Performance of Storm Windows vs Regular Windows

The performance of storm windows vs regular windows can depend on what windows you have to start out with. In this blog we’ll cover typical replacement windows and storm windows, what insulation you can expect from each and what noise abatement performance to expect out of each category.

Storm Windows

Storm windows are a second window pane added to the outside or inside of your already existing window. Exterior storm windows attach to the outside of your window frame and interior storm windows to the inside of your window frame.

Replacement Windows

Replacement windows replace your already existing windows – either by installing a new type of window style or technology, or because the seal on the old window has failed.

close up of one of indow window insert options

Replacement Window Options

The most popular replacement windows are double hung and casement, wood frame, vinyl frame, or fiberglass frame. Casement style windows are more airtight than double hung, so they will provide more insulation and defense against drafts than double hung. Double or triple glazing adds an extra pane of glass with air or gas between them. This provides better insulation and sound reduction (especially triple glazing), but can be very expensive. Low-E coating reflects heat to improve efficiency. Read the consumer report on replacement windows .

“Star-qualified windows can lower your energy bill by an average of 12 percent. That’s only $27 to $111 a year for a 2,000-square-foot single-story home with storm windows or double-pane windows, $126 to $465 if your home has just single-pane windows, according to Energy Star.” claims the replacement window consumer report. Interior storm windows can save an average of 20% on energy bills according to the third party studies.

indow storm windows vs regular windows

Storm Window Options

Adding an interior storm window to a double-pane window can reduce outside noise up to 50% (10-12 dBA). Adding an interior storm window to a single-pane window can reduce noise up to 70% (18.9 dBA). Replacement windows reduce outside noise up to 20%. This data is based on third party studies performed with Indow window inserts. Because the insert is made of acrylic, it blocks sound better than standard window glass. A near airtight seal is created between the insert and the glass, which also helps Indow window inserts reduce outside noise.

Old windows receiving storm windows might need some restoration before this type of performance can be expected. Meanwhile, replacement windows will bring the performance described as soon as they are installed. Storm windows can provide different needs—acoustic or UV protection—in just one room or window that fits that space’s needs.

Analyze your space to determine your needs. Is noise an issue for your? Then storm windows are probably the way to go. You can read our full comparison of storm windows vs replacement windows to get a better idea.

person walking by restored window

How to Get Storm Windows

All inserts are backed by a Snug Fit Guarantee because of our laser measurement system. Here’s how we do it:

We send you a laser measure kit with a fun laser measure tool (pew pew). It works just like a flashlight—with the press of a button, you get the dimensions . Enter the measurements displayed on the tool into our online portal. It checks for accuracy.

Our fit experts check the measurements for accuracy (again). If everything looks good, dimensions are on their way to becoming your custom insert. It’s that easy.

We developed the tool and software (with error detecting algorithm) because it’s the best way we know how to seal windows for winter.

Customer Reviews


4.49 Average 1477 Reviews logo

Matthew L

Indow inserts were easy to measure, order and install. They've provided great insulation for old single-pane and stained glass windows in an antique home. We can significantly feel how much better the home holds heat.

Posted 2 days ago

Ellis W

I ordered two Indow inserts for my home. They are doing a great job, entirely happy with them and the ordering process.

Posted 1 week ago

Elizabeth W

I can't say enough good things about this product and company. Our house is 101 years old and the sidelites next to our front door are single pane ancient wavy glass which means when it gets very cold (Chicago temps) we can have an inch of frost covering the INSIDE of our windows. I was desperately searching for a solution so our front vestibule was not so cold and a friend recommended Indow. The process could not have been simpler and the temperature difference it has made is off the charts.

Posted 2 weeks ago

Austin T

I have several historic single pane gridwork mullion windows. They're beautiful but have almost no thermal protection. Indows proved to be the perfect solution to preserve these windows while getting the thermal comfort we need. They were easy to install and work perfectly!

Posted 3 weeks ago

Kathryn M

Amazingly easy to install even the safety chain holders. I. Noticed an immediate sound level difference and the room atmosphere became more solid feeling and pleasant. They also gave an insulating feature to the window drafts are non existent! The house is 50ft off a State highway that is heavily traveled in warmer months I'm confident the indows will handle it. I'm very pleased!

Posted 1 month ago


We ordered the acoustic inserts to help with road noise, and we've been sleeping so much better with them!

Posted 1 month ago

Sienna K

We used the windows inserts in our skylight. They are great! They the horrible drafts and noise out and were cost efficient. My only comment would be to provide better measurement and installation instructions for skylights specifically. It took us a lot of guessing and research to measure and install because skylight directions were not provided and the windows install guide doesn't always apply to skylights. Other than that though great product and I would buy again!

Posted 1 month ago

ted t

Our home was built in the late 1800s and we have spent a lot of money over the last 20+years restoring it.We did not want to replace the windows with modern windows because of the cost and originality. But the single pane windows come with a price also. the main reason we purchased the Indow window inserts is because of the condensation on the inside of the windows.We would literally have a take a towel and wipe them down every morning in the winter. There would be a puddle on the sill,and wood and water dont get along to well. SO we looked into the best solution to our problem and found Indow. Was reluctant to spend that much money but am super glad we did!! They have been installed now for over two months and our condensation problem has been virtually eliminated.!!! AND our furnace does not run as much as it did before. Over all it was money well spent!! The process was a little scary at first but they have a simple formula. And our contact person,Reed was awesome. Answered any questions i had and was always available.

Posted 1 month ago


Used to block interior side of a garden window in the the kitchen. Without insert, cold air literally poured into the kitchen making a winter jacket almost mandatory when preparing meals or washing dishes

Posted 1 month ago

Rob S

Highly recommend! The team (Brian) took time to help me figure out the best solution. They were made and delivered faster than expected. It was very rewarding to install them because I could feel the cold air get squeezed out as they went flush against the single pane of glass. Solid quality and great fit.

Posted 1 month ago

Alexa L

My inserts fit beautifully into my 125 year old windows - many of which were 5 feet tall. Easy to unwrap and install. Great product and even better service! I liked the process of measuring the windows with a laser measuring tool which was easy to use and precise. The product came in good condition after shipping across country and was well marked. The customer support was excellent.

Posted 1 month ago

Sarah D

Received our Indow Windows and can tell they are blocking a lot of the noise we could hear. Right now the weather is mild, but hoping to notice a big difference when the summer heats up. Our house is in a historic district and we cannot change our windows. They are very drafty and thin glass. We only ordered two, but we are in the process of ordering for four more. Love that we don’t need to drill holes or anything and they just pop right in.

Posted 1 month ago

Allan F

Every thing arrived in perfect condition, thanks to the very secure packaging. Windows fit as expected, although quite tight. After installation we noticed that the cold drafts were gone and the room felt a lot warmer. We are very satisfied with the product and the result.

Posted 1 month ago

Adriana W

Great customer service! Super satisfied with our windows.

Posted 1 month ago

Thomas M

Indow service and product is good. Reduced outside noise considerably.

Posted 2 months ago