Have you ever wondered why you have damp spots or even mould in your bathroom, or behind the robe or around your windows?

No, it does not come from the outside. (except of course if there is some sort of water leakage somewhere).

The main sources of moisture in a home are cooking, baking, but also all other processes where water is used, like having a shower or a bath, using the toilet, washing your hands or the dishes, using the dishwasher or the washing machine, indoor planting, and open water features, like aquariums or indoor ponds and pools.

But did you know that one of the main contributors to the moisture in the air and in your home are us humans?

The absorption of water (H ² O) depends on the temperature of the air. Warm air can hold more water than cold air. Condensation occurs when air with accumulated moisture content through climate and occupancy cools down. If the temperature drops, the moisture content of the air remains the same initially, but the maximum capacity to hold water will be reduced. Consequently, the relative humidity is increased. Once it has cooled down to a point where the existing humidity reaches the saturation value condensation takes place.The relative humidity is 100%. The temperature at which this condition occurs is called the dew point temperature; this depends on the moisture content as well as the temperature of the air.

You might be asking: why is this important? It can’t be that bad. How much moisture/ water can there be?

Well, an average 3-person household can produce around 12L of water a day, this 12 litres does not include any extra humidity due to drying clothes inside, which would increase the amount even further.

The better insulated and the more air-tight our homes get, the more we have to convert our thinking. The temperature inside the house, the air’s moisture content as well as the temperature on the surfaces inside the house is fluctuating constantly and depends largely on the usage by its occupants, as well as heating and cooling habits. If temperatures on walls, ceilings, floors, windows

are colder than the room temperature this can lead to condensation on the surface of the materials, which, if not dried out, can lead to mould and fungus.

But it is also possible that condensation occurs within the construction, for instance within the insulation. This condensation within the wall components can also be harmful in certain circumstances to the structural integrity of the entire home.

If building a truly energy efficient home, there is almost no way around a mechanical ventilation system. I would instead recommend getting an HRV.

Heat recovery ventilation (HRV) is a ventilation system that brings fresh air into your home without letting the heat escape. They can run on a very low wattage, comparable to one light bulb.