Going Green While Replacing Windows

You might need to replace the windows in your home to address a specific issue, or you might be doing so for esthetic, maintenance, energy efficiency or home value motivations. Perhaps your reason is completely unique or a combination of motivations. Regardless of the reason that has started you down the road to new windows, energy efficient windows can help you met all your goals. You might be losing as much energy from closed windows as open windows because most window surfaces have less insulating value than surrounding walls and frames can be poorly sealed. Thankfully, in recent years well made, energy efficient windows are more offered in a number of styles across the country and in a variety of price ranges. A model that is energy efficient can replace just about any single pane window. Although replacing all the windows might be daunting price wise, the long-term savings that you will reap from climate control in your home will far exceed that cost. The change will also increase the value of your home, which is always a good thing. There are few other home improvement projects that yield this many benefits as the simple replacement of single pane windows with energy efficient windows.

The features of windows can vary by model and manufacturer; however, there are some basic features that all energy efficient windows will possess. New energy efficient window will have low-emissivity glass, which means that the outer surfaces of the glass have been treated with special low-emissivity coatings, which allow light to pass through but reflect ultraviolet and infrared light. This will keep heat from coming in through the windowpanes during the summer and protects your artwork, paint and furnishings from fading due to sunlight exposure. Energy efficient windows will also have at least two layers of glass, which will reduce heat transfer. Three layers of glass will provide soundproofing as well as added thermal insulation. The windows all should have insulating frame materials. These materials could consist of synthetic lumber or some newer wood composites, both of which provide better insulating properties and strong frames to a greater extent than the traditional wooden frame. There should also be thermal spacing, or a gap between the panes of glass. This space further improves insulation. Material used in that space can further reduce the amount of heat transfer and condensation. Inert gasses such as argon or krypton can be used as gas fills to further increase the thermal resistance of the window.

Comparison shopping for new windows can be extremely difficult, but is worth the effort. Most home improvement stores, building supply centers and lumberyards will offer a selection of energy efficient windows. However, most stores only carry a single brand and some manufacturers call the standard feature different things in an attempt to stand out. This means that you will need to bring a notebook with you to each store and really study the windows that you are considering. In help comparing the windows I suggest using the standard technical information that must be available for the windows in the Energy Star rating system. The United States Environmental Protection Agency (EPA) put that rating system in place. The information will aid you in comparing the measurable performance differences among all the windows that qualify for the rating. A non-biased and non-profit group named the National Fenestration Rating Council (NFRC) performs the actual tests.

You do not need to become an expert on windows and heat resistance and transfer to make sense of the Energy Star ratings and a well-informed choice. The two most important values to note, and the values that determine the actual rating for the windows are the U-Factor and solar heat gain coefficient. The U-Factor tells you how much insulation the window offers with the basic rate of heat transfer. The lower the U-Factor number, the better the window performs in this function. The solar heat gain coefficient measures how much heat can travel through the window via sunlight into your home. The value range for this is between zero and one. Once again, the lower the number, the better the window performs its function.

The NFRC also provides some additional information about each window's performance in other important areas as well. The air leakage, or AL, figure measures how much air gets past the window in a set time frame and is displayed in cubic feet of air per square foot of the window. Most building codes require a value of 0.3 cfm/ft2, but as with the previous figures, the lower you can go the better. Condensation resistance is most important in areas with high humidity, which can cause excessive condensation. The rating of the window's performance in this area falls between zero and one hundred, with the highest numbers showing a higher resistance to water buildup. The last number you might want to compare on the window information is the visible transmittance, which measures the amount of light the window lets in. This is different from the solar heat gain coefficient because this number only considers the light, not the heat that is allowed into your home although the scoring range also runs from zero to one. In general terms you want the solar heat gain coefficient to be the lowest number you can get and the visible transmittance number to be as high as you can get. As you compare windows, you will most likely need to make some choices, such as what factors are most important in your decision. If you are in a high humidity area or have specific requirements about ambient light in your home you will need to weigh your options and figure out which windows are the best fit for your needs and your budget.

While it might seem easier, and cheaper, simply to add some caulk or weather stripping to your windows in an effort to reduce your climate control expenses, the amount of time and effort necessary to achieve noticeable savings is much higher. Replacing single pane windows with energy efficient windows can be a serious investment of effort and money, the change will provide obvious and immediate benefits. It will not be long before the cost put into purchasing and installing new windows comes back to you in energy savings and increased home value.

Sources:

Efficient Windows Collaborative- Multiple Benefits Fact Sheet

Energy Star- Benefits of ENERGY STAR Qualified Windows, Doors, and Skylights