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Green Building Calculator (GBC)

Green Building Calculator GBC Version 1 provided information regarding whole building Energy Consumption, Carbon in use, Cost of building and Cost of heating a building.

It is an impartial, easy to use, value for money product that can make a real difference to the world around us.

GBC V2 includes carbon footprint calculator for homes and non-domestic buildings
It is aimed at architects and interior designers but useful for all designer disciplines, self builders and constructors.

Different building shapes, methods of construction, materials choices and resultant energy demand and consumption can be compared easily.

With XR Extinction Rebellion, Greta Thunberg’s behaviour change campaign, Architects Declare and Architects Climate Action Network, as well as Government bodies declaring and becoming involved in environmental design in a bigger way, architects and other professionals now have a quick way of creating greener buildings or easing their way into the ‘New Normal’.

Moreover, they will understand why 50mm of stone wool insulation, shown in the ageing textbooks, is no longer enough and sometimes has the wrong properties for the application.

Users will be able to do their own U value calculation independently of manufacturers or suppliers who will do them for free, if using their products.

The GBC Green Building Calculator has been created for:

  • Building Designers: Architects, Technicians and Technologists, CAD users, Surveyors, M&E Engineers, D&B Constructors, Small Builders
    • Particularly aimed at those not using BIM 3D CAD software
    • But will develop a BIM interface in due course
  • Design Students: to evaluate their studio designs to help ensure they are future-proof and competent
  • University Lecturers: to introduce the potential sophistication of building information modelling outside of BIM 3D CAD
  • Advisors: EPC, BREEAM, SAP, SBEM Assessors, Home Energy Advisors, Energy Consultants, Overheating Assessors, Building Performance advisors, Carbon reduction consultants
  • Developer’s Team: Evaluating House type, Wall thicknesses, Plot widths, Site planning, Regulation compliance or improvement, Marketing on Carbon and Building Performance
  • Constructors & Contractors: Design & Build Contractors on Tender Design Development, Contracts with Design Portion, Energy Performance Contracting, Specialist Subcontractors; for cost of variation or substitution evaluations, tendering.
  • Facilities & Property Managers: For in-house adaptation and churn activity
  • Self Builders: to check that quotes with specifications meet building energy targets, before they buy
  • Clients: to do their own project analysis

It also enables manufacturers and suppliers to place their materials, products and their property and cost datasets to populate the calculator with appropriate products in correct applications.  See also:

Easy to use

  • Instructions at every step: (Version 2 instructions to follow shortly)
    • for rows, columns, ranges of cells and individual cells
    • colour coded cells to help show where to engage or not
    • editable cells are open, calculated for you cells are locked
    • Video Instructions will follow too
  • Add your project data:
    • Dimension and numbers
    • Design Targets: Design Life, Temperatures, Hours of operation
  • Choose:
    • Drop Down Lists of Multiple Choice Answers,
    • Lookup tables that populate ranges of cells from datasets
    • Less typing, Less risk of errors
    • ‘Yes’ for Inclusion or ‘No’ for exclusion of elements and components in your project
  • Switches:
    • Turn on or off more layers of sophistication in calculators: examples:
    • Windows: all same size (e.g. offices) ar all different (e.g. houses)
    • Temperatures: all rooms the same or some different
  • GBC carries out as many calculations as possible from the data provided and choices made
    • and only asks for more data when necessary to calculate something new
    • some cells auto-calculate and auto-fill
    • some auto-calculated cells can be overwritten to accommodate variations

Development time:

Version 1 took 440 hours to create and launch,

  • The more hours GBC spend the less hours you need to do the same tasks yourself
  • In GBC’s view: perfection is not the enemy of good
  • GBC includes both simplistic and detailed tables in many worksheets
  • Many more hours will go into adding more functionality over the following months/years.
  • Over 35 versions are envisaged already, more will be added as GBC progresses
  • GBC welcomes suggestions for improvements/corrections (See feedback form)
  • GBC welcomes your priorities for development versions (See survey form)

Bespoke Version B2 took 700 hours to create

  • It is designed to address existing building refurbishment “retrofit”
  • STBA Sustainable Traditional Buildings Alliance are developing it into Options Appraisal Tool
  • Extracted from GBC to become stand alone GRC V1 Green Retrofit Calculator Version 1
  • What has been learned in this development have already started being added back into to GBC V3

GBC Version 2 has taken 1750 hours of development,

  • Announced at Futurebuild 2022 on 1st March 2022
  • Launched 20th April 2022

Bespoke version B6: 850 Hours

  • Interreg Energy Pathfinder project specific development
  • 2 Scottish Island Options Assessments 8 properties and 6 surveys
  • Required additional development (beyond B2) to address:
    • other building types
    • other elements (party walls and party floors)
    • methods of construction (concrete walls and roofs)
    • other materials
    • scenario optioneering and recording
    • summary
    • Survey printed sheets
    • After Interreg Project:
    • Survey smart tablet interface to feed any building type into calculator

Multi-functional Green Building Calculator benefits

  • Multi-functional calculator that addresses many issues to support designers
  • Brings together many calculations in one place, all interlinked so one change filters throughout instantly
  • Energy Performance, Carbon Impacts and Cost analysis tool all in one place
  • An opportunity to do real Value Engineering not cost cutting in disguise
    • E.g. Analyse the result of spending more money on more insulation and/or more expensive glazing choices
  • Embodied Carbon, Sequestered Carbon, Carbon-In-Use calculations
    • for reporting and competition entries
  • V1 for new build and V2 addresses refurbishment in a comprehensive way
  • Not replacing but adding to PHPP, SAP, SBEM, IES, calculations
  • All the parts are in place, correctly formatted, linked to correct data sources, so no more searching your ‘college-knowledge’
  • Does what you want, but thought that you
    • could never do yourself
    • had to pay an arm and a leg for
  • Enables
    • Broader service offering to clients
    • Less reliance on external consultants
    • More in-house skills
  • Saves you time, gives you more

Brian Murphy, Founder of Green Building Encyclopaedia (GBE) created the original components of GBC and he has continued to merge them, add to it, update it and expand its capability.

What it means to declarers

  • Architects Declare, Construction Declare, Education Declare, Structural Engineers Declare, Interior Design Declare
  • Engage robustly with Climate Emergency.
  • Engages with RIBA 2030 Climate Challenge.
  • Enables Architectural competition entries to be supported by competent performance and carbon data.
  • Enables engagement with Architects Climate Action Network campaigns.
  • Preempts Regulatory Changes (Building Regulations Approved Document BRAD Z)
  • Plans to address absent solutions in Regulations (BRAD O)
  • Enables engagement with UK Government Net Carbon Ambitions
  • Enables engagement with National Infrastructure Strategy

Business opportunities

  • Addressing Climate Emergency can become part of user’s ‘New Normal’
  • Enable users to consider alternative scenarios
  • Enable users to offer ‘Deep-retrofit-first’ to their existing clients and attract new Climate-Emergency focused customers
  • Invites not yet engaged developers and clients to join in

What it means to your Practice activities

  • Gives users access to equivalent tools that would otherwise be unaffordable.
  • Facilitates behaviour change by providing data for comparison and justification of better long term choices.
  • Enables defence of good decisions in ‘Value Engineering’, Cost cutting and ‘Substitution’ exercises.
  • Helps users make better well-informed evidence-based decisions at every stage
  • Allows easy consideration and comparison of better than ‘Business as Usual’ and ‘Legal Minimum’ regulations.
  • Allows easy consideration and comparison of Passivhaus, CarbonLite, LETI energy standards over regulations.

What it means to one person and small practices

  • Users can become autonomous and do some additional consultancy services themselves.
  • Enables users to understand their designs better than they may have done before
  • Enables users to do much more than they could before.
  • Outputs feel like more than one person’s efforts

What it means for Universities

  • GBC spent half a day with Plymouth University explaining GBC V2 to users
  • The university staff immediately appreciated the educational opportunity of using GBC V2 with Architectural and related profession students
  • GBC V2 addresses so many design issues simultaneously
  • Many of the issues are not being taught on courses.

What it means to students and graduates

  • Allows students to enhance their philosophy, aesthetics and snappy graphics education with future-facing know-how to become climate emergency competent and eminently employable
  • Students and graduates can acquire new skills for their CV that many Practices do not yet have.
  • Enables ‘year-outs’, graduates and young professionals to bring new services to Employer’s attention.
  • Enable ‘Grey Hairs’ to keep up with induction graduate’s expectations.

What it does not do

It does not replace AECB’s CarbonLite & CL Retrofit or Passivhaus’s PHPP and EnerPHit but enables many to experience what they do to a building that is future-proofed and comfortable.

Users wanting to do Passivhaus need to get formal training before they can focus more on the thermal bridge and air tightness details, calculations, etc.


GBE has developed this product as a MicroSoft Excel calculator because:

  • Many users are already familiar with MS Excel which means that more people can access a quick way into building performance analysis
  • For students who have not been introduced to MS Excel an App and snappy user interface will be developed after the calculations have been mastered
  • Cell functions are colour coded for ease of navigation
  • Instructions will follow shortly
  • It is open-book, not a black box
  • As close to open-source principles adopted, Excel Functions only, no macros allowed
  • All worksheets and cells are visible to see the calculations in action and double check the results
  • It allows user access, interrogation, greater understanding and learning opportunities
  • Carbon literacy is the aim: intuitively knowing what low carbon construction looks like and is

For GBE Green Building Calculator integrity:

  • Worksheets are locked and input cells only are editable
  • No damage should be possible to the calculator functions

In due course a BIM app will be inevitable, there may need to be an interface outside of Excel and inside CAD/BIM software.

Support: Users

Coming soon:

  • Live Zoom: introduction, including demonstration, coaching and training.
  • Recorded Zoom: available from YouTube after live events.

Support: Bespokers

Manufacturers, suppliers, installers and dataset providers

Green Building Calculator Awards

Green Building Calculator Events

GBC tags & long tail keyword phrases

  • Carbon (C)
  • Carbon dioxide (CO2)
  • Embodied carbon (EC)
  • Not the same as embedded carbon
  • Up front carbon (UFC)
  • Sequestered carbon (SC)
  • Biogenic carbon (BC)
  • Low carbon building (LCB)
  • Carbon negative (CN)
  • Carbon positive (CP)
  • Carbon in-use (CIU)
  • Carbon calculator (CC)
  • Building carbon calculator (BCC)
  • Whole building carbon calculator (WBCC)
  • Green building carbon calculator (GBCC)
  • Green Building Calculator ™ (GBC)
  • Carbon counting
  • Carbon accounting
  • Whole Life Carbon (WLC)
  • Design and decision tool (D&DT)
  • Life cycle assessment (LCA)
  • Environmental product declaration (EPD)
  • Environmental building declaration (EBD)
  • Pay-back period (PBP)
  • Carbon-back period (CBP)

Green Building Calculator

© GBE GBC GRC GIC GGC GBL NGS ASWS Brian Murphy aka BrianSpecMan ******
11th June 2020 – 16th March 2024

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