Everything You Need to Know About Home Window Energy-Efficiency

We often take our windows for granted. We enjoy the warmth, light, decor and ventilation they provide, but often do not realize how much of a negative effect they can have on your home’s energy consumption levels. A simple and effective way to lessen the impact is by having energy-efficient windows installed in your home, or by optimizing your existing windows for energy efficiency. There are several benefits to this.

Energy-Efficient Windows Save You Money

The amount of money you save depends on the current state of your windows, and which type of windows you replace them with. The greatest savings amount will occur when going from single-pane windows to double- or triple-pane, Energy Star-rated windows, typically with low-e coatings and gas fills. However, depending on your current SHGC, most customers who make the switch to energy-efficient windows still see a dramatic decrease in their energy bills. If you have single-pane windows now, your savings will be much greater than if you have double-pane windows. Replacing your windows with more energy-efficient windows also immediately benefits your home value.

Improving the Efficiency of Existing Windows

  • Window treatments are coverings which can decrease loss of heat during winter and summer’s gain, but most do not decrease air infiltration.
  • Caulking gaps, cracks and joins which are smaller than a quarter-inch wide is advisable, as well as weatherstripping for your moving components (operable windows, hinged doors).
  • Add storm windows to decrease air leaks and increase comfort levels. Weatherstripping and caulk will lower air infiltration from around your windows.

These are great examples of home projects you can DIY, but if you’re uncomfortable with the tasks, don’t hesitate to call a professional.

How Low-E Coatings are Energy-Efficient

Low-E coatings minimize the amount of ultraviolet and infrared light that can pass through the glass without compromising the transmission of visible light. Emissivity is the ability of a material to radiate energy, while low-emissivity (low-e) means a material transmits less ultraviolet and infrared light. Low-E coatings function by adding a clear, microscopically thin, layer which serves as an invisible shutter which reflects infrared light away from its surface, which reduce loss of radiant heat. These coatings can be on both the inside-facing and outside-facing panels of glass, keeping heat out during the summer and reflecting the indoor temperature back inside.

How Gas Fills are Energy-Efficient

Typically double- or triple-paned insulated glass units (IGUs), energy-efficient windows feature a space between the two panes, which provides an insulative layer between the outer and inner environments. This space is enhanced with even more effective insulation properties when pumped with Argon or Krypton gasses into the space between the inner and outer panes.

How Energy-Efficiency is Measured

  • Energy Star Rating: The premium supplier of energy-efficient products, Energy Star Approved windows have met stringent requirements which mean that these products are upwards of 40% more efficient than common national building code standard requirements.
  • Solar Heat Gain Coefficient (SHGC): This rating refers to the % of incident solar radiation which indirectly or directly enters your home via the sky, the sun, or reflective heat.
  • U-Factor: This refers to the rate that IGUs conduct non-solar heat flow and is usually expressed in units of Btu/hr-ft2–oF. The lower the U-factor, the more insulative qualities the window is said to have.

About the contributor

This guest post was provided by Apex Window Werks, a company which specializes in home window repair, broken glass replacement, window defogging and more. You can find window repair service near you by visiting the website, Currently they service some cities of Illinois, Wisconsin, Ohio and New York states.