Heating Load Calculator

Calculate heat loss and furnace sizing requirements

Building Parameters

Floor Area (sq ft)

Ceiling Height (ft)

Design Outside Temp (°F)

Design Inside Temp (°F)

Wall R-Value

Roof/Ceiling R-Value

Window Area (sq ft)

Window U-Value

Infiltration (ACH)

Wall Heat Loss:4453 BTU/hrRoof/Ceiling:3158 BTU/hrWindows:4200 BTU/hrFloor/Slab:5367 BTU/hrInfiltration:6804 BTU/hr

Total Heat Loss

23981 BTU/hr

12.0 BTU/hr per sq ft

Design Load (with 15% safety)

27578 BTU/hr

Recommended Furnace Size

30000 BTU/hr

Natural Gas:552 thermsElectric:16165 kWhPropane:603 gallons

Based on 5,000 heating degree days at 100% efficiency

Design Tips:

• Infiltration: 105.0 CFM

• Consider a heat pump for improved efficiency

• High-efficiency furnaces: 90-98% AFUE