Determining Your Ventilation Needs
How much fresh air do you need?
Good air quality is based in part on the capacity of the home’s ventilation system. Usually, the unit’s capacity is
measured in CFM (Cubic Feet per Minute) or L/s (Liters per second) of fresh air being distributed in the living
space. Use the ASHRAE 62.2 Ventilation Standard, the Room Count Calculation Method, or the Air Change Per
Hour (ACH) Method to determine your ventilation needs.
ASHRAE 62.2 Ventilation Standard
ASHRAE 62.2 CFM Sizing Chart
Floor Area (ft
2
)
Number of Bedrooms / CFM
0-1 2-3 4-5 6-7 >7
< 1500 30 45 60 75 90
1501 - 3000 45 60 75 90 105
3001 - 4500 60 75 90 105 120
4501 - 6000 75 90 105 120 135
6001-7500 90 105 120 135 150
>7500 105 120 135 150 165
ANSI/ASHRAE STANDARD 62.2-2010 - Ventilation Air Requirements; values in cfm
The above chart outlines the minimum requirements for continuous ventilation.
Room Count Calculation Method
Living Space Number of Rooms x CFM (or L/s) = CFM Required
Master Bedroom x 20 cfm (or 10 L/s) =
Basement x 20 cfm (or 10 L/s) =
Single bedroom x 10 cfm (or 5 L/s) =
Living Room x 10 cfm (or 5 L/s) =
Dining Room x 10 cfm (or 5 L/s) =
Family Room x 10 cfm (or 5 L/s) =
Recreation Room x 10 cfm (or 5 L/s) =
Other x 10 cfm (or 5 L/s) =
Kitchen x 10 cfm (or 5 L/s) =
Bathroom x 10 cfm (or 5 L/s) =
Laundry Room x 10 cfm (or 5 L/s) =
Utility Room x 10 cfm (or 5 L/s) =
Total Ventilation Requirement =
Air Change Per Hour (ACH) Method
TOTAL cubic feet X 0.35 per hour = total cubic feet per hour
Take total and divide by 60 to get cubic feet per minute (CFM)
Example: A 25 ft. x 40 ft. (1,000 sq. ft.) house with basement
1,000 sq. ft. x 8 ft. high x 2 (1st floor + basement) = 16,000 cu. ft.
16,000 cu. ft. x 0.35 ACH = 5,600 cubic feet per hour
5,600 cu. ft. / 60 Minutes = 93 cubic feet per minute (CFM)
93 CFM is your ventilation need
TrueFRESH™ ERV/HRV Ventilation Systems 69-2480EF—17 3
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