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Windows and external doors

You can increase the thermal performance and comfort of your home by upgrading your windows and external doors. They also help to make your home quieter by reducing external noise penetration.

The things you can do to improve the thermal efficiency of your windows depends on the age and type of your property and its existing windows:


Single glazed windows, especially those with wooden frames, can become warped over time. This leads to cracks and gaps around the window panes or around the window frame which can let in draughts. Draught proofing of windows can help improve their thermal performance, whilst retaining the original feature. This is a good option if you live in a listed building or if you want to retain the original single glazed windows.  

Secondary glazing

This is another good option for single glazed windows where upgrade to double glazed windows is not an option. Secondary glazing fits internally over the window frame helping to block draughts. There are DIY options you can try, or professionally fitted secondary glazing is available through the Energy at Home Scheme. If you live in a listed building you will need to get listed building consent to install secondary glazing.

Double / triple glazing

Double glazed windows have two sheets of glass with a gap between them which is usually 16mm wide. It is this gap which creates an insulating barrier to slow down the rate at which heat escapes from the home. Triple-glazed windows are now also available which have three sheets of glass, and therefore two insulating gaps, to provide even better insulation.

If you want to upgrade from single glazing to double glazing and your property is within the World Heritage site of Bath or in a conservation area, you should check to see if you need planning permission by contacting Bath & North East Somerset Council's Planning Department..

High performance external doors

External doors can be a major source of draughts and heat loss. A high performance external door is designed to keep your home warmer and more airtight. They can be constructed of PVC-U, aluminium, timber or a combination of these materials. They often have panels of double or triple glazing with a thermal barrier between the panes of glass which prevents heat passing through. By fitting a door that is insulated and draught-proofed you can prevent heat from escaping and also reduce noise penetration from the outside.

Draughtproofing doors

If you want to retain the original door, you can improve its thermal properties through draught proofing. Check where the draughts are coming from. You can draught proof around the door with brushes or seals. Uninsulated letter flaps and key holes can also be a major source of draughts. Consider fitting draught proofing covers to these. Find more information on how to fit DIY draught proofing here.

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