windows buying

when shopping, take into account the window U-factor and the window SHGC, which depend on the glass, number of panes, and the window frame and details like argon-filled panes and insulated frames. Compare prices, but also the window rating. Make sure that the window rating applies to your climate. Choose a good manufacturer (and installer) and a convenient design (casement windows are more energy efficient).

Compare window ratings

Compare different windows and their rating. In cold climates pay special attention to the U-factor of different windows; it should be less than 0.3 for maximum energy savings.

In hot climates, a low SHGC (below 0.3) coefficient is crucial to get air conditioning savings.

See: Window glasses and panes

Manufacturers rating labels

Manufacturer labels should be considered cautiously. They are often biased. The U-factor and the SHGC and other coefficients should apply to the whole unit, and not just to the glass.

Climate zones

When buying, demand windows qualified for your specific climate zone. The Energy Star ratings (or the European BFRC and other ratings) involve specific climate zones...

See: Windows, Skylights, Glazed doors & Climate

Frames and Glasses

The window glass and its rating (U-factor, SHGC, and other) are important. But there are other features you should also consider, like frames and sashes. Select the best frame materials for maximum efficiency. Fiberglass is often the best option.

See, for details: Window frames and sashes and Window types and designs

Manufacturers

Choose a good manufacturer, but consider the specifications of its different window models. Manufacturers offer different models, with different prices and efficiency.

See: Window installers and manufacturers

Long warranties

Pay attention to warranties. Longer warranties are a good indicator.

Tinted windows

Tinted (bronze, green...) glass windows, provide lower solar heat gain coefficients. But low-E coatings glasses (or a combination of low-e coating and tinted glass) are usually a better buying option.