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So it’s COLD here in Reno, NV. Last week it was nice and sunny and now it’s in the 20s during the day and even colder at night. So I’ve been on a kick lately to help keep the house warmer and make it more energy efficient. I replaced some light bulbs with LEDs and insulated the recessed cans they are in, I added a flapper valve to our stove vent and put some weather strip around the doors. Then I went to see some friends who make Energy Savr Window Inserts right here in Reno, NV.

Our windows aren’t that old by most standards. They are all double pane, but they don’t have any kind of coating and are still fairly cold. We have some nice honeycomb blinds that provide more insulation, but only when they are closed and even then they are drafty around the edges.

The Energy Savr Inserts mount in the window frame and provide another layer of air to insulate and improve the over all energy efficiency of the window while sealing up all the leaks.

Do Energy Savr Window Inserts Work?

TL/DR: yes.

Energy Saver window inserts are an extruded aluminum frame with a membrane of vinyl film. They provide insulation by creating an air pocket between the window and the house. The warm air in your house heats up that air pocket and eventually the window and then the outside world. The additional air pocket slows down that transfer of heat out of your house.

For situations like our uninsulated skylight or single pane windows, they make an easily noticeable difference. After installing an insert in our skylight it doesn’t leak and doesn’t feel much colder than the surrounding ceiling board. For the rest of my windows, which are all double pane, they feel a little warmer to the hand. I used an infrared thermometer to measure the temperature of a bare window and the insert in front of a window and they were about the same. I was dismayed by that at first. Then I went around to the outside and found that the window with an insert behind it was about 5 degrees COLDER than a window without an insert in it. And then I had to think about that for a minute.

Windows WITH inserts are transferring less heat out of the house than a window WITHOUT an insert. So the bare window is warmer on the outside. Makes sense. And that is a pretty good result.

Are Energy Savr Window Inserts Worth It?

TL/DR: Yes

New double or triple pane windows are not cheap. For the sizes in my house you’re talking $600 to $800 per window without installation. For about that much you can put these inserts on all your windows. The cost or replacing fancy double hung or vintage windows is even higher, and you might want to keep your cool retro windows for design reasons. The inserts get you a lot of insulation value for not a lot of money.

How To Measure Your Windows

First, your windows are not square. Mine were off by as much as 3/4 inch from one side to another. For that reason, they want you to measure top, middle, bottom and left, center, right. They take the true dimensions into account so the inserts fit just right.

Measuring an inside corner with a tape measure

Second, it’s hard to measure inside corners. If you bend the tape measure, it’s hard to read exactly where the corner hits. To make it crystal clear, just run the back of the tape measure into the corner, read the tape and add the width of the tape measure case, which is stamped on the side.

Record the measurements on the Handy Measuring Form, then head over to the order page where you can input your measurements and price out your inserts.

How to Install Window Inserts

Installing Energy Savr Window InsertsThey install really easily. The foam tape around the frame squishes against the window frame and holds it in place with no tool or fasteners. You just slide it up into the opening behind whatever blinds or curtains you have, then push in the bottom. To remove them, you can grab the frame and carefully pull them out.


There’s an upper limit to how big an insert they can make and ship. So for bigger windows they do multiple panels that connect together in the center with a piece of H-shaped track. They are a bit trickier to install, but my big window wasn’t too much trouble for me to install myself. Split inserts can be side-by-side or upper-lower, and you can specify which when ordering.

Other Solutions

There are other solutions similar to Energy Savr out there. I haven’t tested the other insert products some of which use a rigid plexiglass panel rather than the flexible vinyl film. I have used the shrink wrap product you can get from Home Depot, like this 3M Indoor Window Insulator Kit. We used this when we lived in a ghetto apartment that had the worst single pane windows that leaked so bad there was FROZEN CONDENSATION inside the windows. They work OK and look terrible. Plus they usually pull the paint off the wall when you rip it off in the spring.

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