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Calculating air exchange rate

I am doing a project for school and I am stuck trying to figure out the air exchange rate for modern homes.

The equation I have is
cm(delta T)
c = specific heat of air
m = mass of interior home

p = m/v

I turned this equation into
cpv(delta T)
p = density of air
v = volume of interior of home

I wanted to know how many air exhanges per hour I had so that i could multiply that into this equation.

Thanks to anyone who can help.

Asked by john doe
Posted Sat, 12/07/2013 - 21:30

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1 Answer

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John,
The air exchange rate depends on many factors, and varies widely from house to house. It can be measured under controlled conditions with a blower door. The blower door establishes a defined pressure difference between indoors and outdoors (usually 50 Pascals), allowing the air exchange rate to be calculated for that pressure difference. In that way, the blower-door operator can distinguish a house with lots of envelope leaks from a house with few envelope leaks.

However, a blower-door test cannot tell you the air exchange rate on any given day, because the air exchange rate depends on such factors as the wind speed, the wind direction, and the delta-T (which governs the stack effect).

Answered by Martin Holladay, GBA Advisor
Posted Sun, 12/08/2013 - 08:50

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