I want to figure out the default number to use to calculate how much green power in RECs a building would need to purchase. The RG that I have states 11.7 kWh/SF-yr for Office. The sample form online shows 17.3 kWh/SF for Office. I’m still unclear if these are already 35% of the total or if I have to take 35% of the default number. And I assume I need to multiply by 2 (70%) because it needs to be for 2 years. I also am not sure which default number to use. I can’t find an addendum on it. Anyone have any insight?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
August 26, 2012 - 2:24 pm
The difference is between the 1999 CBECS data and the 2003 CBECS data. The 11.7 is from the 1999 survey and the 17.3 is from the 2003 survey. I remember pointing out the oversight in the RG several years ago (LEED 2009 should have clearly been based on the most recent CBECS data which remains 2003) to USGBC/GBCI when I was chair of the EA TAG. I also could not find an addendum or interpretation on the subject so I am not sure if the change was published anywhere or not (unfortunately not unusual). Apparently it made it into the credit form however.
Kathryn West
LEED AP BD+C, O+M, Green Globes ProfessionalJLL
154 thumbs up
January 20, 2014 - 2:30 pm
what the heck? I'm searching now to find when this was changed. My project registered prior to the addendum requiring that the energy model number be used. So I was looking into CBECs. It's a public assembly and the 2003 data is about 2 times as much as the 1999 data.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
January 20, 2014 - 7:23 pm
If you buy the cheap RECs double next to nothing is still not very much for many projects.