Get clear on how windows affect energy efficiency

Let’s say your air conditioning system is operating as it should. But you still notice certain rooms getting warmer than others, or maybe you see cooling bills rising higher than expected. What’s to blame? It may be your windows.

At MTB Mechanical, our focus on the Science of Comfort often involves discussions with our customers on the efficiency of their windows. According to the U.S. Department of Energy,  windows are responsible for 25 to 30% of residential heating and cooling energy use. The heat gain can be significant in the warmer months, forcing your A/C system to work harder and driving up energy bills.

Some factors are out of your control, like the placement of your windows and their relation to the path of the sun. But there are other steps you can take to ensure your windows are as energy-efficient as they can be.

Consider replacement windows. 

Older homes were often constructed with windows with single-pane glass. While they can be aesthetically pleasing, single-pane windows are extremely inefficient when it comes to heat loss and gain.

The preferred material is double-pane glass, for both wood and vinyl frames. When choosing your windows, we encourage you to look for ENERGY STAR and NFRC (National Fenestration Rating Council) labels, which ensures you’re investing in highly efficient products.

It’s also wise to look for U-factors. This is the rate at which a window, door or skylight transmits non-solar heat flow. The U-factor is about more than glass –  it also represents the entire window performance, including frame and spacer material. The lower the U-factor, the more energy-efficient the product will be.

Not ready to replace your windows? Take these steps instead: 

  • Check for air leaks, then use caulk and weather stripping around your windows. This helps to keep the heat out for the summer, and in for the winter.
  • If you don’t have them already, add window treatments, and keep curtains, drapes or blinds closed during the heat of the day.
  • Install storm windows and panels.
  • Apply solar control film over window panes to reflect heat, block UV rays and help save energy.
  • Install exterior shading options such as awnings in key areas around your home – and let the compass be your guide in prioritizing where to locate them. Windows on the north or south side of a home are twice as likely to keep treated air inside than those that are on the east or west side.

If you’ve done all you can to make your windows energy-efficient, and you’re still having cooling issues, remember that the expert technicians at MTB Mechanical are here for you year-round. Give us a call at (704) 459-4066 or schedule an appointment online.

Skip to content