Same cooling, different bills: comparing two air conditioners
The cheaper unit to buy may cost more to run. But a smaller, unsuitable unit is not a bargain merely because it consumes less. Start with adequate, comparable cooling capacity.
Three different quantities
BTU/h or tons describe cooling capacity. Watts describe electrical power; kWh describe energy over time. Never enter 18000 BTU/h as 18000 W or infer a bill from cooling capacity alone.
Read labels on equal terms
The FTC explains that EnergyGuide costs use typical conditions and a reference energy price. Compare annual kWh only under equivalent test conditions, then apply your own tariff rather than treating the printed cost as your bill.
References: FTC — How to use the EnergyGuide label
When you only have watts
Estimated energy = W ÷ 1000 × daily hours × annual days × average load. Inverter power varies; test scenarios if average load is unknown. Simple payback is B’s extra price ÷ annual savings, and is not meaningful without positive savings.
Worked example: recovering the price premium
A uses 2000 kWh annually and B 1400 under equivalent conditions. At an illustrative 0.20 per kWh, costs are 400 and 280 currency units, saving 120 annually.
If B costs 300 more, simple payback is 300 ÷ 120 = 2.5 years. Maintenance, changing tariffs and useful life are outside that division. It does not guarantee actual savings.