The project is a CI retail project that only use electricity as energy supply. And we are going to use CBECS data to calculate the amounts of the Green Power and Carbon Offset. So I`d like to know if we can ignore the Carbon Offset we calculated and only purchase the Green Power because the project doesn`t use non-electricity fuel.
Thanks in advance!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5914 thumbs up
October 31, 2017 - 11:23 am
If the project is all electric then all you would need is green power.
Landry Watson
Assistant Vice President - SustainabilityAlexandria Real Estate Equities
29 thumbs up
April 10, 2018 - 11:53 am
It is understood that we have the ability to opt for just green power if we have a project that will utilize only electricity. However, does this mean that we utilize only the value of Total electric energy (CBECS Table C14) - from the ref guide on Table 2 (Renewable Energy Production) -- for example 17.3 kbtu/sf for an office?
What is the column for CBECs C3 used for and why is it not the total of the total electric (C14) and total non-electric?
From the ref guide calcs it certainly indicates that for a electric/fossil combo system you'd use the SF of the project times both of those individual values to obtain your full kbtu/sf value. If I use only the electric value to compute...it would seem as if I'm ignoring any consumption for heating or perhaps DHW in the project. Any thoughts or experience on this is appreciated...thank you.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5914 thumbs up
April 10, 2018 - 6:47 pm
The total does not add up because the electric is expressed in kWh/sf and the gas usage and total are in kBTU/sf. If you convert the electric to kBTU the numbers add up. For an all electric building I think you should use the total value (CBECS C3) to calculate how much green power you would need. I come up with 27.22 kWh/sf.
Landry Watson
Assistant Vice President - SustainabilityAlexandria Real Estate Equities
29 thumbs up
April 11, 2018 - 12:45 pm
Thank you Marcus, I should have caught that. For all visitors to this thread, the Reference guide Table 2 indicates kbtu/sf -- but as we've just confirmed, the actual CBECS Table 14 contains the same values and is properly listed as kWh/sf. Not sure if that typo has been picked up by an update or amendment...but take note if trying to calculate consumption for either the RE credit or the Green Power credit.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5914 thumbs up
April 11, 2018 - 1:10 pm
I use the online Reference Guide so it would have been changed with any update. The table in the online Reference Guide indicates kBTU/sf for the total, kWh/sf for electric and kBTU/sf for gas to make the calculations straightforward for most projects. For an all electric building just convert the total column. kBTU/sf / 3.413 = kWh/sf.
So are you saying that the print Reference Guide has kBTU/sf for the electric column? If so that typo was fixed with an update. This is the major reason I stopped using the print Reference Guide, it is hard to keep up with all the updates.