WORTH KNOWING
The Problem Of Condensation.
An Important Consideration When We Design Your Skylights
An Important Consideration When We Design Your Skylights
Condensation is formed on a surface, when the surface’s temperature falls below the dew-point temperature of the air.
It affects all sorts of windows - especially during the winter period - for instance, in a car, where the windows mist up. The solution is to set the ventilator on warm air, which then blows on the windscreen of the car. When the car is heated, the dew disappears. The air that the heater blows on the windscreen is sucked through ventilation slots, and is often cold . This cold air is usable though, if it has a lower moisture content than the air inside the car. Condensation evaporates faster in warm air, because the latter can absorb a larger amount of moisture.
How Condensation Affects Building Windows
Condensation in our homes is nothing new. However, due to increased insulation and buildings being more airtight, the problem has intensified. As windows, doors and skylights have 7-14 times less insulation than walls and ceilings, they normally form the coldest surfaces of the building. Therefore the moisture problems will occur here first.
Plan For Your Building’s Interior Climate
At the planning stage, it’s important to consider the effects of heating and air humidity. In order to prevent condensation completely, the heating system can be constructed in such a way that a natural circulation of air occurs within the skylight. This will help condensation evaporate, just as the air in the car example helped to de-fog the windscreen.
How Primalux Helps Prevent Condensation On Its Skylights
As a rough rule of thumb, in order to ventilate the skylight without special measures, a skylight should be made in such a way that the upstand is not higher than half the width of the skylight. For example, with a skylight of 80 cm x 80 cm, the upstand should be a maximum of 80/2 = 40 cm high.
Another way to avoid condensation is to measure the inner surface temperature of the skylight - at the coldest spot - and similarly, measure the dew-point temperature of the air in the skylight room. By doing this you can set the heating control so that the surface temperature never goes below the dew-point temperature.
It affects all sorts of windows - especially during the winter period - for instance, in a car, where the windows mist up. The solution is to set the ventilator on warm air, which then blows on the windscreen of the car. When the car is heated, the dew disappears. The air that the heater blows on the windscreen is sucked through ventilation slots, and is often cold . This cold air is usable though, if it has a lower moisture content than the air inside the car. Condensation evaporates faster in warm air, because the latter can absorb a larger amount of moisture.
How Condensation Affects Building Windows
Condensation in our homes is nothing new. However, due to increased insulation and buildings being more airtight, the problem has intensified. As windows, doors and skylights have 7-14 times less insulation than walls and ceilings, they normally form the coldest surfaces of the building. Therefore the moisture problems will occur here first.
Plan For Your Building’s Interior Climate
At the planning stage, it’s important to consider the effects of heating and air humidity. In order to prevent condensation completely, the heating system can be constructed in such a way that a natural circulation of air occurs within the skylight. This will help condensation evaporate, just as the air in the car example helped to de-fog the windscreen.
How Primalux Helps Prevent Condensation On Its Skylights
As a rough rule of thumb, in order to ventilate the skylight without special measures, a skylight should be made in such a way that the upstand is not higher than half the width of the skylight. For example, with a skylight of 80 cm x 80 cm, the upstand should be a maximum of 80/2 = 40 cm high.
Another way to avoid condensation is to measure the inner surface temperature of the skylight - at the coldest spot - and similarly, measure the dew-point temperature of the air in the skylight room. By doing this you can set the heating control so that the surface temperature never goes below the dew-point temperature.
Examples of a modern Primalux skylight insulated against thermal bridges
Be sure to ventilate properly!
Diagram for comparison of the inside temperature and the dew-point temperature as to different relative moisture levels.
Source: DTU (The Technical University of Denmark)
