Btu (thermoc.)
The Btu (thermochemical) variant aligns with the thermochemical calorie and is defined as the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere and is equivalent to approximately 1,054.350 Joules.
Therm
The therm is a unit of heat energy used in the United States and the United Kingdom for measuring natural gas consumption.