Energy Efficient Windows -- A Good Investment?
Learn how efficient windows affect your utility bills
By Brad Painting
Owners of homes or commercial buildings often wonder how quickly the cost of new windows will pay for themselves in lowered utility bills. The short answer is that it depends on several factors, including climate, quality of the upgrade and quality of the building's insulation and air sealing. Windows seem like an obvious place to save energy because we can feel heat radiate through windows during exceptionally hot or cold weather.
Air sealing refers to using caulking and weather stripping to eliminate any unintentional gaps to the outdoors. If your home has poor air sealing, it will swallow most of the energy saved from upgrading windows. Energy-efficient windows will be much more effective in a tightly sealed house. Air sealing itself is a relatively simple and cost-efficient method of improving a building's efficiency. To find hidden air leaks, you can have a "blower door test" done, during which a technician uses a special fan and pressure gauges to test how tightly your building is sealed.
Windows are not great insulators; even some of the the more energy-efficient windows do not block heat flow as well as a typical uninsulated wall. Before you invest in windows, know that you can significantly reduce energy by insulating all walls and ceilings. Windows typically make up 20 percent or less of a building face, and they are more expensive per unit area than added insulation. Insulate walls and ceilings to levels recommended by the U.S. government's Energy Star program before upgrading windows.
Quality of Upgrade
Some window upgrades are more beneficial than others. If you you have any cracks or noticeable leaks in the window pane, it is definitely a good idea to fix or replace them. It is probably also a good idea to replace any single-pane windows. Single-pane windows are vastly less efficient than double-pane windows. The Energy Star program estimates that the typical household can save $465 per year by replacing single-pane windows, but only $126 by upgrading double-pane windows. To realize these savings, the new windows need to be Energy Star-qualified.
Climate plays a large role in how much your windows affect energy consumption. Windows not only conduct heat from the air, but they transfer heat directly from the sun's radiation. Energy-efficient windows usually allow less radiation to pass, but this can actually be beneficial or detrimental depending on climate. Overall, buildings in colder climates will benefit more from window upgrades. Energy Star estimates that a 2,000-square-foot house in New England could save up to $493 per year, but a similar house in Florida would save only $192 per year.
Considering the multitude of factors that affect energy consumption, the return on investment for windows is a bit of a gamble. If considering a large investment, contact an energy modeler to verify that the new windows will have a sufficient impact. A contractor who participates in the Home Performance with Energy Star program can look at your whole house to tell you what the smartest improvements are. Whatever your decision, windows will last several decades and will almost always eventually pay off. The simplest way to estimate your rate of payback is look up your climate zone on the Energy Star website, and then divide your initial investment by the estimated yearly savings.
Federal Tax Credit
You can reduce your initial investment by taking advantage of a federal tax credit in effect until December 31, 2010. It credits you with 30 percent of the cost of qualified energy-efficient home improvement products up to $1,500. Look for the blue oval label that reads "Eligible for up to $1,500 federal tax credit." The 30 percent credit applies only to product costs; installation costs are excluded.
About the Author
Brad Painting is a regular contributor to DexKnows and specializes in green building design.
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