The Most Energy Efficient Replacement Windows

Are window replacements on your home improvement to-do list this year? If not, perhaps they should be. Did you know that heat gain and heat loss through windows are responsible for 25%–30% of residential heating and cooling energy use  in the United States? For this reason, not only is it important your windows are working at their best, but energy efficient windows are an important consideration for both new and existing homes. However, not all replacement windows are made equal, with some being vastly more energy efficient than others. And, choosing the right energy efficient replacement window can help you save up to 20% on your energy bills. When choosing energy efficient replacement windows, the first thing you should look at is the U-factor, which is how energy efficiency is measured. U-factor can range from 0.15 to 0.30 and, the lower the number, the more heat your windows will retain. Ideally, you should look for a U-factor that is no higher than 0.26, especially if you live in an area that is prone to extreme weather. If you are looking to replace your windows this year – or at any point in the near future – we have put together this article to help you understand how to choose the most energy efficient windows. 

Consider the Number of Glass Panes 

Single-pane windows are the least energy efficient types of windows. When replacing your windows, you want to opt for double or triple-pane glass. Double-pane glass is filled with inert glass and it is almost twice as energy efficient as the single-pane units. However, triple-pane glass offers the most energy efficiency. With these windows, you get the best U-factor and very little energy lost. However, triple-pane glass windows are the pricier option, yet what you pay upfront is recuperated over time with greater energy savings. You can also consider glass panes filled with argon for maximum energy efficiency. Placed between the panes of glass, argon gas adds extra insulation to your windows. It is colorless, non-toxic, natural and inert gas that poses no threat to you. For added efficiency, you can also consider filling the frames and sashes of the windows with foam, which reduces their thermal conduction and increases the efficiency.

Choosing the Right Frame

The frame you choose is also vital to how energy efficient your replacement windows will be. There are a variety of different window frame materials on the market today, each offering different pros and cons. Let us take a look at three of the most popular frames. 

• Vinyl: Vinyl is often the most cost-efficient option, but it also offers excellent energy efficiency measures through insulated glass and tight construction that reduces air leakage. 
• Wood: Wood windows can offer some of the best insulative value. The only downside is they require more maintenance than vinyl or aluminum frames. They also have the potential to rot, so therefore do not suit humid or rainy climates. 
• Aluminum: In terms of energy efficient, aluminum is not the best material when it comes to heat transfer and loss. However, they are practical for rainy and humid climates and are incredibly durable, which is a benefit in adverse weather-prone areas. 

ENERGY STAR Certification 

When choosing the most energy efficient windows, you also want to look at the ENERGY STAR Certification, which is the mark of energy efficiency. An ENERGY STAR label means the same thing — an energy-efficient top performer that saves money without sacrificing performance. Here are some data points to consider when choosing an ENERGY STAR Certified window: 

• U-factor: should be between 0.15 and 0.26
• Air infiltration: should be .05 or lower. Air infiltration measures the amount of air that can be leaked through a window.
• Solar heat gain coefficient: its recommended value is .25 or higher for climates prone to cold weather. This measures how much your home can be heated by the sun through the glass.
• Visible transmittance: should be no less than .50 for double pane windows and higher than .40 for triple pane. This measures the amount of light that enters your home through the glass.
• Condensation resistance: should be 65 or higher.

Speak to a Professional 

The most important part of the window replacement equation is finding the right home improvement contractor. This is because energy efficiency is not just about the materials used in the windows, but also how they are installed. Even the most energy efficient windows will not perform as intended if improperly or poorly installed.