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Old 11-30-10, 06:23 AM   #7
RobertSmalls
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It sounds like you're close to measuring the Overall Heat Transfer Coefficient * Surface Area = U*A, which is a measure of the effectiveness of a heat exchanger. UA is the inverse of thermal resistance (Rth), i.e. the average R-value of the house.

You won't get there, though. There's too many variables that are beyond our ability to accurately nail down. Specifically, we don't want to measure change in temperature, but rather heat flux (q). If the house were to cool down uniformly, we could use q = m * specific heat * deltaT, but my observations indicate that different parts of my house have dramatically different temperatures, even when the furnace is off.

The biggest problem is the cooldown of your house isn't the only heat flux in play. You've got significant heat fluxes from solar and metabolic activity, plus your appliances giving off heat.

But if we want to turn "cooldown testing" into a fun little game, we could just compare our dT/dt vs ambient temperature, and make a note of whether it was sunny. I'll log some cooldown test results, but I can also tell you up front: Piwoslaw wins.
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