If I have net rentable area of the office building and total cfm of fresh air fans how would I determine air changes? The building has 369k and the total cfm of osa intake and exhaust is 12k. Additionally I have an 8' x 12' louvre that supplies unconditioned fresh air x 2.
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OSA and ASHRAE codes for such
- Thread starter jr1772
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12k cfm OA is good for 600 occupants. Typical occupancy of a 369,000 ft2 office building might be 2,500-3,000.
ACH = cfm * 60 / volume
If you have 9 ft ceilings for example:
ACH OA = (12000 * 60)/(369000 * 9)
ACH OA = 0.22
Pretty low OA for this big a building. If you supply one cfm/ft2 (typ.) you're talking AHUs at about 3% outdoor air. Typ. office AHU usually around 10-20% minimum OA range.
ACH = cfm * 60 / volume
If you have 9 ft ceilings for example:
ACH OA = (12000 * 60)/(369000 * 9)
ACH OA = 0.22
Pretty low OA for this big a building. If you supply one cfm/ft2 (typ.) you're talking AHUs at about 3% outdoor air. Typ. office AHU usually around 10-20% minimum OA range.
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