Hi All,
My understanding is that the basement should not be counted toward the total number of floors when selecting the baseline HVAC system type (Table G3.1.1A). My building has three stories plus basement and total conditioned floor area of 20,600 sf ( sf does not include attic which is about 5,000sf). I would select PSZ-AC for hybrid or PSZ-HP for electric heat. Am I correct?
Any comments are appreciated.
Thank you.
Ana
Gang:
I have a building which has two DX rooftop systems. Each system supplies 1/2 of
the building, 1st thru 6th floors, with VAV and electric reheat (yuk).
Anyway, I want to replace the existing compressors for these DX systems with
Danfoss Turbocor units. Since these are not centrifugal chillers, there is no
direct means to model them in eQuest. However, there MUST be a curve (or two)
that will simulate a replacement compressor as variable speed.
Any takers?
John R. Aulbach, PE, CEM
Senior Energy Engineer
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If it is conditioned space (heated, cooled, or both), a basement floor is still a floor as far as system selection is concerned. If it is neither heated nor cooled, it might be acceptable to exclude it, but I admit I have never encountered an entirely unconditioned basement on a LEED project before.
DAKOTA KELLEY
Read ?floor? as ?story? and you can see the definition of that term in the Standard (Section 3). Basement is specifically excluded. So in the present case, you fall in System 3 or 4.
_____________
Demba NDIAYE
The ASHRAE definition of "story" led me think that the basement should not be included in the total number of floors. However, Appendix G indicates that for systems 5,6,7 and 8 each floor shell be modeled with a separate system. That being said, if i had four floors plus basement , I would model 5 systems since my basement is conditioned. This approach would be more in line with what Dakota said. Thank you both for your suggestions. Obviously, Appendix G is not clear about this.
Ana,
You are correct. It is not explicitly stated in 90.1, but a floor with conditioned space is a floor regardless of whether it is above or below grade. ?Basement? is too vague of a term in this context. To give you an example, I had a project that was five floors above grade and one floor below grade. The below grade floor was 50% fully-conditioned space (labeled ?basement? storage on the plans) and 50% parking garage. The building area was about 135,000 SQFT gross (with the garage), 120,000 SQFT without the garage, and 97,000 SQFT if the entire below grade floor was excluded. So, the area component was irrelevant; baseline selection came down to System 6 if I counted it as five floors and System 8 if I counted the below grade floor. I counted the below grade floor and went with System 8, and the LEED reviewer drove to my office and gave me a high five, a low five, and an on-the-side five. Then she made me clarify how I calculated my fan power allowance.
DAKOTA KELLEY