What Makes a Window Energy Efficient?

windows on a home

Evidence shows that windows are responsible for about 25% to 30% of heat gain or loss in the heating and cooling of residential apartments. For that reason, it is essential to opt for energy-efficient windows during new construction or when replacing old windows.

When choosing efficient windows, consider the climate in your area, says Peak Residential, a Sacramento property management company. According to Energystar.gov, if you replace your windows with the ones that are Energy Star certified, there will be a 12% decrease in household energy bills nationwide.

So,what are thefeatures of energy-efficient windows?

Features of energy-efficient windows

There are several features to consider when selecting energy-efficient windows. These include:

  • Air leakage: Check the window’s manual for the air leakage parameter. You will notice the numbers which range between 0.1 to 0.3. Air leakage is a measure of the level of airtightness the window possesses. Windows with a lower number have minimal air leakage.
  • U-factor: The U-factor shows how the window conducts non-solar heat flow. This primarily depends on the type of frame the window possesses. For instance, composite, fiberglass, wood, and vinyl frames have more thermal resistance than metallic frames.

However, always consider the overall U-factor of the window and not only the frames. Windows with high energy efficiency have lower U-factor. So, if you are residing in a region where you spend more on energy bills, consider installing windows with a low U-Factor.

  • Visible Transmittance (VT): Visible transmittance ranges between 0 to 1. It indicates the amount of visible light that passes through the window’s glazing.
  • Glazing and coating: Various glazing and coating options exist for energy-efficient windows. Some of them include reflective coating, low-emissivity coating, heat-absorbing tints, gas fills, and insulated glazing. Your choice should depend on the climate in your area. We recommend that you combine the appropriate glazing and gas fill to obtain maximum energy efficiency.
  • Solar heat gain coefficient: This portrays the capacity of your window to prevent unwanted heat gain from reflected or direct sunlight. The solar heat gain coefficient of windows ranges from 0 to 1. Choose windows that have a low solar heat gain coefficient to reduce the cost of cooling your home.


What Makes a Window Energy-Efficient?

With all thefeatures above, the following things make a window to be energy-efficient:

  1. Low-E glass coating

Since the house can still lose energy through the window’s glass pane, you need to reduce the level of energy loss. To achieve this, window glasses now have special coatings that reflect infrared and ultraviolet light. As a result, the house stays warm during winter and cold during summer. Also, it protects your furniture from fading because sunlight does not pass through the window. All this is possible because of the low-E coating on the inner surface of the window’s exterior pane.

  1. Multiple panes

Windows that are not energy-efficient have a single glass pane. Due to this, they lose more energy. However, energy-efficient windows possess three or more panes of glass with air or gas in between them. As a result, energy-efficient windows provide more insulation, soundproof, and resistance to impact.

  1. Gas fills

Since energy-efficient windows have multiple glass panes, they possess spaces in between them. These spaces house a non-toxic, odorless, and colorless gas. Most energy-efficient windows have argon gas within the spaces. The engineers vacuum out air and then fill it with argon gas which is denser than air. As a result, the window will be able to offer more insulation to the house.

  1. Frame quality material

The quality of material that the window frame possesses contributes to its energy efficiency. Several low-cost and durable window frames offer better insulation and also reduce the conduction of heat. They include composite, wood, fiberglass, aluminum, vinyl, or a combination of different materials.

Vinyl provides better insulation than wood. Some window frames are foam-filled and offer more insulation. Always choose windows with durable frames so that your energy-efficient windows can last long.

  1. Weatherstripping

Weatherstripping is a plastic material that helps keep dust out and provides a tight seal along the window’s edges. Energy-efficient windows come with high quality and more weatherstripping that have fibrous materials.

  1. Warm edge spacers

Warm edge spacers help to maintain the space in between multiple glass panes in energy-efficient windows. Also, they provide a seal around the glass panes and frames. Because of this, the window will have less heat transfer and more insulation.

  1. Quality installation

Without quality installation, energy-efficient windows will not offer optimal benefits. Quality installation entails proper insulation between the house framing and the window frames. Also, it helps you to close and open the windows with ease.


The bottom line

When purchasing windows for your property, always look for the Energy Star label or check the National Fenestration Rating Council (NFRC). This will help you to review the rating and also know the energy performance level of the window.