As winter approaches, households across Britain are scrambling for low-cost ways to keep the heat in. With 10% of a home’s heat vanishing through windows, sealing up those gaps is one of the smartest money moves you can make. But energy experts warn that well-meaning DIY attempts often go wrong, leading to wasted money or even damp problems. Jamie Carruthers, an energy advisor at the Centre for Sustainable Energy, said you don’t need to spend thousands on new double-glazing to feel warmer. Instead, it is better to start with simple « draught proofing » – blocking unwanted gaps that let too much air in.
He said: « It is a real shame to spend money on heating all the space inside your home only for that heat to immediately escape through a draught. » He explained that a draught isn’t just wasted air; it physically strips heat from your home and makes you feel much colder than the room actually is.
« I had a draughty window right next to my bed, and it was making me feel much colder than the room temperature would suggest, » he shared with the Express. « If you have a draught nearby… it is common to have the thermostat set higher than you really need in order to stay comfortable. »
By fixing this, he estimated you could save around £40 a year directly, plus another £70 if the warmer room allows you to turn your thermostat down by just one degree. However, Mr Carruthers warned that simply sticking tape over the gaps isn’t enough.
A common error is buying a « one size fits all » strip that doesn’t actually fit. If the strip is too thick, the window won’t close. If it’s too thin, the cold air still rushes in.
He explained: « Draught proof strips come in a few different sizes and variants. Make sure you size the strip correctly for the gap, such that it is nice and snug, but still allows the window to close properly.
« You can measure the gap in advance and buy the right fit. When I draught proof, I often buy a range of sizes and use a little trial and error as I go.
« Also think about what type of strip makes the most sense for the job. I have found that brush strips work quite well for sash windows, as the foam ones can get pulled off by the friction of the sliding window. »
The second mistake is potentially more damaging. In the rush to seal up every crack, homeowners often forget that a house still needs to « breathe » to stop mould growing.
Mr Carruthers warns that there is a big difference between a cold draught and necessary fresh air. He said: « Ventilation is an important consideration. It might seem a bit counterintuitive to block the air leakage from draughts and then start thinking about ventilation.
« However, the key distinction is that ventilation is controlled airflow – which is why it is our friend – whereas draughts are uncontrolled.
« Ventilation is essential for removing pollutants and water vapour from the air, the latter of which can lead to damp and mould issues. To ventilate, you may have trickle vents on windows, brick vents, as well as extractor fans in the kitchen and bathroom. »
If you aren’t ready for DIY, Mr Carruthers suggested low-cost « secondary glazing » – a simple sheet you add to the window frame – which could save £104 off your bills.
He also recommends the old-fashioned method: thick curtains.
« Close your curtains at dusk to trap warmth inside, and open them in the morning to allow the sun to naturally warm the room, » he advised.
Just make sure to tuck the curtains behind your radiators, or you will simply be heating the window glass instead of the room.
