Btu
BTU · British thermal unit · MMBtu · Btu/h
A British thermal unit (Btu) is the heat needed to raise the temperature of one pound of water by 1 °F; one kilowatt-hour equals 3,412 Btu and one therm equals 100,000 Btu.
The Btu is the common unit for heat in U.S. heating and cooling. Energy prices can be compared through it: electricity by the kWh at 3,412 Btu each, natural gas by the therm at 100,000 Btu. One million Btu is written MMBtu.
A Btu is an amount of energy. Btu per hour (Btu/h) is a rate, and it is what equipment capacity ratings mean: an air conditioner listed as “36,000 BTU” removes heat at 36,000 Btu per hour at its rating conditions. Cooling capacity is also given in tons, where one ton equals 12,000 Btu/h.
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