What does relative humidity measure?

Relative humidity specifically measures the amount of moisture present in the air relative to the maximum amount of moisture that the air can hold at a given temperature. It is expressed as a percentage, with 100% indicating that the air is fully saturated with moisture and cannot hold any more, leading to a likelihood of condensation.

Understanding relative humidity is crucial in the context of building performance, as it can significantly impact comfort levels, the potential for mold growth, and the efficiency of heating and cooling systems. Keep in mind that relative humidity does not measure temperature, air pressure, or air flow speed, which are separate parameters in atmospheric science. This focus on the relationship between actual moisture and the saturation point is what distinguishes relative humidity and makes it an essential concept in assessing indoor air quality and environmental conditions.