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False illusion: no battens, no membranes just glass tiles and overheating

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Glass roof tiles

GBE Issue: Overheating (links to all overheating related pages)

GBE Problem & Solution Paper: Overheating <Previous page< >Next page>

False illusion: no battens, no membranes, no rafters, just glass tiles and overheating

False illusion: no battens, no membranes, no rafters, just glass tiles and overheating

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 replacments?

  • Bad news indeed.

Historically a glass or transparent roof tile would replace a tile or two and 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 remember seeing battens but definitely 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
  • Let wind blow rain in to soak your conductivity thermal insulation to stop it working
  • Nowhere for biodiversity, no more bat roosts under the tiles
  • Show off your roof structure, cold water and heating top up tanks, pipes 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.
  • They had a stupid idea and showed it, it remains stupid.
  • 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 round.
  • Sunspaces and greenhouses
    • But because they would be air leaky they may not be very effective

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

Glass Roof Tiles
See Also:

G#2272 “Build Light, Insulate Right, Solar Tight” • BrianSpecMan 2015

GBE Issue: Overheating (links to all overheating related pages)

GBE Issue Paper: Problems & Solutions: Overheating <Previous page< >Next page>

© GBE NGS ASWS BrianSpecMan aka Brian Murphy
1st September 2015 – 8th September 2015

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