Many years ago, the design of the American home was largely based on the goal of trying to stay warm. But those early builders just couldn't prevent the massive amounts of heat and energy lost from drafty, inefficient windows. Although we've come a long way since then with high-tech materials and more efficient designs, the heat exchange through drafty windows still accounts for a whopping 25-30% of our home's energy uses for heating and cooling. Fortunately, there are solutions. If you're trying to improve your home's efficiency, a good place to start is with replacement windows. Choosing the best material for your window frames is the first step.


Wood is the original choice for window frame material, and many homeowners still prefer it to other options even though it's one of the most expensive materials. Why? Well, it's hard to beat the beauty and sophistication of real wood frames, but there are other reasons too. For energy efficiency, wood is at the top of the list because it is naturally non-conductive. However, wood requires maintenance and, as mentioned, it's expensive. But if properly maintained, it can last indefinitely. There are also vinyl or metal cladding options for wood frames that can cut down maintenance but add costs.


Vinyl is one of the most popular window frame materials on the market today, particularly for replacement windows. The reasons are many. One reason is that vinyl requires little to no maintenance. It's also easier to install than some wood options. Also, the hollow cavities in the vinyl frames are typically filled with insulation, which gives them really great thermal properties. However, vinyl isn't as durable or as strong as wood, and it can crack in cold temperatures.


The best insulating window frame material is fiberglass. In fact, it has better thermal qualities than wood and it's stable in any climate, hot or cold. It's also a fairly easy material to work with and can be milled and shaped liked wood. Another benefit is that it's as easy to maintain as vinyl. However, expect to pay about 25% more.

Fortunately, when trying to decide on the most efficient window materials, the National Fenestration Rating Council, or NFRC, has made it easy for consumers. All windows are sold with an NFRC label that lists the window's energy performance ratings. The label includes the window's U-Factor, Solar Heat Gain Coefficient, Visible Transmittance, and Air Leakage ratings.