Single-Pane Vs. Double-Pane Windows: Understanding the Difference

Single-Pane Vs. Double-Pane Windows: Understanding the Difference

At first glance, you can’t tell whether the windows in your home are made with single or double-pane glass. Visually and aesthetically, they look the same. In terms of structure and efficiency, however, there is a significant difference between these two types of windows. We will discuss those differences as well as a couple of quick and easy ways to tell which kind of window you have.

You may already know that double-pane windows are more energy-efficient for your home. Though, you and many others may not be able to replace all your windows due to cost or other restrictions. Not to worry, there are ways to insulate your single-pane windows to reduce drafts and lower your utility bills. 

Let’s start by laying out the differences between single and double-pane windows.

Single-Pane Windows

To put it simply, single-pane windows have a single layer of glass, while a dual or double-pane window has two layers of glass. Single-pane windows come in all the same materials and styles as double-pane windows. What they don’t have is the added insulation of that second pane. As a result, outside noises come through more. That may not matter much if your neighborhood is quiet.

Double-Pane Windows

Double-pane windows have two panes of glass that each have a Lo-E coating, which reflects heat and reduces your home’s energy consumption. In between, the panes are filled with a gas such as Krypton gas or Argon gas as added insulation. Also, inside is a spacer framework that helps hold the panes of glass in place even when they are subjected to pressure. Next, there’s a seal applied that keeps the gas from leaking out, which ensures that the window will continue to perform over the years. 


Energy Efficiency

Naturally, single-pane windows cost less than double-pane windows, but they are not nearly as energy-efficient. If you are building a home or replacing existing windows, you will likely spend more down the road on your heating and cooling bills. In fact, double-pane windows can save you up to 30% annually on your electric bill.

If you live in an older home that still has the original windows, the windows are most likely single-pane. Because the single pane does not insulate well, your room will lose some of its heated or cooled air. The result is a drafty home in the winter. In the summer months, your AC must work all the harder to keep the house at your selected temperature. 

The added layers, insulation, and seals make double-pane windows far more energy-efficient than single-pane windows. The U.S. Department of Energy states that homeowners can save between $126 - $465 annually by replacing their single-pane windows with double-pane.

This gas-filled insulation also helps block outside noises as well. In addition, the low-E coatings on the window glass add more protection by reflecting heat and the number of ultraviolet rays that enter the room. So, along with energy efficiency, you have a little more protection for your furniture and carpets since UV rays will fade them over time.

Overall, double-pane windows are certainly more energy-efficient than their single-pane counterparts. You also have the extra perks of outside noise reduction, the UV filter, and reduced HVAC fees. Additionally, if your HVAC unit is not working as hard to maintain the temperature in your home, the result is less wear and tear on the system and longer working life.

How Do You Know if You Have Single or Double-Pane Windows?

So, how can you tell whether your windows are single or double-pane? There are three common approaches you can take to determine which type you have. The first method is to conduct a visual inspection. Look at the inside edge of your window. If it’s double-pane, you should be able to see the two panes as well as the spacer system that separates them. If there are no spacers, then it’s a single pane.

Another way is to raise the window and place your fingers so that you can touch both sides of the window in the same spot. Note how far apart your fingers are. If they look close enough to be almost touching, then you most likely have a single pane of glass there. 

Finally, the last method you can try is to hold a flame from a lighter or candle up to the glass. When you hold the light to the window, you will see a reflection. Be sure to look at the glass from an angle rather than staring straight. If you see a single reflection, the window contains a single pane of glass. If you see two flames reflecting, there are two panes, each creating a reflection for you to see.

When You Can’t Afford New Windows

Not everyone can replace their single-pane windows with double-pane. Aside from the large upfront expense, many of us rent rather than own and landlords may not invest in this particular upgrade unless the window is defective.

There are ways to improve your windows’ efficiency and cut drafts without replacing them. First, take a look at the window frame, both inside and outside. If you see cracks or space, then you can caulk those areas to seal them up. If your frames are white, then some white caulk will blend well. On the outside, the gaps may be wide enough to take a small amount of spray foam insulation first.

A way to insulate the glass itself is to use insulating window film. Window film is a thicker material than tint, which acts as an insulator. It applies using static cling, so you are safe to install it in a rented home, as it won’t leave any residue behind. If you need light blocking window film as well, then you’ll also have UV ray protection. Most window film comes in solid white or black to block light or frosted for privacy.