How to Reduce or Prevent Condensation in Your Home

Condensation occurs when air hits a cold surface. Air has a limit to the amount of water it can hold in suspension and the amount of water in the air is known as the relative humidity (measured as a percentage). Once air becomes saturated, the relativity humidity has reached 100%. Now as the temperature becomes lower, air can hold less and less water. Condensation occurs when water laden air hits a cold surface, reducing the temperature of the air. This could be glass in windows, cold tiles or metal surfaces. These surfaces are either colder than other surfaces in a room or are of high thermal conductivity so that heat is sucked out of the air. In any case, the air temperature drops to the extent that it can't hold moisture any more and it is deposited on the surface.
To avoid condensation you have several options. Firstly you can vent moisture laden air (e.g from cooking in the kitchen) so that it doesn't end up in rooms. You can do this by using extractor fans or simply opening windows. Portable gas heaters produce lots of water vapour and should be avoided. Another option is to raise the temperature in the room. This makes surfaces warmer so that moisture doesn't condense out. Double or triple glazing also helps because the external surface of inner panes of glass is not in contact with air outside the house. Removing sources of moisture also helps. This includes house plants and damp clothing. Clothes in the washer should be kept there with the door closed until they are transferred to a drier, or hung outside. Drying clothes in rooms or on radiators transfers water to the air where it inevitably condenses out if windows are closed and the room temperature drops. Yet another way of reducing condensation is to use a dehumidifier. This appliance works by circulating air over chilled coils. This causes moisture to drop out of the air (just like it does on your windows) and collect in a reservoir tank.