Forum discussion
NC-2009 EAp2: Minimum Energy Performance
If the energy model uses net area instead of the LEED definition of gross floor area, how is this discrepnacy reconciled?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
April 13, 2011 - 4:59 pm
As long as the two values are within 5% to 10% the discrepancy is not questioned.
David Hubka
Director of OperationsTranswestern Sustainability Services
527 thumbs up
April 14, 2011 - 10:29 am
I was requested by the LEED reviewer to revise the square footage when my energy model did not exactly match the square footage denoted in the preliminary information forms.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
April 14, 2011 - 10:43 am
I'll rephrase - if the values are within 10% it should not be questioned by the reviewer.
Susann Geithner
PrincipalEmerald Built Environments
1297 thumbs up
April 14, 2011 - 11:26 am
We had to explain the discrepancy a couple of times in past projects. We showed a floor plan and highlighted the GSF, the area applicable to EA P2 (conditioned and semi conditioned area) and also for instance areas, which apply to IEQ P1. One argument, which we always made is that the GSF can't be applied to the EA P2- model, because that would result in more ventilation than actually necessary and misrepresent the buildings energy use and savings.
Mike Barker
Principal : Energy / Electrical EngineerBuildingPhysics South Africa
150 thumbs up
April 18, 2011 - 5:57 am
The US GSA has noted that even the various 2D CAD software packages are never accurate - they find up to 10% discrepancies amoung them when displaying floor areas for non-simple floorplates.
This is an issure they wish to address as they transition to BIM using ICF data models.
One good reference worth reading is "Standard Definitions of Building Geometry for Energy Evaluation" by M. Deru and P. Torcellini of NREL. This approach ties in with ASHRAE 90.1