ASHRAE 62.2 Whole-House Mechanical Ventilation Rate

Qtot = 0.03 x conditioned floor area + 7.5 x (bedrooms + 1) (ASHRAE 62.2-2019), and the continuous fan the installer must provide, Qtot minus the infiltration credit the envelope already leaks. The tighter the house tests, the smaller the credit and the larger the fan 62.2 requires - the trade-off a blower-door retest makes concrete. The conservative default is zero credit. Local kitchen/bath exhaust is separate. A sizing aid, not a 62.2 compliance certificate.

q_tot = 0.03 x floor_area_ft2 + 7.5 x (bedrooms + 1); q_fan = max(0, q_tot - infil_credit_cfm); verdict = q_fan > 0 (fan required) else (credit meets Qtot).

ASHRAE 62.2-2019 §4.1 whole-house ventilation rate (Qtot = 0.03 x Afloor + 7.5 x (Nbr + 1)) and the fan flow Qfan = Qtot - Qinf, by name; the 0.03 cfm/ft^2 and 7.5 cfm/person are the standard's rate coefficients.

The whole-house ventilation rate and the fan-flow relation are stated in ASHRAE 62.2-2019 §4.1; the arithmetic is public. The infiltration credit comes from the measured air-tightness.

Estimate. AHJ and licensed professional govern.

Field names used by the API: floor_area_ft2, bedrooms, q_tot, q_fan

• Total required Qtot Qtot = 0.03 x conditioned floor area + 7.5 x (bedrooms + 1); occupants assumed Nbr + 1ASHRAE 62.2-2019 §4.1
• Fan flow Qfan = max(0, Qtot - infiltration credit); the tighter the house, the smaller the credit and the larger the fanASHRAE 62.2-2019
• Infiltration credit the credit is the blower-door natural infiltration; the conservative default is zerofirst principles