Controlling Condensation

Why Bother?

Because excessive condensation can have many negative consequences inside the home that range from potential structural damage over the long term to the development of potentially harmful moulds and fungi, it is prudent to take the necessary steps to control it.

Warm the Interior Surfaces of the Window

One way to increase the condensation resistance of windows is to increase the window’s capacity to reduce conductive and convection heat loss. Windows constructed using warm edge spacers, low-E coatings, gas fills, and non-conducting sash and frames will have a greater resistance to condensation. The interior surfaces of these windows stay warmer.)

Lower Relative Humidity

Condensation resistance also depends on controlling indoor humidity. A relative humidity level of more than 40% inside, when the outside temperature is -20°C or less, may cause condensation even on a well constructed, energy-efficient window.

Some ways to reduce the humidity include disconnecting the humidifier on your furnace and making sure the clothes dryer is vented outside. Also use the power vents in the bathroom when bathing and over the stove when cooking. Don’t over water house plants and avoid drying firewood in the house. A cord of wood can release more than 270 litres of water.

If the condensation problem is severe, opening a window for a short time will ventilate the house and dilute the humidity level. If excessive humidity persists, a mechanical ventilation system, although expensive, will bring fresh air in and exhaust stale air over a 24 hour period. Ensure the unit installed has a heat recovery unit and a relative humidity control.