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GBC About (Calculator) G#38802

By 31 October 2020December 13th, 2021Calculators, Encyclopaedia, Files, Whole Building
GBE Green Building Calculator LogoOnly Draft PNG

GBC About Calculator

GBE > Encyclopaedia > Files > Calculators > Whole Building Calculators > G#38802

GBC About Calculator

GBE Green Building Calculator Logotype Draft PNG

GBC About:

  • The GBE Green Building Calculator ‘GBE GBC’ provides a low-cost Energy Performance and Cost analysis tool for new building designs, for those not engaging in PHPP planning tool, or SAP, SBEM, IES, etc. calculations.
  • This Microsoft Excel calculator was originally developed to permit Post Graduate Architecture students to analyse their own studio building projects.


  • Brian Murphy, Founder of Green Building Encyclopaedia (GBE) created the spreadsheet and he has continued to update and expand it.
  • The consistent results meant that different building shapes, methods of construction, materials choices and resultant energy demand and consumption could be easily compared.
  • My part-time students all took the file to their offices and started applying them to their live projects.

For a Future:

  • With XR Extinction Rebellion, Greta Thunberg’s behaviour change campaign, Architects Declare, ACAN and many other groups and Government bodies declaring and becoming involved in environmental design in a bigger way, we have a chance to engage designers in more scrutiny of what they design.
  • So GBE have restarted development of a calculator that can be useful to enable many more to engage more robustly in meeting new targets as they become commonplace.
  • Moreover they will be able to understand why 50 mm of stone wool insulation, shown in the aging textbooks, is no longer enough, do their own U value calculation independently of manufacturers who will do them for free, if users pay for their insulation. (Whether it is appropriate or competent in that location in the construction)


  • GBE has developed this as an MS Excel calculator (so far) for a number of reasons:
  • Its open-book, not a black box, no hidden pages, all cells accessible to interrogate the calculations
  • It allows for user access, interrogation, greater understanding and learning opportunities.
  • Many will already have and may be familiar with (MS Excel) which enables a larger audience of users a quick way into building analysis.
  • It also allows users to customise, manipulate and develop bespoke versions for the user’s organisation
  • GBE will maintain a stakeholder group to encourage customisation to be shared to be considered for development into the core file for the greater good.
  • Having a large number of users some customising may help with feedback loops developing the Calculator with more features and stronger datasets
  • Other options considered but not adopted yet include Database, if data and version upkeep needs to be delivered and controlled more robustly we will consider this.

Quality Management

  • As a nod to QA procedures all actions are date stamped, and actions recorded in a revision table, if multiple developers become involved then initials will be added against actions.

Scope at GBE launch:

  • Whole Building and Room by Rooms Schedule of Accommodation, areas and volumes, hours of operation, design temperatures, inside and out
  • Room by room heat loss calculator to determine radiator or underfloor heating requirements
  • Analysis of Form Factor and optimal U values to respond to them
  • Elements and secondary-elements are selected from ready-made lists to match the project, their dimensions added by user and their areas are automatically calculated.
  • Since windows and doors come in a multitude of sized then a schedules allows their incorporation
  • Allows users to compare and choose between Building Regulations Part L, LETI, AECB CarbonLite, Passivhaus, EnerPHit, EAMs, etc. including: U values, Airtightness, Form factors, Elevation window %.
  • Automatically see what thickness of different k value insulation materials is needed to meet U values
  • Allows the user to populate and assemble elements by choosing their combination of functional components and then choosing the materials for each component.
  • Costs of insulation and windows are added here to help persuade architects and clients to spend money on insulation and higher performance windows and glazing
  • Allows Architects to cost plan their projects with a Bill of materials, quantities, labour and costs based on building fabric only so far. (Non-external envelope elements and services to be developed)
  • Started building a dataset of materials and products with performance and costs to add to and populate the calculator (Supplier and manufacturer collaboration needed to populate these further)
  • Element Summary to compare calculated U values with selected or target U values
  • Calculates energy losses from each element and secondary-elements to give total losses or demands
  • Calculates each element and secondary elements total demands as a % of the whole
  • Allows comparisons to be made by the user to prompt reconsideration of earlier decisions
  • To spend more money on insulation or better windows to reduce running costs

COVID-19 Lockdown Development

  • Due to the weekly time pressures during the initial creation the content was restricted.
  • Many of the original ambitions remained in separate calculators
  • So the plan is to continue development if demand shows it is useful or required
  • An Architect Client of GBE asked for a Retrofit Calculator for Victorian Terrace this has been started by adding more elements.
  • During Coronavirus Lockdown in between Lockdown Learning On-line CPD the opportunity arose to continue with this calculator’s development.


  • Additions to developed:
  • Refurbishment Elemental Assemblies (started)
  • Embodied Energy, Embodied Carbon, Sequestered Carbon (merging in existent GBE Calculator)
  • Secondary Element Calculators: (Frame %, Ug, Uf, Uw, U values, G Values, datasets) (started)
  • Decrement Delay (using existent equation and data sets) (started)
  • Condensation Check (using existing dataset)
  • Product Datasets: k or U values, Thicknesses, Insulation, Glazing, Building fabric (started)
  • Cost planning: adding non-envelop elements and services to existing building fabric calculations
  • 892 readymade competent elemental assemblies (Using existing mothballed GreenSpecStudio datasets)
  • Create date: 25/03/2018
  • Last edited date: 30/10/2020

© GBE GBC GBL NGS ASWS Brian Murphy aka BrianSpecMan **
31st October 2020

GBC About Calculator
See Also:

GBE Satellite Website

GBC Green Building Calculator

  • GBC Introduction (Calculator) G#38491
  • GBC About (Calculator) G#38802 (this page)
  • GBC ScreenShots (Calculator) G#38796
  • GBC Development Versions (Calculator) G#38792
  • GBC Features Benefits (Calculator) G#38788
  • GBC Case Studies (Calculator) G#38___
    • Architectural Competition Entry (Calculator) G#38___
  • GBC Building Type Analysis (Calculator) G#38___
  • GBC Bespoke Developments (Calculator) G#38___


GBE Past Event

GBE Shop

GBE Video

GBE Projects

GBE Calculator

Psi calculation

WasteCost® Lite

Whole Building Calculators

GreenGauge Advanced Details

GBE Datasets

  • ICE for (EE EC SC Database v3) (currently using 1.6)
  • ICE Database (Jargon Buster) G#1018 N#1037

Thermal Mass Calculator

LCA and EPD datasets

Decrement Delay

Condensation Check

© GBE GBC GBL NGS ASWS Brian Murphy aka BrianSpecMan **
31st October 2020 – 13th December 2021

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