Building Volume
Infiltration & Conditions
Infiltration Flow
Infiltration CFM
—
ft³/min
Altitude Factor
—
relative to sea level
Cooling Season Infiltration
Sensible Cooling
—
BTU/h
Latent Cooling
—
BTU/h
Total Cooling
—
BTU/h
Cooling Tons
—
tons
Heating Season Infiltration
Sensible Heating
—
BTU/h
Heating MBH
—
MBH (× 1,000 BTU/h)
Infiltration Rate Reference
| ACH | Construction Type | Typical Use |
|---|---|---|
| 0.05–0.10 | Very tight — blower door ≤ 1 ACH50 | Passive house, high-perf new construction |
| 0.10–0.25 | Tight — energy code compliant new commercial | Most new commercial buildings post-2010 |
| 0.25–0.50 | Average — some air sealing, older construction | Pre-2000 commercial, mid-range residential |
| 0.50–1.00 | Leaky — minimal sealing | Older warehouse, industrial, poorly sealed |
| 1.0–2.0 | Very leaky — open dock doors, large gaps | Uninsulated storage, loading docks |
Reducing ACH from 0.50 to 0.25 cuts infiltration loads in half. Air sealing is often the highest-ROI energy measure in existing buildings. A blower door test precisely measures envelope leakage.