Put another way:

If you have a perfectly circular floorplate, ASHRAE wants you to model an octagon, with respect to a minimum number of facets.

This specific query reminds me: There was a pretty interesting thought-study presented at ASHRAE's energy conference in 2015 where someone tested this logic, by asking the question (paraphrasing) "how few facets can we get away with and still accurately represent a perfect circle?" I don't recall exactly the answer but the results surprised me with how far you could go in simplifying the shape & still maintain relative accuracy. I believe a 4 sided square (corrected geometrically for volume) in fact performed very closely to the baseline.

If you're sincerely & specifically interested in modeling an octagon as a square, I think you'll find that could actually be pretty accurate so long as you are correcting for conditioned volume / exposed area. I'd seek out that actual paper/presentation while you're at it ;-).

~Nick

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Nick Caton, P.E., BEMP
Senior Energy Engineer
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
E nicholas.caton at schneider-electric.com
F 913.564.6380

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

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