One of the biggest selling points of brand-new windows? Energy efficiency.

You’ve probably heard the claims, “Lower your monthly energy bills and help Mother Earth!” or, “Windows have an unbeatable return on investment!”

Let’s look at the hard science for a minute here. Your windows act as shields for your home. In the winter they keep the cold out, and in the summer, they keep the cold in. But how do they do it? And why might one type of window be better at regulating your indoor temperature than another?

Let’s talk about heat transfer.

You may have fallen asleep in science class the day thermodynamics came up, but we all know that our hot coffee is eventually going to drop to room temperature. This phenomenon is called heat transfer.

A well-made window acts like a thermos. It keeps the heat exactly where it’s supposed to be by cutting down on heat transfer from the outside to the inside of your home.

Windows have two important parts— the glass and the frame. Since the glass takes up most of the space, it has a big role to play in heat transfer.

Scientists have been hard at work on window glass. A simple single-pane glass window allows 85%-90% of the heat to pass through it in either direction. If we double up on the glass, only 67%-73% of heat passes through. Triple it up and you’re down to 57-65%. Beyond that, however, the window gets too heavy to be manageable. Triple-pane glass is the most that most companies will offer. So then how to reduce heat transfer even more?

The glass itself can be engineered to be more reflective. Glass with a small amount of tin or silver oxide baked in will keep your home more comfortable since metal reflects solar energy. At the high end, if you get triple silver Low-E reflective coating, you only let 2-5% of the heat pass through. That is truly impressive.

But glass isn’t the only factor.

Your frame and sash material matter.

How about the material that holds the glass in place?

If you have the choice between sitting on a wooden bench or a metal bench on a hot day, the answer is clear. Metal conducts more heat, making the wooden bench a safer option. Likewise, metal makes for a poor choice for window sash material. Wood window frames are about twelve times more energy-efficient.

But wood frames still aren’t the best material.

That superlative goes to vinyl. Insulated vinyl framing is about four times more efficient than wood. The weather-stripping can be built right into the vinyl, which means there’s no need to use adhesives that can break down over time.

The most energy-efficient windows use insulated vinyl frame material and glass with silver oxide-based low emissivity coatings to cut down on heat transfer.

Be an Energy Star.

The good news is that someone has already done the leg work on energy efficiency.

Energy Star is a program run by the EPA and the U.S. Department of Energy that researches energy efficiency. They run independent trials on dishwashers, refrigerators, and yes, windows. In 2019 alone, ENERGY STAR worked to help Americans save almost $39 billion dollars in energy costs.

If you check out their website, they’ll give you suggestions for windows for your region, and let you know how many panes of glass you’ll need to best insulate your home in your climate.

Don’t let your windows leak.

Remember that thermos keeping your coffee hot? Even the best thermos in the world won’t do you any good if the lid is loose. If you throw that thermos in a backpack, you shouldn’t be surprised when you open it up and there’s coffee everywhere.

In the same vein, the best window in the world can still leak without the right installation. So, partnering with a pro for installation is a must. Every window installation team at Window Nation is factory-trained. We specialize in window replacement, and we’ve installed over one million windows since 2006.

We’ll ensure the most energy-efficient windows are the windows proudly hanging in your home. Get a free quote from Window Nation today and see how much of a difference the right installation makes.