Many homes with older single-pane windows waste energy, leading to high energy bills. They also leave the home less comfortable and may not protect it during severe weather conditions.
When choosing a window, look for those with an Energy Star certification. These are certified by the Department of Energy to meet energy efficiency standards. These include a lower U-factor and argon gas insulation.
Low-E coatings
High-performance windows with Low-E coatings allow natural sunlight to pass through while reflecting heat away from your home. This helps to reduce the amount of energy used in your home during heating and cooling seasons while also helping to protect furniture, carpeting, artwork, and finishes from sun damage.
These glass panels have a thin coating of low-emissivity metal that suppresses radiant (heat) flow through the window. They are often used in conjunction with argon or krypton gas fills to further enhance thermal performance.
They’re available for both replacement and new construction windows and are a great option for passive homes, which generate as much energy as they consume. They can be found in a variety of styles and materials, including durable fiberglass designs. They’re easy to install and provide excellent energy efficiency.
Argon gas fills
Argon gas is an odorless, colorless gas that helps improve the thermal efficiency of double or triple pane windows by blocking out outside heat. It is also less conductive than air and a much better insulator, making it a good choice for energy-efficient homes.
While argon doesn’t expand and contract like glass, it can leak out over time when the seals between the window panes break. This can result in a 10% loss of the gas over 20 years.
Another option is Krypton gas, which is more expensive but is considered a better insulator and performs better than argon in smaller spaces. It’s commonly used in triple pane energy-efficient windows. It can also improve the windows’ U-value and reduce their condensation, which is a major source of moisture.
Insulated glass units
The main goal of an insulated glass unit is to reduce heat transfer through a window, helping homeowners keep their homes cool in the summer and warm in the winter. This helps reduce a home’s energy costs by eliminating the need to run an air conditioning system, and it keeps utility bills low.
An IGU is composed of two or more panes of glass with a space in between them that has an insulating material such as argon, krypton, or other gas. The use of this gas in the windows reduces thermal transfer and thereby improves energy efficiency.
Some IGUs can also be coated with coatings to further enhance their performance. For example, coatings can be applied to the inside surface of an IGU to reflect sunlight and reduce glare.
Spacers
Window spacers are metal components that keep glass lites apart at the right distance. They also provide a buffer against stress from thermal expansion and contraction, help retain special low-conductance gas, and protect the seal between panes from moisture. In addition, they are a key component of energy-efficient replacement windows.
A newer technology is the warm-edge spacer system. Unlike rigid metal spacers, this non-metal creation does not contact the glass, which minimizes energy loss. The flexible nature of this spacer allows it to flex during normal temperature changes, which prevents fracturing and improves energy efficiency.
The best spacers are made of a highly durable material that will stand up to a variety of temperatures. They should be low in conductivity and able to withstand pressure without damage.
Low-emissivity (Low-E) glass
It has a coating that blocks infrared and UV rays while letting visible light pass through. This reduces glare and keeps the inside of your building cool in summer, helping to save energy by reducing HVAC usage. It also prevents warm air from escaping in winter, helping to cut heating costs.
However, Low-E glass does not stop radio-frequency signals. This could be an issue if you use your cell phone extensively in your home.
Windows with a low E coating are more expensive than traditional windows, but they pay for themselves over time by cutting energy costs and saving money on repairs and replacements. When combined with other energy-efficient features, such as insulated frames and sash construction and argon gas fills, they can reduce costs even more.