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Calculating the pressure difference of a home WRT outside

Dan Phillips | Posted in General Questions on

Back in college I was shown a formula that use the temperature difference between indoors & outdoors (Fahrenheit) , and the height of the house (feet), and a fudge factor to calculate what the pressure difference would be between the home and outside (in Pascals).

I can’t seem to find it. Does anyone know that formula, or the elusive fudge factor is?

Dan Phillips

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Dan,
    As far as I know, you need a manometer to determine the indoor-to-outdoor pressure difference.

    For one thing, your list of factors omitted the effect of wind. Remember that the outdoor pressure on the windward side of the house will be different from the outdoor pressure on the leeward side of the house.

    That said, if you want to sharpen your pencil and estimate the delta-P (ignoring wind), here are links to two sites that provide the formulae:

    http://www.engineeringtoolbox.com/natural-draught-ventilation-d_122.html

    http://www.arca53.dsl.pipex.com/index_files/natvent2.htm

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