Data Sources
Climate Data
Heating and cooling degree days are sourced from Open-Meteo climate reanalysis models and NOAA historical normals. HDD and CDD are calculated using a 65°F (18.3°C) base temperature.
Housing Age Data
Median home construction year by metro is sourced from the Census Bureau's American Community Survey (ACS) 5-year estimates. Older homes may require ductwork modifications or electrical upgrades, which affect HVAC replacement costs.
Cost Benchmarks
Base cost ranges are derived from:
- RS Means Construction Cost Data (HVAC section)
- Contractor surveys and industry reports
- HomeAdvisor / Angi national cost data
- Energy Star equipment pricing
Climate Adjustment Formula
We adjust national average costs using heating and cooling degree days:
- Cooling services: Adjusted Cost = Base × (0.9 + CDD/5000 × 0.3)
- Heating services: Adjusted Cost = Base × (0.9 + HDD/8000 × 0.3)
- Dual systems (heat pumps): Adjusted Cost = Base × (0.9 + (HDD+CDD)/10000 × 0.2)
This captures the fact that contractors in extreme climates tend to size equipment larger and charge premium rates during peak season.
Heat Pump vs Furnace Calculator
Our calculator estimates:
- Installation: Heat pump ≈ $3,200/ton. Furnace ≈ $2,500/ton. AC ≈ $2,800/ton.
- Operating (heat pump): (HDD × 0.8 × sqft / 1000 / COP) × electric rate
- Operating (furnace): (HDD × 0.8 × sqft / 1000 / AFUE) × gas rate × 100
- Operating (AC): (CDD × 0.6 × sqft / 1000 / SEER) × electric rate
Assumptions: COP 3.0, AFUE 80%, SEER 16, electric $0.14/kWh, gas $1.20/therm.
Limitations
- Not a substitute for quotes. Always get 3+ written estimates from licensed contractors.
- Equipment varies. High-efficiency units (SEER 20+, AFUE 95+) cost significantly more than baseline models.
- Ductwork unknown. Costs assume functional ducts. Replacing ductwork adds $2,000–$5,000+.
- Permits and codes. Local permit fees and code requirements vary and are not included.
- Seasonal pricing. Emergency repairs in peak summer/winter may cost 50–100% more.