Kilojoule (kJ)
The kilojoule, symbol kJ, equals 1,000 joules and is used for measuring larger quantities of energy. It was introduced to simplify calculations in nutrition, physics, and engineering, where joules alone would result in very large numbers. Kilojoules are commonly used to express the energy content of foods, fuel consumption, and industrial energy usage. The adoption of the kilojoule has standardized energy measurements across scientific disciplines and commercial applications, offering clarity and ease of use in both everyday and professional contexts.
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.