This is a common sight during spring and fall, when a warm day transitions to a cooler night.
Low-E glass is designed to maintain comfortable conditions inside by reducing heat loss through the window, in some cases cutting heat transfer by 50 percent. As the glass reflects the heat energy back into the room, the temperature of the glass exterior falls, which can lead to condensation. But in this case, the presence of moisture outside actually signals that the glass is performing properly.
Condensation on the inside of a window is usually a sign of excessive humidity in the home. Due to high levels of moisture in warm air, it can often result in condensation when coming into contact with a cooler surface, such as a window pane during winter.
You can reduce window condensation by improving air flow and reducing humidity inside your home. When the temperature outside begins to fall, you may need to take certain measures to control humidity levels inside. Some of these measures include:
Using an exhaust fan in the kitchen, bathroom and other rooms where high levels of moisture are often present.
Turning off or turning down humidifiers when they aren’t needed.
Ensuring that all ventilation channels leading outside are unobstructed.
Allowing air to circulate freely through your home for short periods every day.
Venting clothes dryers and gas appliances to direct moisture outside.
Opening the fireplace damper occasionally to allow moist air to escape
If your home’s windows are not well-insulated or haven’t been properly installed, your ability to control condensation will be limited. Over time glass condensation can contribute to mold growth—a destructive presence hidden inside window and wall openings.
Mold is increasingly being linked to child asthma, as well as increases in general respiratory illness, allergies and outbreaks of fungal disease.
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