up roofing.

More recently these have been replaced with lower cost or available solutions:

  • Solar reflective paints (short life needing regular recoating)
  • Light coloured paving slabs (will darken with dust from atmosphere unless washed away by rain)
  • Light coloured top membranes in single layer roofs
  • Loose gravel (not often light coloured, but mid tone and mixed colours)

If the covering is thin or uninsulated then the heat will pass through the covering and into the supporting structure.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Q24 & Q25 Solar reflective paving

GBE Robust Specification

GBE Lectures: Elements: (27.1) Flat roofs

 

P          Old flat roofs with asphalt roof waterproofing:

Some of our earliest flat roofs are waterproofed with asphalt

It was often laid with no solar protection,

  • Just itself with a light dusting of sand rubbed into the surface
  • And sometimes with a dimple texture.

But old buildings (pre 1960s) with asphalt roofs probably have little or no thermal insulation below.

Asphalt roofs may be laid on concrete roofs or timber framed roofs.

Asphalt can cope with being hot and will absorb a considerable amount to heat, once it reaches saturation point then the heat passes through to the roof below.

If it is concrete the roof will absorb the heat, if it is timber the heat will pass through to the space below.

Rooms below these roofs will be hot during the day but the hot asphalt will take time to cool off and keep the building warn late into the evening.

If the heat has not dissipated by morning then the rooms below will remain hot and get hotter.

See Also:

GBE Checklist

GBE Jargon Buster

GBE: Lectures: Flat roofs

 

S          Flooded flat roofs

The Victorian occasionally used flooded flat roofs to keep the space below, cool; the water has the ability to absorb the heat of the sun and by evaporation from the top surface, keeping the water cool and the building cool.

The Victorian steam railways used cast iron segmental water tanks on the roof of the water towers to recharge steam engine’s fuel and water tender, they had the benefit of cooling the space below.

The Austrian Architect Walter Segal who championed self-build construction in the UK invented the Waster Segal Method when designing a building for temporarily decanting his family whilst their house was refurbished.

It used a lightweight timber framed construction with flat roof which had 150 mm. high upstands and no overflows.

The roof could be transformed from lightweight to heavyweight by flooding it with water.

This flooded roof offers:

  • middle term thermal mass from below,
  • solar protection from above
  • resistance to wind negative pressure uplift from above.

The water reservoir needs to be topped up by garden hose on hot or warm windy evaporative days.

See Also:

GBE Checklist

GBE Jargon Buster

GBE: Lectures: Flat roofs

GBE: Link: Walter Segal Self-build Trust

 

S          Reminder “Build Light, Insulate Right, Solar Tight” BrianSpecMan 2015

 

P          New flat roofs with asphalt roof waterproofing

The New British Library on Euston Road, London has asphalt roofing laid on dense concrete secondary slabs laid to 1:40 falls on sleeper walls with cellular glass solar radiation resistant thermal insulation laid in a hot bitumen flood coat, directly on top of the concrete slab.

If the asphalt were applied directly on the concrete, the heat would be soaked up into the concrete, allowing the asphalt to cool quickly and set to harden.

Cellular glass acts as both solar radiation resistant thermal insulation and conductivity thermal insulation.

When asphalt is applied over cellular glass the heat from the asphalt tries to transfer into the insulation.

The heat only enters the surface of the insulation and does not penetrate further, holding the heat in the asphalt preventing it from cooling and keeping it liquid.

Hot liquid asphalt on a 1:40 fall runs down the slope and has to be pushed back up hill, often until it cools to the air and starts to set to harden.

See Also:

GBE Checklist

GBE Jargon Buster

GBE: Lectures: Flat roofs

 

S          Albedo effect:

Albedo is the earth’s brightness or tone (lightness-darkness) as seen by the sun.

Snow/ice capped polar-regions are light, sea is dark, land is light to dark; the overall effect was an albedo of 0.39.

Snow and ice capping to solar regions fluctuates seasonally at opposite poles and the albedo fluctuates with it.

Glaciers shrink permanently and have an affect on the Earth’s albedo.

See Also:

GBE Checklist

GBE Jargon Buster

GBE: Lectures: Flat roofs

GBE CPD: JQ37 Living Roof Specification

 

S/P      Pitched roofs and renewable energy:

What are important are pitched roofs that accommodate renewable energy solar panels on the right slopes.

The panes may be between dormers and chimneys, ideally without being overshadowed by them.

Solar panels include:

  • Solar thermal (ST) for heat
  • Photovoltaic (PV) for electricity
  • Photo Voltaic and Thermal (PVT) for electricity and heat (combine heat and power (CHP) of a different kind)

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (27.2) Pitched Roofs

GBE Products:

  • T15 ST,
  • V10 PV
  • T15 & V10 PVT

GBE Robust Specifications

 

P/S      Flat roofs and renewable energy:

Flat roofs do not provide slopes for integrated panels.

However panels can be fixed on frames to set them at optimum angles to see the sun.

Panels on frames will create shading below the panels

Flat roofs with parapets can create shading nearest to the parapets.

Winter sun angles should be used to determine the distance for placing panels away from the parapet.

Even a panel laid flat on a flat roof will produce renewable energy, but less than the optimum.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (27.1) Flat Roofs

GBE Products: Support systems for T15 ST, V10 PV, and T15 & V10 PVT

GBE Robust Specifications

GBE Lectures: Elements: (27.1) Flat roofs

 

S          Heavyweight flat roofs:

Warm or cold flat roofs place thermal insulation below the waterproof membrane within the roof construction:

  • Concrete deck roofs will have insulation:
    • Below the deck or
    • Above the deck below the membrane.

Concrete flat roof decks offer decrement delay.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (27.1) Flat roofs

 

P          Lightweight flat roofs:

Warm or cold flat roofs place thermal insulation below the waterproof membrane within the roof construction:

  • Timber framed flat roofs may be within the joist zone.
  • Above the top deck below waterproofing

Thermal insulation in timber or metal framed flat roofs needs to offer decrement delay.

Flat roofs should therefore use solar radiation resistant thermal insulation.

The combination of the following will suffer from over heating of rooms below:

  • Timber or metal frame
  • Conduction thermal insulation without solar radiation resistant thermal insulation
  • Normal (not inverted) flat roof.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • G20 Timber frame,
  • G13 Metal frame,
  • P10 Solar radiation resistant thermal Insulation

GBE Robust Specifications

GBE Lectures: Elements: (27.1) Flat roofs

 

S          Heavyweight Inverted roofs:

Inverted roofs place the thermal insulation above the waterproof membrane and below ballast (paving slabs or gravel)

Thermal insulation in inverted roofs need to remain dry whilst immersed in rainwater, so needs to be hydrophobic and frost resistant.

Membranes are now available to try to keep the water off the inverted conductivity thermal insulation.

Expanded or extruded polystyrene are often used in inverted roofs because they are hydrophobic.

Expanded or extruded polystyrene are conductivity thermal insulation, which do not offer solar radiation resistant thermal insulation and decrement delay.

Concrete flat roofs offer solar radiation protection and decrement delay and are not likely to cause overheating below.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (27.1) Flat roofs

 

R          Research needed?

Why have manufacturers started making water barrier membranes to apply over the inverted roof insulation?

Infrared thermography surveys of flat inverted roofs to check to see how well inverted roofs are performing.

 

P          Lightweight Inverted roofs:

Inverted roofs place the thermal insulation above the waterproof membrane and below ballast (paving slabs or gravel)

Thermal insulation in inverted roofs need to remain dry whilst immersed in rainwater, so needs to be hydrophobic.

Expanded or extruded polystyrene are most often used in inverted roofs.

Expanded or extruded polystyrene are conductivity thermal insulation, which do not offer solar radiation resistant thermal insulation properties not enabling decrement delay.

Timber-framed or metal-framed flat roofs without further thermal insulation do not offer decrement delay themselves.

The combination of timber-framed or metal-framed flat roofs and inverted flat roofing will suffer from overheating of rooms below.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (27.1) Flat roofs

 

S          Slogan

Just like ‘Build Tight, Ventilate Right’ a slogan that engages with building air-tight and purposeful ventilation.

The issues of overheating of lightweight construction could do with a slogan too.

Explanation: If you BUILD it LIGHT weight you must INSULATE it RIGHT to keep it SOLAR-TIGHT

Initially: BUILD LIGHT, INSULATE RIGHT, SOLAR TIGHT

Ultimately: BUILD LIGHT, SOLAR TIGHT

BrianSpecMan aka Brian Murphy 11th August 2015

 

P/S      Living roofs

Living roofs include intensive, green roofs or extensive, brown roofs.

Living roofs are usually flat but systems are available for shallow and pitched roofs

Living roofs can provide solar protection due to thermal mass:

  • More protection with thicker build-ups (E.g. Intensive roof, grass, planting, bushes and trees)
  • Some protection with middling build ups (E.g. planted modular tray)
  • Less protection with thinner build-ups (E.g. Sedum mats and rolls).

Living roofs can provide evaporative cooling of water from soil or gravels and from some plant leaves.

Living roofs do not normally provide added thermal insulation (other than in the water reservoir layer); that is provided by the conduction thermal insulation needed by the underlying roof.

New methods of creating living roofs are being researched.

Living roofs can also provide solar shading.

  • Using large leafed, tall plants and dense planting

Living roofs can also provide solar reflection to add to the albedo effect.

  • Using light coloured paving
  • Using light coloured gravels and mulches
  • Using light coloured planting: grey leaves and white flowers

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: JQ37 Living Roof Specification

GBE Lectures: Elements: (27.1) Flat roofs

GBE Lectures: Elements: (27.2) Pitched Roofs

Research underway:

New methods of creating living roofs are being researched now that may provide insulation within the build-up using hygroscopic plant materials benefiting from evaporative cooling.

 

P/S      Living roofs and renewable energy:

Living roofs and solar panels are often good bedfellow, mutually supportive.

Solar panels are often mounted on frames setting them at an optimal angle; this allows the panels to have cooler undersides, helping with PV efficiency.

This arrangement creates shaded spaces behind and below the panels, with varying levels of light leakage at the edges and full sun in front of the panels.

Plants grown from seeds dropped with bird poo as fertiliser inhabit brown roofs.

Brown roof plants inhabit spaces behind, between and below panels.

Brown roof plants providing some shade, cooling effect and evaporative cooling to panels.

As long as plants do not overshadow panels they are complimentary.

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: JQ37 Living Roof Specification

 

S          Panel orientation and pitch:

Panels should ideally all face south but south +or- 30 degrees is okay.

South-westerly is preferred south-easterly since the day warms the longer the sun has been around.

Ideally roof needs to have pitched roof orientation to match.

The roof’s pitch, i.e. angle of roof slope above horizontal, is important, ideally orthogonal (right angle) to the angle of the sun.

Since the angle of the sun varies all year and all day roof pitch is less important.

Even a panel laid flat on a roof will have generate renewable energy, but less than the optimum.

Panel spacing becomes important in solar farms one row must not overshadow the next row in winter.

Solar farms can be ground or roof based.

Tables exist showing percentage of output for different orientation and pitch, compared to optimum

 

S          Solar Thermal (ST) panels:

If ST panels are for domestic hot water they need to face the sun all year but are likely to be most effective during summer and less so in winter.

Domestic hot water used at hand wash bowls, sinks and dual supply washing machines is used in non-domestic buildings too.

If ST panels are for space heating they need to face the sun in winter at lower sun angles so they should be placed more vertical.

It’s suggested these be attached to walls not roofs, and are suitable on the lower, steeper slope of mansard roofs.

Some argue there is insufficient heat in winter, but they can contribute beneficial heat as part of a pre-heat strategy.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: T15 ST Solar Thermal panels

GBE Robust Specification

 

P/S      Building Integrated Renewable Energy (BIRE):

BIRE is argued to be most appropriate, meaning solar panels are incorporated in building construction replacing roof coverings not sitting above them on support frames.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: T15 ST, V10 PV, and T15 & V10 PVT.

GBE Robust Specification

 

S          Building Integrated Solar Thermal (BIST):

ST panels are likely to be enclosures with heat absorbing panels laying on thermal insulation in a sealed enclosure. ST panels glass should minimises external reflection, maximises sunlight entry, maximises internal reflection, to minimise heat egress, maximising performance.

The right insulation needs to be adopted then conducted and radiated heat from the hot panels should not pass through the bottom of the enclosure.

If the heat stays in the panel it won’t enter attics, rooms in roof or bedrooms below to add to overheating.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: T15 ST,

GBE Robust Specification

 

P/S      Building Integrated Photovoltaic (BIPV):

PVs are known to diminish performance when hot; they rely upon ventilation below the panel to keep them cooler.

BIPV panels are likely to be a simple panel replacing the roof tiling fixed over the battens and roofing felt.

This results in a tight ventilation labyrinth below the panel within the batten zone and above roofing felt.

Once PV panels are solar heated they will reradiate from their underside through roofing felt or BRM to heat up spaces below.

In order to overcome this heat build up, a number of options exist:

  • Include sufficient solar radiation resistant thermal insulation below the BIPV reducing heat transfer and uptake in the attic
  • Introduce better passive ventilation above the insulation to keep the underside of the panel cooler.
  • Draw the heat out of the labyrinth into a heat recovery system to:
    • Pre-warm under floor heating
    • Pre-warm solar hot water
    • Contribute to mid term thermal storage vessels

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: V10 PV

GBE Robust Specification

 

S          Building Integrated Photovoltaic Thermal (BIPVT):

PVs are known to diminish performance when hot; they rely upon ventilation below the panel to keep them cooler.

BIPVT panels incorporate ST panels below PV panels.

Once PV panels are solar light/heated they will reradiate from the underside into the ST panels to heat it up.

The ST panel will take the heat away to:

  • Heat domestic hot water (limited scope)
  • Inter-seasonal or daily thermal storage (improved scope)
  • Used in heated swimming pools
  • Be dumped, risking thermal pollution

All of this will potentially offer some overheating protection to the space below the roof.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: T15 & V10 PVT

GBE Robust Specification

 

S          Solar access:

If the building, roofs, glazing and panels all face in the right direction to capture solar light/heat this helps to enable solar light/heat gains.

However the presence of land, buildings, trees or tall bushes, if they are high enough into the sun’s path, can block the sun’s rays.

If they are coniferous they are likely to block the sun’s rays in the summer and winter.

However if they are deciduous they shade buildings in summer, their leaves will fall in autumn, allowing ray’s to reach their targets in winter.

Sunlight passing through a tree canopy between breeze-driven fluttering leaves will fall as dappled light, which is regarded as delightful.

Dappled light reduces the amount of solar light/heat gain but can still cause intermittent glare.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Service Providers: Solar Access surveys

 

P          Solar light/heat gains:

Sun’s rays beam down onto buildings hitting roofs, rooflights, roof windows, walls, windows and doors (glazed or not).

The heat of the sun lands on the outer surfaces of the opaque parts of the building or passes through the glazed parts falling on floors and walls of interiors beyond the glass.

What happens next depends upon their method of construction and materials at their external and internals surfaces.

 

I           Cold Roof & Warm Roof

These descriptions often confuse the general public, and it is worth a moment of our time.

I have see “Why would you use a cold roof, why not insulate?” in online forum.

Its not about insulation or not, its about where the insulation is positioned.

A cold, pitched roof will have the insulation at the horizontal ceiling.

Cross ventilation of the roof void will occur above the insulation in the attic space.

In winter with house heating on roof timbers and the attic space are therefore cold whilst the rooms below are warm.

A better description might be a Winter Cold Roof.

A warm, pitched roof will have the insulation at the sloping rafters.

The cross ventilation must occur above this insulation within the batten zone of the covering.

There would be no need for insulation at the ceiling level.

In winter with house heating on the roof timbers, the attic space and the rooms below are therefore warm.

A better description might be a Winter Warm Roof.

 

P/S      Summer Hot Roof & Summer Cool Roof

I just (04/08/2015) read in an eNewsletter from a fastener manufacturer:

“Traditional cold roof constructions are giving way to their opposite – the warm roof. This method of construction delivers a host of extra benefits and is now commonly believed to be the single best roofing option for the changeable climate of the UK.”

On the face of it that sounds possible, but UK mainstream construction does not understand the different properties of thermal insulation materials, i.e. Conductivity thermal insulation v solar radiation resistant thermal insulation.

So that statement can be wrong if you choose the wrong insulation types.

I just (04/08/2015) read in an eNewsletter from the same fastener manufacturer:

“In a recent article we revealed the many benefits of warm roof constructions and some of the many factors that need to be considered during the complex and delicate process of design and specification.

features and benefits of these superior Warm Roof Batten Fixings include:

  • Versatility – A patented alignment jig ensures perfect nailing through a wide range of insulation thicknesses supplied by popular brands including: [I replaced the names with their materials: PIR, Phenolic, PUR, XPS], ensuring a secure fix into the centre of the rafter every time”

They too do not understand the difference between Conductivity thermal insulation and solar radiation resistant thermal insulation.

Using any of the products listed, all conductivity thermal insulation, summer hot roof overheating will occur.

Whilst high decrement delay materials, not listed above, in their place, summer cool roof will occur.

“Environmental Awareness – A building installed with warm roofing will use substantially less energy than before, reducing carbon footprint”

I am not sure how they come to this conclusion, but:

  • Warm roof may be better, the same or worse than cold roof depending upon the details and the specification
  • Warm roof insulation can be located in the rafter zone creating a cold bridge through the framing
  • Insulation applied on the outside of the rafters avoids the thermal bridge through the framing,
  • Conductivity Thermal Insulation materials listed above will reduce heating energy consumption compared to some other materials of the same thickness and increase compared to others.
  • Radiation resistant thermal Insulation will reduce the heat gains and increase ventilation or cooling energy consumption compared to conductivity thermal insulation.
  • Non-renewable fossil based plastic insulation increases the carbon footprint
  • Plant based insulation reduces the carbon footprint by carbon sequestration during growth
  • If air-conditioning is used to deal with overheating then the carbon footprint goes up

 

P          100% Glass facades

“100% glazed facades without solar shading is like dating-site sex without protection: lots of it, a lot sexier, but bloody irresponsible” based on quote by Robin Nicholson

100% glazed does mean 100% air-conditioned, air conditioning has very high energy and carbon demands, generates heat waste, needs Voltage Optimisation and Legionella health and safety maintenance regimes in place and costs lots of money to run.

Very High OPEX, very High TOTEX

 

P/S      Over preceding decades office facades have evolved:

  • Solid walls with individual windows in openings with internal shutters
  • Solid walls with individual full height narrow windows in openings
  • Solid opaque spandrel walls with horizontal strip glazing with internal blinds
  • Curtain walling with spandrel panels at floor edges and up to 1100 mm. were opaque and inadequately insulated
  • Curtain walling with opaque panels, without thermal break, later with thermal breaks
  • 100% glazed façade with opaque spandrel panel at floor edge internal blinds
  • 100% glazed façade with opaque spandrel panel at floor edge with solar shading on all elevations
  • 100% glazed façade with opaque spandrel panel at floor edge with east-west blinkers on south elevation
  • 100% glazed façade with opaque spandrel panel at floor edge with external south solar shading
  • Design criteria is evolving as software sophistication enables it.
  • Design standards are emerging for glazing different climate zones for different building types

By others:

Passivhaus Webinar: Passive House Windows for Mediterranean Climates ‪https://youtu.be/YHg4Pt1M5Tw  via ‪@YouTube via twitter @JMenendez

 

P          100 % glazed facades and solar light/heat gains:

Letting Agents have begun to dictate architectural style of commercial offices to let, yet again.

On the basis that it’s easy for them to let 100% glazed facades and those who can, want an easy life.

In reality developers want the best net to gross ratio to charge for the largest rentable floor area; profitable low CAPEX

So developers prefer 25 mm glass instead of 300-500 mm of masonry.

It is allegedly desirable by tenants to have 100% glazed unrestricted views.

And in reality every tenant knows they suffer from:

  • Glare from morning and evening direct sun leading to eye strain/headaches/migraines
  • High contrasts between cast sunlight and shade leading to eye strain
  • Excessive overheating on sunny days all year close to the perimeter glazing
  • Unusable space close to 100% glazed facades
  • Lack of modesty screening below desk height
  • Thermal discomfort from coolth in winter
  • They are in the office to work and earn money not gaze out of the building
  • (But they do need to relax the eyes frequently)

The solutions include:

  • External blinds or solar shading
  • Hit and miss screen printed fritting of glass panes to restrict sun’s rays light/heat passing through
  • Double glazed sealed units containing

prisms to reflect sunlight but permit daylight.

tubular insulation that blocks high angled sun but permits low angled sun

  • Internal blinds that are usually ineffective:

Generating heat internally

Make the building look less attractive when they are all set at different heights and angles and if they are distorted or damaged.

  • Opaque furniture is placed against the glass giving the building a more disorganised look
  • Electric task fans to cool individuals in the hot zone adjacent to the 100% glass façade
  • Very cold people on the other side of the building

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • N18 External blinds or L15 solar shading
  • H11, H13, L40 Hit and miss screen printed fritting of glass panes
  • L40 Double glazed sealed units containing

prisms to reflect sunlight but permit daylight.

tubular insulation that blocks high angled sun but permits low angled sun

GBE Robust Specification

S          Solar Exclusion/Rejection: Walls

Heavyweight wall construction including:

  • Solid or cavity masonry made of:
  • Stone, brick, extruded fired clay block, fairfaced dense concrete block
  • Insitu or precast concrete

Will soak up heat of the sun’s rays on outer faces of walls, the heat won’t reach the interior of the building and so has little effect upon the internal temperature.

See Also:

GBE Products:

  • E10 Low Carbon Concrete
  • F10 Reclaimed brick,
  • F10 extruded fired clay block,
  • F10 fairfaced dense concrete block
  • F20 F21 Reclaimed Stone

GBE Robust Specification

 

JB        Rejection v Removal

In a recent HCA conference on Overheating

One speaker consistently used Rejection where I would prefer to hear Removal

He used:

  • Rejecting heat that has already got into a building

I prefer:

  • Rejection: is to not accept or not permit solar radiation into the building
  • Removal: is to remove heat that has already got into the building, by active methods
  • Release: is to permit, allow, enable heat to leave by natural or passive means

See Also:

GBE Jargon Buster

#HCAOVERHEATING

@HCAUK

 

P          Solar absorption:

However if walls are not masonry but timber or light metal framed with light claddings, then the sun’s rays will have a very different effect.

The same effect occurs on timber or metal-framed roofs.

Sun’s rays falling on the cladding will warm the cladding, depending upon the materials of the cladding it will then:

Reflect

Refract

Absorb

Convection

Conduct and/or

Re-radiate

…the heat outwards to air or inwards towards the core construction, attic or interior spaces causing overheating.

See Also:

GBE Checklist

GBE Jargon Buster

 

S          Attics require moisture vapour ventilation:

Building Regulations require permanent ventilation to allow any moisture build up in attics to escape.

Eaves ventilation is a simple method it allows wind pressure to pass through the roof via eaves on both sides.

Ventilation needs to occur at the eaves and other perimeters: gables and parapets or abutments to ensure cross flow.

Ventilation may also be needed up the slope or at the ridge to address hot air rising.

Historically 1 to 3 finger wide gaps were used at eaves and verges.

Plastic parts were invented for predictable, dedicated and deliberate roof perimeter ventilation and costs rose.

 

P          Breathing/Breathable Roofing Membranes (BRM):

Roofing underlays are designed to catch any rainwater entering under tile or slates, shingles or shakes.

Roofing underlays were made of bitumen impregnated natural fibre meshes and are heavy to carry to the roof.

BRMs are moisture permeable but rainwater and air tight, they are lightweight and easy to carry to the roof.

BRMs were introduced and considered as a low cost alternative to perimeter ventilation for moisture release.

However the second serendipitous benefit of roofing underlays and eaves ventilation is releasing heat, but this has been forgotten.

Ventilation for overheating roofs remains an important issue.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: H60-H69 Roofing Felts

GBE Robust Specification

 

P/S      Moisture vapour management in framed insulated construction

Various membranes are used to manage risks of condensation in construction in different ways, by:

For vapour-closed construction: (Common in UK design thinking and construction application)

  • Vapour barriers: restrict or stop moisture vapour from room side entering into construction
  • Breather membranes: encourage moisture vapour in construction to egress (exit) outwards.
  • Any thermal insulation materials should be compatible with vapour-closed construction.

For vapour open construction: (Common in EU design thinking and construction application)

  • Moisture permeable (vapour-open) air tightness membranes inside of thermal insulation permit moisture to pass through either way and stop airflow either way.
  • Moisture permeable (vapour-open) wind tightness membranes outside of thermal insulation permit moisture to pass through either way and stop airflow either way.
  • Breathable Roofing Membranes (BRMs) fall into the vapour-open group of membranes.
  • Vapour open construction needs to be matched up with hygroscopic thermal insulation that can live with and perform well under the influence of extra moisture vapour in the construction.
  • Extra care must be taken if using non-hygroscopic insulation in vapour open construction
  • Extra moisture vapour in hydrophobic insulated roofs will reject moisture and potentially push it towards timber structure and other vulnerable materials.

All membranes need integrity at overlaps, junctions, abutments and if the construction is not layered then also at services interfaces.

Vapour barriers are notoriously badly sealed at services interfaces and in some cases only lapped at overlaps.

Air and wind tightness membranes are significantly better served by a comprehensive set of adhesives, sealants, tapes and grommets.

These accessories must all be as competent as the membranes, especially when subjected to daily and yearly cyclical overheating and cooling, moistening and drying cycles, all trying to destroy the integrity of those seals.

 

R          GBE Future Action:

There is PhD research that suggests combining BRMs without eaves ventilation does not work.

There is PhD research that suggests BRMs are incompatible with bats roosting in roofs

The subject of a future GBE Issue paper.

 

S          Intelligent air and wind tightness membranes for roofs

In Europe they have developed ‘Intelligent’ airtightness and wind tightness layers whose moisture permeability varies with atmospheric conditions: in winter more closed, in summer more open.

So called ‘Intelligent membranes’ perform differently in different weather conditions:

  • In summer the warmer dryer conditions dry the membrane and its moisture permeability increases encouraging heat driven moisture vapour inwards or outwards egress (exit) from construction.
  • In winter the colder wetter conditions damp the membrane and its moisture permeability decreases limiting moisture vapour inwards or outwards entry into construction whilst still permitting moisture vapour inwards or outwards egress (exit) from construction.

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: P14 Airtightness of Building Elements:

GBE Products: P14 Air/Wind tightness systems, membranes and accessories

GBE Robust Specifications: JP14 Air/Wind tightness systems Specification & Guidance Notes.

 

S/P      Historically building were made to be air leaky:

The construction was water and water vapour permeable without damp proof courses and damp proof membranes and air leaky with airbricks, air leaky windows and under floor ventilation to:

Reduce risk of moisture vapour build up

Reduce risk of mould

Supply fresh combustion air to open fires and boilers

Supply cool air to food storage

Today with higher expectations of life style we do not like drafts:

Windows are more airtight to avoid drafts

Windows are more energy efficient to reduce down drafts and improve comfort conditions

Vapour barriers are commonplace (but should be added to old buildings with caution)

Breather membranes are essential if vapour barriers are used

Fitted carpets are commonly added (higher risk of asthma)

But hardwood and laminate flooring is also popular

Fridges and freezers are normal

Balanced flues are commonplace reducing drafts and improving comfort conditions

Increasing costs of heating and carbon reduction targets mean we need to be more energy efficient.

Airtightness measures will be applied but we need to be aware of these historic objectives, construction methods and materials when designing new interventions in old building to ensure we do not get things wrong.

See Also:

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • L10 Windows,
  • K13 laminate flooring
  • K21 Hardwood flooring,
  • P14 Airtightness systems,

GBE Robust Specification

GBE CPD: Retrofit Objectives

 

S          Wind and Air tightness: Targets

We are now encouraged to reduce air leakiness of construction which is the same as improve airtightness of construction.

The Building Regulations Approved Document L (‘Part L’) is woefully inadequate and so is the construction sector in delivering against them, generally.

The current pass level is 10, whilst a library with a better score of 8 is unusable in windy weather due to wind noise and papers fluttering and being blown off tables.

Passivhaus energy design standard requires a pass rate of:

  • 6 for new build (German Climate)
  • 0 for retrofit in EnerPHit standard (German Climate)
  • See the UKs interpretation in Carbon Lite by AECB and Passivhaus Trust

Balanced flue boilers provide dedicated combustion air supply.

Fridges and freezers provide dedicated food cooling and freezing.

Well insulated and ventilated pantry has been

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Passivhaus and EnerPHit accredited products, Or Equivalent Products,

GBE Robust Specification

GBE Code: Design Standards

GBE Code: Briefing Tool

By others:

  • Carbon LIte
  • Passivhaus
  • EnerPHit

 

P          Wind and Air tightness: Risks

The risk associated with increasing airtightness include:

  • Deteriorating indoor air quality as more chemicals in construction materials escape into the trapped air
  • Increased risk of moisture build up
  • Increased risk of:
    • mould > asthma,
    • toxic mould > unusable house, unusable possessions, death, toxic waste, un-demolish-able house
    • rot > potential structural failure
    • saturation > frost damage to masonry
  • Interior temperature increasing with improved thermal insulation and airtightness in summer

 

S/P      Wind and Air tightness: Build Tight Ventilate Right

Everybody that understands how to make high performance competent buildings knows they the building needs to do most if not all the work and services should do the bit the building cannot achieve.

When we fail to invest and build cheaply we become heavily reliant upon services.

When we build somewhere in between we insulate to a level that sees a significant reduction in energy demand and a low level services intervention.

Building fabric should be as competent as possible.

We should be using air and wind tight membranes, tape, sealants and grommets to maintain the integrity of membranes at changes of direction, junctions, boundaries, and service pipe penetration crossings.

Ventilation should be deliberate and purposeful, not unintended or fortuitous.

Passivhaus and EnerPHit require mechanical ventilation with heat recovery to be installed.

It is required to be low level, high performance, high efficiency, high heat recovery,

Mechanical ventilation with heat recovery works well in winter to reduce heating to close to zero.

MVHR must be easily visibly and appreciably controllable:

  • In summer the ventilation system needs a heat recovery bypass to push warm air out of the building or risk overheating.
  • In most cases a boost button could be useful to remove rapid increases in moisture, smoke, smells in kitchen and bathrooms and short-term heat inputs like cooking.
  • Indoor smokers may find it beneficial to use a short term boost button to remove smoke, but larger families who are all smokers may end up with the boost function on more than off, leading to greater expense, energy consumption and carbon generation.
  • When you revert to windows open in the summer the system should have an interlock (contacts on windows) to turn it off automatically
  • It must be on by default when the windows are all closed and the house in occupation to avoid indoor air chemicals and carbon dioxide reaching unhealthy levels.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P14 Airtightness systems

GBE Services: Passivhaus and EnerPHit MVHR

GBE Robust Specification

 

S/P      Layering of construction and services

Simplification is desirable, simplification of service pipe penetrations through proofing membranes, avoiding the need for fire, acoustic and thermal proofing and air resistant grommets and sealants that may be prone to premature failure.

Avoiding out of sequence working and high risk of late arrival of services components interfering with completion of damp proof membranes, other proofing barriers, floor wall or roof construction and finishes.

Simplification is desirable, simplification in building walls, cutting chases, inserting conduit, rendering in, plastering over and painting walls and then feeding cables through conduit.

Skirting board convector heating: heating pipes running above the floor and in front of the walls, behind skirting covers with ventilation slots.

An alternative approach is to layer the construction and services so none of those complications occur.

Dado linings and hollow skirting and dado sections creating places for wiring outside of the wall thickness.

Timber framed walls with a second lining and batten zone inside of the wall creates a place for services without compromising vapour barriers and airtightness membranes.

The batten zones created need to be insulated or they become a route for thermal bypass and heat loss to space where it was delivered by the services.

Thermal bypass allows heat to move to other parts of the building where they may build up and lead to overheating.

See Also:

GBE Products: P20, T32 & T99 Skirting board convector heating

GBE Robust Specification

GBE CPD: Design to Reduce Waste

 

S/P      What are the benefits, if any, of attic over heating?

Hot or hot and humid spaces are beneficial for roosting bats and maternity roosts in particular.

Hot dry spaces will ensure that timbers never reach high moisture content levels and not become vulnerable to rot.

Hot spaces can be a source of renewable heat.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Q53 Bat boxes, Bat entrances,

GBE Robust Specification

GBE CPD: Bats Beds and ZEDs

GBE Library: Bat and Bird Book

GBE CAD: 3D Cutaways

 

S          Can an overheating attic be exploited?

The labyrinth of battens and counter-battens below tiles or slates is a potential source of renewable heat

See Also:

GBE Checklist

GBE Jargon Buster

GBE Case Study: Scottish project that extracted 8 degrees heat from below slates for preheating hot water in winter

GBE Case Study: TSB Retrofit for a Future project in Peterborough.

GBE CPD: TSB Retrofit for a Future project in Peterborough.

 

S          Attics need vents specifically to release solar heat gains:

Historically tiling underlay was not used and roofs ventilated easily between the tiles, creating a breezy, dark but magically illuminated roof space.

Alas underlays were introduced to minimise risk of wind blow rain entering the roof and falling on the ceiling and insulation, instead the rain would be channelled to the eaves to discharge.

But roofs immediately change to airtight except for the continuous eaves 50 mm gap:

  • Hot because the gap was intended to deal with moisture vapour, not enough to deal with heat,
  • Hot because heat rises and there was no ridge vent.

Additional measures need to be in place to deal with wind-washing at the eaves.

  • Wind coming in through the eaves will blow heat out of open fibre or open celled insulation, rendering it ineffective
  • Use of dense, closed surface or closed cell insulation materials, softwood or timber panel product to create wind baffle at the eaves ventilation zone, should solve it.

In Scotland softwood sarking boarding is applied over the roof timbers this made sure the stronger winds had little effect on the interior, the roofing underlay is applied over counter-battens over the softwood sarking.

I have not entered a Scottish roof space to feel if they are any cooler due to the decrement delay by the softwood, it may only have limited effect.

Additional ventilation of the attic is necessary because they overheat in summer.

Perimeter moisture ventilation potentially provides ventilation to remove the solar heat gains.

However this is not normally sufficient and more has to be done.

Ideally there is also ventilation at the ridge or on the slopes to release rising hot air.

But more importantly, sufficient ventilation is needed to deal with significant solar heat gains.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Materials: Softwood, Sarking, Battens and Counter-battens

GBE Products: P10 Dense wood fibre insulation board

GBE Robust Specification

 

S/P      Attic water storage tank insulation integrity

The usual means to protecting cold water in storage tanks from frosts in winter in attics, is thermal conductivity insulation wrapped around the sides and over the top of the tank and no thermal conductivity insulation below the tank platform, allowing heat from the accommodation below to pass through the ceiling to the underside of the tank platform to warm the soffit of the platform and hence the tank and the contained water.

The thickness of insulation to tanks is usually insubstantial, compared to ceiling insulation.

There seems to be little interest in this insulation and the bulk of the water may justify it being ignored.

In reality the crucial part of this system is to insulate between the perimeter of the tank platform and the ceiling or the heat lost from the accommodation below just spreads out from below the platform to the whole attic space and cross ventilation will remove the heat.

This is a substantial source of heat loss from the accommodation below in winter, 3 times the area of heat loss through uninsulated loft hatches; and a substantial route for heat gain to the accommodation below adding to summer overheating.

If solar radiation resistant thermal insulation is required to the ceiling then the same insulation type should be applied to the perimeter of the tank platform and to the cold-water tank.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Materials: Softwood, timber panel products

GBE Products: P10 cold water tank thermal insulation, tank deck perimeter insulation,

GBE Defect Analysis: Water storage tank Insulation

GBE Robust Specification

 

S/P      Attic Hatches insulation and airtightness

The usual means to protecting top floor accommodation from air leakage and heat loss to attics in winter, is thermal conductivity insulation between ceiling joists and over ceiling joists.

The risk is that no thermal conductivity insulation is installed above the attic access hatch, allowing heat from the accommodation below to pass through the hatch into the attic and cross ventilation will dissipate the heat.

This is a substantial source of heat loss from the accommodation below in winter, and a substantial route for heat gain to the accommodation below from summer overheating in the attic.

Attic hatches should also be weather stripped and latched to pull the hatch tight to the weather stripping and preventing air pressure buffeting lifting the hatch.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Materials: Softwood, timber panel products

GBE Products:

  • P14 Thermally insulated and airtight attic hatch,

GBE Defect Analysis: Water storage tank Insulation

GBE Robust Specification

 

S/P      Attic access walk/crawl-ways and storage platforms

Access for inspection and maintenance of:

  • cold-water storage and heating header tanks, valves, pipes, overflows, insulation
  • ceiling mounted lights,
  • roofing and insulation
  • Solar thermal or PV panel and solar thermal storage tank installations, inverters and all their controls
  • Air source heat pumps and their cables, ducts and pipes
  • Mechanical ventilation and heat recovery systems and their ducts or pipes

All these need walkways or crawl-ways installed above increasingly thick thermal insulation.

Storing possessions in the attic is commonplace and the structural design of roofs always requires the timbers to be sized to carry a 25 kg/m2 load.

Once attics have been insulated at flat ceiling level the storage space is lost.

There may be a temptation to a reuse the attic for storage in which case problems occur:

  • Possessions are laid directly on the insulation squeezing it and reducing its effectiveness.
  • Platform boards are laid directly on the insulation, which is necessarily deeper than most ceiling joists, squeezing it and reducing its effectiveness; possessions are laid on the platform squeezing the remaining loft out of the insulation.
  • It is reported that >80% of attic are used for storage and insulation is squashed by possessions in attics
  • Squashed insulation is ineffective increasing heating energy demand, its carbon load and costs to occupants.
  • Attic possession storage is one major barrier to occupants adopting insulation improvements.

Products are now available to create raised access ways and storage platforms above thick insulation.

They include:

  • Stilts and lateral restraint stilts that are fixed to the tops of ceiling joists rise through the insulation zone;
  • Linked by horizontal beams
  • Flooring grade decking boards are fixed on top.

They solve one aspect of the possessions-in-situ problem:

  • No need to empty attic before you start
  • By being possible to assemble small modular areas,
  • Transfer possessions to this platform module,
  • Build the next module where the possessions were removed from
  • Continue until all possessions are on platforms

The other aspect of the possessions-in-situ problem:

  • Fear of potential theft of heirlooms and valuables;
  • Do It Yourself DIY-friendly.
  • Occupants, family and trusted friends can do the installation.

The stilts and the air space within section profile potentially make a thermal bridge through the insulation for 2/3rd of the insulation depth where it is warmer in winter keeping the heat in.

The stilts and the air space also provide a route down for solar heated attic air to penetrate towards the space below.

Plastic stilts with H profile maintain air paths within web spaces small enough that they are unlikely to get insulated when insitu, without a labour intense process.

50 x 50 x 5 mm stilts occurring at 1200 x 600 mm centres is:

  • 01% of the area for thermal bridge (See Repeating Thermal Bridges below)
  • 28% of the area for thermal bypass by air.

50 x 50 mm softwood stilts may be:

  • 30% of thermal bridge for conductivity heat loss (See Repeating Thermal Bridges below)
  • 30% thermal break from solar radiation heat gain by decrement delay

Potential improvement to these systems include:

  • Pre-insulate the stilts internally or externally to minimise the effect of the thermal bridge and the thermal bypass
  • Provide high density decking boards to offer some solar radiation resistance to access walkways (less useful in storage areas) to stop solar radiation heat reaching the ceiling

See Also:

GBE Checklist

GBE Jargon Buster: Repeating Thermal Bridge

GBE Materials: Softwood, timber panel products

GBE Products:

  • P10 raised access walkway/platform
  • K11 high density solar radiation resistance decking boards

GBE Defect Analysis: Water storage tank Insulation

GBE Robust Specification

 

I           Repeating Thermal Bridges

A common repeating thermal bridge is where e.g. stilts bridge a layer of insulation in an element.

As this occurs regularly throughout the element, i.e. the ceiling, this is deemed a repeating thermal bridge and must be accounted for in the U Value calculation for the element by making the appropriate corrections.

See Also:

Building Regulations Approved Document L1A.

 

P          Luminaires (light fittings) mounted in ceiling linings

Luminaires are often fitted to ceilings by cutting a whole in the ceiling and the luminaire is fitted flush with the bottom surface and projecting above.

Most luminaires are not thermally insulated to maintain the integrity of any ceiling thermal insulation, and can create a thermal bridge between the warm room below and the cold floor, attic or roof above.

Some luminaires are not airtight enclosures, sometimes deliberately to ensure there is no heat build-up in the luminaire which may reduce the life of the light-bulb or even the luminaire; connecting the space above and below.

Air passing through a luminaire will carry heat and moisture vapour, reducing the energy performance of the building.

For high performance buildings it is essential to reduce air leakage and heat flow.

  • g. Passivhaus, EnerPHit, CarbonLite, AECB silver or gold

Luminaires will occupy the space of insulation above the ceiling so extra insulation will be needed above the surrounding insulation.

Moulded airtight housings are made to fit over the top of luminaires to make them airtight and stop heat flow.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • P14 airtight housing for luminaires
  • P10 thermal insulation

GBE Robust Specification

 

P/S      Infrared Thermal Imaging or Infrared Thermography (IRT)

In the last 5 years there has been significant improvement in the kit and software so analysis can now be more accurate, focussed, purposeful and intentional.

Normally IRT is most often used for detecting heat loss from buildings but can also be used for detecting heat gain.

IRT can also be used in:

  • Plumbing services surveys to check installation competency in Example: Under Floor Heating (UFH)
  • Leak detection in hot pipes buried under surfaces
  • Planned preventative maintenance activity in Facilities Management (FM).
  • Machinery wear and tear checking to determine the optimum time to replace worn items..
  • Checking if targets have been met in Energy Performance Contracting (EPC).
  • Check on thermal comfort conditions.

 

P/S      Infrared Thermography (IRT) External Surveys Heat Loss

IRT from outside looking at external faces of the building, shows heat escaping through the building fabric, analysis will look for hot spots and other anomalies.

External view heat loss IRT is normally carried out at night after the fabric is cooled down from solar gains to avoid misleading information. Examples:

  • Sun from west will warm the west elevations before sunset.
  • Shadows from adjacent trees and buildings will leave cooler areas.

Interpretation of IRT images can be misleading and analysis of the building materials at anomalies in daylight is essential to check materials and there relative emissivity.

 

P/S      Infrared Thermography (IRT) External Surveys Heat Gain

In the wrong hands IRT can be a misleading method for testing for overheating.

IRT can also be used for detecting heat gain.

External view heat loss images taken in the day will be misleading for a number of reasons:

  • Hot roof surface are unlikely to be showing heat loss from inside to the outside.
  • They will show the external materials heated by the sun.
  • Tell tail signs would be shading on northerly elevations, shading below projecting eaves and porches.

 

P/S      Infrared Thermography (IRT) Internal Surveys Heat Loss

Normally IRT is most often used for detecting heat loss from buildings.

IRT from inside looking at internal faces of the building show heat escaping through the building fabric, analysis will look for cold spots and other anomalies.

 

P/S      Infrared Thermography (IRT) Internal Surveys Heat Gain

IRT can also be used for detecting heat gain.

IRT can be used internally looking at internal faces of the building to show heat entering through glazing and building fabric.

The heat source for IRT internal surveys of heat gain is the sun.

Internal views may well show up shadowing by adjacent buildings and trees

A recent ‘tweet’ showed an internal view of an external door during the prolonged heat wave across Europe.

But the more revealing views would be:

  • Ceilings of timber framed roof
  • External walls of lightweight construction (e.g. timber frames walls) without brick outer leaves.
  • Ceiling hatch if insulation is missing
  • Ceiling hatch open if the roofing sarking boards, roofing underlay or tiles are on show.

These images are likely to show hot ceiling, hot walls, hot roofing.

 

P          NHBC Understanding Overheating Where to Start NF44

This publication was written with the help of the ZCH so unlikely to be anything different here.

I found the same issues raised by ZCH repeated, but one item caught my attention.

Case Study 4 BRE test houses made to British and Swedish building standards.

  • I think the different national standards are a distraction
  • The significant piece of information is the Infrared Thermography (IRT) image of the houses
    • Taken in day time so they show solar heat gains in the outer surfaces of walls and roofs
    • The walls read 30-35 decrees C
    • The roofs read 45-50 degrees C
    • BRE concluded that the high temperatures observed during the day are as a result of:
      • Simulated internal gains
      • And solar gains

My own analysis of the BRE survey:

Infrared Thermography:

  • Taken in day time so they show solar heat gains in the outer surfaces of walls and roofs
  • Heat shadows on walls confirm daytime image
  • The walls read 30-35 decrees C (vertical so an acute angle to the sun)
  • The roofs read 45-50 degrees C (closer to perpendicular to the sun)

Simulated heat gains:

  • A number of 100 watt bulbs representing people,
  • Heat from fridge, freezer, cooking, and entertainment equipment: TV, Computers, etc.
  • These are normally (due to inadequate insulation levels in buildings) insufficient to be the cause of overheating but could exacerbate an overheated situation.
  • In a Passivhaus these gains are exploited to provide all the heating that is needed in a well insulated building
  • The internal simulated gains will contribute very little to the roof temperatures due to the ceiling conductivity insulation preventing heat transfer to a hotter roof space (caused by solar gain)

Solar gains:

  • Will include solar gains through windows and glazed doors and roof lights if present
  • Will also include solar gains through lightwight fabric pitched tiled roofs
  • Roof spaces will be very hot, heated by the 45-50 degree C roof tiles.
  • There is so little thermal mass in the attic to reradiate any heat to warm the roof tiles from inside.
  • The basics of IRT interpretation have not been understood and completely misread.

 

R          Research opportunity:

  • Attic and underside of ceiling temperatures
  • Monitor temperatures of attics and top floor accommodation subjected to suns rays
  • Check IRT images of underside of ceilings:
  • Below flat and pitched roofs
  • Ceilings along pitched roof eaves
  • Below attic hatches
  • Below cold water storage tank platforms
  • With and without correct insulation to cold water storage tanks
  • With and without Solar Radiation Resistant thermal insulation
  • With and without Conductivity thermal insulation
  • With combinations of Solar Radiation Resistant and Conductivity thermal insulation

 

S          Attics need windows for light and ventilation:

I remember an architect including a window in an attic, the contractor thought the architect was nuts, as they do.

Upon completion he asked the architect permission to include a window in every attic he builds in future, which of course was granted.

The opportunities and advantages of having a window rather than just a vent in an attic are numerous:

  • No need to take a torch, freeing both hands to gain safe access and negotiate the ladder, hatch and timbers,
  • Natural daylight is used in place of electric light, reducing future carbon emissions and battery pollution.
  • An attic window could reveal if you left an attic light switched on by accident.
  • An opportunity to add permanent trickle venting to release summer solar heat gains.
  • An opportunity to open window to release:
    • Summer solar heat gains whilst searching for the family camping gear.
    • Winter solar heat gains whilst searching for the Christmas decorations.

A room below a well-insulated attic should not suffer from excessive heat loss via attic window trickle vents in winter.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: L10 Windows, Roof windows

GBE Robust Specification

 

S          Attic windows, rooflights or roof window orientation:

Attic glazing could be a window, rooflights or roof window; it could be in gable walls, dormer or roof slope.

Ideally it would be placed on the northern slope or gable to maximise the daylight without sunlight.

If north is not available, choose eastern slope, dormer or gable for morning sunlight, to minimise solar light/heat gains.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: L10 windows, rooflights or roof window

GBE Robust Specification

 

P/S      Solar light/heat gain & greenhouse effect:

Windows, rooflights and glazed doors will allow some of the suns rays in, reflecting or refracting some light and heat.

Then the same effect as a greenhouse comes into effect the wavelength of light changes and heat will not readily escape back out through the same glass.

So the heat builds up making the space inside hotter.

In summer this is a problem, in winter this is an advantage.

Some of the built up heat will conduct back out through the glazing and opaque construction.

 

P/S      Low emissivity (Low-E) glazing:

In addition to the change in light frequency keeping heat inside glazing in greenhouses and buildings:

High performance glazing often includes low emissivity glass, designed to reflect heat back into buildings.

The combination of overheating and low-E glass can exacerbate the problem to increase or persist longer.

One translucent insulating glazing/cladding manufacturer, with optional glazing performances, regularly downgrades the U Value and omits Low E characteristics in rooflights over spaces if there is no heating or cooling and insufficient ventilation and risk of overheating.

Design criteria is evolving as software sophistication enables it.

  • Design standards are emerging for glazing different climate zones for different building types
  • There are window manufacturers that make windows and glazing specifically for hot climates.

By others:

Passivhaus Webinar: Passive House Windows for Mediterranean Climates ‪https://youtu.be/YHg4Pt1M5Tw  via ‪@YouTube via twitter @JMenendez

GBE Checklist

GBE Jargon Buster

GBE Products:

  • B12 conservatories
  • H11 Translucent glazing curtain walling
  • L10 hot climate windows
  • L10 rooflights

GBE Robust Specification

 

S/P      Internal solar shading:

Internal solar shading, inside of the glass, comes in a variety of forms:

  • Blinds (Venetian, vertical, black out)
  • Curtains
  • Shutters (timber victoria shutters are very effective, but under utilised, rarely deployed)

Internal solar shading is effective at stopping summer sunlight, but they have already permitted the sun’s heat inside.

Internal solar shading ideally needs to be combined with ventilation to remove that heat.

This ventilation could be via the windows, doors, and trickle vents dealing with the problem at the point of source.

If heat is not lost at point of source, then spaces need cooling using passive, active or mechanical ventilation.

If at all possible and in all cases, we should be avoiding air conditioning.

One manufacturer makes reversible perforated blinds silver on one side black on the other:

  • Perforations allow a view whilst the blind offers solar light/heat protection
  • Silver reflects summer sun, turned outwards for use in summer
  • Black absorbs winter sun, turned outwards for use in winter

Inward opening windows will clash with internal shading.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: N10 Reversible perforated blinds

GBE Robust Specification

GBE Services: Shutter refurbishment and upgrades

 

S          Encapsulated blinds:

Venetian blinds can be used effectively when contained within double glazed or double casement windows.

The blind is controlled room-side with cleverly included pull cables.

The blind is enclosed so never gets dusty and remains untouched, undamaged and of consistent appearance.

The blind provides choices between: privacy v view, darkness v daylight, shade v sunlight, coolth v heat.

If the blind is between casements the void could be ventilated to the exterior.

Encapsulated blinds do not clash with inward or outward opening windows

This is a multi-functional, cost effective solution that could survive value engineering, cost cutting and substitution.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Case study: Elizabeth Fry student accommodation, UEA, Norwich.

GBE CPD: L10 Windows

GBE Products: L10 Windows with encapsulated blinds

GBE Robust Specification

 

S/P      Solar gain & thermal mass in floors:

Once inside the sun’s rays will fall on the adjacent floors and walls within eyesight of the sun.

If the floors are made of any of the following then the floor will soak up the heat:

  • Stone, ceramic or porcelain tile
  • On adhesive on sand-cement screed or semi-dry mix bedding; (blended GGBS and OPC)
  • Carborundem aggregate cement granolithic, (blended GGBS and OPC)
  • Petro-chemical resin
  • Sand-cement screed or bare polished concrete (blended GGBS and OPC), terrazzo, resin terrazzo,
  • With thin resilient flooring (Linoleum, Rubber, PVC, etc.)

Floors will absorb heat over sun bathed surface areas, gradually warming from the exposed face into the thickness.

Heat absorption will continue until it reaches saturation point or it reaches any insulation layer

Heat absorption will stop when sun’s path moves out of eyesight of the floor area and there is no more heat to add.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (23) Floors

GBE Products:

  • E10 Blended GGBS cement concrete, recycled aggregates, manufactured aggregates
  • M10 Blended GGBS cement Screed
  • M40 Floor tiles
  • M41 Terrazzo
  • M50 Linoleum, rubber flooring,

GBE Robust Specification

 

P/S      Low thermal mass in floors or finishes:

Low thermal mass floor surfaces prevent heat absorption into the finish or substrate (base) to varying degrees and less advantage can be taken of solar light/heat gains.

Insulating screeds and insulating concrete or alternative concretes will not heat up as much as dense concrete.

  • g. insulating screed
  • g. Aerated concrete
  • g. insulating aggregate e.g. LECA Lightweight Expanded Clay Aggregate
  • g. Hemp-lime Crete floors
  • g. Lime-pumice Crete floors

Timber floors:

  • Parquet flooring bonded directly to the subfloor, (this might just be dense enough to be beneficial)
  • Hardwood floors with resilient acoustic isolation or battens
  • Hardwood floors on timber underlayment (plywood or dense wood fibre)

Carpets with or without underlays

Raised Access Platform floors hide the supporting thermal mass floors away from the sun’s rays.

Spaces below platform floors used as plenum spaces could exploit thermal mass if the ventilation is designed to deposit heat in the floor and purge it at another time, but that needs a level of coordination between disciplines, not often seen.

Suspended ceilings hide the supporting thermal mass floors away from the sun’s rays.

Spaces above suspended ceilings used as plenum spaces could exploit thermal mass if the ventilation is designed to deposit heat in the floor and purge it at another time, but that needs a level of coordination between disciplines, not often seen.

Steel trough permanent formwork soffits of composite steel and concrete floors prevent exploitation of thermal mass of concrete floors from below

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (23) Floors

GBE Products:

  • E10 Aerated concrete, LECA aggregate
  • M14 Clay based screed
  • M15 Hemp-limecrete floors

GBE Robust Specification

S/P      Solar gain & thermal mass in wall finishes:

The same applies to any adjacent sun kissed walls, if the walls are made of cement, lime, gypsum or clay render, plaster or finish they will absorb heat to varying degrees depending upon thickness and density and their substrate (background); however insulating or light plasters and renders will not absorb as much as dense.

If the wall is dry-lined with:

  • Cement and wood particleboard its density is high and will absorb a lot of heat,
  • Dense gypsum and wood particleboard is middle density
  • Cardboard faced plasterboard is low density will not absorb as much.

By virtue of the isolation framework, levelling battens, counter battens or dabs the board is substantially isolated from the background, dry-lining boards can absorb the heat but will not be able to pass it on into the substrate material so have restricted mid-term effect.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (21) Walls

GBE Lectures: Elements: (22) Partitions

GBE Products:

  • K11 cement particle boards
  • K13 Dense gypsum particle boards

GBE Robust Specification

 

P          Thermal mass in external walls and internal partitions

In social media I spotted an autoclaved aerated concrete block manufacturer noting the hottest day on record and smugly asking how many people complaining about the overheating were living in timber framed houses.

This needs taking apart and understanding, it might assume…..:

  • ….overheating has a detrimental effect the day the hot weather arrives
    • The severe overheating years 1976 and 2003 were a result of prolonged spells of hot weather without respite in the night
    • It’s only when the heat hangs about for 2, 3, 4, 5 or longer days and nights that overheating really kicks in and people start suffering sleep deprivation, becoming very ill or die
    • Lack of night time coolth does not allow short term thermal mass to cool down by night-time purging
  • ….solar light/heat gains coming in through the windows and glazed doors and will warm the blockwork walls
    • It will fall on the floor and warm the floor’s thermal mass, acting as short term thermal mass
    • Then warm air rising will heat the ceiling/soffit, acting as short term thermal mass
    • Then excess heat warms the air at the top of the room and will eventually fill the room and hot air near the wall surface will warm the wall surface, acting as short term thermal mass
    • Timber frame walls have little role to play in this respect
    • Blockwork walls have little role to play in this respect not acting as medium term thermal mass
  • ….the worst heat gains come in via the walls
    • I have indicated elsewhere that the greatest problem is the heat that enters via flat or pitched roofs not the walls
    • Most pitched roofs in timber and block buildings are timber framed
      • So in that respect they are all the same
    • Some flat roofs will be concrete others timber
      • Concrete flat roofs:
        • Can stop solar radiant heat entering
        • Can act as short term thermal mass if exposed and visible from below
      • Timber flat roofs:
        • Will not stop solar radiant heat entering
        • With plasterboard ceilings will not be acting as short term thermal mass
      • Except for the example of the British Library, blockwork does not normally form any part of roofs
      • Precast concrete barrel vault plank roofs were used effectively at BedZED
    • ….timber frame is the only part acting against the solar heat gains
      • Timber frame is mostly used with a brick outer leaf protecting from solar heat gains
      • The ventilated cavity will act as a chimney to remove any excess solar heat passing into the cavity
    • ….blockwork is the only part acting against the solar heat gains
      • Blockwork is mostly used with a brick outer leaf protecting from solar heat gains
      • The ventilated cavity will act as a chimney to remove any excess solar heat passing into the cavity
    • ….timber frame has no thermal mass to exploit and heat that gets into the building just stays in the air.
      • The timber frame has little to do with the heat absorption it has more to do with the plasterboard linings acting as short term thermal mass
      • The plasterboard lining is likely to be a lightweight, board will have too low a density to be beneficial in absorbing heat not acting as short term thermal mass
      • Dense boards can perform better if used, acting as short term thermal mass
    • ….blockwork has thermal mass to exploit and the walls absorb the heat that gets in.
      • Blockwork has little to do with the heat absorption it has more to do with the plaster or plasterboard linings, acting as short term thermal mass
      • Plaster is likely to be lightweight and insulating not acting as short term thermal mass
      • Plasterboard lining is likely to be a lightweight, board will have too low a density to be beneficial in absorbing heat and not acting as short term thermal mass
      • Dense boards can perform better, if used, acting as short term thermal mass
      • Autoclaved aerated concrete blockwork if exposed (unlikely) will have too low a density to be beneficial in absorbing heat so not acting beneficially as short or medium term thermal mass
      • Dense concrete blockwork if exposed (unlikely in the majority of houses) will have sufficient density to be beneficial in absorbing heat so acting as short and potentially medium term thermal mass

Conclusion:

  • Plastered or dry-lined lightweight autoclaved aerated concrete blockwork has little impact on the temperature of the interiors of overheating houses and flats
  • Exposed fairfaced dense concrete blockwork could have some impact on the temperature of the interiors of overheating houses and flats.
  • My conclusion then is that plastered or dry-lined lightweight or dense blockwork has little or no greater effect on overheating compared to timber framed.
  • Nothing to be smug about then.
  • But research might be able to prove that one way or the other.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (21) Walls

GBE Lectures: Elements: (22) Partitions

GBE Products:

  • F10 fairfaced dense blockwork,
  • K13 dense dry-lining boards

GBE Robust Specification

 

P/S      Thermal mass

Thermal mass works at different time scales:

  • Short term surface thermal mass is most effective over short periods of hot days having time to cool off in between.
  • Mid term elemental core thermal mass works at seasonal scale, progressively warming from winter to summer and cooling from summer to winter.
  • Long term external thermal mass works at inter-seasonal scale, stores heat outside of building fabric in soil below or above a buried building.

Serviced heat stores are a separate set of solutions.

See Also:

GBE Checklist

GBE Jargon Buster

 

S          Effectiveness of short term thermal mass:

Heat has to be absorbed by the surface into the material and on into the thickness.

Thermal mass is not well exploited when it is small in area and thick.

Thermal mass is most effective when it is large in area and thin: walls, floors and ceilings are potentially effective.

Steel trough and concrete composite floors will not absorb heat from below

  • but could absorb heat from above if exposed.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Lectures: Elements: (21) Walls

GBE Lectures: Elements: (22) Partitions

 

P          Effectiveness of mid term thermal mass:

Mid term elemental core thermal mass works at weekly, monthly or seasonal scale, progressively warming from winter to summer and cooling from summer to winter.

Heat has to be absorbed by the surface into the material and on into the thickness.

Over the year the average daily temperatures rising towards summer, will raise the temperatures of the element cores offering thermal inertia.

Opening windows to cool a space will only cool the air (if the outside air is cooler) once the windows are closed the exposed thermal mass will rewarm the space rapidly.

See Also:

GBE Lectures: Elements: (21) Walls

 

S/P      Effectiveness of long term thermal mass

Long term external thermal mass works at inter-seasonal time scale.

Thermal mass of subsoil around a buried or bunded building is exploited; no thermal insulation is used between building and subsoil.

Thermal insulation is located beyond the subsoil so that heat can be stored in the subsoil around, behind, above and below the building.

The summer heat warms the building fabric and then passes through the floor and walls into the subsoil.

Heat can penetrate the right types of soil at about 1 meter per month; 6 months of heating will warm 6 meters of soil.

Insulation needs to surround and corral 6 meters of subsoil.

Ground water movement could remove the heat so that needs to be considered in the geometry of the insulation.

The geology (subsoil types) and topography (surface profiles) of some geographical areas (locations) are better than others:

  • (E.g. London: clay, shallow bowl)
  • (E.g. Manchester: sandy, sloping towards coast)
  • (E.g. Fenland: peat on clay, flat)

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: Zero Energy Building

GBE Products: E20 Below ground conductivity thermal insulation

GBE Robust Specification

 

P          Serviced Heat Stores:

Serviced heat stores are a separate set of solutions and come in a variety of formats

  • Domestic Hot Water Cylinders and overheating
  • Domestic Hot Water heat store
  • Heat Store for Central Heating

See Also:

GBE Checklist

GBE Jargon Buster

GBE CPD: Zero Energy Building

GBE Products: Heat store systems

GBE Robust Specification

 

P          Domestic Hot Water Cylinders and overheating

When we had a domestic hot water cylinder fail it needed replacing the service agreement meant British Gas were called out to do their best.

The rather battered foam insulated cylinder was replaced with a new thickly insulated package with polyethylene sheath surrounding mineral fibre conduction thermal insulation and copper cylinder.

British Gas pays millions on endless TV advertising persuading us they are the right people for the job

  • The British Gas engineers have for a long time regarded the rest of the plumbing world as cowboys
  • With one sentence all the advertising money and effort is wasted…

The Engineer promptly informed us that he did not believe in thermal insulation on domestic hot water systems:

  • The airing cupboard will now not be hot as it was before so it won’t dry your clothes
    • But the washing line is where your dry them and the airing cupboard is where you store and air them
  • He was obliged to insulate the first meter of pipes beyond the cylinder, which he does begrudgingly
    • The remainder of the pipes in the airing cupboard are left uninsulated to warm the cupboard all year round, once warmed the heat then reaches out to the landing and the bedrooms.
    • British Gas have a lot of Service customers so its fair to assume the other houses are in a similar state uninsulated pipes warming the upper floor rooms.

Pipe lagging or lack of it is another source of heat adding to the overheating problem.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Y50 Pipe insulation and Cylinder insulation

GBE Robust Specification

 

S          Domestic Hot Water heat store

Hocketon Housing Project (HHP) has an effective Heath Robinson solution for domestic hot water.

HHP use a 1m3 plastic drink container as a heat store (usually contained in a metal cage for transport) with 300 mm conductivity thermal insulation surround to keep it hot.

The heat store being well insulated, avoids overheating the house (which is itself well insulated and could readily overheat if this heat was not well contained).

The water inside is the heat store is held at 40 degrees C the temperature the hot water will be used at, avoiding using more energy than necessary to heat the water to a higher temperature, and avoiding adding cold to be able to use it.

Investigate the heat source: no ST panels visible, PV & Wind turbine were added later, did the MVHR provide excess heat?

A separate pipe passes through the heat store, domestic cold water passes through the pipe, heat transfers from the heat store into the cold water, domestic hot water is passed along well insulated short pipes to the kitchen sink, ?washing machine?, wash basins and shower.

Pipe runs are not buried in construction (in or under concrete floors, under ceramic tiles, in blockwork walls) but adopting the layered construction approach.

Pipes are inside the spaces, boxed into ducts and very well insulated, accessible to repair, maintain and upgrade.

Pipes do not pass through vapour barriers, breather membranes, damp proof membranes, and thermal insulation; do not make air leaks or thermal bridges.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Pipe insulation,
  • Y50 duct conductivity insulation,
  • Y50 heat storing insulation

GBE Robust Specification

GBE CPD: Hocketon Housing Project (HHP)

 

S          Heat Store for Central Heating

Heat stores have evolved from rocks to salt to phase change materials including waxes.

Today vessels with the right recipe of wax for optimum energy storage and release are used effectively.

They are added to energy management systems that monitor inputs (renewable heat and renewable energy) and demands (heating and hot water) and optimise the use each is put to.

Whenever there is excess heat to requirements it can be put into the heat store by passing the heat through pipes running through the storage media and transferring heat to the media.

When there is insufficient heat to match demands the process can be reversed and the heat drawn out of the storage media.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: T50 & Y21 Heat stores for central heating

GBE Robust Specification

 

P/S      After Heating comes Domestic Hot Water

As some begin to make competent buildings (Passivhaus, EnerPHit, Minergie and SuperE) the high levels of thermal insulation means heat loss is down to a minimum.

The next slice of the energy consumption cake that needs to concern us is hot water.

We need to insulate the domestic hot water pipes and vessels to similar levels of efficiency or their heat might tip the balance to create overheated buildings.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • S11, Domestic hot water
  • T15 renewable energy ST
  • T50 & Y21 heat stores,

GBE ToolBox: Passivhaus, EnerPHit, Minergie and SuperE,

GBE Robust Specification

 

P          Uninsulated central heating pipes add to overheating

Pipe lagging or lack of it is another source of heat adding to the overheating problem.

Historically (1960’s housing for example) hot pipes were buried in screeds and run in floor and attic voids without insulation squandering excessive amounts of hear where it was not needed, added to overheating, or was lost to the atmosphere.

In winter heat loss to the building fabric will potentially warm the interior of the building but just as easily warm the voids in the construction or the atmosphere.

In summer heat loss to the building fabric will potentially warm the interior of the building when you least require it.

Today pipe runs should not be buried in construction (in or under concrete floors, under ceramic tiles, in blockwork walls) but adopting the layered construction approach.

Pipes carrying hot water buried in construction lose heat into that construction, rather than deliver it the intended location.

The only exception to this is deliberate under-floor heating where the pipe is cast-in to transfer heat to the fabric effectively.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Hot Pipe and
  • P10 Duct conductivity thermal insulations

GBE Robust Specification

 

P          Uninsulated domestic hot water pipes add to overheating

Pipe lagging or lack of it is another source of heat adding to the overheating problem.

Domestic hot water pipes are often long runs between cylinder and bathrooms and kitchens in poorly planned house layouts.

These uninsulated pipe runs mean we run a lot of hot water from cylinders towards taps before the hot water arrives, as soon as the tap is turned off, the long run of pipe filled with hot water then looses its heat into the construction, ducts or voids or to the atmosphere.

Today British Gas Engineers replacing hot water cylinders are only obliged to insulate the first meter of pipe from the cylinder.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Hot Pipe and
  • P10 Duct conductivity thermal insulations

GBE Robust Specification

 

P/S      Lagging pipes or insulating ducts

When lagging is so labour intensive and costly it makes sense to consider alternatives.

When pipe insulation is often pre-manufactured to be small section and consequentially ineffective, alternatives should be considered.

Filling a duct space including getting around the back of the pipes is easier than lagging the pipe.

Filling the duct space offers greater insulation to resist heat loss,

Creating filled voids with no air movement and no eddy currents stops thermal loss to the voids and dissipation.

Every little loss of heat helps to minimise the cumulative overheating from many sources.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Hot Pipe and
  • P10 Duct conductivity thermal insulations

GBE Robust Specification

 

P          An incompetent workforce for future-facing adaptation

The Construction shows where National and International Plumbing Apprentices of the year competitions occur, judge their skills on their pipes but never on their insulation work.

Donated appliances and materials are never the water saving or energy saving varieties or versions.

This may be indicative of the curriculum content and the skills acquired.

Multi-skilling of tradesmen is severely frowned upon by the skills councils, who control the curriculum of apprentices.

Multi-skilling is allegedly eroding the skills of any one tradesman.

And maybe it is all about protectionism looking after jobs?

They do not want multi-disciplined low skilled tradesmen out there.

But the system we have adopted does not control cowboy builders.

This does not prepare our workforce for reality and the enormous programme of work under Energy Company Commitment (ECO) if it has not been killed off and GreenDeal if it ever starts.

Our workforce is discouraged from carrying insulation with them when they know they will be opening up ducts, floors, walls and roof to find uninsulated pipes.

Instead they are expected to do their plumbing and electrics then close up the ducts ignoring uninsulated pipes and uninsulated voids that potentially create thermal bridges.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Hot Pipe and
  • P10 Duct conductivity thermal insulations

GBE Robust Specification

GBE Applicators and Installers: Trained Approved Accredited

 

P          Domestic Building Hot Pipe Lagging

Lagging in prevalent use in the 1960’s was made of loose woven hessian strips; it is ineffective as conduction thermal insulation.

There was very little of it (thickness) and it was labour intensive to wrap around a pipes if unrestricted and almost impossible if against a wall or floor, so the temptation to do very little of the pipe (length) was real.

If inspection happened it would only occur for those parts easily inspected, the vast majority remaining uninsulated.

In domestic buildings the specifications might well ask for insulation on domestic hot water and heating pipes but very few people police it and it does not happen.

Speculative housing developers know the pipes will not be insulated even if specified, they do not want to pay for something they are not getting; so they do not specify it, do not get it and do not pay for it.

The DIY market sells extruded hollow foamed plastic or rubber conduction thermal insulation for small size pipes.

And the pipe runs are predominantly inaccessible.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Hot Pipe conductivity thermal insulation
  • P10 Duct conductivity thermal insulations

GBE Robust Specification

 

P          Commercial Hot Pipe Insulation & Labelling

In commercial buildings the specifications require insulating and identification labelling of pipes carrying heat or coolth amongst others.

Inspection is likely to happen so it might be fair to assume insulation happens, at least where it is on show and easily inspected.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Hot Pipe conductivity thermal insulations
  • P10 Duct conductivity thermal insulations
  • Y54 Pipe labelling

GBE Robust Specification

 

P/S      Accessible services

Since hot water and heating services are a significant source of heat that can contribute to overheating, it is recommended that they be designed to be more accessible, insulate able and upgradable, than has been common to date.

Service ducts behind walls or between serviced rooms are commonplace in offices.

Services ducts could become common in homes but they may be smaller to suit the nature and content of the services required.

Integer house at BRE campus has:

  • Accessible services allows ability to:
    • Inspect and check the electrics and check plumbing is insulated.
    • Maintain services in use
    • Upgrade and replace services and insulation.
  • A 300 mm wide door into a 400 mm service duct between two bathrooms,
    • This gives access to and enables maintenance of both bathrooms’ services:
      • Supplies and Wastes.
    • Skirting boards and door architraves are 150 mm deep and hollow construction with fast release fasteners
      • Contain electrical and communication wiring (avoiding buried cables)
      • Allows rewiring in short time,
      • Allowing additional services to be added easily

BedZED has:

  • Hollow 300 mm deep skirting with separated power and communications wiring (avoiding buried cables)
  • Movement joint covers with power wiring to light fittings
  • Dado panels or dado rails concealing power and communications wiring (avoiding buried cables)
  • Uses prepared looms of cables for rapid installation on site

Hollow voids created need to be insulated or they become a route for thermal bypass and heat loss to spaces where it was not delivered by the services.

Thermal bypass allows heat to move to other parts of the building where they may build up and lead to overheating.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • Y50 Hot Pipe and
  • P10 Duct conductivity thermal insulations

GBE Robust Specification

GBE Case Study: Integer House at BRE campus

GBE Case Study: BedZED

 

S          Suspended timber floor insulation

Adding conduction thermal insulation or acoustic insulation into ground and upper timber floors and accommodating services is simple enough except the physical action is fiddly.

For a long time now nylon meshes have been stapled to the tops of joists and slung between the joists creating a hammock to fill with insulation.

But if you watch anybody installing them your will observe a fault that develops as the job progresses.

The first few joist spaces work okay but as they progress across the floor they push down on the mesh to create the required depth in the current hammock, and the insulation in the first and subsequent joist spaces progressively rise above the joist zone.

What is happening is the nylon mesh is pulled and slips through the staples shortening the length one side of the staple reducing the capacity of the hammock.

When the softwood boards are relayed the insulation above the joists becomes compressed and ineffective.

Ineffective insulation allows heat or coolth to transfer more readily and overheating can happen more easily.

There are rigid scored and foldable sheets that can be stapled into place to support the required thickness of insulation without the risk of slipping and compressing, thus allowing effective conduction thermal insulation.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 conductivity thermal/acoustic insulation support

GBE Robust Specification

GBE Literature

 

Heat sources: Surrounds

P          Urban Climate Issues including Urban Heat Island Effect (UHIE)

Urban areas are characterised by:

  • Higher density of buildings
  • Taller buildings
  • Large surface areas for:
    • Surface solar heat gain
    • Heat loss to the outside air
  • Raised outdoor air temperatures
  • Fire resistant brick and stone facades with high thermal mass surface
  • Durable brick, stone, tarmac or concrete pavement with high thermal mass surface
  • Solar heat gains falling on south facing facades and pavement concentrating heat build up
    • Overheating at the building edge
    • Difficulty losing heat from high thermal mass facades
    • Difficulty losing heat from flat vertical glazed facades with hot air ‘sticking to the surface’
      • Needing irregular planes to push the heat away from the surface to allow other heat out.
    • Raised temperature across urban area than surrounding rural area
  • Urban canyons between buildings along main roads
    • Wind penetration into parallel canyons allowing cooling
    • Static air in streets orthogonal (right angles) to canyons remaining sheltered from cooling winds

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • H21 H30, H31, H43, H60, H62, H64 Low thermal mass cladding,
  • Q23, Q30 Q55 low thermal mass paving

GBE Robust Specification

 

S          Trees create coolth in urban areas:

Trees provide shading from the sun’s heat and can cool the air below the canopy.

There may be an element of evaporative cooling below the tree canopy.

Car parking below trees allow the cars to avoid overheating

Seating below trees provides respite from oppressive heat

Trees in gardens can shelter a south and west elevations and patio to avoid hot spots

Trees in large numbers helps to increase the extent of these advantages

  • Tree lined avenues protect building facades and pavements from overheating and reflecting heat back
  • Squares and parks provide islands of coolth

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Q31 Trees

GBE Robust Specification

 

P/S      Heat sources: People/Pets:

BRE has a test laboratory that includes hear sources representing humans; they are black-coated cylinders with open top and bottom and 100 watt light bulb mounted internally.

Other information sources say a human is equivalent to 80 watts and a bald headed male is 100 watts.

The amount of heat varies according to size, age, health, amount of clothing and activity:

  • Babies are less wattage than adults
  • Different size dog breeds will generate different wattages
  • Old and frail adults will be less wattage than young and healthy adults
  • Active people are more wattage than stationary people
  • Making love or Wii games activity generates more wattage and heat and increases metabolism
  • Less clothing will increase heat losses, more clothing will keep more heat in
  • People who have exercised outdoors have raised their metabolism and will continue to generate higher wattage for a while after exercise when they re-enter the house
  • Drinking alcohol raises surface temperature
  • Low fat, high calorific diets can increase metabolism and generates more wattage and heat
  • High body mass index (fat not muscle) provides fat which acts like thermal insulation, so lower wattage

A young couple moved into a Passivhaus and found it was a little cool so they bought a dog/had a baby: sorted.

Canary wharf towers with 10,000 occupants generate 1,000,000 watts of heat, let alone IT equipment and Solar gains.

 

P/S      Heat Generating Services for living:

P/S      Plugged-in Equipment/Appliances

Every day living requires use of many appliances, some essential others non-essential, some continuous and others intermittent, some on or of and others on sleep mode.

 

P/S      All rooms:

  • Many appliances have a frequent repeating ‘has he turned me on yet’ function/chip/process
    • This can be a significant background drain when the appliance is ‘off’
    • When an appliance is turned on it gets ready for use quicker
    • Updated manufacturing standards are pushing for lower background demands
    • Not all manufacturers adopt the lower demand standards
    • All energy demands eventually convert to heat
      • Adding to the room temperature and in summer adding to overheating
    • Today most devices with clocks have a clock chip which correctly resets when powered on
    • Turn all appliances off at the wall or at a switched extension lead
    • Arrange extension leads & switches to allow all appliances to be turned off from wall supply easily
  • Many appliances and equipment have their own Voltage Optimisation (VO) circuits to cut off the peaks in the variability in voltage from the mains, potentially avoiding many sort term over performance opportunities and reducing running costs.
    • VO can be provided at the mains intake to the house, at the 13 amp socket or in the kit.
    • Fridges and freezers can benefit from VO at the socket
    • Air conditioners can benefit from VO on the kit
    • Most other appliances have it built in.
  • Indicator lights:
    • Many appliances, extension leads and control gear have indicator lights:
      • To provide information (is it on or off, is the wall switch on or off, which mode)
      • To help locate in the dark (but we usually find the switch with muscle memory)
      • To act like Christmas tree fairy light (just for effect)
      • Whilst they are likely to be LED they are low heat and low energy demand
      • Many indicator lights make the meter run, power stations stay on, burn fuel, waste heat & water
    • Lights-on generate heat:
      • Incandescent light bulbs generate as much heat as light
      • Halogen lamps generate lots of heat and light
        • In some retail: lights provide all the heating that’s needed and more than is wanted in summer
        • Low energy versions of halogen lamps are available that generate far less heat
      • Compact Fluorescent Lights CFL are very efficient and generate less heat
      • Light Emitting Diode (LED) very high light output with virtually no heat
        • (NB: LED are directional and very different characteristics to the lights they often replace)
      • Ceiling mounted fans:
        • Whilst using some energy to turn fans they will also generate a little heat
        • But their overall effect is to improve comfort conditions by moving hot and humid air away from occupants
        • The perceived improvement can be considerable
        • They have the potential to achieve 2-3% cooling
      • Floor mounted mobile oscillating fans
        • Act in similar ways to ceiling mounted fans
        • If there is any source of cooler air, they can be located to push cooler air through a building or room.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • T70 Ceiling fans,
  • V12 Voltage Optimisation,
  • V21 LED and CFL luminaires,

GBE Robust Specification

 

P/S      Home/Office and Offices

See Also: All rooms, Living rooms, Kitchens/Utilities, Bathrooms

Computers

  • Generate heat when on or when in sleep mode and even when off (always switch off at wall)
  • Like televisions generate heat when on (say 8 or more hours of the day)
  • In some cases 90% of the heat is generated when on stand by mode, (say 16 or less hours a day)
  • Adding to heating and in summer adding to overheating
  • The off button does, but sometimes the switch at the wall is best
  • Energy Star rating does not do enough to solve this
  • There is a CEN standard but only one manufacturer follows the standard (IAmEco in Ireland)
  • IAmEco: very low energy in use and standby, modular for upgradability, easy to maintain, hardwood to love.

Monitors:

  • Generate heat when on or when in sleep mode and even when off (switch off at wall)
  • Old cathode ray tubes (CRT) monitors generate heat
  • Thin Film Transistors (TFT) monitors generate little heat
  • Liquid Crystal Display (LCD) monitors
  • Flat screen TVs can generate considerable heat, take care in your choice

Printers/Plotters

  • Negligible heat output but ozone output requires deliberate ventilation
  • And ink powder is dangerous always wash after contact

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • N10, N11, N12, very low energy in use and standby equipment, modular for upgradability, easy to maintain

GBE Robust Specification

GBE CPD: Low energy ITC

GBE CPD: Greening Your Office

GBE CPD: Greening Your Home

 

P/S      Living rooms

Televisions generate heat when on (say 8 or more hours of the day)

  • In some cases 90% of the heat is generated when on stand by mode, (say 16 or less hours a day)
  • Adding to heating and in summer adding to overheating
  • Energy Star rating does not do enough to solve this
  • The off button does, but sometimes the switch at the wall is best

Video, DVD, Blue ray, Set top boxes, recorders,

  • All have their demands and their sleep mode demands.
  • They all generate heat, turning off completely reduces that heat

Digital radio: is high-energy consumption

  • Especially big battery consumption
  • Use re-chargeable batteries to reduce toxic waste

Wood burners:

  • Used in a Passivhaus where demand are lowest these usually cause overheating
  • Can cause sever overheating when matching demand with minimum fuel input is difficult to correlate?

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • N10, very low energy in use and standby equipment, modular for upgradability, easy to maintain

GBE Robust Specification

GBE CPD: Low energy ITC

GBE CPD: Greening Your Office

GBE CPD: Greening Your Home

 

P/S      Kitchen/Utility

Fridges and freezers

  • Today we find it difficult to live without
  • A 24-hour continuous function generating heat at the rear cooling panels.
  • Today fridges and in particular freezers are better insulated and demand less energy.
  • In summer they work harder and generate more waste heat when its not wanted in the kitchen/utility.
  • Voltage optimisation is effective at taking peaks out of energy supplied to fridges and freezers and heat generated

Cookers are intermittent, powerful and used all year

  • Mostly not very well insulated, so generate heat, which needs to be lost in summer
  • More salads in summer mean the cooker is used less but the fridge used a bit more.
  • Cooking processes more often than not generate moisture vapour, steam, aromas
  • Most of which needs to be removed to avoid problems within construction

Microwaves use less energy and generate less heat than cookers.

Kettles generate short bursts of heat and intense steam,

  • Heat only the amount you require.

Clothes Tumble Dryers:

  • are intermittent, powerful,
  • generate long bursts of heat and humidity
  • mostly used in wet weather but
  • for flat dwellers they may be in use all year
  • some occupiers will use them all year
  • some occupiers will hang wet clothes on radiators or over baths adding humidity without the heat

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • N10, N11, N12, very low energy in use and standby equipment, modular for upgradability, easy to maintain
  • V12 Voltage optimisation

GBE Robust Specification

GBE CPD: Low energy ITC

GBE CPD: Greening Your Office

GBE CPD: Greening Your Home

 

P/S      Bathrooms/Dressing/Bedrooms:

Baths & Showers:

  • Moisture vapour, steam and heat gains to bath room or shower room
  • Needs ventilation to remove it or it tries to pass through building fabric or condense and activate mould spores
  • Avoid power-showers, they increase energy and water demand
  • Take shallow baths or shorter showers

Toothbrushes:

  • Very low to no heat generation,
  • Battery power and battery toxicity, use re-chargeable batteries

Hair dryers:

  • Short term high heat input, drying wet hair raising moisture vapour in room

Hair curlers/straighteners

  • Short term high heat input, drying damp hair raising moisture vapour in room
  • High risk of being left on by accident
  • Risk of being left on deliberately for fast start next day, generating long term heat output and overheating, and fire risk

Under floor heating:

  • Desirable luxury using too much energy for such short period demands (cold bare feet in the morning)
  • Make sure its on a timer to cut off quickly

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • N10, N13 very low energy in use and standby equipment, modular for upgradability, easy to maintain

GBE Robust Specification

GBE CPD: Greening Your Home

 

P/S      Circulation spaces, doors and partitions between them and rooms

When BedZED’s ZEDfactory analysed the future climate and the necessary response to it they made recommendations and a checklist of actions, they included:

  • All internal partitions should be conduction thermally insulating
  • To keep the hot side of a building hot and keep the cold side cold
  • In order to achieve this partitions could be: for example
    • Insulating autoclaved aerated concrete blocks
    • Extruded fired clay bricks or blocks
    • Extruded pumice lime blocks
    • Unfired clay blocks
    • Hollow partitions fully filled with:
      • conduction thermal insulation if the heat is in the air
      • solar radiation resistant thermal insulation if the heat is solar light/heat falling on the partitions
      • combined conduction and solar radiation resistant thermal insulation if both conditions occur
    • Extruded or cast hollow fibre reinforced gypsum partitions with or without cavity fill.
  • In addition all internal doors should be self-closing to help in the same quest.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • K10, K30 insulating partitions,
  • K10, K30 thermal mass partitions,
  • P10 conduction and solar radiation resistant thermal insulation for partitions

GBE Robust Specification

GBE Lectures: Partitions

 

P          Open Plan Stairwell in Living Rooms

Hot and warmer air rises and colder air falls.

Eddy currents can be formed where the hot and cold replace each other.

Living rooms which have stairwells rising to upper floor landings provide the opportunity for warm or hot air to rise and escape from the room to the landing.

In summer upper floors are likely to be warm or overheating due to radiant solar gains passing through the roof into attics and upper floors.

Hot air entering through lower floor windows can rise in the room and escape up the stairwell to add to the landing and upper floor overheating.

In winter colder air in the upper floors can leak down to the lower floor via the stairwell to create cold draughts and thermal discomfort for the occupants.

Introducing door, screen, partition or insulated curtain lobbies around stairwells can help to overcome heat or coolth transfer up or down.

 

S/P      Stairwells and stack effect

Adding rooflights or windows at the upper floor landing can release overheated air from landings, help with cross ventilation when used with upper floor room open windows and open doors between rooms and landing.

Once the upper floor landing heat has been released via windows or rooflights on the upper floor, heat from the connected spaces on the lower floors can rise up the open stairwell and be released.

The action of warmed air on lower floors escaping to upper floors and out through rooflights or windows or vents is known as the stack effect.

Stack effect gets is name because it mimics the effect of a heat rising from a fire in the grate up and out of the chimney stack.

Stack effect is reliant upon the warmed air rising being replaced with more air which can be warmed and rise.

This effect can be used to cool the whole house in summer.

Conversely heat loss in winter from those rooflights and upper floor windows can cool the upper floors and cool air can fall through the stairwell and be replaced by warm air from lower floors.

Rooflights and windows over stairwells should ideally be very good insulators for winter and if required be protected with solar shading in summer.

 

P          Porches/Lobbies:

Porches project outside the house volume

  • They may be at the front or back door or both
  • They may be opaque or transparent or a mixture of both
  • They need to be secure with a lockable outer door
  • They need open able low and high vents, that can allow:
    • Ventilation and passive heat loss from porch

Lobbies will be within the house volume and may be inside of the front or rear door

  • Ideally they are the wet and dry boot room, cloak room,
  • A place to do business with callers without entering the house
  • Big enough for visitors to get in shut the door behind before opening the next

Porches and lobbies protect the front and rear doors from weather and wind

  • Help to minimise heat loss in winter
  • Help to minimise coolth gain in winter
  • Help to minimise wind access to the interior
  • If they have secure door, low and high vents, can allow:
    • Cross ventilation of house and passive heat loss from open front and rear doors

Porches on the sunny side of the house can capture heat of the winter and summer sun and feed it into the house

  • This potentially leads to benefits or overheating
  • Make sure porches can be ventilated effectively.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product: B12 Competently ventilated porches

GBE Robust Specification

GBE CPD: Greening Your Home

 

P/S      Conservatories

Recent statistics indicated that 80% of UK conservatories are heated

  • This can be an enormous drain on energy, money and lead to large carbon production

This suggests that conservatories are either:

  • On the wrong side of the house not bathed in sun unable to act as a sunspace
  • They are used as a extension of the house to enjoy the view of the garden, daylight, sunlight
    • They will have very poor thermal insulation values through the glazed parts so need heating
    • Having occupied the conservatory part of the year
      • The occupants choose to stay all year and need heat on during the heating season
      • In stead of retreating to the better insulated and lower demand house

Conservatories often have no roof ventilation and some side ventilation or just the doors

  • If they are on the sunny side of the house they will overheat and may be fitted with solar shading internally
  • The solar shading prevents or restricts:
    • Enjoyment of the views
    • Ventilation of the interior

Building Regulations require that conservatories be separated from the house by doors and windows

  • Doors and windows that were part of the original house.
  • To reduce the risk of increasing the heating load of the whole house by adding a heat loosing extension.
  • But it is fashionable to make the conservatory open plan with the rooms it is attached to.
  • So the connecting doors and windows are removed once approval is given.
  • If the conservatory is on the south side, then conservatory and the whole house can overheat

One solution is to glaze the conservatory with translucent multi-walled insulating plastic glazing that:

  • Does not gain too much heat in summer
  • Does not loose too much heat in winter
  • May significantly reduce heating costs
  • Obscures the view of the garden (so what was the point?)

Another solution is to decorate the adjacent room with a mural of the interior of a conservatory with the views.

Jacuzzis in Conservatories

  • Are kept hot and evaporate moisture vapour and heat into the conservatory
  • Are likely to lead to condensation in the evening
  • Potentially cause interstitial condensation as it passes out of opaque parts of the walls
  • Potentially cause rot to any exposed timber.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • B12 conservatories with competent ventilation,
  • L40 insulating translucent glazing,
  • L15 external solar shading

GBE Products: SunSpaces

GBE Robust Specification

GBE CPD: Greening Your Home

 

S/P      Balconies within the volume of tower blocks and slab blocks

Balconies in the heating season are often cold and damp.

Pigeons or gulls often overtake unused balconies.

Balconies are often used as storage for bikes and other durable goods.

Glazing them in can make them more useful as extra living space and more useful as storage space.

Glazing in a balcony on the south and southeast sides may lead to overheating.

Glazing in can be with sliding glass/sashes that will change the character of the balcony and restrict airflow

Glazing in with hinged glass panes that move aside retains the character of the balcony and avoids risk of overheating

Balconies could be used for secure external clothes drying, but blustery wind conditions may make this impractical.

Glazing in will help with reducing blustery wind conditions and encourage balcony clothes drying removing the risk of humidity adding to the overheating.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • L10 balcony enclosing glazing,
  • E30 & F30 cantilever balcony thermal breaks,
  • N10 clothes drying lines

GBE Robust Specification

GBE CPD: Greening Your Home

 

P/S      Internal secure clothes drying in summer and winter

Especially in urban and high-density developments, inadequate provision is made for clothes drying.

Today we do need secure provision because of the risk of theft; internal drying does that for you automatically.

EcoHomes does and Code for Sustainable Homes did included requirements for external and/or internal clothes drying.

Internal drying options includes lines hung over baths, not ideal by any means if you want to bathe at the same time.

Internal clothes drying will add to internal humidity that will add to any overheating, so ventilation becomes important or external drying needs to be considered.

Enclosed but ventilated balconies can provide secure external weather protected ventilated clothes drying.

Sunspaces can also offer secure external weather protected ventilated clothes drying.

An alternative for tight sites is to include a small portion of their storage area as a dedicated internal clothes drying and airing cupboard.

The finishes must acknowledge the wet clothing that may drip and will evaporate into this space.

This cupboard heated by radiator like a bathroom towel radiator, with controlled ventilation and heat recovery.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product: N10 Clothes drying line, Raising hanging systems, Clothes drying cupboards,

GBE Robust Specification

GBE CPD: Low energy ITC

GBE CPD: Greening Your Office

GBE CPD: Greening Your Home

 

S/P      SunSpaces

Sunspaces have been used:

  • Successfully at: Hocketon Housing Project (HHP), Integer Housing, Gallieons Housing Association.
  • Mostly successfully at BedZED
  • Unsuccessfully at Integer house at BRE Campus, Swaffham wind turbine visitors centre, Keyworth Building LSBU.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product: B12 Competent Sunspaces

GBE Robust Specification

GBE CPD: Greening Your Home

 

S          SunSpaces: Hocketon Housing Project (HHP)

The sunspaces have high thermal mass materials and finishes to floor and wall between sunspaces and house

  • Brick outer wall, ceramic tiles on adhesive on concrete floor on conductivity thermal insulation on DPM

High performance triple-glazed Low-E windows to the house and double-glazed Low-E glazing to the sunspace

They create an inside-outside space for outdoor activities in sheltered conditions

  • Providing a good area for DIY, arts and crafts activity, drying cloths, meals, sitting and chatting, etc.
  • In summer the sunspace has the doors, low level windows and high level rooflights open allowing heat to escape easily
  • In winter the sunspace has the doors, low level windows and high level rooflights closed allowing heat to build up, some internal shading blinds help to cut down on glare.
  • Overheating can definitely occur hear but intentionally, in the middle of winter with ice on the ground outside the ‘out of house’ workspace is available for ‘outside’ work but not subject to external conditions, away from the cold.
  • Retreating to the house avoids the overheating.
  • When the sunspace is hot then the doors and windows between the sunspace and the house are opened to permit heat transfer to the house interior to heat its exposed thermal mass, insulated from the surrounding ground.
  • The sunspace will reheat and then continue to warm both spaces.
  • Immediately the sun disappears the doors and windows need to be shut to prevent the captured heat for escaping.
  • When the sun returns and the sunspace are hot again the process can be repeated to warm the house.
  • In the evening the sunspace users will feel the temperature fall they should then retreat to the warmed house not turn on heating in the sunspace.
  • Sunspaces offer great potential for out-of-building solar clothes drying, avoiding the humidity generated from entering the interior and avoiding adding to any potential overheating.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product: B12 Competent Sunspaces

GBE Robust Specification

GBE CPD: Greening Your Home

 

S/P      SunSpaces: BedZED

The sunspaces have high thermal mass materials and finishes to floor and wall between sunspaces and house

  • Brick outer wall, ceramic tiles on adhesive on concrete floor on conductivity thermal insulation on DPM

High performance triple glazed Low-E windows to the house and double-glazed Low-E glazing to the sunspace

  • Sunspace glazing includes PV cells in the toughened glass interlayers,
  • These offer some shading but they also reradiate heat inwards.

They create an inside-outside space for outdoor activities in sheltered conditions

  • Providing a small area for one or two people at a table doing small-scale DIY, arts and crafts activity, meals, sitting and chatting, hanging and drying cloths in the space, parking bikes, etc.
  • In summer the sunspace has the doors, low level windows and high level windows open allowing heat to escape easily
  • There is timber decking within the sunspace serving upper floors of the maisonettes it acts as solar shading
  • There is concrete floor within the sunspace at Party floors it acts as solar shading for the floor below
  • In winter the sunspace has the doors, low level windows and high level windows closed allowing heat to build up
  • Overheating can definitely occur hear during sunny spells, retreating to the house avoids the overheating.
  • When the sunspace is hot then the doors and windows between the sunspace and the house are opened to permit heat transfer to the house interior to heat its exposed thermal mass, insulated from the ground.
  • The sunspace will reheat and then continue to warm both spaces.
  • Immediately the sun disappears the doors need to be shut to prevent the captured heat for escaping.
  • When the sun returns and the sunspace are hot again the process can be repeated to warm the house.
  • In the evening the sunspace users will feel the temperature fall they should then retreat to the warmed house not turn on heating in the sunspace.

The sunspaces are mostly successful however the top floor flats do have a problem with overheating:

Precast concrete roof provides the decrement delay needed to stop heat entering through the roof

The sunspace does not have solar shading at the very top and this leads to overheating in the sunspace

This also leads to solar penetration of the upper windows and overheating of the top floor flat.

  • A solution could have been to extend the roof over the sunspace to create solar shading.
  • Subsequent designs by ZEDfactory solve this problem and they also incorporate sun-blinds and awnings on projects.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • B12 Competent Sunspaces,
  • L40 Low-E glazing, Double glazed sealed Units,
  • ZEDproducts,

GBE Robust Specification

GBE CPD: Greening Your Home

 

P/S      SunSpaces: Integer House at BRE, Design team: 1NTEGER

At Integer House the sunspace is more like a greenhouse in a garden with garden paving and gravels between inside.

The wall between the sunspace and the house is timber weatherboarding so there is significantly reduce thermal mass on show to exploit.

The house windows may be double-glazed and sunspace single glazed and aluminium framed reducing efficiency.

The glazed slope has internal louver blinds that are digitally controlled and when it started, controlled by and at the whim of visitors to the website via the Internet.

There is no occupant so there is no heat-capturing regime in place.

The top floor of the house has one room open to the sunspace it overheats and there is no way to insulate it from the sunspace so there is no escaping the overheating other than to not use the space.

Most recently the sunspace glazing has been changed to orange coloured PV glass

  • Since all south facing rooms and the top floor space get all their sun/daylight/moonlight from the sunspace they all receive orange sun/daylight/moonlight.
  • Some rooms have no alternative natural light source

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product: B12 Competent Sunspaces

GBE Robust Specification

GBE CPD: Greening Your Home

 

S          SunSpaces: Galleons Housing Association Thamesmead, London

Initially tenants did not understand the sunspaces but once moved in and exploring how to use them, they found they did not want to live without them.

 

P          SunSpaces: EcoCentre Swaffham Wind Turbine Visitors Centre

At Swaffham the sunspace is a reception, atrium, café, exhibition area.

There is no separation at the line between the sunspace and the offices; it is broken, open, with corridors leading to spaces on the north side on all levels.

The line between offices and sunspace is expressed timber framed and plasterboard, so there is no thermal mass on show to exploit.

It is not known if the partitions next to the atrium are conductivity or radiation thermally insulated.

The partitions between the office space and sunspace may or may not be insulated and if insulated may have conductivity thermal insulation but not likely to have solar radiation resistant thermal insulation.

The sunspace is glazed with aluminium framing reducing efficiency, on timber structure.

The glazed slope has external translucent roller blinds that are automatically controlled responding to sunlight.

There is no heat-capturing regime in place.

There is no ventilation opening for heat removal and introducing of coolth in replacement air.

The upper floors are exposed to the sunspace it overheats and they overheat, there is no way to insolate them from the sunspace so there is no escaping the overheating other than to not use the spaces.

This building was designed to fail or value engineered, cost cut or substituted and built to fail.

When the building funding dried up EEDA East of England Development Agency moved in and fitted air conditioning.

An environmental burden from then onwards.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • B12 Competent Sunspaces,
  • F10, F20, F21, thermal mass wall finishes
  • M40, M50 Thermal mass floor finishes

GBE Robust Specification

GBE CPD: Greening Your Home

 

P          SunSpaces: Keyworth Building, London South Bank University

Keyworth House has an 8 storey atria on the south side, 100% glazed in full view of the sun with no solar shading.

The glazed wall is aluminium curtain walling with fixed glazing and low level 2 replacement air intake vents and revolving door, there are no obvious air vents in the top of the glazing.

Backing onto the atrium is 8 storeys of office spaces that are used as staff rooms, computer design suites, design studio and toilets.

The exposed wall face to the atrium is plasterboard spandrel panels and glass windows; the floor is ceramic tiling, so negligible thermal mass on show to soak up the heat.

These office spaces have open able windows on to the atrium with internal sun-blinds.

A corridor links these offices with classrooms on the north side, it has 6 storeys of class rooms and 1 storey of studio/exhibition space extending up to the 8th storey.

The Atrium is filled with mid day solar light/heat and the highest levels overheat since there is not obvious means to loose the heat at the top.

The offices facing the atrium are bathed in solar light/heat with internal binds that will heat up and the only mean to lose that heat could have been to open the windows to the atrium, but there is no coolth there.

The atrium heat passing though the opaque and glazed wall to the atrium also warms the offices.

The open able windows to the atrium can only introduce hot air to the rooms; they have exposed thermal mass to floor soffits that is insufficient for the purpose.

These rooms are unusable for all intent and purposes in sunny weather and are only used by the most determined students and lecturers.

Doors from these offices to the corridor can be left open to alleviate the overheating by thermally polluting the corridor and potentially on to the teaching spaces beyond on 6 floors and studio/exhibition space on top floor.

This building was designed to fail or value engineered, cost cut or substituted and built to fail.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • B12 Competent Sunspaces,
  • F10, F20, F21, thermal mass wall finishes
  • M40, M50 Thermal mass floor finishes
  • U10 stack venting systems

GBE Robust Specification

GBE CPD: Greening Your Home

 

P/S      Overheating in Student Accommodation

Penny Poyser’s TV series ‘No Waste Like Home’

  • Showed households lifestyles and sought ways to improve environmentally and save money.
  • 1 programme focussed in a multiple occupant 10 student house
  • They all had their own bedrooms and different musical tastes and all had their own music centres on to drown out the others, potentially allowing them to concentrate on studies with familiar rather than distracting music.
  • Striking was that they all left their music on permanently if they were in the house or in college.
  • 10 sources of heat on permanently adds to the room temperatures and potentially to any overheating.
  • 10 sources of energy consumption drawing from the energy inefficient mains supply driving up fuel demands and carbon dioxide generation.

Recent purpose made student accommodation had adopted an approach akin to Hotel access cards on locks:

  • This is connected to the electrics of the student space automatically turning off everything except the fridge.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • V22 Powering down/up systems in
  • P21 Door ironmongery
  • W40 Access Control

GBE Robust Specification

GBE CPD: Greening Your Home

 

S          Government Soft Landings (GSL)

Historically the RIBA discouraged Architects from revisiting building to review their performance, thus avoiding the risk of being sued for incompetent buildings.

This approach meant architects and engineers could design poor performing buildings, never find out and continue to repeat their failings.

Government Soft landings is better known as Soft landings.

Yet another attempt by Government to get better results from the construction industry, where facilities management is now seen as a major contributor to building sustainability.

Mechanical & Electrical contract specifications increasingly call for bespoke computer controlled Integrated Building Energy Management Systems (IBEMS) that often are not handed over adequately to the Facilities Managers.

Facilities Managers (FM) are often not qualified to operate sophisticated IBEMS and often resort to turning the controls off and running the buildings manually.

Soft landings was introduced to create a prolonged hand over period where the designers:

  • Run installation testing, commissioning to optimize and configure the systems to work with each other effectively.
  • Educate, train and/or coach the FM in the use of the IBEMS or the services, monitors and controls.
  • Introduce better-structured Operation & Maintenance Manuals (O&M) manuals.
  • Designers in all disciplines potentially learn of their failings and can be aware of them when they design the next one
  • They may even work together and come up with better solutions
  • Sadly there is a risk with bunker mentality they may blame each other for the failures

Coincidentally Building Information Modeling/Management (BIM) is FM driven, requiring better computer models of the buildings to be handed over with built in O&MM information.

COBie is the FM classification system required in BIM to deliver the FM information in a consistent format.

Soft landings should include Post Occupancy Evaluation to check if the users are satisfied with conditions.

BSRIA created Soft landings.

See Also:

GBE Checklist

GBE Jargon Buster: BIM, BSRIA, Building Information Modeling/Management, COBie, FM, Facilities Manager, IBEMS, M&E, MEP, O&MM, Operation & Maintenance Manuals, POE, Post Occupancy Evaluation

(GBE BRM ’14 – ‘15)

GBE Library:

GBE Links: Government Soft Landings, Building Information Modeling

 

P/S      Facilities Management with gusto: Suffolk County Council HQ: Ipswich

A building being created for a software house, they went bust close to completion of construction, leaving a constructor with a building needing to be completed and a building needing a new tenant or owner.

Suffolk County Council took on the task and completed it as their-own new head quarters, but needed to remodel it to suit their needs.

The Facilities Manager is being proactive and finding solutions to problems.

One side of the fully glazed building overheats due to solar light/heat gains; whilst the other side is cold.

Exploiting the under-floor heating pipes they now take the heat from the south hot side of the building, absorbed into the floor, collected by under floor heating pipes working in reverse and move it to the cold north side of the building, heating that side, keeping more of the staff happy more of the time.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • T31 Under floor heating and cooling,
  • W60 Whole building heat management systems

GBE Robust Specification

GBE CPD: Greening Your Office

GBE Evidence Based Case Study

 

P          Communal Services

P/S      Communal and District Heating:

The demand for energy and resource efficiency has lead to the adoption of communal and district heating in domestic developments.

The challenges include:

  • One large efficient boiler in preference to a multitude of boilers
    • Boiler needs to be modulating to maintain efficiency as demand fluctuates through seasons
    • Only enough modules are engaged so all engaged modules work at peak performance
  • Removing the inefficiency of uninsulated domestic plumbing in many houses or flats
  • Reducing heat loss from distribution pipework and within houses or flats
  • Achieve a better overall performance with district heating that individual systems
  • Individual metering and billing is essential to garner responsibility from users

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • T20 Communal and District heating systems,
  • T20 Heat distribution systems,
  • Y50 Competent pipe insulation

GBE Robust Specification

 

P          Combined Heat and Power (CHP)

The demand for energy and resource efficiency has lead to the adoption of combined heat and power in communal and district heating in domestic developments.

Fuel is burned to generate heat to turn water to steam to drive generators to create electricity.

The heated steam is recycled but in many cases it’s cooled back to hot water then reheated to steam.

The cooling back to water wastes energy and CHP combined with Communal or District Heating uses the waste heated steam or waste heated water to circulate to buildings with a heating demands and replaces burning more fuel.

In the heating season excess heat can be put to good use for room heating and domestic hot water.

However in summer the demands are lower, no heating needed but domestic hot water still required

The boiler is usually in a separate energy centre so overheating of housing units is not normally an issue.

Excess heat generated in summer risks being wasted or dumped.

Options exist for using the excess heat

  • Adding to inter-seasonal thermal storage
  • Adding to long-term thermal mass
  • Adding to swimming pools (but that takes away the cooling effect desired of swimming pools in summer)
  • Adding to Jacuzzis’ but you would need a lot of them and then have a moisture vapour issue
  • Convert to cooling in Combined Coolth, Heat and Power (CCHP)

See Also:

GBE Checklist

GBE Jargon Buster

GBE Product:

  • T50 Inter seasonal thermal stores
  • F10 low carbon thermal mass materials
  • CCHP
  • Heat to Coolth converters

GBE Robust Specification

GBE CPD: Greening Your Home

 

P          Communal space heat pipe distribution:

Heating pipes are distributed through blocks of flats via vertical ducts usually within communal stairs and/or horizontal ducts in communal corridors above ceilings.

Following an immature standard: Heating flow pipes deliver at 80 degrees C and return pipe at 50 degrees C.

The 30 C degrees of heat has to be lost to the building, predominantly via radiators and inevitably from insulated and uninsulated pipework.

Radiators need to be very efficient at delivering heat to the rooms.

Insulation to pipework, bends and valves need to be continuous, competent and efficient at preventing heat loss.

Ideally the duct needs to be insulated, not just the pipes, not providing air in which eddy currents can move freely to dissipate heat

Insulating ducts as well as pipes is not seen as normal practice and unlikely to happen.

In reality the insulation to pipes is insufficient for 30 C degrees and these loses heat the horizontal and/or vertical ducts.

Pipes below floors lose heat to the floor/ceiling voids/ducts and they then heat the floors above.

Communal corridors are often long and connect to stair cores with self-closing fire doors, so cannot lose heat readily and suffer from excessive over heating in winter.

Hold-open devices on fire doors with automatic release on fire alarm, may help to release this heat

The heat from corridors may be sufficient to heat some unheated flats.

Ventilating vertical ducts at the top and bottom to loose heat is possible, horizontal ducts are more difficult.

Smoke ventilation provision is often adopted to help release excess heat.

Performance specification requiring the return to be no more than 50 degree C means the installer will remove, or not add, all insulation on the return pipe to loose as much heat as possible in the corridors.
But we should be designing systems that do not deliver more heat than is needed and never have to loose heat.

Possible solution to this problem:

  • Design all housing to Passivhaus and avoid the need for heating pipe altogether
  • Use smoke vent shafts to passive ventilate overheating long corridors and stair shafts
  • Add windows at ends of corridors to encourage passive longitudinal ventilation

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • T50 Competent appropriately sized communal heating systems that do not generate or waste excess heat
  • U14 Smoke venting systems
  • Y50 High performance pipe insulation
  • Y50 Competent duct insulation

GBE Robust Specification

GBE Evidence based case Study: ZCH event Stephen Harper & Galliard Homes

 

P/S      Consumer Interface Unit (CIU):

A control interface within a home that comprises a heat exchanger, which transfers heat from the community heating network to the individual home’s internal heating and/or hot water distribution system.
These deliver heat at 80 degrees C in the flow pipe and leave the house at 50 degrees C in the return pipe
This is a permanent source of heat for heating and hot water in winter and heat for hot water in summer.
This is a permanent source of heat contributing to potential overheating.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Y50 High performance pipe, valve and CIU insulation

GBE Robust Specification

GBE Evidence based case Study: ____

 

P/S      Communal Space or Area Heating:

In some cases it was felt necessary to heat communal stairwells and corridor spaces.

Under floor heating in screeds or below ceramic tiles were adopted leading to overheating.

But as was described before, communal distribution pipes are already providing heating to the corridor slabs

Under floor heating is unnecessary.

Heat loss from flats may well be sufficient to heat communal corridors and stairwells.

Solar light/heat gains to glazed stairwells should be sufficient to heat stairwells on sunny days in winter,

Solar light/heat gains to glazed stairwells will overheat in summer and should be avoided.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • H11 curtain walling
  • U10 venting systems

GBE Robust Specification

 

P/S      Compartment walls in communal areas:

Compartment walls between communal corridors or communal stair cores and houses, flats or maisonettes

These walls may have an uninsulated cavity; they offer an escape route for heat, through one leaf into the cavity.

The cavity will then act like a chimney and the heat rises to the highest point, then warms both leafs of the wall and then heat spaces beyond, leading to potential overheating.

A potential solution is to fully fill the cavities of these walls with convection thermal insulation to stop air movement.

This potentially conflicts with acoustic insulation function of these walls.

Choosing the right insulation material that deals with both thermal and acoustic performance is the answer.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • P10 Party wall full-fill convection thermal and acoustic insulation
  • F10 K10 K30 P10 highly insulating and acoustic party walls

GBE Robust Specification

 

P/S      Passive Ventilated Open Plan Offices with Atrium/Atria:

Passive ventilated offices are an ambition for designers but a nightmare for services engineers

Its not rocket science either.

Atria offer stack effect ventilation and cooling opportunities if there are:

  • Ventilators, windows or rooflights at the top of the atria.
  • Means for replacement air entry at the bottom via vents or windows.

Open plan offices adjacent to the atria need to have windows at the building perimeter.

Stand back and hey presto it works.

Alas in numerous cases it did not, some of the floors worked and others stayed static leading to humidity, stale air and overheating.

Mechanical Engineers do not like passive ventilation of open plan offices with atria and insist upon mechanical ventilation creating a permanent energy demand.

Upon investigation the lowest floors do benefit from the cooling stack effect but as their heated air enters the atria it passes the edges of the floors above and traps the hot air on those floors preventing it from entering the atria.

There is a simple solution that probably needs active Building Energy Management System BEMS to control it.

The perimeter vents or windows will probably be opened wide by the occupants, if they are all set the same then the problem occurs, the top floors will open their windows wide and nothing happens no cooling effect.

What is needed is for the windows to be regulated so the top floor has the windows open widest and the bottom floor open least, the middle floor open to a middle setting.

Now all three floors can compete on level terms for the cooling effect of the atria stack effect, all three sets of hot air escape from the floor edge, none overpowering the other.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • U10 controllable adjustable venting systems in perimeter walls,
  • U10 & U14 stack ventilation in atria roofs

GBE Robust Specification

 

 

2.         OVERHEATING AFTER ENERGY SAVING RETROFIT

 

S          Fabric First:

There is a reasonable assumption that overheating can be solved by ventilation.

This is on the basis that glazed area solar heat gains are greater than potential heat loss through building fabric and glazing; removing heat in the air could help, but this ignores:

  • Mid term thermal mass thermal inertia
  • Solar gains through opaque building fabric, which can be considerable.

Ventilation can either be passive (preferred), active (preferred), mechanical (if you have to), or (at worst) air conditioning.

This assumption may be true but with increasing services energy costs we have to focus on getting buildings to do most, if not all, of the work themselves.

“Fabric First” & “Build Light, Insulate Right, Solar Tight”.

Only then should services be employed to deal with any shortfalls that cannot be met by competent and effective building fabric alone.

“Build Tight, Ventilate Right”.

See Also:

GBE Checklist

GBE Jargon Buster:

GBE Products: E10, F10, F30, P10, P14 Fabric first solutions

GBE Robust Specification

 

P          Regulation preoccupation:

In the UK we are regulated to reduce energy demand, by Building Regulations Approved Document L (Part L).

Part L focuses on thermal conductivity of floors, walls and roofs:

  • U values made up of k values and thicknesses.
  • Made up of all individual components and thermal insulation materials.

Sadly our regulations are wholly inadequate to:

  • Meet carbon targets that have been set by EU or UK Government

See Also:

GBE Checklist

GBE Jargon Buster

 

P          Regulation missed opportunity:

The above issue relate to keeping heat inside, cold outside and apply to the winter heating season.

What UK Regulations fail to engage with is summer (cooling season) solar light/heat gains and risks of overheating.

Sadly our regulations are wholly inadequate to:

  • Deal with overheating.
  • Do not understand or engage with:

Solar light/heat gain through opaque building fabric

Radiation resistant thermal insulation

Decrement delay.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Equations

GBE Data Sets

GBE Calculators

 

P          Assessment Tool Misconceptions:

There is provision within the Building Regulations Approved Document L to use Standard Assessment Procedure (SAP) software and Appendix P.

We are informed that this was not intended to check for overheating, but it is often assumed to do so and is used for this purpose.

It requires a cost benefit analysis to justify change and this can be avoided or fudged to ignore the issue.

Passivhaus Planning Package (PHPP) software is capable of doing an overheating check, but it is not as robust as it might be hoped.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Equations

GBE Data Sets

GBE Calculators

 

P          The overheating check in SAP:

(extract from NHBC/ZCH Understanding overheating Where to Start NF44)

The overheating check in SAP is used to assess the risk of overheating and demonstrate compliance with Criterion Three (limiting the effects of solar gains in summer) of Approved Document L1A.

The SAP tool considers the effects of solar gains, external temperature, geographic location and the thermal properties of the construction itself (for instance thermal mass).

However, the tool has limited ability to deal with the complex interactions between the contributing factors that are described in this guide and, being a compliance tool, it does not offer the designer any diagnostic information to remedy a ‘high risk’ of overheating.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Equations

GBE Data Sets

GBE Calculators

GBE Toolkit

 

I           Heat Properties

Heat movement, heat loss and its reduction works in a number of different ways, some uses conventional thermal insulation and others use other material properties:

  • Eddy currents:
    • Heat in open air or voids can rise and coolth in air or voids can fall, they can replace each other if in close proximity and set up circulating air currents in air or voids, called eddy currents.
    • Eddy currents can help dissipate heat
    • Heat on one side of insulation can be circulated by eddy currents within the material if the material is relatively open fibred or open celled
  • Convection Resistance
    • Insulation that stops air circulating can hold warm air stationery and stop heat dissipation
  • Conductivity Resistance (Resistivity)
    • Air held still helps to stop heat loss by dissipation,
    • Air trapped in the cells or between fibres of insulation materials is held still and stops heat loss.
    • Usually low density materials where heat transfers through the fibre or substance of the material
    • Recognised by the Building Regulations and compliance schemes.
  • Solar Radiation Resistance
    • Higher density thermal insulation materials with relatively poor conductivity resistance
    • Heat transfer by Conductivity is slower in these materials
    • The time it takes to transfer from one side of the material to the other is Decrement Delay
  • Thermal Bridge
    • (previously know as cold bridge)
    • where a high conductivity material or component passes through a low conductivity material
    • provides a route for heat loss or coolth gain.
  • Thermal bypass or flanking
    • Where heat finds a way to bypass thermal insulation by finding a route of less resistance though open air, voids or thermal bridges, for example.
  • Wind washing
    • Cold air from outside entering a roof through eaves ventilation slots and hitting open celled or open fibred insulation and washing the heat our of the fibres, drawing more heat out of the ceiling insulation.
    • Ventilation air movement in ventilated cavities with partial fill cavity insulation with an open fibre or open celled surface insulation; will draw heat out of the surface of the insulation and cool it down, drawing more heat from the wall.
  • Radiation
    • Heat transfer by radiating across air spaces or air cavities in materials or air cavities between materials
  • Solar Radiation Reflection
    • Reflective materials have more or less effect on sunlight
    • Aluminium foil (the flatter the better) (more effect) in some multi-foil insulation
    • Aluminised polyethylene (less effect than aluminium) common in multi-foil insulation
    • Mirror glass (more effect)
    • Smooth glass (less effect that mirror glass)
  • Long pathways
    • Higher density materials with higher conductivity can be compensated for by having long pathways through the material e.g. a highly cellular material with long path ways through the wall of the cells
  • Emissivity Resistance (e.g. Low E)
    • Different materials have different surface emissivity and modify the rate at which heat leaves the surface of those materials
    • Infrared Thermography images may indicate an anomaly but the images need to be interpreted by visiting the building in daylight to see if the anomaly is heat loss or high emissivity materials at the surface.
  • Surface Resistivity
    • All external building elements (walls, roofs, soffits) exhibit a resistance to heat escaping from their surfaces and are permitted a value for surface resistivity in U value calculations.
    • Internal surface resistivity also happens and it too can be included in calculations.

 

P          Conduction thermal insulation:

Virtually all insulation materials in the UK market have this characteristic, but with varying levels of performance.

Properties needed include:

  • Relative low density
  • Lightly compacted high density fibres with lots of air space
  • Ability to hold air in a stationary state in its air spaces
  • Low conductivity to minimise conduction heat transfer

Material include:

  • Least effective include: dense wood fibre and cellular glass
  • Middle of the road include: expanded polystyrene, mineral wools
  • More effective include: extruded plastics
  • Winners include: aerogels
  • Way out in front: vacuum insulated panels (VIP)

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Aerogel, VIP,

GBE Robust Specification

 

S          Radiation resistant thermal insulation:

Most insulation materials in the UK market do not have solar radiation resistance in abundance.

Those that do have varying levels of performance.

Properties needed include:

  • Relatively high density
  • Highly compacted low density fibres with little air space
  • Ability to absorb solar heat gain into the fibre or body of the material
  • Ability to hold air in a stationary state in the air spaces or air bubbles
  • Store heat in the body of the material or fibres
  • Store heat for a long time
  • Not let heat pass through for an extended period (decrement delay)

Materials include:

  • Ineffective: VIPs (the Sun’s rays reach earth via the vacuum of space)
  • Least effective include: extruded and expanded plastics and mineral fibres
  • Outright winners: dense wood fibre and cellular glass

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Dense wood fibre, cellular glass

GBE Robust Specification

 

P          Convection thermal insulation:

Some insulation materials in the UK market have this characteristic and have varying levels of performance.

Properties needed include:

  • Closed cell or closed surface materials that do not readily allow air to pass through
  • However open cell and closed surface material will still allow some eddy currents within to transfer heat from one side to the other.

Materials include:

  • Least effective include: low-density plant, animal or mineral fibre materials, open celled plastics,
  • Middle of the road include: closed-face open-celled plastics, closed cell plastic
  • Outright winners include: dense wood fibre, cellular glass, aerogels and vacuum insulated panels.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products:

  • P10 dense wood fibre,
  • P10 cellular glass,
  • P10 aerogels
  • P10 vacuum insulated panels

GBE Robust Specification

 

P/S      Which types of thermal insulation do you use?

Solar radiation resistant thermal insulation around a lightweight building will reduce solar heat gain keeping interiors cool in summer.

No solar radiation resistant thermal insulation in lightweight construction, permits summer solar light/heat gain/entry.

Whilst solar radiation resistant thermal insulation has conductivity insulation characteristics as well, these are not as effective as conductivity-only thermal insulation; but the thicknesses required for solar radiation resistance will exceed the thickness required for conductivity.

If you combine solar radiation resistant and conductivity insulation, in lightweight construction, then use more solar radiation resistant and less conductivity insulation; not the other way round.

Conductivity thermal insulation around a lightweight building, lightweight roof or heavyweight building will reduce heat loss keeping interiors warm in winter.

Solar radiation resistant insulation around a lightweight building or lightweight roof will reduce heat loss keeping interiors warm in winter.

Solar radiation resistant thermal insulation is more expensive than conductivity thermal insulation and you need more of it, for a competent building.

Conductivity thermal insulation without solar radiation resistant thermal insulation in lightweight construction is incompetent construction.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Radiation resistant thermal insulation, conductivity thermal insulation

GBE Robust Specification

 

P/S      Competency

On the assumption that my opinion is correct:

Conductivity thermal insulation without solar radiation resistant thermal insulation in lightweight construction is incompetent construction.

As designers begin to know this and ignore it, they too become incompetent.

Quantity Surveyors that ‘Value Engineer/Cost Cut’ away from competent, with client or project team approval, take no responsibility.

Design and Build or General contractors will continue to substitute or surreptitiously substitute and make your buildings incompetent, don’t sign off stage payments (equals approval of surreptitious substitutions) without checking first.

Consider using a Declaration of Conformity signed by the Contractor/Subcontractor’s Directors, that they have not substituted conductivity insulation in place of solar radiation resistant thermal insulation.

Consider Building Performance Contracts with draconian fines for incompetent buildings.

See Also:

CBx Seminar on Energy Performance Contracts

GBE GBS A90 Appendix DofC Declaration of Conformity

 

S          Quality

“There is hardly anything in the world that some man cannot make a little worse and sell a little cheaper, and the people who consider price only are this man’s lawful prey.”

John Ruskin (1819-1900)

 

S          The Truth, the whole truth and nothing but the whole truth

Don’t compromise on CAPEX and suffer at the hands of OPEX, TOTEX is the answer.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Calculators:

  • Whole Building U values, areas, consumption, fuel, carbon
  • Whole Building embodied energy/carbon, Sequestered Carbon

 

S          Monitoring, Metering and Control: Knowledge is everything

Can Facilities Managers manage overheating if they do not have data?

Many companies are now offering better information from your buildings operation so you can identify where for example:

  • How much energy is consumed in different parts of a building with itemised bills
  • More energy is generated than is needed
  • More energy is delivered than is required
  • Energy is wasted
  • Temperatures, Humidity and Indoor Air Quality can be monitored

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: Monitors, Meters, Controls

GBE Servers: Energy Data Service Providers

GBE Robust Specification

UKGBC & Innovate UK event Measuring Energy and Indoor Air Quality Innovation Showcase

 

P          An open and shut case

Combining no solar radiation resistant thermal insulation with ample conductivity thermal insulation in the same lightweight building or lightweight roof construction will lead to solar heat getting in, not being able to get back out, leading to overheating.

QED.

GBE believes this to be the primary cause of the majority of cases of summer overheating in top floor lightweight roof and wall construction accommodation.

There are many other secondary causes of summer overheating that exacerbate the primary cause.

Fiddling with the secondary causes won’t help until you have fixed the primary cause.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Radiation resistant thermal insulation, conductivity thermal insulation

GBE Robust Specification

 

P/S      Overheating of warehousing

Warehousing is vulnerable to solar heat gain and overheating.

Few will see the overheating because it remains at high-level due to thermal stratification.

Ventilation at high level can remove it in summer.

In winter ventilation equipment at high level can push hot air downwards and circulate the air, neutralising the stratification.

Simple fans can achieve this when ceilings are not high.

Warehouses are usually made of lightweight steel frame and thin metal cladding with the wrong choice of thermal insulation type and material.

Glass wool was swapped for stone wool for fire performance in warehouse construction, now it needs to be swapped for:

  • Dense wood fibre or and lots of it for solar protection and overheating
  • Cellular glass and lots of it for solar protection, overheating and fire performance.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation, fire insulation

GBE Robust Specification

 

P/S      Overheating of chilled warehousing

Food warehousing kept at lower temperature is particularly vulnerable to this solar heat gain problem.

Nobody will see the overheating because it is neutralised by the chilling equipment working all year round and working harder on sunny days, with this insulation strategy.

Food warehouses are usually made of lightweight steel frame and thin metal cladding with the wrong choice of thermal insulation type and material

Glass wool was swapped for stone wool for fire performance in warehouse construction, now it needs to be swapped for:

  • dense wood fibre and lots of it for solar protection and overheating
  • cellular glass and lots of it for solar protection, overheating and fire performance.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation, fire insulation

GBE Robust Specification

 

P/S      Overheating of retail warehouses

Retail warehouses are vulnerable to this solar heat gain problem.

Retail warehouses are usually made of lightweight steel frame and thin metal cladding with the wrong choice of thermal insulation type and material.

Glass wool was swapped for stone wool for fire performance in warehouse construction, now it needs to be swapped for:

  • dense wood fibre or and lots of it for solar protection and overheating
  • cellular glass and lots of it for solar protection, overheating and fire performance.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation, fire insulation

GBE Robust Specification

 

P/S      Overheating of Food retail

Food retail will have areas of cooler air adjacent to chilled and frozen food cabinets

Food retail will have cold storage areas back-of house

Pitched or flat roofs with the wrong insulation strategy will permit solar heat gain.

Nobody will see the overheating because it is neutralised by the chilling equipment working all year round and working harder on sunny days, with the wrong insulation strategy.

Glass wool was swapped for stone wool for fire performance in warehouse construction, now it needs to be swapped for:

  • dense wood fibre or and lots of it for solar protection and overheating
  • cellular glass and lots of it for solar protection, overheating and fire performance.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation, fire insulation

GBE Robust Specification

 

P/S      Overcoming overheating of attics and top floor accommodation

If there is mid-term thermal mass in the core of the roof above habitable top floors then this may protect the spaces from overheating, as long as night-time cross flow and/or passive stack ventilation purging is possible, to cool down that thermal mass.

Sunspaces without solar shading at the south side of buildings connected to top floor accommodation can contribute to overheating and may make cross ventilation more restricted.

If there is internal short-term thermal mass between attic spaces habitable space below with ventilation in the attic and habitable spaces below then overheating may be reduced or alleviated.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: K11 high thermal mass boards forming attic floor above insulation

GBE Robust Specification

GBE Case study: BedZED.

GBE Lectures: Pitched roofs

 

P/S      Thin Insulation: a preoccupation of thin conductivity insulation, manufacturers and us

The plastic thermal conductivity insulation sector promotes reduced thickness to achieve required U values.

And we are all too keen to adopt these reduced thicknesses in our building elements.

Thin conductivity insulation means thin walls so we can continue to build with roughly 300-400 mm walls.

Thin external wall construction allows developers to squeeze more houses on a site.

This reduced thickness is all about conductivity resistance and ignores solar radiation resistance.

Thin conductivity insulation has been restricted to foamed plastic insulation but other materials are increasingly available in the market including:

  • Aerogel
  • Vacuum insulated panels (VIP).

Conductivity thermal insulation is acceptable in heavyweight construction.

Solar radiation resistant thermal insulation is essential in lightweight construction.

Lightweight construction needs to be thicker to accommodate solar radiation resistant thermal insulation

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation

GBE Robust Specification

GBE Lectures: External walls

 

P/S      Lightweight external walls: Combining conductivity & solar radiation resistant thermal insulation

Glass wool insulation used for conductivity thermal insulation currently has a large market share it is cheap.

There will always be a temptation to use cheap insulation, but beware the risk of overheating.

Plant based fibre insulation used for solar radiation resistant thermal insulation currently has a small market share it is expensive.

You may be tempted to use a combination of conductivity and solar radiation resistant thermal insulation to reduce costs.

If this is the case then sufficient solar radiation resistant thermal insulation to achieve the decrement delay, should be determined first, then the remaining thickness of conductivity insulation, in combination, to achieve the required U-value.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation

GBE Robust Specification

GBE Equations, GBE Datasets, GBE Calculators

GBE Lectures: External walls

GreenSpec Case Study: bere:architects’ Larch House is the UK’s first zero carbon (code 6), low cost, Certified Passivhaus, built as prototype social housing and launched at the 2010 National Eisteddfod for Wales.

 

P/S      Lightweight external walls: thicknesses of conductivity & solar radiation resistant thermal insulation

The characteristics of the different insulations include:

  • conductivity thermal insulation will permit solar radiation heat to pass through into the building
  • conductivity thermal insulation will prevent internal heat getting out easily
  • solar radiation resistant thermal insulation will delay solar radiation heat passing through into the building
  • The time it takes for the radiant heat to flow through is dependent upon thickness and time
  • Sufficient thickness of solar radiation resistant thermal insulation will delay flow until the sun has set and the roof can cool outwards without overheating the top floors.
  • Insufficient thickness of solar radiation resistant thermal insulation may let the heat flow in the evening and may lead to overheating in the top floor bedrooms or flats.
  • Sufficient solar radiation resistant thermal insulation to achieve the decrement delay, should be determined first, then the remaining thickness of conductivity insulation, in combination, to achieve the required U-value.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation

GBE Robust Specification

GBE Equations, GBE Datasets, GBE Calculators

GBE Lectures: External walls

 

P/S      Lightweight external walls: Conductivity thermal insulation and vapour open/closed?

Firstly do not use hydrophobic conductivity insulation (mineral wool) in:

  • A vapour open system (airtightness layer inside and vapour permeable wind tightness membrane outside)
  • Only use them in a vapour closed system (with vapour barrier inside and breather membrane outside)

Unless you carryout hydro-thermal moisture movement analysis over time

  • WUFI or Delphi software are suitable to check where the interstitial condensation might occur
  • If the interstitial condensation can occur in the hydrophobic insulation do not use it
  • Hydrophobic insulation subject to interstitial condensation will see condensate occupying the air spaces
  • Air spaces with condensate will prevent the insulation from insulating

Research opportunity: if mineral wool (hydrophobic) and plant based (hygroscopic) insulation are used in the same system, will the moisture vapour or condensate migrate towards the hygroscopic and be absorbed into the fibres?

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation

GBE Robust Specification

GBE Equations, GBE Datasets, GBE Calculators

GBE Lectures: External walls

 

S/P      Lightweight external walls: Order of conductivity insulation & solar radiation resistant thermal insulation

If the solar radiation resistant insulation is in the outer position and the conductivity thermal insulation is in the inner position:

  • Solar heat will enter the wall, hit the solar radiation resistant insulation and stop
  • The solar radiation resistant insulation will start to warm from the outside inwards, the conductivity insulation will be kept cool
  • Timber will be hot at the outer edge and cooler inwards
  • Internal moisture vapour will pass
    • Outwards if vapour closed construction is adopted
    • Outwards if vapour open construction is adopted
  • Conclusion below

If the conductivity insulation is in the outer position and the solar radiation resistant thermal insulation is in the inner position:

  • Solar heat will enter the wall, pass through the conductivity insulation then hit the solar radiation resistant insulation and stop
  • The solar radiation resistant insulation will start to warm from the outside inwards, the conductivity insulation will be kept hot
  • Timber will be kept hot and drive moisture vapour:
    • Outwards if vapour closed construction is adopted
    • Outwards and inwards if vapour open construction is adopted
  • Timber kept hot will tend to dry reducing risk of mould.

If the solar radiation resistant insulation sandwiches conductivity thermal insulation:

  • Solar heat will enter the wall, hit the solar radiation resistant insulation and stop
  • The solar radiation resistant insulation will start to warm from the outside inwards, the conductivity insulation will be kept cool
  • Once the solar radiation resistant insulation has reached saturation point throughout its thickness the heat will flow
  • The solar radiant heat will flow from the solar radiation resistant insulation readily pass through the conductivity insulation, hit the solar radiation resistant insulation and stop
  • The solar radiation resistant insulation will start to warm from the outside inwards, the conductivity insulation will be kept hot
  • Timber will be kept hot and drive moisture vapour:
    • Outwards if vapour-closed construction is adopted
    • Outwards and inwards if vapour-open construction is adopted
  • Timber kept hot will tend to dry reducing risk of mould.

If the conductivity insulation sandwiches solar radiation resistant thermal insulation:

  • Solar heat will enter the wall, readily pass through the conductivity insulation, hit the solar radiation resistant insulation and stop
  • The solar radiation resistant insulation will start to warm from the outside inwards, the outer conductivity insulation will be kept hot and the inner conductivity insulation kept cool.
  • Timber will be kept hot through the outer thickness and drive moisture vapour:
    • Outwards if vapour closed construction is adopted
    • Outwards and inwards if vapour open construction is adopted
  • Timber kept hot will tend to dry reducing risk of mould.

Conclusion:

  • On the basis that the further into the element the heat penetrates the harder/slower it will be to get back out at the end of the day and the risk of overheating bedrooms.
    • Solar radiation resistant thermal insulation outside of conduction thermal insulation wins for me.

Research Opportunity:

  • If combining of different insulation types is likely to occur in the future we need to have better understanding of:
    • How moisture moves between them
    • How heat moves between them
  • IRT surveys looking at ceilings of upper floor rooms under roofs.
  • IRT surveys looking at ceilings of upper floor rooms under roofs with different insulation types.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Solar radiation resistant thermal insulation

GBE Robust Specification

GBE Equations, GBE Datasets, GBE Calculators

GBE Lectures: External walls

GreenSpec Case Study: bere:architects’ Larch House is the UK’s first zero carbon (code 6), low cost, Certified Passivhaus, built as prototype social housing and launched at the 2010 National Eisteddfod for Wales.

 

S          Modern Methods of Construction

Modern Methods of Construction (MMC) tend to include:

  • Prefabricated construction
  • Off site manufacturer
  • On site factory production
  • Flat panel Elements: (21) Walls, floors, roofs
  • Pods: bathrooms, shower rooms, WCs, service pods, kitchens, plant rooms,
  • Modules: Whole flat, Half a flat, ‘Bedroom-bathroom-corridor-bathroom-Bedroom’

Can include: all services, fitted furniture and equipment

More skilled workers are required in the factory in weather-free, controlled temperature, comfortable, ergonomic working conditions.

Processes include: Line Production, Lean Production, Just In Time (JIT) Logistics, KanBan

Benefits include: greater productivity can occur with less waste and packaging.

Installing, fitting, testing, calibrating, commissioning of services can be done in the factory

Different skills are needed on site for handling, assembly, final connections testing and commissioning and final closing in finishes.

 

P/S      Thin Wall Insulation in Modern Methods of Construction

There is a preoccupation with thin construction and the MMC world are seduced by this issue as well.

Structural Insulated Panel Systems (SIPS) are an example of thin MMC.

Thinner conductivity thermal insulation usually comes from stronger k-values requiring less thickness to meet U value targets.

Stronger k-values usually come from petrochemical based conductivity thermal insulation including:

  • Extruded Polystyrene (XPE), Polyurethane (PUR), PolyIsocyanurate (PIR), etc.
  • Now come from Aerogels and VIPs

Structural, conduction thermal insulation bonded to Orientated Strand Board (OSB) sheer resistance planes; all you need is a cladding and a lining and all is well; except no solar radiation resistant thermal insulation to protect from overheating.

Brickwork outer leaf to SIPS will help to protect the walls and rooms beyond from overheating.

But SIPS roofs need solar radiation resistant thermal insulation to protect the attic and top floor accommodation from overheating.

None of the SIPS building systems offer additional solar radiation resistant thermal insulation as part of their standard specification.

 

S/P      Thin Internal Wall Insulation in Innovative Methods of Construction (IMC)

The Technology Strategy Board (TSB) (Now Innovate UK) ran the Retrofit for the Future (RftF) competition to refurbish housing to achieve 80% energy and carbon reduction.

Many eras of housing, their materials and construction types were included across the UK to get a good representative set to convert and monitor for 2 years.

Amongst the projects was a proposal to digitally scan the rooms as the survey, send the survey to a shipping container outside with Computer Aided Design (CAD) software to design the interior fit out, its files sent to Computer Aided Design Computer Aided Manufacturing (CADCAM) milling equipment to cut the panels, mark their location on each panel, then the panels are transferred to the house to achieve an accurate fit out in 90 minutes.

Subsequent projects in the GreenDeal programme have adopted the idea to fit out a house in a day.

However the material they have chosen are thin petrochemical foamed plastic, moisture resistant, conductivity thermal insulation and these are placed on the inside face of the solid external walls separated with battens leaving a cavity.

The insulation will stop heat that would otherwise drive outwards through the wall and drive out moisture,

  • Now the wall will progressively become wetter
  • Any embedded timbers will become saturated to potentially rot and collapse
  • Moisture will reach the inside face of the solid outside wall and gather there,
  • Reactivating any spores in the air or on the surfaces leading to mould,
  • Mould can go undetected for a long time and may start growing fruiting bodies that
  • Can grow to touch the outer face of the internal dry linings,
  • Grow into the lining and reach the internal surfaces,
  • Leading to mould on room surfaces, potentially to asthma, potentially toxic mould and possible death.

One company has promoted its activity on line and has 1000 properties to process.

 

S          Thick Wall Insulation in Innovative Methods of Construction (IMC)

Thick walls are not the end of the world, in fact they will probably help avoiding the end of world for human occupation.

Thick wall panels came in the form of Insulated Structural Panel Systems (ISPS).

Manufacturers or ISPS think of 400-600 mm panels as nothing special.

Hollow structural framed and lined panels filled with non-structural thermal insulation in quilts or batts or loose filled with wet or dry flake or fibre.

Thicker conductivity thermal insulation usually comes from weaker k-values requiring greater thickness to meet U value targets.

Weaker k-values come from mineral, animal or plant based conductivity thermal insulation including:

  • Mineral fibre, Sheep’s Wool, Cellulose fibre/flake, wood fibre, flax, hemp, hemp-lime, straw, cotton, etc.

But a bonus of plant based conductivity thermal insulation is they are effective solar radiation resistant thermal insulation too.

Effective solar radiation resistant thermal insulation in roof and wall panels will protect the interior from overheating.

Another IMC is Cross Laminated Timber Panel (CLTP) framed and Insulation in-filled panels.

These use Hemp-lime or Straw bales as infill with lime render outside and lime plaster inside.

Hemp-lime and lime would be problematic if applied insitu on site due to the slow setting and strengthening time so the innovation comes from complete finishing of the panels off site

All applying, setting, curing, hydrating, hardening, drying, strengthening of wet trades, materials and finishes can occur off site avoiding delays and simplifying in-sequence work.

Other advantages of plant based thermal insulation are:

  • They are hygroscopic and moderate moisture in the atmosphere around the element
  • By absorbing the moisture into the fibres lets the insulation do its thermal conductivity job very well.
  • Sequestering of Carbon Dioxide out of the atmosphere, releasing Oxygen, converting it into cellulose plant fibre.

 

P          Grant funded insulation works:

The GreenDeal (now withdrawn), Energy Company Obligation (ECO) (now shrinking) and other recent grant funded retrofits have to work within a regulatory confines.

British Standards Institution (BSI) Publically Available Standard (PAS) PAS 2030 is there to regulate these works.

PAS 2030 requires competent materials, products, equipment, installers providing applications backed up by recognised guarantees or warranties.

The Micro-generation Compliance Scheme (MCS), Energy Technology List (ETL) of approved technologies, materials and installers exist.

Such lists appear restrictive and big players can afford approval processes whilst alternative materials are less likely to be included.

These schemes are left vulnerable to limited choice of approved, sometimes inappropriate and incompetent materials on offer and being installed.

See Also:

GBE Checklist

GBE Jargon Buster

GBE Products: P10 Radiation resistant thermal insulation

GBE Robust Specification

GBE CPD: GreenDeal, Methods, Materials,

GBE Links: ECA, ETL, MCS.

 

S          Radiation resistant thermal Insulation is available in the UK market

We used to teach about this characteristic in University in the 1970’s but materials were not available in the market place.

Today they are, in Europe the problem has been understood and they have developed the products to address it.

The Greens are bringing these products into the UK and promoting their use.

There are numerous suppliers: http://www.greenspecdownload.co.uk/index.php?cID=631

However the UK market obsessed with Fiduciary rules; mainstream construction is not interested in investment, or in climate change, so the problem remains unresolved and the solution remains a fringe benefit.

See Also:

GBE Checklist

GBE Jargon Buster: Fiduciary rules

GBE Materials & Properties

GBE Products: P10 Radiation resistant thermal insulation

GBE Robust Specification

GBE Suppliers

GBE Installers and Applicators

 

S/P      Solid Walls: Hard to treat?

Those in the know describe solid wall brick or stone buildings (Prior to 1919) as ‘hard to treat’.

The walls do not have cavities to insulate so walls need to be insulated either externally or internally.

Historic buildings in conservation areas may have architectural details that discourage or complicate external insulation.

The same buildings may also have internal details that discourage and complicate internal insulation.

In these buildings without these complications external wall insulation (EWI) is usually the simplest, safest and best option, subject to the details.

Because of brick or stone, these walls already provide protection from radiant solar light/heat, so should avoid overheating, insulation used need only be conductivity thermal insulation.

But it needs an airtight outer finish or it could suffer convection losses and wind washing heat out of its surfaces.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • E30 & F30 Thermal Bridge solutions
  • K10 & K13 &
  • M21 EWI,
  • P10 IWI,
  • P14 Airtightness Systems,

GBE Robust Specification

GBE CPD: Retrofit Historic Fabric

GBE Lectures: Elements Walls

 

P          External Wall Insulation (EWI): the details that fail

Buildings are never simple and often have external services and other construction that complicates and compromise the installation of External Wall Insulation (EWI).

Soil and vent pipes, rainwater downpipes, Gas and Electric meter cupboards, Gas pipes, Cable TV and Broadband, Overhead Power or Telephone cables, Balanced flues, Flues, extract fans, TV Ariel, Satellite Dishes and cables, external lights and CCTV, waste pipes and gullies with raised curbs in the pavement next to the wall, etc.

Other building junctions include: attached outhouses, bin stores, garages, carports, conservatory, porches, bay and oriel windows, eaves and verge details, ground level details, etc.

Under Energy Company Obligations (ECO) there are often template specifications and details for standard applications on uninterrupted wall surfaces and internal and external corners and abutments at edges, roof eaves, gable verges and ground level.

There may also be standard details for the services and abutments encountered, but often with a provision ‘when practical’ and these details may be compromised in the standard specification and details.

There are solutions that are expensive materials, but are not yet well known or widely known in the industry.

Ideally the services are removed and replaced outside of the thickness of the new insulation, but these solutions are beyond the skills of the Insulation installers.

The ECO companies do not want to engage services contractors or the whole process starts getting expensive.

Pricing of the works is often hurried to meet artificial deadlines, with robust safety margins and profits built in.

When the works is carried out the standard details which are labour intensive, time consuming and costly, are avoided and the insulation stopped and started either side of services with a working space for installation, creating massive gaps in the insulation and thermal bridges through the walls.

These Thermal bridges will lead to internal condensation in the vicinity of the services, mould will form where the condensation occurs.

Mould leads to asthma, a burden on the NHS; potentially toxic mould, uninhabitable buildings, irretrievable possessions, un-demolish able buildings, no-entry building sites.

Condensation can lead to embeded timbers becoming saturated, leading to rot and potential structural failure.

 

S          External Wall Insulation (EWI): the solutions lay in details

Solutions to the problems described above are being developed all the time but we may not always be aware of them.

For the reluctant ECO installer there are thin insulation solutions for external services:

Aerogel thin and high performance conduction thermal insulation bonded to weather resistant cladding boards.

These are cut to negotiate services supports and installed behind the services across the width of the services and applications/installation zone, abutted and weather-proofed to the EWI.

These materials are not cheap but the avoid the condensation, mould and other subsequent risks.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • H20 Thermal Bridge solutions for EWI
  • M21 EWI External Wall Insulation

GBE Robust Specification

GBE CPD: Retrofit Historic Fabric:

GBE CPD: GreenDeal: Targets Tactics Techniques

GBE CPD: GreenDeal: Manner Methods Materials

GBE CPD: GreenDeal: Rhetoric Risks Remedies

GBE Lectures: Elements: (21) Walls

 

S          Solid Walls: Breathing walls need Breathing Insulation

When insulating internally or externally existing ‘breathing’ solid walls need a ‘breathing’ insulation.

Gypsum plaster or cement render should be removed to permit breathing and moisture transport

Clay based and cork granule insulated renders and plasters are available that offer:

  • Airtightness
  • Thermal insulation
  • Thermal mass
  • Thermal break
  • Decrement delay (if used externally)
  • Moisture mass
  • Moisture vapour permeability
  • Moisture transport

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • M21 Insulating render and plaster
  • M24 Clay based Insulating render and plaster

GBE Robust Specification

GBE CPD: Retrofit Historic Fabric

GBE Lectures: Elements (21) Walls,

GBE CPD: Materials Render,

 

P          Easy to treat inadequately

Other types of walls are likely to include cavity walls (Post 1919), which by inference are ‘easy to treat’.

But if easy means filling cavities with insulation then they will only ever be ‘easy to treat inadequately’.

My interpretation of ‘treat’ here means in terms of meeting carbon reduction targets.

50 mm cavities filled with 50 mm of insulation is wholly inadequate.

With brick, stone or blockwork in outer and inner leaves, walls already provide protection from radiant solar light/heat.

To avoid overheating, the insulation used need only be conductivity thermal insulation but no harm done by choosing solar radiation resistant thermal insulation as long as the thickness deals with the conductivity requirement.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • F30 CWI,
  • K10 & P10 IWI,
  • P14 Airtightness Systems,
  • E30 & F30 Thermal Bridge solutions

GBE Robust Specification

GBE Lectures: Elements Walls

 

P          Inside, within or outside or a combination

Starting with an uninsulated cavity wall you have a number of options in where you insulate the wall.

It could be entirely inside, some inside, some in the cavity and some outside, but never entirely outside.

Some permutations work but uninsulated cavity with insulation outside will not, because external insulation would be redundant.

Since cavities are at least in theory ventilated, all heat loss will occur in the cavity and external insulation will do nothing to change that.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • F30 CWI,
  • M21 EWI,
  • K10 & P10 IWI,
  • P14 Airtightness Systems,
  • E30 & F30 Thermal Bridge solutions,

GBE Robust Specification

GBE Lectures: Elements Walls

GBE Calculators:

U value and Interstitial Condensation Calculators,

Hydro/Hygro thermal moisture movement calculators: WUFI, Delphie

 

P/S      Party Walls: Cavity Construction

Compartment walls between:

Houses, maisonettes or flats; including top floors, rooms in roof and attics

Communal corridor or stair risers and houses, maisonettes or flats

Not long ago whilst monitoring new homes it was discovered that uninsulated cavity party walls where leading to overheating in attics and passing heat through roof tiling to the sky.

Heat loss through only one leaf of bricks or blocks, one half of the cavity wall, will enter the cavity,

This can happen from one or both sides at the same time

The cavity acts as a chimney and the heat rises to the highest point in pitched roof or the top floor under a flat roof

This then heats the 2 leafs of the cavity wall then heats the spaces beyond

The spaces beyond may be attic space or it may be room in the roof or top floor flat, or upstairs in maisonette

This will add to heating or overheating of any spaces

Overheating communal spaces can use the cavity to loose heat

The cavity can move the heat to other locations with overheating potential

The Building Regulations have been revised to avoid problems in future homes but problems remain in existing.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • E30 & F30 Thermal Bridge solutions,
  • F30 CWI,
  • G20 Solid wall solutions
  • P10 Acoustic Solutions,
  • P14 Airtightness Systems,

GBE Robust Specification

GBE Lectures: Elements Walls

 

P/S      Party Walls: Solid Walls

Terraces of houses in a conservation area or the external face is ornate may be difficult to insulate easily.

The Floors may be timber so offer no thermal mass to exploit.

Using internal insulation to external walls will cover up the existing thermal mass in the walls.

Internal loadbearing walls of brick and plaster may offer a little thermal mass

Internal partitions of timber stud, lath and plaster offer a little thermal mass

Internal partitions of solid timber and plaster skim offer a no thermal mass

New partitions of timber stud and plasterboard usually offer no thermal mass

The solid party walls are the only remaining opportunity for thermal mass, if exposed.

Cement render should be left on to use its thermal mass

Gypsum plaster may need to be removed to ensure the brick wall thermal mass can be exploited, but risk reducing acoustic performance of the party wall.

High density clay plaster could be added to offer thermal mass as well as airtightness and moisture mass.

 

 

 

3. COMFORT AFTER FUTURE FACING ADAPTATION

 

S          Solar orientation and ventilation or shading:

We are encouraged to provide large glazed areas on the south elevation (facing south + or – 30%) this is:

  • Potentially beneficial in the winter (heating season) and
  • Probably problematic in the summer (cooling season)

In summer we need to balance summer glazed area solar light/heat gains with one or two options:

  • Ventilation and/or
  • Summer solar shading.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • L15 Solar Shading,
  • L40 G Value in Glazing,
  • U10 Ventilation

GBE Robust Specification

GBE Lectures: Elements Walls

GBE Calculators: U value v G value calculators

 

S          Passive Ventilation:

Comes in the form of either or a combination of:

Cross ventilation:

  • Windows or vents either side of the building allowing fresh air in one side and hot air out the other side
  • Actuated vents either side of the building that open at night to allow outside air to pass through the building cooling down voids in the floor construction and the floor soffit

Stack effect:

  • Heated air is more buoyant and will rise in a space and it can be released:
    • Via flues
    • Through vents
    • Or at high level via rooflights or roof windows
    • Via hybrid stack effect:
      • Glass block faced external vertical duct heated by the sun
      • Vents on each floor open able to the duct
      • Vents at the top that are open able to the air
      • Once the optimum temperature is achieve the vents are all opened to draw heat from the floors up the vent to the sky.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • L10 Secure Venting Windows, Secure venting rooflights and roof windows,
  • U10 Venting systems

GBE Robust Specification

GBE Lectures: Air Movement Through Buildings Series

GBE Case Study: BRE Environment Building

 

S          Active Ventilation:

Often a passive ventilation system with a special rotating cowl

  • Which has a tail fin to ensure it faces into the wind and catches prevailing wind,
  • Driving it down into the building and
  • Pushing stale or hot air out of the building via windows, doors, rooflights or the same cowl
  • Or through leaky building fabric in the building envelop (external walls and roofs).

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: U10 Active Venting systems

GBE Robust Specification

GBE Lectures: Air Movement Through Buildings Series

 

S          Build tight ventilate right:

Building Regulations address airtightness of building fabric in particular eternal envelop (walls, roofs and occasionally floors)

Building Regulations targets are wholly inadequate and do not show any signs of improvement despite initial promises.

A building with an airtightness level of 8 is described as noisy, draughty and unusable in windy weather.

Building Regulation permit levels of up to 10 and constructors can achieve anywhere between reported 0.1 and 27.

Building fabric should be as competent as possible.

Ventilation should be deliberate and purposeful, not unintended or fortuitous.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: P14 Wind and air tightness systems

GBE Robust Specification: P14 Wind and air tightness systems

GBE Lectures: Air Movement Through Buildings Series

 

P/S      Compromised envelope:

Architects worried that occupants will create condensation and mould conditions, considering making construction air-leaky to reduce risk.

Air leaky construction could also help with overheating if the heat can escape in the air egress.

However the same will apply in winter and occupants will have to pay to keep homes at comfortable temperatures.

For many millions that are already classified as in fuel poverty this is not a sensible solution.

Instead buildings should be airtight to control heat loss and purposefully passively, actively or mechanically ventilated to manage moisture build-up and control indoor air quality.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • P14 Wind and air tightness systems;
  • U10 passive active or mechanical ventilation systems

GBE Robust Specification: Wind and air tightness systems

GBE Lectures: Air Movement Through Buildings Series

 

S          Passive Ventilation with heat recovery:

A development of stack effect passive ventilation system: where exhaust air ducts pass through intake air ducts via a heat exchanger that allows transfer of heat-only from one to the other whilst airflows remain separated.

E.g. Ventive systems are designed to retrofit into existing brick chimneys.

Summer bypass is essential in these systems to avoid overheating.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Lectures: Air Movement Through Buildings Series

GBE Products:

  • U10 Passive Ventilation
  • T50 Heat Recovery systems

GBE Robust Specification

 

S          Active Ventilation with heat recovery:

Developments of active ventilation system where exhaust air ducts pass through intake air ducts and allow transfer of heat only from one to the other whilst airflows remain separated.

Summer bypass is essential in these systems to avoid overheating.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Lectures: Air Movement Through Buildings Series

GBE Products:

  • U10 Active Ventilation
  • T50 Heat Recovery systems

GBE Robust Specification

 

S          Passive or Active Summer Solar shading:

Comes in a wide range of formats, locations and purposes:

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: Solar Shading, Alternative Solar Shading

 

S          External solar shading to walls, windows and doors:

Fixed eaves overhangs, porches, Porte cochere, veranda, balconies, etc. positioned outside of and above windows or glazed doors acting as solar shading to prevent summer solar light/heat of opaque parts or entering glazed parts.

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: Solar Shading, Alternative Solar Shading

GBE Products: L15 Solar Shading, Alternative Solar Shading

GBE Robust Specification

 

S/P      Living Walls as external shading to walls and potentially roofs too:

Whilst living walls are excellent to look at, they are often an environmental conundrum.

If irrigated:

  • They can consume vast amounts of:
  • Water
  • Chemicals to clean it
  • Energy and carbon to deliver it

They offer:

  • Leaves which offer weather protection to the walls
  • A place for nature to inhabit and seek food: insects and birds
  • If irrigated additional cooling effect of evaporation from plants and soil or growing media
  • Pollution absorption from air to leaves, if the species of plants are selected to be appropriate
  • Cooling effect of solar shading in front of walls
    • This becomes especially important with lightweight walls, cladding and insulation
    • This becomes especially important if it extends onto the roof

NB: They can annoy architects if they cover up their precious details.

Nature does its own thing.

Birds nesting in them might poo on your pavement, get used to it, don’t ban the birds.

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: L15 Solar Shading, Alternative Solar Shading

GBE Products:

  • Q38 Support systems for ground based living walls
  • Q38 Irrigation-Free Living Walls

GBE Robust Specification

 

S          External brise soleil to glazed parts:

External solar shading is used outside of glazed openings to prevent summer solar light/heat entering.

Positioned and configured to permit winter solar gain, with added challenge of glare and perimeter overspill protection.

Brise Soleil comes in different formats: (the flowing relates to UK, northern hemisphere,

Cantilevering from the wall above the glazed part shading from high level summer solar light/heat:

  • If its only the width of the glazed part the shading will be ineffective when the sun is not orthogonal (right angles) to the wall and glazing
  • In the winter the sun light/heat can pass below and enter the building via the glazed part
  • Winter beneficial heat gains may be accompanied by glare

Vertical in front of the glazed parts:

  • Will be effective if there is no gap between its edge and the wall jamb
  • Depending on the blade profile and spacing may permit beneficial winter solar light/heat gains and many risk glare

Vertical and set a distance from the glazed part:

  • This borders on architectural frippery, offering intermittent shading
  • But they may offer some solar shading to the surrounding walls (beneficial if lightweight construction)

Blinkers: cantilevered from the wall and beside the glazed part:

  • If its only the height of the glazed part the shading will be ineffective when the sun is high with sunlight/heat leaking around the top
  • These can be effective protecting:
    • Southerly elevation glazing with low angle morning and evening sun light/heat
    • East and west elevation glazing from southerly sun light/heat
  • These are ineffective protecting:
    • Southerly elevation glazing from winter or summer, southerly solar light/heat

Northerly bries soleil: is ineffective, architectural frippery, is a waste of money and suggests incompetence.

Same solar treatment on all elevations: is architectural frippery, ¼ is a waste of money and suggests incompetence.

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: L15 Solar Shading

GBE CPD: L15 Solar Shading alternatives

GBE Products:

  • Q38 Support systems for ground based living walls
  • Q38 Irrigation-Free Living Walls

GBE Robust Specification

 

S          Venice and Venetians

They know a thing or two about overcoming overheating in tight urban spaces

The details of architectural facades reveals a lot

Balconies are often placed on both sides of a corner of a building

  • (Potentially a structural and thermal bridge challenge)

Balcony balustrades are perforated to allow air passage

External ‘French’ doors open inwards and wide to allow airflow across corners through two sets of doors

  • Refreshing the internal air and potentially dragging or pushing hot air out

Internal blinds are passed through the door openings and draped over the balcony balustrade

The sloping blinds provide:

  • Solar shading
  • Some light passage bouncing off the balcony and room floor (potentially with glare if the floor is reflective)
  • Some pre-cooling to the air passing through the two sets of doors

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: Solar Shading, Alternative Solar Shading

GBE Products:

  • L20 ‘French Doors’
  • L30 Balconies,
  • N10 Blinds,

GBE Robust Specification

 

S          Adjustable external brise soleil to glazed parts:

With addition of pivoting supports allowing blades to be angled to suit sun’s location, orientation or angle of projection.

May be driven by motors to acknowledge panning sun’s path across sky and time of year.

May be controlled by learning software that remembers sun’s position at different times and seasons.

Can be used to exclude sunlight but maximise daylight entry.

Bouncing light off surfaces of blades can absorb ultra-violet (UV) light.

See Also:

GBE Products

GBE Robust Specification

 

S          External blinds, awnings and umbrellas:

External shading outside of glazing prevents summer solar light/heat reaching and entering windows, rooflights, roof windows, etc.

Not deployed in winter to permit solar light/heat gain and sometimes deployed to reduce glare.

Outward opening windows may clash with external blinds.

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: L15 Solar Shading Alternatives

GBE Products: N10 External blinds, Awnings, Umbrellas

GBE Robust Specification

 

P          Light shelves:

Not to be confused with solar shading but sometimes they are combined with solar shading.

Solar shading to lower casements and light shelf to upper casements of same window

They occur some distance down from the top of a window creating a ‘shelf’.

Light shelves can be internal and/or external of the glass.

They reflect sunlight and/or daylight into the building.

Bounce light off top surface of a horizontal light coloured and reflective surface, sometimes glass or water.

The light passes through the upper window frame, onto the ceiling or soffit of the floor or roof.

This bounces the light deep into the section of building, increasing light levels furthest from windows.

In addition to the light, heat from the sun can pass through as well and then heats the interior.

Windows opening inward and outward should not clash with light shelves.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: L15 Light shelves

GBE Robust Specification

GBE CPD: L15 Solar Shading

GBE Robust Specification

 

S          Solar shading to flat roofs:

In exceptional circumstances the roofs may also be protected by external brise soleil.

In UK it is commonplace for roof plant areas to be shielded from view from below and adjacent.

In France it is commonplace for roof plant areas to be shielded from view from below, adjacent and above with metal grilles over the whole roof area, that have the potential to become solar shading as well as visual barriers.

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: Alternative Solar Shading

GBE Products:

  • Q40 Roof plant room enclosure
  • L15 roof solar shading

GBE Robust Specification

GBE Image Bank

 

S          Solar shading of pitched roofs:

Exceptionally pitched roof are shaded

See Also:

GBE Jargon Buster

GBE Checklist

GBE CPD: Solar Shading, Alternative Solar Shading

GBE Products: L15 Pitched roof solar shading

GBE Robust Specification

Case study: Grand Designs: galvanized expanded metal mesh on pitched framing above profiled metal roof.

 

S          Decrement Delay:

Another term is Thermal Lag (Time delay or lag, not pipe lagging/conduction thermal insulation).

Decrement delay is time it takes for radiant heat to pass through an element of external envelop of buildings.

The time it takes to hit the outside surface, to pass through it and come out of the inside surface.

High thermal mass materials usually but not always have the characteristic.

Conductivity thermal insulation can have the characteristic but most insulation materials do not.

Solar radiation resistant thermal insulation is conductivity insulation that does not perform very well, its high density makes it absorb heat and slows its passage down for an extended period.

Materials with decrement delay characteristics:

  • Dense wood fibre (E.g. Diffutherm products) does offer high decrement delay.
  • Cellular glass (E.g. Foamglas) does offer high decrement delay.
  • Middle density wood fibre offers medium decrement delay.
  • Cellulose flake (recycled newspaper) (E.g. Excel Warmcel) offers medium decrement delay.

Materials not offering decrement delay:

  • Foamed and extruded plastics
  • Mineral fibres
  • Animal hair
  • Bird feathers

Materials appearing to have decrement delay (under radiant heat source tests) but after a short period reach full saturation and then heat flows:

  • Multi-foils

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: P10 Radiation resistant thermal Insulation Products

GBE Robust Specification

GBE Equation: Decrement Delay

GBE Dataset: Decrement Delay

GBE Calculator: Decrement Delay

 

S          Phase Change Properties:

Water can be ice, water or moisture vapour (steam), it goes through 2 phase changes to manifest in 3 phases.

Changing phases requires heat energy transfer to occur.

For water to turn to moisture vapour requires heat in the water to be released from the water.

Phase change materials are selected for the greatest capacity to absorb, store ‘latently’ and release heat at phase changes.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: K13 Phase Change materials,

GBE Robust Specification

 

S/P      Evaporative cooling:

The same occurs in a moist building material for it to dry requires heat to be lost from the material.

Hence buildings feel colder during or after rain or other precipitation (snow, rain, mist, fog), when wind is drying buildings.

If walls are damp from previous rain then some absorbed heat will warm moisture and evaporate it.

Moisture vapour will be driven inwards and outwards, cooling the wall.

If the wall has a cavity then some moisture will evaporate into the cavity, it being ventilated will remove moisture from cavities and cool the walls.

See Also:

GBE Jargon Buster

GBE Checklist

 

P          Diminished performance when moist:

Water penetration through outer leaves of cavity walls will run down inner faces of outer leaves.

If cavities are fully filled with conductivity thermal insulation the outer face of mineral fibre insulation will become moist. Full fill cavity insulation needs to be hydrophobic (rejects water from its fibres or into its air spaces).

Moisture entering the outer face of insulation will occupy air spaces between fibres in insulation, preventing it from its optimum performance in the moistened thickness.

Mineral fibre’s conductivity insulation performance is quoted at different moisture content levels.

 

S          Phase Change Materials (PCM):

Waxes are popular for this purpose.

Early products in the market were metal cassettes filled with wax.

Plasterboards with wax pellets in the mix came next.

Today GRP equivalents using plant fibre and plant resin make up honeycomb boards containing wax and/or clay recipes pellets in the cells.

(E.g. EBB products & lehmorange products).

Phase change materials offer lightweight buildings similar properties to high thermal mass buildings.

Today 10 mm of PCMs in board format can have equivalent thermal mass of 120 mm of concrete.

Use of PCMs could reduce the thickness of thermal mass walls.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: K13 Phase Change Materials

GBE Robust Specification

 

S          Thermal mass:

Brick, stone or concrete are materials exhibiting thermal mass, it is one contributing factors making up solar light/heat protection and decrement delay.

A recent building in Austria with

  • 700 mm thick extruded fired clay block walls
    • (For U value, thermal mass and decrement delay),
  • Open-able windows
    • (For fresh air and cross ventilation),
  • No heating, no ventilation, no cooling services;
    • Maintains 22-26 degrees C all year round.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • M20 M40 High thermal mass decrement delay wall materials,
  • F10 Extruded fired clay blockwork

GBE Robust Specification

GBE Case Study: 2226 Austrian building

 

S          Thick walls, deep sloping window reveals:

The Victorians knew a thing or two about building, which we can adopt in today’s high performance buildings.

When using thick walls deep reveals at windows can lead to high contrast glare.

To overcome glare, sloping window reveals can soften the contrast by letting daylight or sunlight spread onto sloping reveals.

Victorians like the French only 20 miles away on the other side of the channel (and all the way to the Mediterranean sea) use shutters to windows to provide solar shading in the summer and thermal insulation in the winter.

Victorians used shutters internally in a cooler climate.

French mostly but not exclusively use shutters externally in a hotter climate.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Services: C51 & L10 Window Shutter refurbishment

GBE Robust Specification

GBE Library: EH Study of Window upgrades in Glasgow

 

S          Thermal mass combined with Phase Change Materials:

Thick walled buildings may be okay on low-density developments but may not be practical on small urban sites.

Reducing thickness of thermal mass walls by replacing some with phase change materials could offer the best of both worlds.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • K11 Thermal mass boards,
  • K13 Phase Change Material Boards

GBE Robust Specification

 

S          Effective Phase Change Materials (PCM)

For phase change materials to be effective they need to absorb heat and have the means to release the same heat to be able to absorb more heat at a later time.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • K13 Phase Change Material Boards

GBE Robust Specification

 

S/P      Ineffective use of Phase Change Materials (PCM): BRE Campus Innovation Park:

The cross-laminated timber panel (CLTP) school building on the BRE Campus that was later converted into medical centre includes a computer server cupboard.

The computer server is left on long periods of the day and gets hot and continues to push out heat.

The cupboard is lined with PCM lining boards, they absorb the heat of the server.

If the server was turned off at night then the PCM could lose its heat and then the following day the server could be turned back on and when heat builds up the PCM absorb the heat again.

But the habit of leaving servers on overnight means the PCM cannot lose heat, so they cannot be available to absorb more heat the following day.

The server cupboard could have been naturally ventilated the server providing the heat to start the stack effect.

The ventilation system could have included heat recovery to reuse the heat elsewhere.

The ventilation of the server cupboard could have saved the expense of the PCMs.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: K13 Phase Change Material Boards

GBE Robust Specification

 

?S/P?  Use of Phase Change Materials (PCM) in core of roofs:

WWF Living Planet Centre Woking

The incorporation of PCM boards within barrel vault roof construction needs to be better understood by me at least.

If a PCM board is located towards the top of the roof element is it there to capture solar heat gains and prevent them entering the building?

If a PCM board is located towards the bottom of the roof element is it there to capture convected heat from below and remove it from the building?

When a PCM boards absorbs heat and reaches saturation point does it then start to radiate, convect or conduct any of its heat?

Could the upper level PCM absorb solar radiation heat and when saturated then reradiate or conduct it downwards?

If reradiated or conducted downwards would appropriate propertied thermal insulation help to prevent this?

If reradiated downwards does the inner plywood lining offer any resistance to reradiated heat?

It is light coloured rather than dark, which might help; it is unfinished and matt which might not.

During the June/July 2015 hot days the building experienced overheating and staff on the upper open plan floor chose to work on the lower floor when possible.

The client and design team are in discussions trying to understand the problem and come up with solutions.

The client is aware of this document on the NGS website and plans to investigate it further.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • K11 Plywood lining,
  • K13 Phase Change Material Boards,

GBE Robust Specification

R          Research Opportunity:

Academic research or manufacturer’s data needed to understand PCM action when heat saturated

 

S/P      Beneficial or problematic solar heat gains

If there is sufficient thermal mass, absorbed heat and time then building fabric can act as a ‘thermal flywheel’.

The thermal mass absorbing heat at a time of plenty to release it later when the sun’s heat is gone for the day.

Releasing heat to rewarm rooms, potentially into the evening, can avoid needing to turn heating appliances in winter but can be a problem in summer.

The first mention of heating, suggest this is a winter (heating season) only issue.

In reality solar heat gains in summer usually result in overheating and solar heat gains in winter can be beneficial.

The areas of glazed openings on different elevations will influence the size of the problem and/or benefit.

See Also:

GBE Jargon Buster

GBE Checklist

 

S          Purging of heat from thermal mass overnight

Once high thermal mass elements have absorbed excess heat from spaces, they need to be cooled to allow it to continue to offer this service the following day.

During daytime under floor heating pipes with cooler liquid drawing heat from floors can move heat towards colder parts of the building.

Overnight perimeter vents can be opened and colder night air can pass over surfaces of thermal mass to cool it, ready for the following day.

Concrete hollow cores plank floors can be cooled using air passed through the hollow cores (E.g. Termodeck)

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • E60 Hollow core plank ventilation floor;
  • T31 under-floor heating and cooling

GBE Robust Specification

GBE Image bank: BRE Environment Building, etc.

GBE Case study: Elizabeth Fry student accommodation, UEA, Norwich.

 

S          Windows and purging of heat

Windows can be opened both sides of a double sided building with clear routes available from one side to the other.

Prevailing winds can push external air into and through the building, pushing internal air out the other side.

If the external air is cooler than the internal air then the cooler external air passing through can flush out the warmer internal air.

If any internal thermal mass is on show and has been exploited it will have absorbed any excess heat.

The cool external air can flow across the surface of the exposed thermal mass and cool it, eventually purging the heat out of that thermal mass.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • L10 Heat Purge Windows
  • U10 Vents

GBE Robust Specification

 

P/S      Good windows for purging of heat:

Windows that open wide and allow uninterrupted flow of air are best.

Side hung casements are good.

Mid point vertical or horizontal pivot windows are good

Projecting swivel windows can be good

Inward or outward opening windows may clash with any internal or external solar shading.

Windows that slide down and up are good.

Vertical sliding sashes are good.

Make sure vertical sliding sashes are not painted solid and ironmongery still works

You may wish to consider upgrading the sash windows to reduce permanent air leakage due to loose fit sashes.

A window is available where the whole casement moves outside of the face of the wall, it allows vertical (heat driven) or horizontal (wind driven) ventilation on 4 sides whilst maintaining the <100 mm safety gap.

Security is a major issue if the occupant needed to leave the house and wanted to continue to purge.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products:

  • L10 Heat Purge Secure Windows
  • U10 vents

GBE Robust Specification

GBE Library: EH in Glasgow: Upgrading windows

GBE CPD: Retrofit Housing

 

?P/S?  Windows that may or may not work for purging heat

Because air intake vents (AIV) replacement air vents (RAV) are often automated, they can be open when it is windy outside.

Wind baffles can be added to restrict drafts affecting occupants, they may then make the AIV or RAV less effective or even ineffective.

Buoyancy of hot air in stack effect situations should overcome resistance and draw air in and drive it out despite the baffles.

Buoyance and stack effect ventilation needs a building section that has uninterrupted route from entry to heat source to exit, to be effective.

Cross flow ventilation may find baffles a restriction.

Cross flow ventilation needs a building section that allows uninterrupted cross flow from one side to the other.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: U10 air intake vents (AIV) replacement air vents (RAV)

GBE Robust Specification

 

P          Bad windows for purging of heat:

Tilting inward bottom hung windows:

  • Will clash with curtains, blinds and internal solar shading
  • That are positioned normally in openings will offer no easy route for airflow through the window:
  • Narrow triangle at both sides, close against the window jamb will restrict flow.
  • Narrow gap at the head of the window close against the window lintel will restrict flow.

Tilting outward top hung windows:

  • May clash with external solar shading
  • That are positioned normally in openings will offer no easy route for airflow through the window:
  • Narrow triangle at both sides, close against the window jamb will restrict flow.
  • Narrow gap at the bottom of the window close against the windowsill will restrict flow.

ROSPA rules preventing children falling through windows mean opening restrictors will prevent the windows being opened wider then 100 mm at the extreme and less in the triangles at the sides.

Building Regulation’s ambitions with purge ventilation is to clear moisture vapour and smells.

The same issues apply to opening doors; different problems apply to sliding doors.

Windows that do not open:

  • Architect’s aesthetics:
    • Wanted simplified lines so would not allow opening casement
    • One out of x panes opening, only at one position, preventing in and out flows
    • Patio doors are the only openings on an elevation or to a room (no means for security whilst purging).

 

P          Urban Heat Island Effect (UHIE) complicates purging and cross ventilation

High thermal mass materials can be warmed by solar heat gain during daytime.

  • In landscape or pavement
  • In the façade of the building

In the air layer adjacent to the building (say 1-3m) the air will be warmed to quite high temperatures.

When the same materials are adjacent to windows, then the air outside the window will be warmed by these two thermal masses during summer days.

Air drawn in though the window for cross ventilation or purging will be pre-warmed and offer no cooling effect.

The pre-warmed air will add extra heat to the interior leading to overheating instead of cooling or purging.

 

P          Reasons why windows will not be left opened during the day or night for purging

People do not use purge ventilation using opened ajar windows due to:

  • Fear of crime (burglar entry)
  • Noise (other people’s air conditioners, extract fans, traffic, revellers)
  • Animal entry (Foxes in the news recently)
  • Insect entry (tropical flies have been identified in the UK)
  • Pollution (car traffic, industry, waste to energy incinerator plants)
  • Smells (bin stores nearby, catering shops ventilation exhausts),
  • Insurance (security obligation and get out clauses)

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: L10 Secure Purging Windows

GBE Robust Specification

 

S          Alternatives to windows for purging heat

An alternative to windows promoted by ZCH literature is vents associated with windows and doors

The may consist of window like construction and may even be included as a casement or glazing substitution

The will have internal open and close able well-insulated and weather-stripped blanking panels.

They will have insect resistant perforated metal sheet or mesh to allow air to pass through.

Being perforated/meshed the air passing through may not be too windy to disturb interior objects, papers, etc.

Being of narrow dimension will not be passable by burglars, offering security whilst ventilating.

Can be open when the external air is cooler

With at least one vent on both sides of a building and can permit cross flow for purging of heat.

Ideally each room would have its own vent.

Can be closed if the external air is static or hotter than internal

Can be opened for normal ventilation, purging of humidity or smells.

Can be left open overnight, can be used for ground floor or basement flats.

Case Study:

Seminar building at the Innovation Farm near Cambridge:

  • There are full height wall panels that open to reveal ventilation meshes to the exterior.

BRE Environment Building:

  • Automatically Actuated Opening casements at floor level permit air to pass through the building through the double skin hollow floor to purge heat from the floor’s thermal mass.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: L10 Secure Purging vents

GBE Robust Specification

GBE Image Bank: Seminar building at the Innovation Farm near Cambridge,.

 

 

P          Consequence for Building

When buildings overheat:

  • Services become over used, may reach their limits, overheat and trigger shut-offs.
  • Building fabric may start to show sign of weakness and fail.
  • Adhesives, sealants and tapes may fail.

See Also:

GBE Defect: Heat activated polymer migration from phthalate plasticised PVC resilient flooring coved and capped skirting into adhesives leading to failure of waterproofing in wet rooms and easy clean corners in hygienic rooms.

 

P          Consequences for Staff and Management

World FM reported on SOM Architect’s Post Occupancy Evaluation (POE) survey report, May 2015, including a recent survey of building occupants in many businesses, in many sectors.

The striking issue was that whilst almost all issues scored fairly well, thermal comfort was consistently the worst scoring topic of all with very low satisfaction scores.

See Also:

Library: http://www.som.com/ideas/research/post_occupancy_evaluation_survey_report

 

P          Consequences of Overheating on Business

Staff’s reduced capacity to concentrate on tasks

Reduced productivity of workforce

Staff absenteeism

Ineffective buildings lead to loss of workforce

 

P          Consequences of Overheating on UK PLC’s Energy and Carbon Targets

Air conditioning uptake in homes:

Today: 3% (B&Q sell them for DIY)

2050: 50% predicted (exacerbating the problem for those without)

Increased: energy consumption, costs, and carbon generation.

Failing: to meet carbon targets.

More European fines to UK Government, paid for by our dwindling tax reserves, so achieved by more reduced public services and July 2015 diversion from Zero Carbon targets.

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: U10 Passive, active or Whole House Ventilation Systems

GBE Robust Specification

 

P          Consequences of Overheating on Indoor Air Quality (IAQ)

Indoor air pollution:

PM, SO2, NO2, CO, O3, VOCs, Radon

See Also:

GBE Jargon Buster

GBE Checklist

GBE Products: IAQ fixed monitors; hand held detectors

GBE Robust Specification

 

P          Consequences of Overheating on Health

Heat stroke

Heat exhaustion

Heat syncope

Heat cramps

Death

 

P          Who is at health risk?

Residents who are at home during the daytime experience significantly greater overheating exposure with implications for their health and wellbeing.

Elderly over 65 years (hit significantly by 2003 heat wave)

  • Elderly do not complain and put themselves at risk

Chronically ill

  • Children and elderly with lung and heart conditions

Socially deprived

Low income

P          How big is the death risk?

14-30th August 2003 heat wave: 70,000 extra summer deaths in Europe (Peer reviewed statistics quoted in Wikipedia)

https://en.wikipedia.org/wiki/2003_European_heat_wave

SE France hardest hit with 14,802 (60% excess deaths)

2003: 2091 heat wave deaths/annum UK (17% excess deaths) HSQ 2005

0-64 years old: 236 (11% excess deaths); 65-74 y o: 74 (3%); 75+ y o: 1,781 (23%); London: & SW: 1063 (65%)

2050: 7000 heat wave deaths/annum UK (predicted)

Compared with:

2012/13: 31,000 Excess Winter Deaths (EWD) (UK)

2013/14: 18,200 (EWD) (UK)

2014/15: >40,000 (EWD) highest in 15 years (UK)

2014: 4200 air pollution deaths/year London-wide

2014: 2.4 million people in fuel poverty (paying more then 10% of income on heating) (UK 2013 official statistics)

2014/15: 1,084,604 people in food poverty received three days’ food up 19% on previous year.

(The Trussell Trust UK’s largest network of food banks)

2015: 2380 Number of deaths after benefits withdrawn

http://voxpoliticalonline.com/2015/08/27/known-number-of-deaths-while-claiming-incapacity-benefits-nears-100000/

27/08/2015: Europe is having a heat wave (Spain’s worst in 30 years; >8 weeks) (Malta > 4 months)

http://www.weatheronline.co.uk/weather/maps/forecastmaps?LANG=en&CONT=euro&MAPS=vtx&LOOP=0&LAND=euro&MORE=1&UP=0&R=0&DAY=0

UK is almost unaffected by this 2015 heat wave.

How many will die this year? Will this be another wakeup call? Will it be ignored? “Oh no, its just weather”.

 

S/P      What can be done to help the vulnerable?

Moving the must vulnerable occupants away from the most, into the least, vulnerable properties, helps.

The building that are made vacant can then be refurbished in the ways described here.

Do not move less vulnerable occupants into the most vulnerable buildings, you just make them unwell and more vulnerable later.

 

P          Consequence of Overheating on low-income families

We will risk the occurrence of Fuel Poverty problems at both ends of the year

We risk needing affordable warmth and affordable coolth.

Well we already have the problem.

Government already pays winter heating allowance every year instead of insulating their buildings once.

Will this get the chop next to afford the MPs 11% pay rise and the gambling banker bonuses?

An estimated 20% of houses are vulnerable or already overheating

How long before society demands summer cooling allowance to be paid to the most vulnerable?

 

S          What next?

This paper started before the HCA UK, ARCC, EPSRC conference: ‘Overheating and IAQ in new housing’

I will update this when the seminar papers are published and I think of anything else.

Follow Twitter handles and hash tags:

@HCAUK @ARCCCN

#HCAOVERHEATING #IAQ

http://www.gov.uk/housing/design-and-sustainability http://www.arcc-network.org.uk

So what? Now what? Data sheets: http://www.arcc-network.org.uk/sowhat

Event organisers were encouraged to develop and publish Contract/Specification Performance Requirements

GBE will republish them.

GBE Overheating Images

  • Covers of documents
  • EU Overheating

GBE Overheating See Also

GBE Jargon Buster

  • Theme:
    • Overheating
    • Refurbishment

GBE CPD

  • Overheating (cut down version of this paper illustrated)

GBE Library

  • List of related documents by authoritative bodies
  • ZCH
  • DECC
  • NHBC

 

© GBE NBS BrianSpecMan aka Brian Murphy 2015


© GBE NBS ASWS BrianSpecMan aka Brian Murphy
29th May 2015 – 21st January 2016


See Also:

GBE : Overheating

Overheating Issue Paper
Images:


GBE Issue Paper Overheating: 1 Radiant V Conductive heat flows


© GBE NGS ASWS Brian Murphy aka BrianSpecMan
11th June 2015 – 27th August 2017