Tennessee Climate Zone Heat Load Calculator
Estimates residential heating load (BTU/hr) for Tennessee homes using Manual J simplified methodology, accounting for climate zone design temperatures, envelope area, insulation R-values, infiltration, and internal gains.
IECC 2021 climate zones for Tennessee
Total heated living space (200–20,000 sq ft)
Typical residential: 8–10 ft
IECC Zone 4A minimum: R-20 or R-13+5ci
Typical residential: 12–18% (5–40%)
Infiltration factor applied to volume × ΔT
ASHRAE standard: 70°F (65–75°F)
Enter your home details and click Calculate.
Formulas Used
Conduction Heat Loss (each assembly):
Qcond = U × A × ΔT
- ΔT = Tindoor − Toutdoor design (°F)
Infiltration Heat Loss:
Qinf = 1.08 × CFM × ΔT
- CFM = (Volume × ACHnatural) / 60
- ACHnatural ≈ ACH50 / 20 (Sherman-Grimsrud)
- 1.08 = ρ·Cp·60 = 0.018 × 60 (BTU·min/hr·ft³·°F)
Total: Qtotal = Qwall + Qceiling + Qfloor + Qwindow + Qinf
Assumptions & References
- Outdoor design temperatures from ASHRAE Fundamentals Handbook 99% heating design conditions for Tennessee cities
- Climate zones per IECC 2021: Tennessee spans Zones 3A (Memphis, Nashville) and 4A (Knoxville, Chattanooga, mountain areas)
- Methodology follows ACCA Manual J (8th Edition) simplified residential load calculation
- Infiltration ACHnatural = ACH50/20 per Sherman-Grimsrud simplified model