The Great Escape
The moisture produced will quickly reach 'Saturation Point' if confined, especially in the kitchen and bathroom, more so if the air is cool. If the room has an opening to the outside, such as a window opening, the moisture would be able to escape and be replaced by fresh air. Unfortunately, there are two problems here; Firstly, if it's particularly cold outdoors, opening the window will cause heat loss within the room, reducing the holding capacity of the air as the temperature drops. Secondly, though an open window will allow air to escape outdoors and at the same time let fresh air in, it does so without any control and the rapid build-up of moisture would overtake its escape. Obviously, an alternative controllable method of doing this is required, namely, by means of an extractor fan.
To effectively control condensation, the removal of moisture from source is important, as this decreases the volume of moisture in the air and by ensuring that the air is warm will increase its carrying capacity. If done in a balanced way, this combination will prevent the air from reaching saturation point.
The Good Old Days?
The fact that the modern home seems more prone to condensation is no co-incident. Everything today is designed to fit better. Modern Upvc windows and doors have draught proofing seals built-into their design, modern double-glazed timber windows and door frames also have seals inserted into the frames when manufactured. All these features of good design, certainly produce draught-proof homes; unfortunately, this is often at the expense of required ventilation.
By contrast, in the homes of old, it was a different story; curtains were often draped over doorways, and windows to form a barrier from draughts. Another feature of the older house was the fireplace/flues, very often in each room, including the bedrooms. This combination of draughts and ventilation (via the flues) provided a good means of air changes and ventilation.
I'm not suggesting here that you move out of your draught-proof home, but this does go a long way to illustrate the fact that ventilation and regular air changes are an important factor in condensation control. In the kitchen and bathroom, an extractor fan is the first step, but you will also need air vents so as to provide an air supply. Also ensure that there are air bricks to the outside walls and that they are not blocked.
