Terms to Learn When Shopping for New Windows

When you're in the market for new home windows, you may come across more style choices and types of glass than you were expecting. Understanding the differences in those choices will help you to pick the best windows for your home. Note a few terms to learn when you're shopping for new windows so you know the best options for your home.

Air infiltration

This refers to the amount of air that passes through the seals of the windows. If your home tends to be very draughty or very stuffy, you may need windows with a lower air infiltration and better seals.


Conduction refers to heat transfer through a material, and specifically from a warm surface to a cool surface. If your home is located in a very warm area or it gets lots of direct sunlight, shop for glass with a low conduction rating. This will help to keep that summertime heat out of your home so it's cooler and more comfortable inside.


Daylighting means the illumination of indoor spaces by way of windows. When talking to your window contractor, ask about what style of window would improve daylighting if you want more light in a certain room. If you want less light, such as for a bedroom, ask how you might reduce the daylighting. Your window contractor can then recommend a different style or size of window, or a specialty glass, that increases or reduces the amount of light that passes through.


Emissivity refers to a material's ability to radiate energy; for glass, it often refers to how much daylight will pass through the glass, versus being bounced off the glass surface. If your home has lots of direct sunlight, you might want low emissivity, or low-E glass, to keep the interior cool and reduce glare on televisions and computer screens.

Fading factor

Most glass will have some type of coating that helps to protect it and keep out cold, heat, and sunlight; the fading factor of glass will take into account that coating and specifically how it would affect furniture fabric, carpeting, timber floors and other items in your home. The fading factor will tell you if those materials and surfaces are at risk of being damaged, or if the glass coating will protect their colour, not allow timber to dry out, keep houseplants from getting too much sun and the like. For very large windows that may allow in lots of sunlight, note the fading factor so you know items in the home are protected.