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
The British Thermal Unit (Btu) is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is primarily used in the United States to describe the energy content of fuels and the power of heating and cooling systems.
Btu (15°C)
The Btu (15°C) is a specific variant of Btu to reflect the energy needed to raise the temperature of water at 15 degrees Celsius by one degree.
Btu (15.6°C)
The Btu (15.6°C) specifically refers to the energy needed to raise the temperature of water from 60°F (15.6°C) to 61°F.
Btu (15.8°C, Canada)
The Btu (15.8°C, Canada) is a variant of the British thermal unit defined as the energy to raise the temperature of one pound of water by one degree Fahrenheit at a starting temperature of 15.8°C. This definition is tailored to Canadian standards reflecting the country's historical reliance on both imperial and metric.
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.
Btu (3.9°C)
The Btu (3.9°C) is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at the temperature where water reaches its maximum density which occurs at approximately 3.9°C (39°F).
Btu (I.T.)
The British Thermal Unit (International Table) is a unit of energy commonly used in the United States defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere.
Btu (I.T., pre-1956)
The Btu (I.T., pre-1956) refers to the International Table Btu, a specific definition used before 1956. It represents the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere.
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.
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.