Energy Savings Calculator
Estimate annual energy consumption and cost savings when upgrading from an existing HVAC system to a higher-efficiency model.
Formulas Used
Annual BTU Load:
Annual BTU = Cooling Load (tons) × 12,000 BTU/hr/ton × Operating Hours (hr/yr)
EER Conversion:
EER (BTU/Wh) ≈ SEER × 0.875
(Accounts for mixed part-load vs. full-load operation per AHRI Standard 210/240)
Annual Energy Consumption:
kWh = Annual BTU Load ÷ (EER × 1,000)
Annual Savings:
ΔkWh = kWhold − kWhnew
ΔCost ($) = ΔkWh × Electricity Rate ($/kWh)
Assumptions & References
- 1 ton of cooling capacity = 12,000 BTU/hr (ASHRAE definition).
- SEER-to-EER conversion factor of 0.875 is an industry-standard approximation per AHRI Standard 210/240 and widely used in DOE energy analyses.
- SEER (Seasonal Energy Efficiency Ratio) reflects seasonal average performance; EER reflects full-load performance. This calculator uses SEER as the primary input for both systems for consistency.
- Minimum federal SEER standard for residential central AC (as of 2023): 14 SEER (North) / 15 SEER (South) per DOE 10 CFR Part 430.
- Operating hours represent hours the system runs at or near full cooling capacity per year. Typical residential: 800–1,500 hrs/yr; commercial: 1,500–4,000 hrs/yr.
- Electricity rates vary by region. U.S. average commercial rate ≈ $0.12–$0.14/kWh; residential ≈ $0.13–$0.17/kWh (EIA, 2024).
- This calculator estimates cooling energy only. Heating, ventilation, and auxiliary loads are not included.
- Actual savings may vary based on climate, building envelope, thermostat setpoints, and equipment sizing.
- References: ASHRAE Handbook – Fundamentals; AHRI Standard 210/240; U.S. DOE Energy Efficiency & Renewable Energy (EERE); U.S. EIA Electric Power Monthly.