Replacement Window FAQ: What Are the Most Energy Efficient Windows?

When researching the best replacement window, there are several important considerations. From style to material, there is no one-size-fits all for beautiful replacement windows. However, one element all homeowners should be considering is how energy-efficient their chosen replacement windows are. 

Windows are one of the most important and complex elements of a home. They allow air and light into the room, and they give us a lovely view of the outside world. However, they can also be a big source of unwanted heat gain in the hotter months, and heat loss in the cooler months. This is important to know because heat gain and heat loss through windows are responsible for 25%–30% of residential heating and cooling energy use, according to energy.gov. 

Do not fret – there is a simple way to avoid these issues when installing new windows. The solution? Energy efficient windows. In this article, we will be taking you through everything you need to know about energy efficient windows, and which replacement windows are the most energy efficient. 

What Are Energy Efficient Windows? 

Energy efficient windows basically refer to the glaze and frame of your window materials. Not only can the right glaze and frame material make your house more comfortable year round, but they also have the added bonus of reducing your energy bills. 

Energy efficiency of windows is measured by the U-value. This value can range from 0.15 to 0.30 and, the lower the number, the more heat your windows will retain. Ideally, you should look for a U-factor that is no higher than 0.26, especially if you live in an area that is prone to extreme weather.

Here is everything else that makes up an energy efficient window:

• Low-e glass: this glass uses a transparent coating to minimise the amount of heat passing through the glass while still allowing light through.
• Double glazed windows: when combined with low-e glass on at least one pane and argon gas in between, double glazing provides the best thermal performance.
• Window frame material: a frame with a low U-value assists in reducing the whole window U-value. Frames that use timber, uPVC, or a composite aluminium/timber design are generally best.
• Window seals: good window seals are essential to improving energy efficient performance. 

Benefits of Energy Efficient Windows 

• Better insulation
• Eco-friendly
• Lower utility bills 
• Can protect your furniture and flooring from sun damage
• Reduces outside noise
• Less maintenance than normal windows due to reduced condensation
• A more temperate and comfortable home 

The Most Energy Efficient Windows

1. Multiple Panes of Glass

Double-pane glass filled with inert gas insulates nearly twice as well as single-pane counterparts, making replacing your old single pane glass windows the obvious choice. Then you have triple-pane glass, which offers even more insulation. Triple Pane will increase the overall efficiency of the window unit and decrease the rate of energy loss or U-value. While triple pane glass does cost more, the more expensive up-front cost will typically provide you with a good return on investment.

2. Low-E Glass Coatings

Low-Emissivity (Low-E) glass coatings are layers of thermal protection that help reflect summer heat and retain interior cooling in the summer months and reflect cool outdoor temperatures and retain interior warmth in the winter months. Low-E glass also blocks UV rays that cause your home's furnishing and floor to fade.

3. Argon Filled Glass Panes

Argon is a natural, inert, colourless, non-toxic gas that is denser than air. When placed between panes of glass, argon adds additional insulation. The benefit of argon is that it can even further reduce the transfer of heat or cold, making a home much more energy-efficient and comfortable.

4. ENERGY STAR Certified Replacement Windows

One of the easiest ways to tell if your replacement window is energy efficient is to look at the ENERGY STAR rating. When your window choice meets or exceeds the ENERGY STAR rating, you can be confident knowing your window will be saving you money on your energy bill. Check out our handy guide on performance ratings here.

5. Foam-Fill

For extra energy efficiency, choose foam-filled frames and sashes. Many manufacturers offer foam filled frames and sash extrusions that can increase the efficiency of those components.

Choose Quality Replacement Window Installers 

At the end of the day, choosing the most energy efficient windows is pointless if you do not find the right contractor to install them. Even the best performing window on the market, if installed incorrectly or out of scope of best practices, will leak air like a sieve. That is why it is vital you find a quality replacement window installer alongside choosing the most energy efficient window.