Joules
The joule (J) is the SI unit of energy. It is named after the English physicist James Prescott Joule. It is the amount of work done when a force of one newton moves an object by one meter in the direction of the force also known as a newton-meter.
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.