We have 4 A/C Units providing air conditioning to a building, two of them are 100% OA units and two of them are providing the total air supply cfm (OA + recirulated air) is 7000 cfm and 8600 respectively, including 1100 cfm of OA in each. I was wondering the guide does NOT specifically says that for the flush the equipment needs to provide 100% OA, but instead 14000 cf/sf. even if through the process you are recirculating air. Is this assumption correct? The project is located in Florida, if the equipment provides OA 100% 24hr/day it may humidify the drywall indoors and cause a problem.
Thanks
Allison Beer McKenzie
Architect, Director of SustainabilitySHP Leading Design
LEEDuser Expert
646 thumbs up
April 17, 2014 - 3:19 pm
Victor- the required volume of air (14,000 cubic feet) has to all be "outside air". This does not mean that the system has to deliver 100% OA, but rather, that if the system is delivering a mix of OA and recirculated, you can only count the OA portion toward the total volume.
Saju Varghese
SUSTAINABILITY COORDINATORJALRW Eng. Group Inc.
39 thumbs up
April 18, 2014 - 10:28 am
Great, if that is the case we can definitely provide that volume in about 40 days, system running as originally intended. Is there any reference in regards to that I can forward to our engineers for clarification? There is a believe out there that the equipment have to run 100% OA to be considered "flush out". Any reference? Do we need to maintain the min ventilation per sf of 0.3 cfm of option 2?
Allison Beer McKenzie
Architect, Director of SustainabilitySHP Leading Design
LEEDuser Expert
646 thumbs up
April 18, 2014 - 10:38 am
LEED NC 2.2 used to refer to "100% Outside Air", so that could be where the percepion is coming from. The equivalent credit in LEED 2009 does not refer to a need for 100% outside air anywhere, it just gives a total volume of outside air. It also doesn't specifically say it doesn't have to be 100% OA, though, so I know it's not exactly what you're looking for. We have done flush outs that do not use 100% OA several times and we have not had problems on review.
Saju Varghese
SUSTAINABILITY COORDINATORJALRW Eng. Group Inc.
39 thumbs up
April 21, 2014 - 5:40 pm
Thanks for your reply Allison, really helpful