Choosing Windows

This article first appeared in the Austin American Statesman.

Greenbuilder logo

Choosing Windows

Mary McLeod, City of Austin Green Building Program

We all love lots of windows. We love the natural light, the views, and the fresh air we get from them. But nowadays there are so many kinds of windows available, it's hard to make a choice. We want windows to be attractive, let in plenty of light, and be energy-efficient. We don't want them to feel drafty or have condensation problems. And we want all this for an affordable price. Here are some questions commonly asked about windows which may help you make a smart choice.

I live in an older house and often feel uncomfortable near the windows. Should I replace them or add storm windows? Replacing windows or adding storm windows is costly. Try these measures to improve comfort and reduce energy bills before you decide whether to purchase new windows. Caulk around all trim and stationary parts and weather-strip the moveable parts, to cut down on air leaks. Install insulated drapes or shades to reduce heat loss in winter, and install solar screens or awnings to reduce solar heat gain in summer. If you are having a problem with condensation on the inside of the glass in cold weather, try to reduce indoor sources of moisture. Install exhaust fans which vent to the outside in bathrooms, the laundry and kitchen.

I'm building a new house and the price my builder quoted for double pane insulated windows is a lot higher than single pane. Are double pane windows worth the price?

A typical window is almost like a hole in the wall. Modern window technology combines many features that go a long way to overcome the "hole effect", but at a price. If you know what a given feature can do for you, what it will cost you, and whether there is a cheaper measure to achieve the same result, then you can make an informed decision.

Most people get double pane windows because they think they will save them money on their heating and cooling bills. Yes, they will reduce heat loss, and therefore save on winter bills, but since we usually have mild winters in Central Texas, this potential for savings is small.

A standard double pane helps even less in summer. However, a double pane window with a special coating applied to it will greatly reduce heat gain from the hot summer sun. This coating is called low-e (short for emissivity). To work well in the south, it must be applied to the outside surface of the inside pane of glass. In the north the low-e coat is applied to the inside surface of the outside glass to keep heat inside. Be sure an uninformed salesperson doesn't order the wrong kind! Double pane windows also reduce noise and the incidence of condensation. The seals on double pane windows have improved over the past few years, so failure of the seals is less likely. However, it does make sense to compare warranties carefully.

Besides checking the warranty, is there any other way I can compare one window brand with another? Yes. Look for the NFRC label. That stands for the National Fenestration Rating Council. (Fenestration is the architectural term for windows.) First, look at the U-Factor, which serves as a good measure of heat loss in winter. The lower the U-factor, the better. The NFRC rating considers the whole window as a unit, including glazing, the sealing method and the frame material. Next, look at the Solar Heat Gain Coefficient . In our hot climate, the lower the better. Finally, look at the Visible Transmittance. This number should be as high as possible. In summary, look for the best possible combination of numbers--the most light for the least solar gain and the least heat loss.

Don't skimp on your window budget. A high quality window has so many benefits--lower energy bills, less maintenance, reduced fading of furniture and carpets, improved security, beauty and comfort--it pays to make a good window investment.

For whatever types or kinds of windows one chooses, there are always the suitable window shades for it!

The City of Austin Green Builder Program is a voluntary home-rating system that encourages energy-efficient and environmentally sound building, remodeling, and home maintenance. For more information, call 499-7827.

You can find more information including the Sustainable Building Sourcebook compiled by the City of Austin's Green Builder Program at the Sustainable Sources website.

copyleft 1997: You are encouraged to copy and redistribute this article provided that you acknowledge the City of Austin's Green Builder Program as the source. Please attach this statement.

Return to:

Sustainable Sources | Building Sources | Articles: Sustainable Building and Beyond

Webmaster: Bill Christensen