Double Glazing

The energy saving potential of double glazing is typically 5-10% of the heating costs of a property which is single glazed. This usually means that it is more cost effective to implement other measures, such as upgrading insulation, unless your windows need to be replaced.

Also local planning restrictions and listed building status can mean that any double glazing must have wood frames, which can increase costs still further.

However, if you are replacing your windows they now must be double glazed to meet current building regulations.  Funding is available for replacement or secondary glazing through the Green Deal and if you’re in receipt of benefits through ECO or NEST.

There are other benefits to double glazed windows, such as reduced condensation, reduced noise ingress and improved security.  If you do not want to replace all your windows it may be worth replacing windows in the rooms you heat most. Ask your window installer about the following options:

  • Fitting double glazing units in some existing timber windows.
  • Triple Glazing options and higher standard glazing (such as thicker units).

When replacement glazing is fitted, it is important that debris isn’t allowed to bridge any cavities, and that the windows are well sealed with no draughts coming through.

Secondary Glazing

If double glazing is not possible, you could consider secondary glazing. This can be done by fitting a second layer of glass inside your existing window. Whilst less convenient than new windows the costs are much lower.  Plastic film is also an option if fixed secondary glazing is too expensive.

System Shrink tight film with fixing tape Rigid clear plastic with magnetic or screw fixings Glass pane with wood or aluminium frame
Cost £2 – £4 per square metre £20 – £40 per square metre Over £300 per window
Issues Good for one season only Magnetic fixings can be removed and refitted more easily than screw fittings Most expensive alternative


For local joiners who can build secondary-glazed units in timber to match your requirements, try:

  • Tony Harris, Lower Down, Nr. Lydbury North        01588 680450
  • Peter Hockley, Wotherton, Chirbury                     01938 561346

Ensure while fitting secondary glazing that all windows are well sealed around the edges and well draught stripped.

The Clean Energy Centre, Newtown has several types of secondary glazing for you to view and try. Please phone Jeremy Thorp on 07722 722863.

For an aluminium sliding version see

For DIY options see:-