The warmer, the more moisture

Per degree in temperature increase the air absorbs a whopping 6,25% more moisture. This doesn’t seem much but between 18°C and 22,6°C both at 50% relative humidity, this is an increase of 32,80%.

Where in the past the comfort temperature in a house in winter was +18°C, today it is +22,6°C.

The result of this is that with the same relative humidity of 50% the warmer air has a whopping 33% more moisture absorbed.

The warmer air expands a lot in volume and will inevitably absorb all the moisture in the area, usually out of the floor, cellar or crawling space.

The problem is that the vapour pressure increases exponentially from 1032 Pa to 1372 Pa, wherefor it gets over the limit with a lot of internal condensation in a vapour open wall construction. The result of this will be more damage.

Since warm air rises and absorbs a lot of moisture the most damage will inevitably occur on the top floor. This damage isn’t occupant behaviour, but regular construction physics.