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Condensation on Windows

Narayani Karthik Feb 8, 2019
A common problem every household faces in winters is condensation on windows. Let's discuss its causes and how it can be tackled.
Frost accumulating on the inside of windows during winters is not uncommon. Ignoring this problem can cause accumulation of water inside the glass, which eventually starts damaging the flooring and window sills by constant dripping.
This problem is termed as condensation on windows, and it is caused by excessive humidity in the house caused due to various reasons. Let's look into some of the common causes and remedies for this problem.


When the air comes in contact with a non-absorbent surface which is at a temperature lower than the dew point, the moisture in the air settles down on the surface in the form of small droplets of water.
Dew point is the temperature at which the water vapor in air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. Condensation on windows is generally more common in winters.

In Summers

In summers, the atmospheric temperature is high and the air is humid, while the temperature inside the house is comparatively lower. In such conditions, exterior condensation on the windows is quite common.
This happens because the outer surface of the window is at a temperature lower than the dew point temperature of the atmosphere outside. So, the main reason for condensation on the outer side of windows in summers is uninterrupted use of air conditioning all day long.
This problem is also observed on car windows. The difference in the temperature inside and outside causes a difference in the summer dew point temperature. For instance, in parts of south-eastern United States, summer dew point temperatures range between 65-75ºF.
So, if the inside temperature of your home or building is within this specified range, exterior condensation on the window is bound to occur. The water droplets formed in the creeks of your glass windows taint the clear look of the windows.
Since the relative humidity in the atmosphere cannot be controlled, the best way to prevent condensation in summer is to warm the inside surface of the windows by raising the thermostat setting or by using exterior shutters. Also, if your home is surrounded by a lot of trees and shades, then this problem is less common.

In Winters

In winters, the condition is an exact opposite of that in summers. Heaters and firewood are used to keep the place warm, and the atmospheric temperature is much lower than what it is inside homes.
Due to this factor, the dew point is relatively dependent on the temperature inside the home. When the warm moist air inside comes in contact with the inner surface of the windows (which is cooler because of the external atmospheric temperature), dew drops are formed on the inside of the windows.
This is one of the major reasons why dehumidifiers are used extensively during winters. A relative humidity of 40% works fine, but exceeding this percentage will result in condensation. As per the Home Ventilating Institute (HVI), 8 air changes for bathrooms and 15 air changes for kitchens are recommended on an hourly basis.

Tips to Combat Condensation

Excess moisture is not a good thing when it comes to your home or health. Let's look into some methods to check the condensation on windows:

Bring Down the Moisture Level

Regulate the use of humidifiers, and avoid using them beyond a certain setting. Tending to plants inside home is not advisable in humid environment.
One can make a terrace garden to tend to plants, where the plants too can get required exposure to sunlight. Leaking pipes and drainage problems are also factors that increase the moisture inside homes, so get them repaired.
Check your gas appliances time and again for proper functioning, as their malfunctioning can emit a lot of moisture along with dangerous contaminants into the atmosphere, which can pose health hazards too. So, make sure your home is equipped with a carbon monoxide alarm.
Wood fires are generally used in winters to keep the house warm, so make it a point to open an exit path for the moisture-loaded air. Also, the wood should be dried in an open space before using it in the hearth.

Ventilation is Important

More the ventilation, more is the air circulation and better is the regulation of moisture content inside the house. When cooking, doing laundry, or bathing, make sure to open the windows for some time to let the excess moisture out.
It is also advisable to run the exhaust fan inside kitchens and bathrooms for a longer time to dehumidify the air inside, as these places contain the maximum amount of moisture. It is recommended to raise the temperature inside the house by insulating the garden windows to keep them warm.
One can also use direct warm air supply ducts to windows or ceiling fans, as opposed to air conditioners, to remove excess moisture from the air. Also, make sure that sources of moisture like aquariums, fish tanks, and water dishes are covered.
These tips will help you keep this annoying condensation issue that spoils the chic look of your beautiful home at bay.