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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 to 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 | istock.com

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