Btu (15.8°C, ISO)
The British Thermal Unit (Btu) is a traditional unit of heat, defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. The Btu (15.8°C, ISO) is a specific variant standardized by the International Organization for Standardization (ISO) based on the calorie defined at 15.8°C.
Foot-pounds
A foot-pound (ft-lb) is a unit of work or energy in the Imperial and U.S. customary systems that is the amount of energy required to exert a force of one pound over a distance of one foot.