Insulate Windows

12 Ways To Insulate Your Windows For Winter

Read how you can insulate your windows to keep warm this winter, these cheap hacks will not break the bank, but will cut your energy bills.

How to insulate your windows

When the cold snap happens each year, keeping warm in our homes becomes a priority. With Ofgem price caps soaring over the last few years, and with the pressing issue of climate change, there has never been a greater need to be more energy efficient.

Windows contribute 20% of heat loss from a room, so any small changes you can make to insulate windows will have an impact on your energy bills and the comfort of your home.

How windows lose heat

How windows lose heat

For the 80% of homes that have double glazing, upgrading to ultra-efficient triple glazing can be three times more energy efficient than if the windows are old double glazing. But currently, only approximately 0.17% of homes in the UK are taking advantage of triple glazed windows.

For anyone who isn't ready to invest in replacing their windows, there are several things that can be done to help save money and keep warm.

Insulating your windows can help to reduce how much energy is lost through the window and keep rooms at a healthy temperature without costing a fortune.

Reducing heat escaping through a window can be best achieved by adding barriers and there are several ways to do this.




The simplest way to reduce heat escape through a window is by fitting a blind.

The Energy House at the University of Salford tested a variety of blinds and found the following reductions:

Type of blindHeat loss reduction
Roller blind fitted with zip side channels with Low-E fabric33%
Blockout honeycomb blind in a framed bead fit system so gaps are minimised32%
Roller blind fitted with side channels22%
Standard roller blind15%


The experiment was conducted with a modern double glazed low-e window comparative to the same window with no covering.

Specialist thermal blinds that zip into place will achieve the best results. But, even a standard roller blind can still make a difference for a budget solution.

Solid shutters can insulate windows

Solid shutters can insulate windows

Solid shutters

Solid shutters were a common feature in Georgian houses and have again started to become a popular form of window covering.

In the research at the Energy House, plantation shutters demonstrated a 28% reduction in heat loss.

Shutters are aesthetically pleasing, practical, highly versatile and can be fitted with curtains for additional insulation.

Thick curtains can insulate windows

Thick curtains can insulate windows


The University of Salford continued its research and found that for anyone with single glazed windows, drawing curtains can save up to 20% heat loss.

Other figures range from 15-25% savings, and that would depend on the type of glazing and thickness of the material. What is certain is that curtains can make a considerable difference not just to reduce heat loss, but also to reduce draughts and help keep a living space warmer.

When choosing curtains, opt for heavy fabrics like wool or fleece, as they are better at trapping heat. Adding a thermal lining to these curtains further enhances their insulating properties.

Just don't ever close your curtains over a radiator, as this will trap the heat and it can escape through the window and not into the room.

Choose Energy Efficient Glazing

Everest windows have U-values as low as 0.80 W/m2K.

Layer blinds and curtains

To get the best reduction in heat loss and to stop cold air and draughts a layered approach helps to make a difference.

Think like the Georgians who had shutters with heavy drapes. Or, blinds and curtains combinations for more thermal insulation.

Use sunlight and daylight

Timing of closing and opening curtains, blinds and shutters is also important and can make a difference in heat retention and heat loss.

Closing curtains and shutters as soon as the sun goes down will help to retain the heat in the room. Always open the curtains or shutters as soon as the sun comes up to take advantage of any solar gain to warm the room for free.

However, if you have a north-facing room that can't benefit from direct sunlight it can be more of a challenge to heat the room. For those rooms, it might be best to add additional insulation to the window (as below) or consider triple glazed windows.

Caulk the edges

Caulk the edges

Research shows that if it's windy outside, heat loss from the home increases and heat demand peaks. The best way to combat the effect that wind can have is to tackle draughts in the home.

The Energy Saving Trust reports that draught proofing doors, windows and gaps can save £90 a year (for an average 3 bed semi).

Plugging any draughts around the edges of badly fitted windows, or old window frames can stop the little gusts of air that in winter will be ice cold.

Run your hand around the frames and you can feel where there are any draughts. Simply use a quality caulk or silicone to fill in the gaps around the frame.

Foam tape

Foam tape

Instead of using a caulk, a self-adhesive foam tape is a quick and easy fix that will help to stop any draughts.

Great for older windows, or window openers that don't have a perfect seal to close, foam tape can seal gaps in warped door and window frames.

Measure and cut the tape to fit the specific size of the gaps, ensuring a snug fit to prevent draughts effectively.

According to Tesa, a provider of insulation solutions including draught excluders, using their products can lead to a reduction of up to 40% in energy costs.

Window film

Window film

Window film is effectively like a thick cling film wrap for windows.

A window film kit typically includes a plastic shrink film that's applied to the indoor window frame with double-sided tape. After installation, you use a hair dryer to shrink the film, removing wrinkles and creating an airtight barrier.

The film creates an insulating barrier, reducing heat loss. It's claimed that a quality window film can reflect up to 30% of the room's heat back into the room in the winter. Although cheap film kits are probably less than this.

For a quick and relatively cheap solution to provide extra window insulation, this is well worth considering.

They are particularly useful for single-glazed windows, or where upgrading to triple glazing isn't feasible. However, window film does look like you have cling film on your window.

Bubble wrap

Another cheap hack to insulate windows in rooms that you might not use is to apply a super-insulating layer to the glass.

Bubble wrap is made of air pockets that act as insulators trapping heat and reducing heat loss.

To apply, mist water onto the window glass and press the flat side of the bubble wrap against it. This method is especially useful for seldom-used rooms where aesthetics are less of a concern.

Whilst ugly to look at from both the inside and outside, bubble wrap can be a temporary and super cheap insulator for your windows in extreme situations.

Draught excluder

Draught excluder

A trick that your grandmother or great-grandmother would have used is to fill fabric tubes with insulating material, like rice or old clothing. Sometimes called draught snakes or sausage dogs.

Placed at the base of doors or windows to stop cold air from entering, they can be homemade from old clothing or towels, making them a sustainable and cost-effective solution.

A great solution for anyone who likes crafting and wants to add a decorative touch.

Secondary glazing

For anyone living in a listed building, the main drawback of not being able to replace original single glazed windows is most apparent in winter.

Original windows made from leaded panes, Crittal windows, or wooden sash windows all look beautiful. However, they are not energy efficient and the heat loss through single glazing can be nearly four times as much as triple glazing.

The only effective solution for listed buildings is to install secondary glazing. This ranges from a DIY plastic frame that pushes into place to a made-to-measure fitted frame with glass.

The gap created between a window and the secondary glazing creates a thermal barrier that has two main benefits. The gap helps the window to reduce heat loss and is effective at noise reduction.

Formal testing demonstrates that secondary glazing can reduce heat loss by 63%.

Energy efficient glazing

Based on U-values, Everest energy-efficient triple glazing is 200% more energy efficient than old double glazing and 65% more efficient than Everest energy-saving double glazing.

The U-value difference between single glazed windows and double or triple glazing is as much as 4.8 to 0.80 W/m2K.

By installing a window with a low U-value you will have a noticeable difference in room comfort and lower heating bills.

Everest triple glazing is one of the highest-performing glazing units on the market with an industry-leading 0.80 U-value making it ultra-energy efficient. Choosing energy-efficient Everest windows can help lower your energy bills and reduce your carbon footprint.

Double Glazing →

Our high-quality double glazed windows will keep your home warm, safe and quiet.

Triple Glazing →

Our triple glazed windows are our most energy-efficient, with an A++ energy rating.

Secondary Glazing →

Secondary glazing is perfect for listed buildings to improve energy efficiency and reduce noise.

Don't forget condensation

Condensation is created by excess moisture in the air that forms on cold surfaces. It's most often noticed on windows when it's colder outside than inside.

The main concern from standing water and moisture is mould, and black mould is exceptionally bad for our health.

Condensation will be at its worst when the weather turns cold. To avoid constantly wiping the windows with a cloth, the more winter-proofing measures you can apply to your windows will help.

Firstly, ventilation is key to reducing moisture in the air. In Winter when opening windows means heat loss, try a dehumidifier.

Another cheap tip is to buy plants that take moisture from the air, these can help to reduce the condensation on your windows.

Spider plants, peace lilies, snake plants, Boston fern and aloe vera are all house plants to have in bathrooms, kitchens and bedrooms.

Insulate Your Windows – Summary

Heat loss reduction
Triple glazing (compared to old double glazing)83%
Double glazing (compared to single glazing)75%
Secondary glazing63%
New double glazing (compared to old double glazing)49%
Integrated honeycomb blind in a framed system32%
Window film (quality)30%
Plantation shutters28%
Standard roller blind15%

Source and Everest data.

At Everest, Energy Efficiency Is at the Core of What We Do

When you choose Everest, not only do you make your home warmer and reduce your energy bills, but you also reduce your CO₂ emissions by consuming less energy to heat your home. We ensure an environmentally friendly manufacturing process and recycle all old products.