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MarketManager » Loads and Sizing
Q: What does the in2/ft2 value in the building construction forms have to do with infiltration CFM?


As you probably know, in2/ft2 refers to "for every square foot of area, there is one square inch of leakage area." For example, in ASHRAE fundamentals, sliding windows are given a value of 0.057 in2/ft2. So a 141 ft2 sliding window would have an effective leakage area of 8.04 in2.

MarketManager uses the LBNL model as defined in ASHRAE Fundamentals 1997 [25.22] to find the infiltration airflow rate in CFM :


AL is the leakage area in square feet

CS is the stack coefficient

D T is the average indoor-outdoor temperature difference for time interval of calculation

CW is the wind coefficient

V is the ave wind speed

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