The Best Way to Insulate Windows

Custom fit means great performance

Indow window inserts are made out of acrylic glazing and edged with our patented Compression Tube. The tubing compresses when pressed inside your window, holding the insert securely in place while sealing out cold drafts, hot air, and outside noise. The tight seal delivers superior performance and ease of use, making our window inserts an excellent way to insulate your windows.


Flexible compression tubing creates tight seal

The tight seal between the Compression Tube and your window frame provides exceptional window comfort performance, keeping at bay cold drafts and blocking heat during the summer. Indow storm window inserts provide superior comfort no matter the weather or temperature outside.

The tight seal on Indow window inserts helps make them the best way to insulate windows


50-70% Decrease in noise penetrating windows

Hush noise so you can sleep and live comfortably. When placed over operable single-pane windows, Standard Grade inserts dampen noise by up to 10dBA, which equates to 50% noise reduction. Acoustic Grade inserts reduce noise through operable single-pane windows by up to 18.9 dBA, equivalent to a 70%+ reduction. When placed over operable double-pane windows, Acoustic Grade inserts reduce noise by up to 12 dBA, equivalent to more than a 50% reduction in noise and an STC rating of 42 to 45.* 

*Overall noise reduction performance depends on how much noise is coming through walls, ceilings, floor, and doors. The window noise reduction will be less when Indow inserts are placed over double-pane windows. Indow inserts are not recommended to reduce noise coming through laminated double-pane windows. 

the best way to insulate windows also provides great window soundproofing


Reduce energy use by up to 20%

A U.S. Department of Energy study found that installing Indow inserts led to a 20% reduction in heating, ventilating and air-conditioning use in a Seattle home.

A separate study by Portland State University’s Green Building Research Lab found similar results from the use of our indoor storm windows. Comparing gas usage before and after installing Indow window inserts in four Portland-area homes, the lab found heating-energy costs were reduced by an average of 19%. 



Indow window inserts have 94% of the insulation of standard double-pane windows. The surface of an acrylic Indow insert is much warmer than the surface of a pane of glass, so you’ll feel warmer even if the air temperature in both cases is the same. Increasing the surface temperature of your window space leads to increasing the mean radiant room temperature. This allows you to keep your thermostat at a lower level for ever further increased savings. Read more about this study from the Green Building Lab.

** R Value measures the thermal resistance of a material and its effectiveness at keeping the outside out and the inside in.


Indow inserts + single-pane data provided through independent testing conducted by the US Department of Energy’s Pacific Northwest National Lab and Portland State University’s Green Building Research Lab. Actual performance will vary depending on condition of window.

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