The air in our homes is quite humid. Water vapour is released by many activities including cooking, bathing, and drying clothes. Depending on the temperature, air can absorb significant amounts of water vapour, but as the temperature cools, the amount of moisture the air can hold falls. When this happens, the moisture is released. This commonly happens on cool surfaces such as windows or exterior walls and is actually the same as the process which causes rain.
Water vapour is released into the air by a variety of activities in the home. Large volumes of moisture can be released from cooking and bathing, but other activities will also release moisture.
Drying clothes on radiators or using a tumble drier without a condenser or outdoor ventilation will release a large amount of steam into the air. In fact, every time you breathe out, you release some water vapour into the air. During the night, with two people sleeping in a room, more than a pint of water is released into the air, which will contribute to the formation of condemnation.
At a temperature of 20C, a cubic metre of air can hold approximately 17g of water vapour, whereas at 10C, the air can only hold 9g of water per cubic metre. When warm, moist air comes into contact with a cold surface such as a wall or window, the temperature falls, and the air can no longer hold as much moisture, so it condenses. This formation of liquid water on a surface is what we see as condensation.
Condensation on non-porous surfaces like windows and tiles is not a major problem – although if it forms on floors, it can be a slipping hazard, however if condensation forms on surfaces where it can soak through into the underlying material, it can create long term problems.
The most immediate problem caused by condensation is damp. Damp forming in walls can cause the plaster to crumble and create unsightly stains on the paintwork. The damp can also lead to wallpaper peeling away from the wall. In wooden window frames, condensation can soak into the wood and cause it to rot.
Damp can be expensive to repair, but it is also a breeding ground for problems with mould and dust mites that can release allergens and toxins into the air that can damage your health.
Mould thrives on damp surfaces and can spread quickly across walls and ceilings creating unsightly black patches. Toxic black mould in bathrooms and bedrooms can be extremely harmful for the health of people with weaker immune systems such as small children and the elderly and can also trigger conditions such as asthma. Some moulds can be cleaned using fungicide or dilute bleach, but others need to be professionally removed.
It is possible to reduce the amount of moisture that is released into the air of your home. Simple changes such as closing the bathroom door when bathing, using pan lids when cooking on the stove, and drying clothes outdoors can all help, however, to avoid condensation altogether, you need to improve the ventilation in your property.
Installing modern, energy efficient extractor fans in bathrooms and kitchens will quickly remove moist air from those rooms and reduce the amount of moisture that can escape to cause condensation elsewhere. Systems such as the EnviroVent Cyclone 7 include a humidity sensor which can measure the amount of water vapour in the air and adjust their power levels to increase the speed with which they expel air.
While extractor fans in bathrooms and kitchens are highly effective at dealing with condensation caused by bathing and kitchens, they are limited to the rooms where they are installed. To deal with other sources of condensation such as plants, pets, and clothes drying in the home, a whole house ventilation system may be more appropriate. Positive Input Ventilation Systems (PIV) such as the EnviroVent ATMOS have a central unit which is usually located in the loft. This draws fresh air into the home at roof level, passing it through filters to remove allergens such as pollen and then gently distribute it through your home to replace the moist air and prevent condensation for good.
EnviroVent have detailed guides to help you reduce condensation in your property, and also information about the different types of ventilation systems available:
You can also book a free home survey from one of our local ventilation specialists. They will visit your home, identify the sources of moisture in the air, and provide you with advice about the best way of dealing with them. Simply fill in your postcode below to find an expert near you.
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