I’ve been working on a LEED project with VRF & DOAS in San Jose, CA. For the LEED Energy Model, EnergySoft suggested attaching the DOAS to 10 sq. ft. dummy rooms, and then "connecting" the VRF systems to them as their outside air source (the only way their 90.1 performance calculation can handle DOAS.) However, this put the fan power for the model through the roof.
I then matched the DOAS "rooms" to the size of the area they actually serve (66000 ft. for DOAS-1 & 44000 ft. for DOAS 2.) This was the only way to reduce the fan power hit on the energy model. But, it was still much higher than on a sister project with a nearly identical VRF system, but no DOAS.
In reality, the DOAS provide outside air directly to the interior VRF cassettes. So, the question is, is there a way to reduce the DOAS hit on the fan power of the energy model? This is supposedly the state-of-the-art for energy efficient HVAC, but the addition of the DOAS ends up cutting my energy performance credits in half.
Any help is appreciated.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
March 8, 2019 - 12:02 pm
This sounds like a question for EnergySoft technical support. You could also try the bldg-sim group at onebuilding.org