Controlling Indoor Humidity

Every year we get lots of questions about window condensation and the effects it has on windows. Here are some of the most common indoor humidity and window condensation questions and answers. To read about external window condensation, check out the article on windows and condensation.

How does indoor humidity affect window condensation?

Excessive humidity is the cause of most window condensation. As the outside temperature drops, the window glass temperature also drops. When warm, moist air comes in contact with the cold glass pane, the moisture condenses and forms water droplets. Determining when the condensation will occur and preventing it depends on the energy efficiency of the window, the relative indoor humidity of the home and the exterior and interior temperatures.

In winter, is it a good idea to use a humidifier in my home?

While some people may find it easier to breathe humidified air, humidification can sometimes have negative side effects. Humidifiers need to be cleaned regularly so that mold and bacteria do not build up in their filters. Also, if the air is humidified excessively , condensation and other excess humidity related problems can occur.On the plus side, humidified air can help to reduce static electricity in carpets, shrinkage in wood furniture and wall cracks sometimes caused by over-drying. You must carefully weigh the advantages and disadvantages of humidification since too much humidity can cause condensation and other humidity related problems.

If I increase the relative humidity in my home in winter, can I lower the temperature and save energy?

Although there is a relationship between how warm you feel and relative humidity, the human body quickly adjusts to moderate changes in humidity levels. If you feel cold at 65 degrees F, the humidity level won't really matter; you'll still feel cold.Besides turning off the humidifier, how else can I reduce indoor humidity in winter?

• Vent all gas appliances, clothes dryers and exhaust fans to the outside. Your attic and crawl space should also be ventilated. Cover the earth in the crawl space with a good vapor barrier.
• When you cook, make sure to run the exhaust fans in the kitchen. When you bathe or shower, run the fans in the bathroom until your mirror is clear. Be careful not to overheat exhaust fans by running them too long.
• Avoid storing firewood in your house or basement.
• If you have a forced air furnace, make sure your home is properly ventilated by installing a fresh air intake. If your home is extremely 'tight' it may be helpful to install an air-to-air heat exchanger.

As the outside air temperature drops, you should also decrease the humidity level within your home. The bottom line: maintain a relative humidity level as you can for comfort, then reduce the humidity level when condensation occurs. In many homes, this simply means turning off the humidifier or reducing the sources of humidity in the home.If you feel like your windows are damaged or in need of replacement, consider a winter home renovation and replacement project. Winter is a great time to take advantage of quick installation and still experience savings from the increased energy efficiency found in new replacement windows. Call us to schedule a free consultation today!