Condensation Problems
Condensation forms on a surface when the temperature of that surface is below the dew point of the surrounding air. As air is cooled, its relative humidity rises until it reaches a point where it is saturated and can no longer hold on to all the moisture in the atmosphere. The temperature at which this occurs is the dew point and it will vary according to the initial moisture content of the air. When you take a bottle of milk out of the fridge you will immediately see droplets of water forming on the outside of the bottle. This is condensation. As air passes over the surface of the can or bottle its temperature is reduced and it can no longer hold on to all the moisture so it deposits it on the cold surface. When this process happens the air has reached its dew point. This is why when temperatures drop in an occupied property, the air can no longer hold onto all the moisture that has been generated so it will migrate to the coldest parts of the house and condense onto the windows and walls.
To understand the solutions to condensation the causes have to be identified. In a property of 4 people, each will contribute approximately 4 pints of moisture per day through showers, baths, boiling kettles, cooking etc. This adds up to well over 100 pints of water vapour per week - a huge volume of moisture, which must go somewhere. Add the other airborne contaminants which exist in a typical home - dust, tobacco products, exhaust gases - even chemical emissions from furnishings and building products - it's not difficult to understand the scale of the problem.
In the past there would be a natural escape for this hot, damp and poor quality air through ill-fitting windows and doors, uncarpeted floor boards, lofts without insulation and so forth. As the stale air left the building it would be replaced by fresher, albeit colder air - draughts!! Now, with improved building features such as cavity wall insulation, double-glazing and draught proofing, 'natural ventilation' is prohibited. Stale, humid air is trapped, making the condensation problem in the dwelling worse, causing streaming windows, which will inevitably lead to musty smells, dampness and ultimately mould growth.
