BTU (International) (BTU)
The British Thermal Unit (BTU), symbolized as BTU, is an imperial unit of energy used to measure heat. One BTU is the heat needed to raise one pound of water by 1°F. The BTU originated in the 19th century, during the Industrial Revolution, for heating in the UK and the US. It is still used in HVAC systems and energy production. The BTU connects imperial and metric energy systems, especially in countries that use imperial units for industry.
Joule (J)
The joule (J), recognized as the SI unit of energy, is named in honor of physicist James Prescott Joule. It represents the amount of work performed when a force of one newton moves an object over a distance of one meter. The joule is widely used in physics, thermodynamics, and engineering, providing a standardized way to quantify energy across mechanical, electrical, and thermal processes. Its implementation has enabled researchers and professionals to measure and compare energy values with accuracy and consistency around the globe.