Replacing windows with aluminium frames

New windows change how warm and quiet a home feels for years after they go in.

Aluminium frames are slim and long lasting, and they can be recycled.

When the old windows are due

The Energy Saving Trust lists the signs that it may be time to replace a window.

The trust puts the life of good double glazing at 20 to 35 years, when it is installed properly and looked after.

The frame and the glass

A frame's design and its material both affect how much heat escapes. Windows that perform well come in every main frame material, aluminium included.

Double glazing has two panes with a gap between them, filled with air or a gas such as argon. Triple glazing has three panes and holds in more heat again.

Low emissivity glass (low E glass) has a thin coating of metal oxide on one inner surface. The coating reflects heat back into the room and still lets the daylight through.

A window's energy rating runs from A++ to E and covers the frame and the glass together. The label also shows its U value, a measure of how easily heat passes through. The trust treats the overall rating as the better guide to how much energy a window will save.

Fresh air and a way out

The Energy Saving Trust says new windows are usually more airtight than old ones. Replacement windows usually have trickle vents, also called background ventilators, which let a little fresh air into the room.

Rooms that make steam, such as kitchens, bathrooms and utility rooms, need more ventilation than the rest of the house. That normally means a fan as well as a window that opens.

An upstairs window can be the way out in a fire. The Planning Portal says a replacement window should give at least the same chance of escape as the one it replaces. In England, the usual measurements for an escape window are these.

In England, glass low in a wall, or in and beside a door, has to be safety glass. That covers any panel up to 800mm from the floor, and glazed doors up to 1500mm.

Older and listed homes

The Energy Saving Trust says that in a conservation area, work on a home has to preserve or enhance the character of the area. New windows are still possible there, chosen to suit the building and the street.

Changing the windows of a listed building needs listed building consent. The Energy Saving Trust suggests asking the council's conservation officer before making any change.

Secondary glazing is a second pane fitted on the inside of the existing window. It keeps heat in and leaves the old window as it is. The trust says reversible kinds don't usually need listed building consent.

Permission and sign off in England

Since 1 April 2002, the building regulations in England have covered all replacement glazing.

An installer registered with a competent person scheme can sign the work off without involving the council's building control. The householder then receives a certificate showing that a registered installer did the work.

A householder fitting windows themselves, or using an unregistered installer, asks a building control body to check the work instead. That can be the council's building control team or a registered building control approver.

GOV.UK warns that a home without approval for this work may lack the certificates of compliance needed when it is sold.

The Planning Portal says new windows that look similar to the old ones don't usually need planning permission. A new bay window counts as an extension. New upstairs windows in a side wall must be obscure glazed, and either fixed shut or more than 1.7 metres above the floor.

Listed buildings need consent, and an Article 4 direction from the council can remove the usual freedom to change windows. Leaseholders may need their landlord's permission first. Where aluminium frames will look quite different from the old ones, the local planning authority can say whether permission is needed. Planning policy in Wales may differ.

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