What Passes Through Your Windows?

Homeowners know that letting the glare of the sun into a home can boost the heat index indoors as well as cause interior damage and fading. That’s why more people are opting to replace their ordinary glass windows with glazed windows.


Window glazing allows us clear views of the outdoors even as it absorbs, transmits and reradiates light and heat. Glazing doesn’t solve all problems with the sun’s glare and heat, but if you select the right glazing, there are many advantages that you can enjoy. Visible light is just one example. Visible light is the part of the electromagnetic spectrum that we can see – and it is what brightens up every room in a home.Passes-Through-Windows-1

In energy-efficient windows, measuring the window’s capacity for visible light is expressed as VT, or visible transmittance. The higher the VT, the more visible light.

Even with glazing, windows will still admit ultraviolet and infrared light. Glazing does a lot, however, to mitigate the sun’s potential damage to your home. Ultraviolet light is the part of the spectrum between visible light and X-ray. Our eyes cannot see it, but we can certainly see the negative effects of too much exposure to it. Ultraviolet light makes interior accessories, such as fabric and wallpaper, fade. Infrared light, on the other hand, begins at wavelengths of 780 nanometers. Also known as heat energy, it is the energy that we feel when we feel the warmth of the sun on our skin.Passes-Through-Windows-2

Low-emissivity (Low-E) glazing is engineered to limit the absorption of ultraviolet and infrared light without limiting the transmission of visible light. It features a microscopic metallic coating that functions much like the silver lining in a thermos, by reflecting the temperature of the room inside.

There are also some things that do not directly pass through the glazing but still impact the energy performance of the window. Air leaks around the windows, for instance, lessen your window’s ability to retain heat or cold. The wrong window frames can cause you to lose or gain heat or cold too. Metal frames with no thermal breakers are especially conductive.

So what can you do?

  • Choose better glazing material. There are various options available on the market today, ranging from clear to etched glass. We recommend double-pane windows instead of the traditional single-pane window if you wish to maximize energy savings.
  • Choose according to your climate. Energy-efficient windows bear labels from the National Fenestration Rating Council and ENERGY STAR® that indicate the unit’s energy capacities. Some values – such as a high SHGC – are good in cold climates, but won’t work as well for homes in warm climates where there’s a need for cooling rather than heating. When considering what kind of glazing and window frames to get for your home, always take into account the climate and typical weather conditions where you live.Passes-Through-Windows-3
  • Position your windows properly. North-facing windows will need little shading. If you must orient your windows south, east or west, make sure that you have ample shading devices whenever necessary. Overhanging tree branches that may get in the way of daylighting should be pruned back.

Final Section

Lastly, hire the right help. Benefiting from a good window product does not start and end with choosing the right type of glazing or framing; installation plays a key role in the results. Choose a professional who has extensive experience, offers competitive rates and is licensed or registered with your state. Where possible, choose a company that also has a partnership with trusted brands, as they have more specialized knowledge in installing quality windows.

Author Bio

Based in Cypress, Texas, Dennis Rupp heads the marketing department at Renewal by Andersen of Houston. He studied home design at the University of Houston and offers 35 years of solid experience in the industry.




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