How to Shop for Energy Efficient Windows

By Vernon Trollinger, December 27, 2017, Energy Efficiency, Green, Home Improvement, Save Money

While most homeowners love their homes, not every home is perfect. There are one or two things the homeowner would like to change, such as an outdated bathtub for a new walk-in shower or updating the look of their kitchen. And then there’s occasional “uh-oh” of the unexpected repair. We’re going to identify several projects and some of the ins and outs of what you can expect.

How to Shop for Energy Efficient Windows | Bounce Energy Blog

How to Shop for Energy Efficient Windows

There has been LOTS of hype about installing energy efficient windows over the past few years. While Energy Saver-rate windows do a great job of reducing your home’s energy usage, they are expensive investments. Not only is there the cost of the window, but also other building materials, plus labor and the disruption to your home life. So, one of the first things a home owner should ask themselves is “Does my home REALLY need new windows?”

To answer that, consider a visit to Lawrence Berkeley National Lab’s Home Energy Saver (HES) website to see how quickly some basic energy efficiency upgrades pay you back. As an example for windows, we entered a 2,000 sq. ft home built in 1975 with double-pane windows. According to the HES website results, upgrading your windows offers little payback. That’s because windows take up between 5% and 15% of your home’s exterior exposure (or envelop). Yearly savings tend to be low, only $7, assuming the old windows are in reasonably good shape. Of course, there can be other mitigating factors such as metal window frames that conduct heat in and out of your home, insufficient sealing, poor installation, damage, and poor overall quality.

When it comes to single-pane windows, it’s not entirely an open and shut case to replace them, especially when it comes to historic homes. One expert argues that repairing and restoring wooden windows dating from before 1940 saves more money than installing replacements. “Wood windows made before this time were constructed with individual parts, each of which can be repaired or replaced. The wood itself is denser and of higher quality than what is grown today, and it is generally more rot and warp resistant than modern wood.” In some cases, homeowners may find that the combination of old wooden windows and storm windows perform as well as replacement windows. In fact, many newer storm windows come with the same low-emissivity coatings (Low E) found in energy efficient replacement windows but at a fraction of the price.

That all said, one important factoid to keep in mind is that installing new energy efficient windows will recoup 73% of their investment when the home is sold. Plus, newer windows may also increase the likelihood of a sale.

How to Shop for Energy Efficient Windows | Bounce Energy Blog

How to Choose the Right Windows

If you do decide to replace your windows with energy efficient windows, you’ll need to determine the kinds of window you need. Both the climate of where you live and the direction the window faces (north or south) effects your window choices. Windows and skylights gain and lose heat through drafts, conduction, and radiation.

Drafts — You want the window to seal well. Windows that don’t seal well allow outside air to enter around the window itself or around the frame.

Conduction — Heat travels through the window’s glass, glazing, and frame. Windows are rated in U-factors, which measures how fast heat moves through the window from the inside or the outside. Lower U-factors mean better performance. Low-U windows contain an inert gas between two panes of glass that acts as an insulator. Low-emissivity coatings (Low-e) involve a thin coating on the glass panes that reduces heat conduction through the glass. This lowers the U-factor further, which significantly reduces heat conduction, but also adds to the cost of the window.

Radiation — Heat enters the home in sunlight. It also exits the home by radiating from warm things inside such as people, walls, and furniture. Windows with solar heat gain coefficients (SHGC) help control the amount of heat that is radiated through the window. A window with a high SHGC rating prevents heat radiating out in the winter — which is great for cold climates. A window with a low SHGC rating keeps heat from radiating into the home — which is great for blocking heat gain from the sun in summer.

So, if you’re in a climate with cold winters and hot summers, choosing the right window to face in the right direction is key. For example, you’ll want a low-U, low SHGC window in south or southwest facing walls to keep out the hot summer sun and a low-U, high SHGC in north walls to retain heat during the winter.

How to Shop for Energy Efficient Windows | Bounce Energy Blog

How Much Money Can You Save with Energy Efficient Windows?

According to Energy Star, homeowners in the ERCOT region of Texas that replace ALL their single pane windows can expect to save 31% off their annual energy bills. If they replace double pane windows, annual savings drop to between 14% and 17%. So, for example, a 2’ x 3’ Energy Star Qualifying window with Low-E glass sells for $180. If your home has 12 single pane windows and you replace each with one of these new windows, that will cost you $2,160 —excluding the cost of labor and other materials. Given an average Texas annual residential electricity bill of $1525.20, these new windows could save 31% or about $472 annually. That would mean each window would pay for $39 of its price in the first year —again, excluding the cost of labor and other materials. Double pane windows would see about half that rate of return.

As mentioned at the beginning, there’s a lot to bear in mind. Energy Star qualifying energy efficient windows do work, but they are expensive and the rate of return annually isn’t much to crow about. And while a homeowner can do nearly as well by repairing or restoring old wooden windows and/or investing in newer storm windows, they can also recoup a sizeable chunk of a replacement window investment when they sell their home. In short, the nub of whether to replace or not boils down to two important questions: how long do you want to remain in your home and just how bad are your existing windows?

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About 

A native of Wyomissing Hills, PA, Vernon Trollinger studied writing and film at the University of Iowa, later earning his MA in writing there as well. Following a decade of digging in CRM archaeology, he now writes about green energy technology, home energy efficiency, DIY projects, the natural gas industry, and the electrical grid.

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