# Temperature

The primary unit of temperature is degrees Celsius. However, temperature can also be specified in other units, such as Fahrenheit [°F] and Kelvin [K]

The primary unit of temperature is degrees Celsius. The Celsius scale was defined in the 18th century. The scale is defined so that purified water has a freezing point of 0 °C and a boiling point of 100 °C.

However, temperature can also be specified in other units, where Fahrenheit [°F] and Kelvin [K] are the most commonly used. A difference in temperature of 1 degree is the same for both Celsius and Kelvin.

Kelvin’s absolute zero
0 degree K on the Kelvin scale, also called absolute zero, is equal to -273.15°C. The Kelvin scale only uses positive values, which is an advantage when performing calculations.

Conversion rates
The conversion rates for these units are as follows:
[K]                 = 273.15 + [°C]
[°F] = 32 + 9/5 [°C]

The use of the Kelvin scale
The Kelvin scale is most often used for building installations, as calculations primarily involve temperature difference (ΔT).