Once you narrow down what type of window you need (wood, vinyl, etc.), you'll want to choose styles. The simplest course is to stick with the same style as your old windows, but if you're doing a gut renovation, new construction, or upgrading very old windows, you have more choices available.
There are several replacement window types available, including these common styles:
No matter what style and frame material you choose, you will want to buy a well-built replacement window. Experts suggest looking for replacement windows that have been certified by the National Fenestration Rating Council (NFRC) and the American Architectural Manufacturers Association (AAMA). The NFRC rates energy efficiency, while the AAMA certifies the quality of a window's materials and construction.
The National Fenestration Rating Council conducts laboratory tests to determine how well a replacement window keeps heat in and cold air out. An NFRC-certified window will carry a label that outlines how energy-efficient the window is, based on the following criteria:
Some NFRC labels also carry ratings for air leakage, water leakage and/or condensation resistance. These ratings are optional for NFRC certification, but local building codes may require them. The NRFC website also offers more information about these ratings.
According to the Energy Star website, qualification is determined by the NFRC U-factor and SHGC ratings. The windows with the highest ratings are further distinguished with a Most Efficient award. To find out what Energy Star climate zone you're in and to learn more about Energy Star requirements, see the Energy Star website.
If a window is Energy Star-qualified, it has been certified by the NFRC, so there's no need to check for an NFRC label, although additional information may also be found on the label.
State and federal programs sometimes offer incentives to purchase energy-efficient windows, doors and skylights. The Database of State Incentives for Renewables and Efficiency is a good place to search for incentives in your state, as well as information about federal programs.
Is it cost-efficient to replace your windows to reduce energy costs? This depends largely on the condition of your existing windows, experts say. If your windows are old, leaky or damaged, installing replacement windows is more likely to save you money in the long run than if you're replacing windows that are just a few years old and in good condition. EnergyStar.gov estimates that you will save an average of 12 percent on energy costs if you install Energy Star-qualified windows. If you're renovating your home with the intent of selling it, replacement windows may increase the value of your home, depending on what type you choose, but might not return the full cost of the project. Talk to your real estate agent first and ask if they think doing so will be a worthy investment.
Experts say it's important to choose the best kind of replacement window glass for your climate. The NFRC label on a window includes information about the glass, and retailers and contractors use the same terminology, so it's helpful to be familiar with it.
The answer to this question depends on whether you plan to replace the entire window or the sashes only. You will need to replace the entire window -- frame, trim and all -- if an existing window is damaged, and experts say that this is usually a job for a professional. The new window will be more energy-efficient than a window with only the sashes replaced, since it will have new flashing, sealants, caulking and insulation. However, this is the most expensive method of window replacement if you also incur labor costs.
If you are replacing only the window sashes, you have two options. The first, a sash replacement kit, is the least expensive option, according to Fine Homebuilding magazine; you simply remove the old sashes, install new jamb liners and insert the new sashes. The second option is what is referred to as a sash-and-frame unit or an insert -- or, more commonly, a replacement window. This consists of the sashes with a thin frame around them that fits inside the existing window frame. This is the easiest option, according to Fine Homebuilding magazine, and you can judge the energy efficiency better than with option one, since the NFRC will have rated the entire frame-and-sash unit and not just the sashes.
Renovation experts say that even just replacing your window sashes is not an easy job -- especially if you're inexperienced. However, if you decide to try it, some of the websites included in the Our Sources section of this buyer's guide offer step-by-step instructions on how to install a sash replacement kit or a replacement window.
According to ConsumerReports.org, many major window manufacturers train and certify their own installers, so it's possible to find a contractor who can both sell and install your replacement windows. This could make things easier if problems arise at some point in the process. ConsumerReports.org also advises that you hire an installer who is certified by the American Window and Door Institute or InstallationMasters. Recommendations from friends and neighbors, or an online resource that offers feedback from others in your area, can also be helpful. Sites such as Angie's List and HomeAdvisor.com (see Our Sources) have databases of local installers with verified reviews from the installers' customers.