Damp Information
Condensation
The phenomena of condensation is brought about by the cooling of warm moisture laden air when it comes into contact with lower temperatures or a cold surface.
In a house this can be seen on windows as a film of water often referred to as streaming, on plaster as a damp patch often discoloured by the presence of black spot mould, and in wardrobes causes mildew, a greeny type of mould that grows on clothes and shoes, and the conditions can also be accompanied by a musty smell due to the mould growth and other bacteria that can also affect upholstery, drapes and carpets where excess humidity exists. Each household having its own characteristics that will produce excessive moisture in the air one way or another ranging from steam in the bathroom produced by bathing and showering, to cooking in the kitchen and washing in the utility room, each area being a formidable factory for manufacturing excess humidity that then floats around the house adding to the existing interior atmosphere. For the most part this is quite invisible and remains so during most of the daylight hours, all carried aloft by the warm air we surround ourselves with for comfort. This is usually produced by our heating systems such as gas central heating, electric bar fires, or perhaps just sunlight shining through the windows. The heating systems themselves do not produce moisture with the exception of flame gas fires that in fact do produce water vapour in the air when burning, but because the air is warmed up, it can hold a proportionate amount of water until something occurs to suddenly lower the temperature such as night time and the heating is turned off. When this happens any excess moisture in the air will immediately be converted to actual water where it comes into contact with colder surfaces, and on a regular basis can actually build up on a plaster surface so that there is enough moisture left during the daytime for mould to germinate, before total drying out can happen. Fortunately this tends to disappear during the warmer months of summer as night time temperatures remain higher. However winter still constitutes six months of cold nights and days and it is during this period that buildings can become affected by excessive humidity. Albeit the environments caused are detrimental to health particularly to those who have respiratory problems such as asthma and emphysema.
Ways of reducing water in the air
- Dehumidifier (free standing powered unit that collects water in a sealed vessel)
- Powered extractor fans (bathrooms, kitchens and utility rooms)
- Dehumidistat extractor fans. Similar to ordinary extractor fans except they can be set to activate automatically when humidity levels reach a certain point.
- Passifier ventilators that allow only warm air into the property.
- Ordinary louvered or grille ventilators that allow natural escape of air from the rooms fitted with them. This relies upon internal air pressure being higher than the external air pressure. Unfortunately when this becomes reversed cold external air is then drawn into the house causing drafts which people then block up and produce condensation again.
There are also a host of small dehumidifiers on sale that work by absorbing humidity into silicate crystals. However these soon become saturated and when dried out as recommended by the manufacturers, just dispel the water back into the internal atmosphere. In this regard I would not recommend them.
One very successful way of controlling condensation is to install one of the positive input ventilation units (PIV) produce by the Nuaire Group. These work by stabilising the internal atmosphere and once installed are easy to maintain and although electric powered are very quiet and economical to run especially when compared to savings made by not having clothes ruined, and black mould to annually paint over.
