Factors Influencing New Window Energy Efficiency

There are several different value areas you may be considering when choosing new windows for your home or building, and energy efficiency is often at or near the top of this list. Not only will energy-efficient windows make your home more comfortable by limiting temperature loss, they will also save you money on utility costs while also limiting your overall carbon footprint in the process.

At Rocky Mountain Windows & Doors, we’re proud to offer a wide variety of window installation options to our clients, including everything from new construction windows to window replacements for any need you may have. When evaluating your options for new windows, what are the most important variables to consider within the realm of energy efficiency that will ensure you make a good choice in this area? Here’s a rundown.

factors window energy efficiency

Glass Efficiency

Likely the single most important factor to be keeping in mind as you move through this process is the glass efficiency rating of any given window – that is, the rate at which the glass is able to block heat transfer. This is typically measured in terms of U-value . Newer construction windows will generally have a rating between 0.30 and 0.40, while older/replacement windows come in closer to 0.50 or higher. As you may have guessed, the lower the U-value, the more efficient the window will be at blocking heat transfer, with 0.30 or lower being ideal.

To help illustrate just how important this variable is in judging a given window’s efficiency, consider that a 500-square foot room filled to 70% capacity with high-efficiency windows may save you as much as $50 per month on your utility bill in the winter and $40 in the summer when compared to a window with a rating of 0.75 or greater.

The primary way to ensure you get efficient glass is by going with at least double-pane glass, if not triple-pane , in your windows. Triple-pane windows will generally have two layers of glass with a layer of argon gas in between to further help insulate the unit and block heat transfer. It’s rare to see single-pane glass used today, and you should almost never do so if energy efficiency is a top priority.

Glass Coatings

In addition to the glass itself, window efficiency is impacted heavily by the selection of the proper glass coatings for the unit. These coatings, which typically consist of an outside coating and an inside coating, each serve to enhance the other in helping achieve maximum energy efficiency results.

One such coating is Low-E glass, a thin layer of metal that’s permanently bonded onto both sides of the glass while it’s still in molten form. Low-E glass serves to reflect heat away from the room in summer, helping to keep it cooler inside. In winter, Low-E glass defuses solar radiation, which heats up the window’s surface but not the air trapped between the window and its frame – thus insulating that space without any loss of light or other outside-world visibility.

Along with Low-E glass, a company known as 3M manufactures a product called 3M™ Solar Gard which is applied to the inside of windows to help block unwanted solar radiation from entering your home. This coating can be used on its own or in conjunction with Low-E glass for even greater energy efficiency results.

Window Installation

Another major variable in the energy efficiency of your new windows: The quality of their installation and how the windows are actually anchored in your home. The last thing you want is for air to leak around or even through your new windows, which can be referred to as infiltration, and will inevitably lead (over time) to significant energy losses.

If you’re planning window replacements, it’s important to make sure this job is carried out by professionals like ours, who have the tools, expertise and know-how to ensure your windows are properly installed. As professional window contractors with years of experience in this area, we’re here to answer any questions you may have about the energy efficiency of our products or installation methods.

If you work with less reputable entities or individuals, on the other hand, you risk not just having windows that are of subpar quality, but also inferior installation practices. This can lead to the aforementioned air leakage issues, which will invariably decrease your energy efficiency over time – simply because it allows more of the heating or cooling you’re trying to keep inside your home to escape outside of it instead.

Window Frame Construction

The frame of the window also plays a huge role in how efficient it is. This is where companies that are more concerned with cutting costs than actually producing good, efficient windows will often cut corners, resulting in negative energy efficiency consequences over time.

Ideally, your window installer should have multiple window frame material options, including wood, fiberglass, vinyl and aluminum. Each of these materials has its own advantages and disadvantages, but it’s ultimately up to you to decide which frame is the best fit for your needs. Some may be better in certain climates or geographic areas than others, so it’s ultimately important you choose wisely based on where your home is located.


Speaking of region, it’s the final factor that will often be important to consider when choosing new windows. If you live in a climate with extreme temperature swings, your needs likely vary from those of someone who resides somewhere with more moderate weather conditions throughout the year.

Warm and cold climates each call for different window and even window frame materials, which is why we often recommend looking to professional window contractors like ours if you’re unsure about which material to choose for optimal efficiency. We can’t wait to sit down with you and evaluate your needs and the windows you currently have. Our job is to help you get beautiful new windows that are also energy efficient – for a reasonable price, too!

For more on the important factors that influence window efficiency and how to prioritize them, or to learn about any of our new door or window installation services, speak to the pros at Rocky Mountain Windows & Doors today.