I'm modeling a residential building with water to air heat pumps in all apartments. There is a retail space in the building too, which doesn't have an HVAC system designed and only capped condenser water pipes have been provided. I previously excluded the retail space from LEED scope, but have been asked to include it after the design review, with system #7 (VAV with Reheat) modeled in both baseline and proposed cases (due to 90.1 exception G3.1.1a). However, in the proposed case, I'm stuck using electric heat for this space, since there is no HW loop in the design and I cannot use the heat pump loop with VAV system in eQuest, and the energy costs are too high. Would you recommend that I use a water to air heat pump system for the retail space in the proposed case since that reflects the most likely scenario, and justify it to USGBC that a VAV system is highly unlikely to be installed?
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Christopher Schaffner
CEO & FounderThe Green Engineer
LEEDuser Expert
963 thumbs up
December 27, 2012 - 4:39 pm
I think you have two choices.
By the letter of the law, use System #7 for both, and include an identical boiler in both the baseline and proposed. Nothing says you have to use electric heat in the future spaces - the VAV system should include a boiler. Under this scenario the energy consumption of the retail space is included, but neither base or proposed is rewarded (or penalized)
I think you could also follow the scenario you've outlined, provided you could get the owner to commit in writing that WSHP system would be used in the retail area, either installed by the owner, or as a condition of rental.