Secondary Author(s)

Withers Jr., Charles; Moyer, Neil; Fairey, Philip

Report Number




Buildings; Air Flow; Ventilation; HVAC; Humidity; Moisture


Field investigations were done in seven restaurants (subsample of a 63 commercial buildings study) to identify uncontrolled air flows and pressure imbalances. Testing included building airtightness tests, identification of building air barrier location, duct system airtightness, characterization of pressure differentials, building air flow balance, and infiltration/ventilation rates. All restaurants were found to operate at negative pressures which ranged from -0.003 inWC (-0.8 Pa) to -0.173 inWC (-43 Pa) and averaged -0.051 inWC (-12.7 Pa) under normal operation. The variables which affect depressurization are large exhaust fans, missing or undersized make-up air, intermittent outdoor air caused by the cycling of air handlers, dirty outdoor air and make-up air filters, and building airtightness. These uncontrolled air flows and pressure imbalances impact energy use, ventilation rates, sizing of heating and air conditioning systems, indoor comfort, relative humidity, moisture damage to building materials, mold and mildew growth, operation of combustion equipment, and indoor air quality.

Date Published



Reference Publication: Cummings, J. B., C.R. Withers, N. Moyer, P. Fairey, and B. McKendry. "Field Measurement of Uncontrolled Air Flow and Depressurization in Restaurants". ASHRAE Transactions, 1996, Vol.102, Part 1, p.859

Local Subjects

Buildings - Air Flow; Humidity; Buildings - HVAC; Buildings - Moisture; Buildings - Ventilation


FSEC Energy Research Center® Collection



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