# British thermal unit

Physical unit
Unit name British thermal unit
Unit symbol ${\ displaystyle \ mathrm {BTU}}$ Physical quantity (s) (Thermal) energy
Formula symbol ${\ displaystyle E, \, W}$ dimension ${\ displaystyle {\ mathsf {M \; L ^ {2} T ^ {- 2}}}}$ system Anglo-American system of measurement
In SI units ${\ displaystyle \ mathrm {1 \; BTU = 1055 {,} 055 \, 852 \, 62 \; J}}$ Derived from Fahrenheit degrees , pounds sterling

The British thermal unit is a unit of energy . Your unit symbol is BTU or Btu , its symbols W . The Btu does not belong to the International System of Units (SI) and is defined as the heat energy required to heat a pound of water by 1 degree Fahrenheit . Since this energy differs depending on the temperature of the water due to the temperature-dependent heat capacity , there are several definitions of the Btu.

The International (Steam) Table Btu was defined as 1055.05585262 joules according to the International (Steam) Table Calorie (cal IT ) .

... Btu ... joules calorie ... watt hour
1 Btu IT 1055,05585262 J. ≈ 252 cal
1 MBtu = 1,000 Btu ≈ 293,071.070.159.3 Wh
1 therm = 100,000 Btu
1 MMBtu IT = 1,000,000 Btu IT 1055.05585262 MJ ≈ 293.071.070.159.3 kWh
= 0.293.071.070.159.3 MWh

When specifying heat pumps (especially air conditioning systems ), the cooling capacity (incorrectly) is often given in Btu for imported devices. What is meant here is BTU per hour (BTU / h).

1000 BTU / h ≈ 293 W.

The power dissipated in heat is also given in BTU / h for devices to be cooled in data centers .

The natural gas -Consumption is sometimes in MMBtu (million British thermal units; MM comes from a thousand thousand) indicated. 1 MMBtu corresponds to 26.4 cubic meters of gas, based on an energy content of 40 MJ / m³ (11 kWh / m³).

The units Quad (quadrillion British thermal units) and Therm are derived from Btu .

## Individual evidence

1. sizes.com: British thermal unit