Forum discussion
NC-2009 EAp2: Minimum Energy Performance
Is it possible to use PHPP software (Passive House Planning Package) for energy modeling on a LEED-NC project? Does anyone have experience with this?
Would an alternative compliance path be required? And would it be risky to use a modeling software not on the ASHRAE 90.1-2007 list of approved software? Thank you.
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Christopher Schaffner
CEO & FounderThe Green Engineer
LEEDuser Expert
963 thumbs up
October 26, 2011 - 2:16 pm
Two points
1) to my knowledge there is no "ASHRAE 90.1-2007 list of approved software"
2) to meet the requirements of 90.1-2007, a simulation program must meet all the requirements of Section G2.2.1. Among these are requirements that the program explicitly models (a) 8760 hours per year and (d) ten or more thermal zones. I'm not terribly familiar with PHPP, but I don't believe it does either of those things.
LEED has granted exceptions to projects in special circumstances, for example modeling of very simple buildings with tools like Energy 10. But in this case, I would think that the PHPP software would only be appropriate for a house, in which case, I would expect you to be using LEED for Homes, instead of LEED-NC.
Lyle Axelarris
Civil Engineering Intern, LEED GADesign Alaska
26 thumbs up
October 26, 2011 - 4:32 pm
Thank you. This is a casual inquiry, which I have not dug into too deep, so thank you for your guidance.
This is a NC project, so I have advised the person who asked me this question to make sure it meets the requirements of 90.1-2007, or use different software. Thank you again.
David Posada
Integrated Design & LEED SpecialistSERA Architects
LEEDuser Expert
1980 thumbs up
October 27, 2011 - 2:43 pm
Since PHPP doesn't do hourly simulations, it wouldn't meet the requirements of G2.2.1that Christopher mentioned. The accuracy of PHPP in predicting actual building performance has been confirmed by a number of studies, but primarily for buildings that are meeting the very stringent PH requirements for insulation, glazing U-values, air tightness, etc. For modeling a baseline code-complient building, PHPP has been less accurate, so it would be hard to use for modeling both the design case and baseline case.