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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
  • I had originally considered Spon pricing books but the discussions I 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.
  • I will seek Manufacturer’s and Suppliers support to populate the products spreadsheets with cost data.
  • There is a QS who wanted to build the Green Building Price Book 20 years ago, if GBC takes off and generates revenue then I will ask him to 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, I know many may not go that way and may focus on lowering embodied carbon (EC) raising sequestered carbon and IUC in use carbon.
  • I have developed the whole building & elemental calculators to determine the demand heat source(s) size
  • I 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 I bring it forward, I probably will)
  • I have met the man who can help me to build this module, I will engage with him once version 2 is published.
  • I am adding a Services Bill of materials/quantities/costs, EE EC & LCA in version 2 (bringing parts from v3 and v6 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, Minergie, 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 some 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 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 so 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 2020
  • Version 2 will be October/November 2020
  • 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 is mostly included in 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 GBC GBL
14th September 2020


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