Tooltip Tags: ventilation

Dew point is the temperature below which the equilibrium between evaporation and condensation is tilted towards condensation, i.e. condensation starts to form.

Dew point is also a proxy the vapour pressure. Comparing the dew point of one area to another makes it possible to see where vapour is being generated or conversely removed (normally through ventilation).

Relative humidity is defined as the measure of how much vapour is in the air compared to air’s capacity to hold vapour – expressed as a percentage.

It is a function of vapour pressure (quality of vapour) and temperature. As temperature rises, air can hold more vapour.

Conversely as temperature drops, air holds less vapour until it meets the dew point at 100%RH, when dew or condensation forms.