Concept
Delta Temperature Conversion
The conversion between Celsius and Fahrenheit or Fahrenheit and Kelvin is not a simple coefficient (multiplier) like other unit categories as for example length, pressure, currency, and Energy. Due to the conversion formula when for example converting an absolute Fahrenheit temperature to Celsius, T°F=T°C x 9/5 + 32, you have both a multiplier and an offset to consider. To correctly convert a delta temperature from Fahrenheit to Celsius you have to use the formula ΔT°F = 9/5 ΔT°C.
If you set a delta temperature to a unit within the unit category Temperature, Building Operation incorrectly converts the value as an absolute temperature. By setting the delta temperature to a unit within the unit category Temperature Diff, Building Operation correctly converts the delta value.
Temperature A: 23°C (73.4°F)
Temperature B: -18°C (-0.4°F)
Diff Temperature = Temperature B - Temperature A
-18°C - 23°C = 41°C
-0.4°F - 73.4°F = 73.8°F
Inccorrect conversion of a delta temperature from Celsius to Fahrenheit, when the unit of the value in Building Operation is set to °C.
T°F=T°C x 9/5 + 32:
41°C x 9/5 + 32= 108.8°F
The correct delta value is 73.8°F, not 108.8°F .
Correct conversion of a delta temperature from Celsius to Fahrenheit, when the unit of the value in Building Operation is set to Δ°C.
ΔT°F=ΔT°C x 9/5:
Δ41°C x 9/5= Δ73.8°F
The conversion results in the correct delta value of 73.8°F.
By default, units are converted automatically depending on your operating system's regional settings. You can also select to display values in units according to the International System of Units (SI), the United States Customary Units (US), or as configured in the connected objects, that is, the original unit of the value. For more information, see Units .
Building Operation converts the unit of a variable independent of its context. To correctly convert a delta temperature, the unit of the delta value must belong to the unit category Temperature Diff.
Adding or Changing a Unit and Prefix for a Value
Units
Unit Selection Dialog Box