Inputs
CustomBuilding dimensions
Floor area2,000 ft²
Enter conditioned floor area (not lot size).
Area unit
Avg. ceiling height8.0 ft
Used to estimate building volume.
Height unit
Air tightness (blower door)
Baseline ACH508.0
Blower door result at 50 Pa. Older homes can be 8–15; newer code homes often 3–5; high-performance < 2.
Target ACH504.0
Your expected post-sealing air tightness.
ACH50 → ACHnat divisor20
Rule-of-thumb conversion depends on exposure & stack/wind. Typical range 15–25. Higher divisor = lower natural infiltration.
Climate & HVAC
Heating degree days (HDD)4,500
Cooling degree days (CDD)1,100
Cooling COP3.2
Used to estimate cooling input energy from sensible load.
Heating system
AFUE0.92
Enter AFUE as a decimal (e.g., 0.92). For heat pumps enter COP (e.g., 3.0).
Electricity price ($/kWh)0.15
Gas price ($/therm)1.50
Used only if heating system is gas.
Project economics
Air sealing cost (capex)$2,200
Includes labor, materials, and diagnostic testing. Adjust to your quotes.
Escalation2.5%
Horizon15 yrs
Discount rate6.0%