Relative humidity depends on temperature. Two relative-humidity percentages measured at different temperatures do not reveal on their own which air contains more moisture. Cool outdoor air can show a high relative humidity while still containing less moisture than warmer air indoors.
Vapour pressure provides a more comparable estimate of the moisture load in the air. Comparing indoor and outdoor vapour pressure helps show the direction of the moisture difference: when outdoor air contains less moisture, a short air refresh may support drying after that air enters and warms indoors.
The reverse can also be true. A lower outdoor relative-humidity percentage does not automatically mean ventilation will help, and a high outdoor percentage does not automatically mean it will not. Temperature and the underlying moisture relationship both matter.
EnvIQ can use current indoor and outdoor temperature and humidity evidence to explain whether short ventilation is likely to be useful. Guidance should also consider room conditions, extraction, safe window use and the risk of overcooling the home.
Missing, stale or poorly placed readings reduce confidence, so EnvIQ should make that limitation visible rather than give a strong recommendation. Vapour pressure does not identify the cause of damp, prove that ventilation is adequate, replace inspection or guarantee that a room will dry.