Energy Savings Calculator (Old vs New HVAC System)
Compare the energy costs of your old HVAC system versus a new high-efficiency unit to estimate your annual and lifetime savings.
Seasonal Energy Efficiency Ratio of existing unit (typically 6–14 for older systems)
SEER2 rating of new unit (modern systems: 14–26+)
Cooling capacity of the HVAC system (1 ton = 12,000 BTU/hr)
Estimated hours the AC runs per year (varies by climate; 800–2000 typical)
Your local utility rate per kilowatt-hour (U.S. average ~$0.13/kWh)
Expected lifespan of the new HVAC system (typically 15–20 years)
Total installed cost of the new HVAC system (optional, for payback calculation)
Formulas Used
Power Draw (kW):
kW = (Tons × 12,000 BTU/hr) ÷ (SEER × 1,000)
Annual Energy Consumption (kWh):
Annual kWh = kW × Annual Cooling Hours
Annual Energy Cost ($):
Annual Cost = Annual kWh × Electricity Rate ($/kWh)
Annual Savings:
Annual Savings = Old Annual Cost − New Annual Cost
Lifetime Savings:
Lifetime Savings = Annual Savings × System Lifetime (years)
Simple Payback Period:
Payback (years) = Installation Cost ÷ Annual Savings
CO₂ Reduction:
CO₂ Saved (kg) = kWh Saved × 0.386 kg CO₂/kWh
(EPA eGRID national average emission factor)
Assumptions & References
- Power draw formula: kW = (Tons × 12,000) ÷ (SEER × 1,000) — derived from the SEER definition (BTU/Wh converted to kW).