Whole Building Embodied Carbon Intensity: include parking in area used to normalize results?


I’m curious if there is policy, standards, or official guidance out there regarding normalizing whole building embodied carbon results by building area to obtain an intensity value (kg CO2e/m2 or /sq ft), and how parking and/or underground construction should be treated.

I’ve heard various practitioners and/or jurisdictions take different approaches to this.

There are two parts this the question:

  1. Should ALL construction of a building be included in the carbon assessment? I think this is a ‘yes’. All construction including underground spaces and building-integrated parking (parking levels) should be included in the carbon calculation.

  2. Should ALL construction area be included in the area used to normalize the GWP by? This is a bit trickier. Some folks exclude parking levels from the area quantity, and only normalize total building GWP by the habitable area (or non-parking area); while others only use above-grade areas and ignore anything below grade.

I understand that the official Government of Canada (NRC Whole Building Guidelines on LCA) is to use all the area including parking levels and any underground areas, but that others including the Canada Green Building Council prefer to use just habitable (non parking) areas to normalize by. Some jurisdictions only use above grade areas. Obviously, the area selected will greatly impact the resulting embodied carbon intensity.

Does anyone have some official guidance on this from outside Canada?

Thank you!

Hello Ryan,

That is correct; from what I understand, there is no consistency in including or excluding the basement from the building area. There are also some variations in how we define the area, such as GFA (Gross Floor Area), NLA (Net Lettable Area), GBA (Gross Building Area), NIA (Net Internal Area), etc.

AIQS (Austrian Institute of Quantity Surveys) and RICS (Royal Institution of Chartered Surveyors) are being used as a reference in Australia but not quite sure about other regions. Given the momentum in ICMS3 (Cost and Carbon Standard), I believe the RICS area definition has a high possibility of being used as a consistent definition across regions.

Regarding the references, I’ve attached a new Upfront Carbon Guideline as part of Green Star (a voluntary rating system in Australia), which defines GFA and the inclusion of basements into the analysis.


The following link is to ICMS 3


All the best,

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