Low-E Windows

Low-Emissive Windows Are Key to Green-Home Building

By John Voket

According to the latest NAHB Remodelers survey, high-performing, Low-emissive (Low-E) windows are the most common green building products used by residential remodelers.

So what’s the low down on Low-E? Enter Nick Gromicko and Ethan Ward representing the National Association of Certified Home Inspectors (nachi.org).

They say Low-emissivity glass, aka low-E glass, uses a microscopically thin and virtually invisible metal or metallic oxide layer incorporated in the glazing surface to control heat transfer through insulated windows, reducing energy loss by 30 percent to 50 percent.

Low solar-gain low-E glass is also spectrally selective and is best suited to cooling-dominated climates, where the biggest concern for windows is blocking heat transmission. These windows are made with sputtered low-E coatings that consist of either two or three layers of silver. They are sometimes called double-silver or triple-silver low-E windows.

The report goes on to say, that installing low-E windows can provide significant energy efficiency and savings, especially in hotter climates where windows with a low solar heat-gain coefficient (SHGC) are most effective.

Computer simulations have shown that advanced window glazing with spectrally selective low-E coatings may reduce electric space-cooling requirements of new homes in hot climates by more than 40 percent.

Full disclosure: Nick and Ethan also report that low-E windows are the culprit of melted vinyl siding installed on nearby houses and buildings. Apparently, intense heat reflected by the windows can be focused on neighboring surfaces, similar to the burning effect of pin pointing the sun rays through a magnifying glass.

The effect has caused numerous claims because of melted or distorted siding and several fires according to the NACHI report. In our next Remodeling Month report, we’ll chill and take a look at energy saving HVAC systems.

Reprinted with permission from RISMedia. ©2014. All rights reserved.