Building Pressurization Calculator

Calculate required supply/exhaust airflow to maintain positive or negative building pressure per ASHRAE 62.1 and IMC.

Desired pressure differential (0.02-0.10 in. w.g.).
in. w.g.
Total conditioned volume.
ft³
CFM per sq ft of envelope at 0.3 in. w.g. (0.1-0.4 typical).
CFM/ft²
Total exterior surface area.
ft²
1 for positive (more supply), -1 for negative (more exhaust).

Results

Leakage CFM-CFM
Required Supply/Exhaust Imbalance-CFM
Air Changes from Leakage-ACH
Pressure Direction-
References: ASHRAE Standard 62.1 Section 5.9: Building Pressure; IMC Section 401.3; ASHRAE Fundamentals Chapter 16