The Glorious World of Glass

Understanding the Technical Details of Window Glass

When buying new windows, you want to carefully shop different styles when it comes to how they open; you might prefer a casement window that opens on a side hinge, versus a standard single-hung window that slides up and down, for added air circulation into the home. However, you also want to consider the technical details of window glass along with the style of windows you choose, as the glass of windows will be what helps to actually insulate your home against outside heat and cold. To choose the best window glass for your home, note a few technical details you'll want to consider and understand when it comes to your options.

Low-E coating

Low-E coating reflects or bounces back heat, but not light. If you live in a very warm climate, you might request low-E coating on the outside of the window glass. If you live in an area with bitterly cold winters, ask for low-E coating on the inside of the glass, to keep heat inside the home.


The U-factor also helps to keep in heat, and this is important if you live in an area with long, cold winters. The lower the U-factor, the better the glass is at keeping heat inside the home.

Solar heat gain

Solar heat gain refers to blocking heat specifically from the sun. The lower the number, the less heat from sunlight that can pass through the window. Keep this in mind if you live in a cold climate; you'll want a high solar heat gain factor, as this will allow more heat to pass through the windows, keeping the home as warm as possible during wintertime.

Visible transmittance

Glass may have additives in its mixture that diffuse light, and this can be important for windows that face streetlights or for homes in areas with bright sunlight. The higher the visible transmittance, the more light that passes through the window. For a bedroom window, or for a sunroom, choose a window with low visible transmittance, and this will create some cooling shade in that room.

Insulated glass

Insulated glass typically refers to double-glazed or triple-glazed windows, which include more than one pane of glass with a layer of air or argon gas between them. This type of insulated glass provides more insulation against outside temperatures as well as outside noise. If you live near a busy roadway, airport, school, or other such distraction, it can be worth investing in triple-glazed or triple insulated glass.