Hi there,
When a proposed building model includes parking garage DCV based on CO - How should the control of the baseline model garage fan volume be controlled?. Should the baseline model also control ventilation based on CO level or can it be at a fixed volume? ASHRAE 90.1 doesn't seem to describe control methodology or schedules for parking garages which is surprising given how significant the energy consumption can be.
We have submitted preliminary design stage documentation and had provided an exceptional calculation with fixed flowrate control for the baseline model and the proposed based on CO. We received the following comment back from the assessor:
"The Baseline case description should provide evidence that garage demand control ventilation is not standard practice for similar newly constructed facilities (three facilities built within the past five years of the project registration date) where the project is located"
Where does this requirement come from? - it's certainly not in ASHRAE 90.1. Why is DCV for parking garage extract so special that it needs to be demonstrated it's not common practice at the site location - we don't need to do this for any other energy conservation measures?
The prerequisite criteria is based on demonstrating a percentage improvement compared to ASHRAE 90.1-2007 - not compared to what is typical practice at the site location...
I would have thought LEED would be promoting DCV rather than making it more difficult to achieve credit for doing the right thing.
Cheers
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
November 20, 2015 - 4:59 pm
The reason this is treated this way is that some codes in some areas require this strategy. This is a process load (90.1-2007 does not regulate it) and savings must be claimed via an exceptional calculation. The baseline for an exceptional calculation is always related to standard industry practice in that particular location. You don't do it for may other strategies because 90.1-2007 gives us the baseline, in this case it does not.
Scott McMillan
9 thumbs up
November 22, 2015 - 12:54 am
Thanks Marcus,
Slightly confused however, as the LEED 2009 credit language includes parking garage ventilation as regulated (non-process) energy in the list of examples:
"Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes"
So if its considered non-process (in LEED 2009 anyway) we shouldn't be required to demonstrate that DCV is not common practice.
Worth a try arguing that do you think?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
November 23, 2015 - 9:56 am
I see your confusion. However, I don't think you have a leg to stand on when arguing this. 90.1 does not regulate parking garage ventilation despite the incorrect language, so there is no defined baseline. USGBC/GBCI has defined the baseline as as varying depending on local requirements. LEED Interpretation 10371 addresses this issue.