Insulate Old Windows Without Replacing

A close-up image of a person installing window inserts. They are wearing a black dress and have a clear bracelet on their left wrist.

Have you noticed a draft coming in from your windows during the colder months of the year? If you have old, out-dated windows, they could be responsible for a significant amount of heat loss and air leakage in a home.

In addition, windows with cracked glass, broken seals, and poor insulation cut into the energy efficiency of the home, by overworking the HVAC system and driving up energy bills.

So, if your home is already having trouble maintaining a comfortable temperature for more than a few minutes, and it seems impossible to keep the house warm, it may be time to consider new insulation options for the windows.

6 Ways to Insulate Windows without Replacing Them

1. Install Window Inserts

Tall, vertical window framed with old, red brick and white paneling, with a window insert inside the frame.

Window inserts offer excellent insulation during those frigid winter months while being cost-effective compared to full window replacements.

Window inserts fit over the existing interior window. Some, like the ones from Indow, are held in place using compression tubing, creating a tight seal around the window frame without damaging the window or the frame. Indow inserts are made with acrylic, which has much higher insulation properties than glass. So, even if installed in front of windows with small cracks or poorly sealed windows, the inserts will eliminate drafts and improve the overall energy efficiency of the home.

The inserts are low-profile and are virtually unnoticeable when installed. A great option for historic homes, the inserts are custom measured to fit perfectly and won't damage the historic nature of the home, letting you preserve their beauty.

Inserts not only reduce drafts and help maintain a comfortable temperature within the home, but there are also options that can offer significant soundproofing capabilities or provide light blocking and UV protection. These are beneficial to have all year round, as window inserts also provide great insulation in the warmer months.

2. Bubble Wrap

If the need for a warmer home is urgent, covering the windows with bubble wrap is an option. Bubble wrap is not the most aesthetically pleasing or permanent solution, but it is cheap and easy to do in a pinch.

For the best results, choose a wrap with larger bubbles instead of the smaller bubbles, and cut the wrap so it covers the window and overlaps the seams. Mist the glass panes with water and apply the bubble side to the damp windows. The bubble wrap can be taped into place, but there is a risk that the tape will peel the paint off the walls if left for too long. For even better insulation, double up the layers of bubble wrap.

This will block the window's view, but light will still pass through the bubble wrap to brighten your space.

3. Traditional Caulk

If you feel a draft coming in through the windows, they may need some fresh caulk. Caulk is easy to apply and can be used to seal gaps between the window, the frame, and the wall.

Before applying, it is best to scrape off any old caulk and peeling paint in order to achieve a proper seal that will last.

4. Insulated Glass Units

Two sheets of glass are leaning against a wall, an example of an insulated glass unit.


If your window frame is still in good condition, you could just replace the glass with insulated glass units. Insulated glass units are made up of two sheets of glass separated by an inert gas. This separation diffuses heat transfer in and out of your home, in order to provide more insulation.

Sometimes referred to as double-pane glass, insulated glass units are a sealed system, so if one of the sheets of glass cracks or breaks, the entire unit must be replaced. The unit can be customized depending on how much insulation is needed.

You can choose thicker or thinner pieces of glass (the thicker the glass, the better the insulation), the width of the spacer (the piece that separates the glass where they meet at the edge of the window frame), and the type of gas that is used between the panes (commonly used gases include argon, krypton, or a mixture of the two). Depending on the customization, however, these units can get costly fast.

5. Thermal Curtains

One of the more design-friendly insulation options is to put up thermal curtains. These aesthetically pleasing window coverings have a special thermal lining that holds in warm air during the winter and blocks out the heat during the summer for year-round use.

Thermal curtains work best if they are floor length and wide enough to sufficiently cover the window. For further insulation, Velcro tape can be added to the curtains and wall for a full seal.

These curtains can be used year after year and opened during the warmer days. In addition to their insulating capabilities, thermal curtains also block out light and act as noise dampeners. However, you'll have to decide if you want insulation benefits or sunlight and a view, as you cannot have both with these curtains.

6. Draft Stoppers

A draft stopper is a snake-like, cloth tube filled with materials like sand, beans, rice, or batting. They are typically laid across cracks in doors and windows to act as a fabric weatherstripping by preventing cold air from leaking in and warm air from escaping out.

Draft stoppers can be found at home goods and home improvement stores, but it is also an easy and fun DIY project for the crafty crowd. Simply choose the preferred fabric, cut and sew it into tubes long enough to cover the width of the windowsill and fill it.

Draft stoppers do not block the window or prevent it from opening when necessary. However, they can only cover the bottom of the window and cannot cover the top or the sides. Therefore, they may not be able to provide complete insulation if there are cracks throughout the seal.

How Indow Can Help

A person is installing a window insert into their window. They are wearing a purple sweater, hoop earrings and brown glasses.

Indow offers a range of window inserts that fit the needs of every home. With our inserts, homeowners don't have to spend replacement window levels of money to get effective insulation.

Indow window inserts allow you to enjoy the comforts of your home all year round. Our easy-to-install solutions not only make your home more efficient and safe, but our custom options ensure you get the best fit for your home.

Reach out today for a free estimate.

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