Btu (mean)
Btu (mean) is a unit of energy used primarily in the United States defined as the heat required to raise the temperature of one pound of water from 59°F to 60°F under standard atmospheric pressure.
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.