ASHRAE 62.2.2013 for existing homes

These ASHRAE fields assist in determining the ventilation requirements for an existing home. They are an extension of the Air Sealing recommendation.

To open the fields, go to the refine screen, open the air sealing recommendation, scroll down to the bottom of the existing and improved values and click yes to open the fields.

Notice that the improved blower door reading for this home is 2279 CFM50, which coincides with the ASHRAE CFM50 min requirement of 2279. Since these two numbers match, no mechanical ventilation is required.

The ASHRAE CFM50 min requirement of 2279 was achieved with the addition of the kitchen and bath fan data.

You will see in this next example that the house is out of balance for ventilation.

Using the same modeling results but with a lower estimated blower door reading of 2000 CFM50.

This results in the need for mechanical ventilation.

Notice that the required full time mechanical ventilation rate is now 26.3 CFM (24 hours per day). The minimum CFM50 has stayed the same at this point because additional ventilation has not been added.

To correct the needed mechanical ventilation, you will need to install new mechanical ventilation or update the current fans in the home to a higher CFM50. Updating only the current fans in the home might not achieve the ventilation required.

About ASHRAE

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has determined that a home's living area should be ventilated at a CFM rate determined by adding 3% of the conditioned space floor area to 7.5 times the number of bedrooms plus one [formula: vent CFM = 0.03A + 7.5 (# bedrooms + 1)] as published by ASHRAE 62.2 in 2013. In a tight home, mechanical ventilation is necessary to achieve this ventilation rate. ASHRAE Standards are revised every three years.
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