Knowra British thermal unit British thermal unit The British thermal unit (Btu) is a unit of energy historically defined as the heat needed to raise one pound of water by one degree Fahrenheit. Its exact value depends on the specified temperature and water conditions.
Energy : A conserved physical quantity that can be transferred or transformed to produce changes in matter or motion. The Btu is one unit for measuring energy.
International Table Btu : A Btu defined as exactly 1,055.05585262 joules. This standardized variant is widely used in engineering and energy statistics.
British thermal unit per hour : A unit of power equal to one British thermal unit transferred or used per hour. Heating and cooling equipment often rates capacity in Btu per hour.
Kilowatt-hour : A unit of energy equal to the use of one kilowatt of power for one hour. Electricity bills commonly use this energy unit instead of Btu.
Heat : Energy transferred between systems because of a temperature difference. The historical Btu definition specifies an amount of heat transfer.
Thermochemical Btu : A Btu defined as approximately 1,054.35 joules. This variant fixes the Btu value using the thermochemical calorie.
Heating, ventilation, and air conditioning : The building-services field concerned with indoor heating, cooling, ventilation, and air quality. HVAC systems commonly state heating output and cooling capacity in Btu.
Watt : The SI unit of power, equal to one joule per second. A watt measures the rate of energy transfer, unlike the Btu’s energy quantity.
Temperature : A physical quantity that characterizes how hot or cold a system is. The defining temperature rise is one degree Fahrenheit.
Joule : The SI unit of energy, equal to the work done by a force of one newton over one metre. Btu quantities are commonly converted to joules for scientific use.
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