When we look into the LEED Reference Guide for Option 1, it seems to require a VAV system which we do not have (see pg. 168). We can show compliance with ASHRAE 90.1 Mandatory requirements but not the modulating air handling units and not the fan static pressure reset, both of which are features inherent with a VAV system. Is there something we're missing that would still allow us to use the Core Performance Guide efficiency requirements and not have to go to the effort and expense of an energy model?
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Erik Dyrr
Director, Sustainable Buildings and OperationsKEMA
80 thumbs up
February 10, 2010 - 10:19 pm
Can you inform us of the type of air handling you do have?
The modulating aspect would still apply. If single zone units, then it is an on/off scenario.
Dave Intner
Firmitas Architecture & Planning90 thumbs up
February 17, 2010 - 12:24 pm
Thanks for your reply, Erik.
The project is utilizing constant volume packaged gas/electric units, however, the units are specified with a variable frequency drive (VFD) which will allow them to maintain a constant airflow to the space as the filters load up (and their static pressure drop increases). The higher filtration for this project is a result of the space being an OSHPD 3 occupancy.
By an ‘on-off’ scenario, are you talking about the fan shutting off when there is no demand? Due to the code's ventilation requirements, the fan will run when the space is occupied, continuously.
Erik Dyrr
Director, Sustainable Buildings and OperationsKEMA
80 thumbs up
February 17, 2010 - 1:07 pm
With a typical constant volume system I don't know how the project could meet the requirements of modulating the airflow. The only option I can think of is to modify the system with zone dampers controlled by occupancy or CO2 sensors. But this is not likely a feasible option.
Dave Intner
Firmitas Architecture & Planning90 thumbs up
February 18, 2010 - 11:46 am
Thanks Erik. It seems we're in a situation where code ventilation requirements are trumping opportunities for efficiency.
Christine Beaton
BR+A Consulting Engineer14 thumbs up
March 16, 2011 - 11:45 am
The question I have is are they asking for there to be VAV flow. I read the CPG to say that drives are required for VAV systems not that VAV systems are required. Based on this, can it be argued that constant volume systems are exempt from this requirement? We've gotten this credit when our motors were exempt for being too small and our systems exempt for being chilled water cooling or on a base building VAV AHU (efficiency requirement). Why not this? We're not installing a constant volume system, just reutilizing one in a renovation. Interested in people's thoughts on this. Worse comes to worse, we can just submit and find out but looking for others' experience.
Paul Conrad
Energy EngineerCLEAResult Consulting
346 thumbs up
March 31, 2011 - 10:25 am
Christine,
I've never attempted to submit in that manner, but with how difficult GBCI reviewers can be on this particular credit, I have my doubts that it would be accepted. If you do submit, please share with us the review comments, so that we can better understand how GBCI feels about this particular approach.
Sorry that I can be of more help,
Paul