It's a rule-of-thumb derived from many observations and calculations made over the years. There's nothing special about the number 6 - it just happens to be the factor that gives a reasonable approximation (when working with cubic feet). It's 6 because it works.
[I'm assuming that the number actually is 6 - I know damn-all about HVAC, but I've got a pretty good idea where estimation "rules" come from].
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"Love justice, you who rule the world" - Dante Alighieri
Interesting, how subjective is this "rule of thumb" is it specific to standard office space, warehouse etc? I realize this would differ with a given application such as computer room or a room with an oven in it.
Estimating Cooling Load for Building
Re: estimating cooling load for a building
