Your Questions GBC Answers

GBC > Q&A > C#344

Your Questions


My directors have asked me to look into the Green Building Calculator and I was wondering whether you could please help me with a few queries I have?

GBE Answers


Thank you for your Director’s enquiry, very happy to answer.

  • In your description it says that it provides cost information of different materials.
  • Where does this information come from?
  • Is this something that we will have to get from manufacturers and input it manually or does it connect to a database?
  • Initially the file is populated by your own enquiries from manufacturers and suppliers
  • At Tender stage it can be populated by your tenderer/contractor as a pricing document
  • This information could be used to populate your own rough prices look up table
  • GBC had originally considered Spon pricing books but the discussions we have had suggest these are not reliable enough and may be contributing to QS’s poor cost planning and the ‘race to the bottom’ our industry is experiencing.
  • GBC will seek Manufacturer’s and Suppliers support to populate the product spreadsheets with cost data.
  • GBC have access to LCA datasets that also include cost data, these will be considered for inclusion in GBC but we will seek confirmation from manufacturers
  • 20 years ago there was a QS who wanted to build the Green Building Price Book, he is now retired, we have discussed what he planned then, if GBC takes off and generates revenue then GBC will reengage with his ambition and embed it in GBC.
  • How it compares with the PHPP software?
  • I understand that this calculator explores different heating options and doesn’t rely solely on a heat recovery system like Passivhaus, but in terms of the other calculations it does, how does it compare?
  • Does it have the same extent of calculations?
  • My practice is unclear on which licence to purchase.
  • This is not equivalent to PHPP, however you can get an impression of what PH or EnerPHit (or AECB’s Carbon Lite & CL Retrofit) will do to your building’s U values, Insulation thicknesses, if you choose it as your energy target.
  • Whilst PH is a great route to low energy in use, GBC knows many may not go that way and may focus on lowering embodied carbon (EC) raising sequestered carbon and IUC in use carbon.
  • GBC have developed the whole building & elemental calculators to determine the demand heat source(s) size
  • GBC have also developed the room by room calculator to work out radiator/UFH coil sizes or start with boiler size and work out insulation thicknesses to match the boiler.
  • This version of GBC calculator does not have a Services Design Function yet (Version 16 unless we bring it forward, we probably will)
  • GBC have met the man who can help to build this module, GBC will engage with him once version 2 is published.
  • GBC is adding a Services Bill of materials/quantities/costs, EE EC & LCA in version 2 (bringing parts from v3 and v6 much sooner)
  • PHPP software compares the calculated version to the Passivhaus criteria (so gives a benchmark).
  • In your description it says it does a comparison with different standards.
  • Does this mean that it will provide the various criteria for Passivhaus,  BREEAM etc?
  • After a Form factor calculation you are promoted to set your U value targets, then you choose between Regulations, which should be local to the project (e.g. E & W, S or NI or other national standard) and design standards: UK GBC, ZCH, PH EnerPHit, CL, CLR, BREEAM, etc. targets
  • You choose and set targets, the U values permeates the calculator, when you assemble your building elements it tells you Pass, Unregulated Pass or Fail.
  • This may equate to your benchmarking?
  • You can then adjust insulation thicknesses to get Pass all round.
  • You should use PHPP for PH calculations not GBC.
  • This calculator will help with BREEAM area calculations and speed up some of the tedious fruitless calculations.
  • These calculations are useful as part of the design process, rather than totalling up and changing nothing.
  • Version 2 will have LCA calculations in it. (Brought forwards) 
  • This is based on your own specific or bespoke elemental assemblies, so it is not restricted to the 1200 or so in Green Guide to Specification.
  • You get an instant answer without waiting for BRE to do their bespoke calculations for you.
  • In time GBE Product datasets will have useful data to support Passivhaus, BREEAM, etc.
  • Is version 3 the latest one on the market?
  • It has a lot of attractive functions!
  • Version 1 was released June-July 2020
  • Version 2 will be Spring-Summer 2021
  • Version 2 is being developed with Embodied Energy, Embodied Carbon, Sequestered Carbon, LCA, Bill of materials, Quantities, etc.
  • Version 2 should be the one that is needed by many
  • Version 3 functions are mostly included in the latest scope of version 2
  • Do let me know which functions are of interest from version 3 if any have been missed out.

© GBE GBC GBL NGS ASWS Brian Murphy aka BrianSpecMan **
Satellite Websites: GBE GBL
14th September 2020 – 29th April 2021


Your Questions GBC Answers