Affordable Window Insulation: A Stashbee Guide

Heat loss through windows causes higher energy bills and is bad for the environment. Read our guide on affordable ways to insulate your windows.
No-one wants to waste money. The energy price guarantee means the average UK household’s energy bills will be £3,000 a year from April 2023

Up to 18% of heat loss from homes is through windows, and air leaks are one of the the biggest contributors to that. Stopping those leaks is good for your energy costs and the planet, and means you don't need to crank up the radiators to compensate. 

Replacing single glazed windows with double glazing is expensive. The Energy Saving Trust estimates that installing A-rated double glazed window frames typically costs around £7,500 and saves £195 a year (so, that's about 38 years before it pays off!)

We’ve got some energy efficient and affordable options to stop the heat, and your cash, going out the window. 

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1. Apply window insulation film

Window insulation film creates an extra layer of air between the glass of your window and the room. This acts as an insulator.

But does window insulation film work? In short, yes - it works pretty well! 
  • Some films reduce the heat transfer of the window by up to 50%! This is especially helpful for single pane windows.
  • Film insulation for windows is cost effective, easy to install and can be taken down when the weather warms up. 
  • Your windows need to be clean before you apply the film and you need a hairdryer to shrink it to fit.
  • The film is made of plastic so if you intend to take it down each year, it’s not the most sustainable solution - but many people leave it up all year round.
  • You can buy window film insulation kits at B&Q, DIY direct, Wickes and most other DIY retailers.  
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2. Stick on foam strips

For windows that open, you can buy self-adhesive foam strips from DIY stores including B&Q, Screwfix, Toolstation and Robert Dyas
  • Make sure that you choose the right size for the gap in the window you’re filling – too big and the strip will get crushed, too small and you’ll still lose warm air!
  • If you want to draught-proof a sliding door, use double sided strips with glue on one side and a brush on the other to allow the window to slide. DIYdirect sells a double sided strip with a brush for all window types for extra insulation. 
  • Foam strips aren’t a permanent solution and the glue might damage paintwork when you come to remove and replace the strips - but they can lost a long time.
Snow Flake

3. Install window brush strips

Metal or plastic strips with brushes or wipers attached are better for sash windows and longer lasting than foam (but more expensive). Again, size matters, so measure carefully before you buy. You can hire professionals to carry out the work for you or buy to DIY at Low Energy Supermarket

4. Fill the gaps

An easy way to plug the gaps in sash windows is using old newspaper. It's cheap and sustainable, but a bit unsightly and not airtight. A better solution is Gapseal - a filler you squeeze in the gaps. If your windows don’t open, Energy Saving Trust recommends using a silicone sealant in the gaps to plug them permanently.

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5. Buy (or make) window draft excluders

You can buy draught excluders designed to sit on a window ledge, similar to what you might use on a draughty door (but smaller). We think these are best used in conjunction with one or two of the other suggestions on this list.

6. Add thermal curtain liners

Thermal curtains reduce the movement of air, which better insulates any room. The cost depends on how many windows you have and how expensive your taste is. 
  • If you want to keep your existing curtains and blinds, you can buy thermal curtain liners to fit behind them. Dunelm has thermal curtain liners to use with eyelet and pencil pleat curtains from £16, as does Amazon
  • John Lewis has curtain liners for pencil pleat curtains in a wide range of widths and drops from £20. 
  • If you need new curtains or blinds most homeware stores have ones with thermal lining available. 
  • If you’re in the market for a new window treatment the Energy Saving Trust says that hollow blinds, fitted into place with a sealed frame, and sealed shutters will also help cut draughts and keep your heat in for longer. 
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7. Fit secondary glazing  

Secondary glazing is  cheaper than installing new double glazing and a good solution if you live in a conservation area which won’t allow double glazing. 
  • Secondary glazing can be uPVC, aluminium or timber and temporary or permanent. 
  • It works by fitting a second pane of glass in a frame to the inside of your existing windows trapping air between the panes of glass. 
  • DIY kits are available, using polycarbonate or acrylic sheets and magnetic or clip-fit mounting systems. 
  • Magnetic secondary glazing is easy to install and remove and is available from the Plastic People and Secondary DIY Glazing
Person Holding A Hot Drink With A Blanket On

8. Use Bubble Wrap as Insulation  

The most affordable and quick solution on the list is to tape bubble wrap (bubble side facing the glass), to your windows.

This solution isn't necessarily cheaper than window film and just as unsustainable if you're buying brand new bubble wrap, but if you happen to have lots of it lying around the house already, it could be an option (especially for those outhouse, garage and extension windows that you don't need to see out of anyway).

Once all your spare bubble wrap has been used on your windows, if you need to wrap anything, here's our guide to 10 Environmentally Friendly Alternatives To Bubble Wrap.

If you’re looking for easy ways to make a bit of cash as well as ways to save, if you have a spare space you could rent it out as storage to someone who needs it. Find out how much you could earn and how to become a Stashbee host here

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Updated 14th Apr 2023

Written 13th Jan 2023