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.
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.