For energy saving advice and support
in the Bristol and Somerset area:
0800 082 2234

High performance external doors

Replacing your old door with a high thermal performance door can keep your home warmer and reduce your fuel bills.

High performance external doors are 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 (either air or an inert gas like argon) which prevents heat passing through. The double or triple glazing has the added bonus of cutting out noise from outside.

Not only are modern doors better insulated, but they are also likely to fit much tighter in the door frame and therefore reduce draughts.

How do you measure the energy efficiency of a door?

An energy efficient door is one that keeps the heat in effectively, and stops it escaping to the outside. Like fridges, washing machines and other appliances, new doors are given an energy efficiency rating from A-G, with A being the most efficient. Anything less than an E won’t meet the building regulations currently in force in England and Wales.

Not all high thermal performance doors are glazed. Some are solid and made from timber or aluminium

The rate at which heat is lost through a door (including its frame) is described as its ‘U-value’. The lower the U-value, the slower the heat is lost from the house and the more energy efficient the door is. Doors must have a U-value of 1.8 or less to meet building regulations. 

When should I buy more energy efficient doors? 

Around 18% of heat lost from your house is likely to come from the doors and windows, so significant energy savings could be made by replacing old doors with new ones. If fitted individually, new doors could cost in excess of £1000, but when bought alongside new windows (most window companies will also fit doors) they could work out cheaper.

There are other advantages to replacing doors to bear in mind, such as aesthetics, security, noise reduction and fire safety. Whatever your reason for replacing doors, it is worth making sure the new ones are as energy efficient as possible.

If you live in a conservation area or your house is listed there may be restrictions on the replacement of external doors and windows. In such cases you should contact your local conservation or planning office to discuss the options available.

Image: Steven Miric |

Need more help?

We can advise you about saving energy, or help you understand what grants and support you're eligible for:

Contact us

Need advice about saving energy? Want help with grants and support?

Send us a message and one of the team will get back to you as soon as we can*:

Data Protection: I understand the information supplied on this form will be stored by the Centre for Sustainable Energy. I understand that I may be contacted by the Centre for Sustainable Energy for the purpose of giving impartial energy advice. I understand that the Centre for Sustainable Energy will not pass my details on to any third parties.

* We aim to respond to your enquiry within two working days.

Translate this page


Download the PDF

Download this PDF document

This information is available as a freely downloadable PDF from this page.

For more domestic energy advice, view all our advice pages.