The energy in our room air comprises sensible heat (that we can feel) and latent (hidden) heat.

The heat measured with a thermometer is sensible heat.

Latent heat, conversely, is energy absorbed when water, for example, is evaporated. it is ‘stored’ in the resultant steam. A thermometer cannot measure latent heat. The higher the room humidity, the greater the latent heat present.

The total of sensible and latent heat is known as enthalpy.

Condensation wheels generally transfer only sensible heat, while sorption rotors also transfer significant amounts of water vapour.