Green Building Calculator

Create Greener Buildings

Green Building Calculator

GBE Green Building Calculator provides information regarding whole building Energy Consumption, Carbon in use, Cost of building and Cost of running a building.

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

Version 2 will include 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:

  • Clients: to do their own project analysis
  • Self Builders: to check that quotes with specifications meet building targets, before they buy
  • Building Designers: Architects, Technicians and Technologists, CAD users, Surveyors, M&E Engineers, D&B Constructors, Small Builders
  • Design Students: to evaluate their studio designs to help ensure they are future-proof and competent
  • 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
  • Facilities & Property Managers: For in-house adaptation and churn activity
  • University Lecturers: to introduce the potential sophistication of building information analysis outside of BIM CAD

Easy to use

  • Instructions at every step:
    • for rows, columns, ranges of cells and individual cells
    • colour coded cells to help show where to engage or not
    • editable cells are open others are locked
  • 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 in your project
  • GBC carries out as many calculations as possible from the data provided and choices made
    • and asks for more data when necessary to calculate something new

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 has both simplistic and detailed tables in many worksheets
  • Many more hours will go into adding more functionality over the following months/years.
  • Over 29 versions are envisaged already, more will be added as GBC progresses

Some of the features of Version 1

  • Whole Building and Room-by-room schedule of accommodation: add dimensions, areas and volumes calculate automatically, add: hours of operation, design temperatures inside and out
  • Room-by-room heat loss calculator: determine radiator or underfloor heating requirements; to size the boiler or insulate to meet the boiler size.
  • Analysis of Form Factor: optimal U values to respond to them, thickness of different insulation materials
  • Elements and secondary-elements: select from ready-made lists to match the project; dimensions are added by the user and their areas are automatically calculated
  • Schedules of windows, rooflights and doors: as they come in a multitude of sizes
  • Building Performance Targets: Users can compare and choose between:
    • Building Regulations Part L, LETI, AECB CarbonLite, Passivhaus, EnerPHit, Environmental Assessment Methods, other national standards, etc.
    • including: U values, Airtightness, Form factors, Elevation glazing percentage and orientation
  • Automatically and instantly see what thickness of different k-value insulation materials is needed to meet targeted U values
  • Elemental Assemblies: Allows user to choose a combination of functional components and then choose the materials or products for each component
  • Costs of insulation, windows and energy savings: Helps users to persuade clients to spend money on insulation and higher performance windows and glazing (Version 1)
  • Bill of materials, quantities, labour and costs:
    • enables cost planning and proper value engineering (Version 2)
    • based on building fabric only (Version 2) services  in later versions
  • Element Summary: compare calculated U values with selected or target U values. highlighting ‘pass’ of ‘fail’
  • Summary of calculated energy losses or demands:
    • For each element, secondary-element and whole building
    • Totals elements and secondary elements as a percentage of the whole
  • Allows comparisons to be made, by the user, to prompt reconsideration of earlier decisions

GBE Green Building Calculator provides a low-cost way into Environmental design and Specification.

It improves on some aspects of BREEAM and Green Guide to Specification to avoid the greenwash.

GBE Green Building Calculator produces real calculations for real buildings with generic materials and/or real products.

GBC Versions 2

Green Building Calculator V2 is being developed now, including:

  • Retrofit:
    • Historic fabric element upgrades, inside or out
    • Add domestic furniture fixtures & equipment
    • Add domestic services,
    • Add solar shading, decking, pergolas,
    • Add hard and soft landscape
  • Bill of materials, quantities, labour and costs
  • Embodied Energy, Embodied Carbon, Sequestered Carbon Calculator (EE EC SC)
    • ICE Database v1.6 > v3 (for EE EC)
  • Life Cycle Analysis & Environmental Product Declaration results
    • Add LCA and EPD data sets
  • Decrement Delay Calculator (overheating prevention)
  • Condensation Check
  • Domestic Landscape Elements
  • Basic Civils & Infrastructure Elements
  • More Generic Material datasets
  • Domestic MEP Services

Version 3 to 29

  • Green Building Calculator will be updated continuously during the following years adding many planned features
  • See: List below
  • See: GBC Development Versions (Calculator) G#38792

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.
  • Engage 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
  • 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.

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 to students and graduates

  • Allows students to enhance their philosophy and snappy graphics 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.

Version 3 and beyond

Versions 3 to 29 will develop, seek support to develop or seek licences to include:

The order is subject to GBC user feedback:

  • Non-domestic Landscape Elements
  • Non-domestic Furniture Fixtures & Equipment
  • Non-domestic MEP Services
  • More Generic Material datasets
  • More Product Datasets
  • Civils & Infrastructure Elements
  • Waste minimisation and recycled content
    • GBE’s WasteCost®Lite calculator
  • Thermal bridge & Psi values
    • GreenGauge Advanced Details
  • Thermal Mass Calculator
  • Plastics Avoidance or use of recycled content
  • BIM Apps for numerous CAD software
  • Whole Project Budget calculations (Fees, overheads, profits, preliminaries, etc.)
  • EU and International versions


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

  • It is open-book, not a black box
  • Close to open source principles adopted, 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
  • Many users are already familiar with MS Excel which means that more people can access a quick way into building performance analysis

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.

Future Development

  • GBC will maintain a stakeholder group to ensure we make what you want and need
  • Having a large number of users will help with:
    • error detection, feedback loops, encouraged by free upgrade versions
    • developing GBC Green Building Calculator with more features and stronger datasets
  • We will encourage customisation requests to be shared; ideas will be considered for development into the core file for the greater good
  • Users will be invited to review the 20 version’s order of development, in case users want something sooner, by popular demand

Early User Feedback

“Green Building Calculator is an amazing product. Both novices and advanced users will appreciate this calculator. It is just the tool that the industry and practitioners need!”

DJ Maloney via LinkedIn


If you have not seen this calculator yet, here it is people! What a fantastic tool this is created by BrianSpecMan Murphy at GBE Get stuck in

DJ Maloney via LinkedIn

#sustainabledesign #sustainableconstruction #sustainablesolutions #thefutureisbright #retrofitting


Green Building Calculator brings material properties, embodied carbon and costs all in one place

Brian’s Green Building Calculator (GBC) is a tool designed for the Specifier to select the optimum product to achieve Green.

Martin West RIBA MSt Cantab of Syndicate West Architects (former Director of RHWL)

Pricing: Version 1

  • Student: £4.88
  • 1 – 3 person practice: £48.88
  • Larger practice: £98.88
  • Self-Builders: Wales TAN6 OPD: £4.88
  • Self-Builders: Others: £48.88

Price of 20 versions will increase progressively with increased functionality

Crowd funding is an option GBE have considered to speed up 20 version development.

Bespoke versions


  • Student and lecturers price as above
  • Lectures regarding functionality, building performance, low carbon building, datasets, equations, calculations, results, future development
  • Zoom Live or recorded demonstrations
  • Post pandemic (COVID-19): In-University lectures, demonstrations, analysis of results
  • Price on Application (free software option: Version 1)

Support: Users

  • Email helpline:
    • Email questions and responses will be added to new page or FAQ
  • Coming soon:
  • Live Zoom: introduction, including demonstration, coaching and training.
  • Recorded Zoom: available from Vimeo/YouTube after live events.
  • Powerpoint CPD: GBE Green Building Calculator + GBC Future Development.
  • Telephone Helpline: To be announced, if found necessary.

Support: Bespokers

  • Support by Email, Telephone Helpline or Video call package
    • Questions and responses will be added to new page or FAQ

Support: Manufacturers and Suppliers (Dataset providers)

  • Stakeholder steering group: including manufacturers and suppliers
  • Email helpline:
    • Email questions and responses will be added to new page or FAQ
  • Zoom meeting to introduce opportunity to be included in Green Building Calculator
  • GBC Product Import Spreadsheet:
    • Download latest (once completed) for free
    • Completed by you, at your speed, at your expense
    • Audited by GBC for correction or completion by you or by GBC
    • Products, Accessories and Systems
    • Sizes, properties and certification
    • Appropriate Competent Applications
    • Specification Clauses
    • Suppliers
    • Correlation to any BIM Models & Product Data Files
  • Coming soon:
  • Guidance for completion of Import Spreadsheet
  • Live Zoom: introduction, including demonstration.
  • Recorded Zoom: available from Vimeo/YouTube after live events.
  • Powerpoint CPD: GBC Green Building Calculator + GBC Future Development.
  • Telephone Helpline: To be announced, if found necessary.

Green Building Encyclopaedia

Green Building Encyclopaedia (GBE) is a growing information resource about creating healthy, environmental and efficient buildings – giving you the know-how to be able to engage robustly with these and other issues and still have the freedom to make them beautiful.

GBE includes design advice, guidance and technical detail regarding the selection, design or specification of building methods, materials, services, systems, products and whole buildings.

The GBE Green Building Calculator is abbreviated to: GBE GBC

GBC Pages on Green Building Encyclopaedia

GBC Latest Additions


Green Building Calculator Awards

GBC V1 Green Apple 2020 Award. View of V2

International Green Apple Award 20210 for Environmental Best Practice Carbon Reduction Silver Winner National Green Specification


Green Apple Award 2020 Winner logoGreen Apple National Silver Environment Award 2020Prestige Awards Central England 2020

GBC Awards Long and short listed but no prize:

ASBP Awards 2021 Logo PNGConstruction Computing 300 x 300

GBC in ASBP Newsletter

ASBP 2021 Award Video Long list PNG

GBC Video in ASBP Award entry long-list

  • 11 entries 7th is Green Building Calculator
  • Version 2 is still under development (January 2021)
  • GBC V1 did not make the shortlist
  • Awards Announcements at Healthy Building Conference
  • 25th February 2021

GBE Events

  • Think BIM Accelerating Change Summer Conference
  • 26th May 2021
  • GreenBIM 2021 Webinar
  • Digital Sustainability Technology Panel Discussion
  • Presentations by:
    • Lee Barnett, Curtins
    • Brian Murphy, Green Building Calculator
  • Panel Discussion:
    • Lee
    • Brian
    • Johanna Jarvinen, One Click LCA
  • Slido Survey
    • Qs set in advance by panel members

Green Building Calculator

© GBE GBC GBL NGS ASWS Brian Murphy aka BrianSpecMan **
11th June 2020 – 7th June 2021