Wondering if solar screens can save as much energy as new windows? It’s a common idea for homeowners who aren’t quite sure they’re ready to invest in window replacements to consider solar screens. But can they save as much energy as new windows? Are sun screens a good alternative to new windows?
Here’s who might consider them.
If you have single-pane windows, or double-pane windows with clear glass (aka no argon gas or low-e coatings), screens are better than doing nothing if you can’t afford to replace the windows.
They’re less expensive, albeit a temporary fix.
But otherwise, they’re probably not going to be worth the investment.
Here’s a quick way to tell. If you don’t feel heat on a summer’s day in Arizona when you touch window glass from the inside of your home, solar screens wouldn’t reduce your air conditioning bills by much, if anything. A room temperature window means the existing windows are successfully deflecting heat, keeping it outside where it belongs. Adding screens would make the rooms darker inside the home, but that’s about it.
It wouldn’t keep the room cooler.
If you feel the heat, however, then heat transfer inside the home is a major issue. They don’t have insulation between the two panes of glass, so heat is conducted right into the home.
And while solar screens can deflect a significant amount of light so it doesn’t enter the home, it won’t keep ambient heat out of the home, any more than trees, awnings or other forms of shade.
How do they work?
Solar screens block the sun through a simple polyester or fiberglass fabric weave. The tighter the weave, the more shade it provides.
They provide simple shade.
And their effectiveness is often measured by shading coefficient numbers, rather than the solar gain coefficient that measured for windows, ranging from 0.50 – 0.70 for interior installations, and 0.14 – 0.33 for exterior installations (based on openness of the weave and color).
The lower number the better.
However, keep in mind that solar screens with those lower numbers have a tighter weave and darker color, which means the interior of the home is darker, too. A dark gray or black screen covering on windows blocks more sun, but is it worth having dark, gloomy rooms? It’s something to consider.
Another “con” is that solar screens only help during the day; they do nothing at night when ambient temperatures are scorching. Today’s low-E windows with two or three reflective coatings work 24/7. It also keeps heat inside the home during winter, which solar screens cannot do.
Because solar shades do not use the same rating system as windows, it’s not possible to accurately compare them. This is unfortunate, as we’d very much like to insert a chart that compares a few different manufacturers with a few window manufacturers! It’s disappointing.
Exterior vs Interior Solar Shades
Exterior solar shades are designed to be removed or flipped during the winter, and must be removed to clean the windows, all of which shorten their lifespan. They also can fade quickly in our desert climate. You can buy retractable ones, but those have an even shorter lifespan than ones mounted in the window frame. Therefore, when you’re shopping for estimates, be sure and ask about the warranty. It often reflects manufacturer confidence in how long their product lasts.
If you’re considering solar shades that mount on the interior of a home, we don’t recommend them. They might create darkness, but heat has already passed into the home through the window, with ample opportunity to disperse into the home in the space between the glass and the roller shade.
In our opinion, they’re simply not effective, especially when compared to modern windows that use low-e3 or low-e4 technology, and argon gas between the panes.
Look Closely at Ratings
It’s smart to ask about the technical specs they share for the product. Is it just for the screen, which is preferred, or does it include the window glass?
Most provide the latter.
Since the energy efficiency of glass varies widely, depending on the number of panes, thickness of the glass and any coatings, films, tints or additives used to make the glass more energy efficient, those numbers shouldn’t be relied on. They can be very misleading, especially if they’re based on old single-pane windows, or if they include energy efficient glass that your home may not have.
If the ratings includes both screen and window, you’ll need data that uses windows comparable to yours.
What about Window Tints?
If you’re comparing solar screens to window tinting, it’s important to look closely at the ratings there, too. Films last longer than solar screens, but they also block sun in the winter, which means you’ll be running that heater more.
They also make a room even darker than solar screens, which many people dislike.
Even more importantly, both tint and solar screens will void your window warranty, since it interferes with how the product operates. It hampers any low-e coatings on the glass, blocking its ability to reflect, which is then compounded by all of the dirt and debris a solar screen will trap against the glass. The low-e coatings stop working entirely.
And even worse, trapped dirt and debris can prevent a window’s weep holes from draining properly, leading to extensive water damage. This is common. Solar screens can be difficult to remove or flip, so most homeowners actually clean their windows even less than they might have otherwise, which impacts efficiency.
They Simply Don’t Compare to Replacement Windows
In our opinion as window experts, it’s far better to save up and replace old windows with more energy efficient product, and skip any aftermarket films or screens. If the windows are newer than twelve years old, they do more harm than good. And if the windows are older, then you’ll be surprised just how much windows have improved in the last decade. New replacement windows can save a lot more money on your heating and cooling bills than a screen or film could ever do. They’ll last a lot longer, too.
If you’d like a quote on replacement windows, we’re offering free argon upgrades, a free lifetime installation warranty, AND $200 off if you act fast. Request a no-obligation appointment, if you’d like us to come out to your home.