The cost of air conditioning is driven by both the equipment and the conditions it has to handle. Electricity price matters, but so do cooling load, runtime, system type, efficiency, thermostat settings, outdoor temperature, duct losses and whether the compressor operates at a fixed or variable speed.
Room air conditioners and central systems use different efficiency information
ENERGY STAR publishes room-air-conditioner criteria using Combined Energy Efficiency Ratio (CEER) together with cooling capacity. For central air conditioners and heat pumps, seasonal ratings such as SEER2 are used. A seasonal rating is not the same thing as a constant electrical draw, so HomeBillLab does not treat SEER2 alone as an exact cost-per-hour input.
If you know measured or documented electrical input, that can be used for an operating-hour scenario. If you have annual electricity use from a label or product document, an annual-kWh method avoids pretending that a variable-speed system always runs at one power level.
What changes the running cost?
Electricity rate
The same air conditioner can cost more or less to operate under a different utility rate or time-of-use period.
Cooling load
Hotter weather, direct sun, air leakage, weak insulation and internal heat gains can increase the amount of cooling required.
Equipment behavior
Inverter and variable-speed systems can modulate rather than draw one fixed power level whenever they are on.
Distribution
Duct condition, duct location and fan energy can influence whole-system energy use in central systems.
Official U.S. references
- ENERGY STAR — Room Air Conditioners
- ENERGY STAR — Room Air Conditioner Key Product Criteria
- ENERGY STAR — Air-Source Heat Pump Key Product Criteria
- EIA — Electricity prices and factors affecting prices
Reviewed: 27 September 2026. Published child guides will appear automatically below this hub after launch.
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