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Transform a cold home with upgraded windows and doors

Energy efficient windows will help stop escaping heat in its tracks. They’ll keep your home cosy and go a long way towards keeping your energy bills low, as well as stop noises from the street disturbing your peace and quiet.

What are energy efficient windows?

Energy efficient windows either have double glazing - two panes of glass with a gap in between - or triple glazing, which has three panes. The glass is covered in a very thin coating of metal oxide to retain your home’s heat while still letting light through the glass. The glass panes are generally 16mm apart, and the gaps can be filled with a gas such as argon to further boost insulation. 

The window frames are made from either uPVC, wood, aluminium or steel, or a composite. Whichever frame you choose will impact the end cost, with uPVC being the cheapest and wood the most expensive, but more sustainable.

Just as homes are given an Energy Performance Certificate (EPC), windows are ranked on a scale of energy efficiency, from E to A++. The higher the ranking, the better your new windows will keep out the cold, and the bigger the savings you’ll see on your bills.

How much can you save with energy efficient windows? 

A-rated windows - one of the highest performing - would cost £15,000 to install in a semi-detached house, according to the Energy Saving Trust. You’d save £165 on your energy bills each year, along with 375kg of carbon dioxide.

Installing energy efficient windows

Double or triple glazed windows should be installed by a professional. Look for one who’s registered with the Glass and Glazing Federation - their directory will point you to someone near you. You should choose an installer who’s registered with the Competent Person scheme, which means they’re guaranteed to fit your windows to building regulations.

Other considerations around energy efficient windows

Planning restrictions

In most cases, you won’t need planning permission to install your upgraded windows. But if you live in a conservation area, there will likely be restrictions on whether and how you can modify your windows, as their appearance can’t differ from the aesthetic of the area you live in. And if you live in a listed building, the windows will likely be protected as they’re of historic interest, but you may be able to get planning permission for secondary glazing.

Avoid condensation with ventilation

Because replacement windows are sealed up to keep out draughts, they can sometimes run the risk of increasing condensation due to the lack of ventilation. To counter this, consider installing trickle vents, which let in a small amount of air even when the window is closed to ensure condensation doesn’t build up.

If you see condensation between the two panes of your double glazed window, it’s a sign the seal is broken, and you’ll need to replace the glass.

Sash windows

Sash windows - a traditional style of windows, with two separate panes of glass that slide up and down - are generally poor at keeping in the heat. It’s possible to replace these with units that look similar but have double glazing to keep out draughts. However, this can be expensive, so you might want to look into secondary glazing instead.

Secondary glazing

Secondary glazing comes in lots of price options to suit any budget. The cheapest - but most temporary - fix involves simply sticking some film to the frame. The next step up is magnetic or clip-on acrylic or polycarbonate sheets, which can make a huge difference to how much heat your home loses. Or, you can hire a professional installer to build and install bespoke secondary glazing for your windows. This is the most effective option, but also the most expensive.

For another cheap fix to boost your home’s temperature - that works alongside energy efficient glazing - you can hang heavy curtains or install hollow blinds to keep the heat in at night.


A new front or back door could be just the ticket for keeping out draughts. Newer doors tend to come with insulation built in, and you can also add extra insulation where needed, such as in the letterbox. You’ll need to get building regulations approval to install a new door. 


No matter how much glazing you install, a glass room still won’t be as warm as one with walls. So, if you’re trying to save money on heating, it makes little sense to heat your conservatory in the colder months. 

However, an underutilised advantage of having a conservatory is that it can act as an extra layer insulating your home. To make the most of it, install a sealed sliding door, plus blinds or heavy curtains, between the conservatory and the other parts of your home. But remember, you’ll only get the benefit of the conservatory’s insulating properties if you refrain from heating it.

From quick fixes like heavy curtains, to high-tech solutions like heat pumps, there’s so many ways to warm your home and lower your energy bills. Don’t know where to start? Join the waitlist for Heatio Flexx.


Ready to be a part of this smart connected network?

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