Windows may seem “drafty” due to a process known in physics as convection. Convection can lead you to believe that your windows are drafty when, in fact, they are not.
What is Convection?
Convection occurs when air gives up its heat to the cooler glass and sinks toward the floor. This movement sucks new, warmer air toward the glass that is in turn cooled, creating a draft. What you are actually experiencing is the process of warm air forcing colder air to move due to differing density properties. Heated air circulates through the home. When it reaches window glass it effectively pushes the existing cold air off the glass.
Try this easy experiment to experience how convection works: Fill a glass with ice and water. Let it stand for about ten minutes. When you return, place your hands around (but not touching) the glass. You will feel cold air on your hands as warm air pushes it away from the glass surface. Convection is actually proof that your new windows or replacement windows are energy efficient and working well.
Tips to reduce convection:
- Leave your blinds or window treatments open about a ¼ inch, so that heated air can reach the glass.
- Make sure that couches or other furnishings do not obstruct your heat register exchanges.