Free online tool to calculate moist air enthalpy instantly. Use total heat content analysis for fast, precise energy modeling and HVAC coil sizing. No sign-up required.
Enthalpy measures the total "energy battery" of the air. It counts both the heat of the air itself and the energy hidden inside the water vapor.
h = 1.006·T + W·(2501 + 1.86·T) kJ/kg dry air. Reference: 0°C, 0% RH. T clamped to [−40, +60]°C.
Rule of Thumb: Enthalpy tells you how much total energy (cooling load) an AC unit needs to remove from the air.
Checklist: Enter air temp and humidity. Read total energy in kJ/kg. Compare return air enthalpy vs. supply air enthalpy.
Quick Tip: Removing moisture (latent heat) often requires more energy than just cooling the air (sensible heat).
Sensible heat is the energy that changes the temperature of the air. Latent heat is the energy required to evaporate or condense water vapor in the air.
Engineers calculate the difference in enthalpy between the return air and the supply air to determine the total cooling capacity (kW) required for the coil.
In the Metric system, it is kJ/kg (Kilojoules per kilogram). In the Imperial system, it is BTU/lb (British Thermal Units per pound).