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ASHRAE 62.2 Whole Building Calculation Sheet

3/11/12 Adjusted building pressure with all fans running to reflect slope of regression.

This is an Excel based spreadsheet that includes a Macro for clearing all the entered data. By entering the State or Province, the city the square footage, the number of bedrooms and the number of floors, the sheet will calculate the appropriate 'N' factor and the basic CFM for whole building ventilation. By adding a blower door number, the sheet will calculate the rate and subtract the infiltration credit based on Standard 136. And by entering any existing fans airflows in bathrooms or the kitchen, the sheet will calculate a modified rate that will allow those fans to remain in place.

There are two primary ventilation system components to the ASHRAE 62.2-2010 Standard: whole building ventilation and local exhaust ventilation. The basic whole building flow rate can be fairly easily calculated from the formula included in the Standard or by referring to the table. But the rate can be reduced by using the "infiltration credit" if a blower door has been used to verify the performance of the building, but it requires reference to a second ASHRAE Standard (136) .

This spreadsheet does that calculation automatically. It includes the Standard 136 weather data for over 200 cities in the US and Canada. The sheet will also make the calculations required for existing buildings, allowing existing fans to remain installed in bathrooms and kitchens. The sheet also calculates the 'N' value, ACH50, ACHnatural, and a target CFM50 for achieving 0.35 air changes per hour.