Do Windows Block UV Rays?

When filtered through the Earth’s atmosphere, the electromagnetic radiation given off by the sun paints a spectacular portrait on the canvas of the sky, thanks to the visible light that has inspired many artistic masterpieces. But, viewed from a scientific perspective, sunlight is a fairly complicated phenomenon that encompasses not only the light rays that you can see but also the ultraviolet (UV) and infrared rays that you can’t. Windows were invented to invite sunlight into homes, so it’s obvious that window glass doesn’t block the visible portion of the sun’s rays. But what about UV rays and infrared light?

Ordinary Windows vs. Energy-Efficient Windows

Different types of radiation generate different wavelengths of energy that can pass through or become absorbed when they encounter the electrons in various substances. Visible light is not absorbed by the electrons in standard window glass, so it passes through ordinary windows unchecked. On the other hand, some infrared light and UV rays—but not all—are blocked by standard window glass. The penetration of infrared light is the reason why glass can feel warm on a sunny day, and solar heat can invade your home and drive up your cooling costs. In the case of UV rays, scientists classify these in terms of UV-A and UV-B, both of which are associated with tanning, sunburns, and skin damage. UV-A rays can also cause premature fading and wear in furniture and draperies. Standard window glass blocks UV-B rays but not UV-A.

Fortunately, technological advances have led to the development of energy-efficient windows that not only dramatically reduce heat transfer by blocking infrared rays but also substantially block harmful UV rays. The low-emissivity (low-E) glass coatings found in windows that qualify for the ENERGY STAR^® program are particularly effective because they block most UV and infrared rays while letting visible light stream into the home.

NewSouth Window Solutions is proud to manufacture and install some of the industry’s most energy-efficient replacement windows in homes throughout the South. We offer windows that help homeowners reduce their energy consumption and potentially lower their cooling and heating bills, and they come with a host of additional benefits as well. Contact us today if you’d like to learn more.