A large proportion of the heat lost from your home is through the windows; a study by Peterborough City Council suggested that it was as much as 18%. This could equate to a saving of about £130 on your annual heating bill if you were to fit double glazing!

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How it works?

All home lose heat through their windows, but double glazing reduces this by trapping a layer of insulating air between two pains of glass. The effects is that heat cannot pass through so easily and remains in your home. It has the same effect of noise too which is a useful side effect if you live near a noisy road.

There are various types of window to choose from, including triple glazed. There will be styles and frame materials to choose from, but should have most an energy efficiency rating to help guide your choice (although there is no obligation for manufacturers to do so currently). For a list of all windows and their frame material and energy rating, visit the BFRC website.

Secondary glazing is an option where you might not be able to or want to replace your windows. They are a pane of glass fitted inside the existing window frame, and are considerable cheaper, if less effective. They are ideal if you live in a conservation area or your building is listed prohibiting the use of replacement windows.


You will have to comply with building regulations if you are going to replace your windows. And if you live in a conservation areas there are further rules so you must check with your local planning office.

If you are planning to self fit you will need to apply for building control approval.

We will only recommend certified and accredited installers. Ensure that you ask you installer for a certificate to demonstrate compliance to all the relevant rule and regulations when the installation is complete.

Costs and Maintenance

Cost will vary significantly between the styles and materials that you can chose, but as glazing will last for at least 20 years it is well worth ensuring that you fit windows with a good energy saving rating.

You will need to clean your windows. Periodically the seals can fail in a pane – you will see condensation begin to form in the gap between the glass – and you will need to replace the pane. This can generally be done without replacing the frame.


Replacing your windows for double glazing can save you as much as £135 per year. If you were to use secondary glazing you could save £85 per year based on the Energy Saving Trust studies on an average sized 3 bedroom semi-detached home.

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There are other benefits to improving your glazing:

  • Reduced CO2 Emissions – by reducing the amount of energy that you need to heat your home you reduce the amount of carbon that you produce
  • Improved Comfort – by replacing your windows with air tight and sealed windows, draughts will be reduced making your home more comfortable and pleasant to stay in.
  • Noise – Double and triple glazing reduces the amount of noise that can enter your home – particularly useful if you live near a noisy road or airport.
  • Condensation reduction – As double glazed windows are better insulated they do not create large amounts of condensation on the inside of the glass.
  • Lower fuel costs – With less heat loss there is no need to burn so much fuel, thus saving you money!

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Can fitting double glazing cause condensation?
If there is not a sufficient level of background ventilation in the room, condensation can occur, but some replacement windows will have trickle vents incorporated into the frame that let in a small amount of controlled ventilation to stop this. Condensation can sometimes occur on the outside of new low-e glazing. This is because low-e glass reflects heat back into the home and as a result the outside pane remains cool and condensation can build up in cold weather - this isn't a problem. Low-e glass actually prevents condensation appearing on the inside of your window as it would if your double glazing featured standard glass, as in the inside pane is kept warm by its special coating.
Do replacement windows need to comply with building regulations?
Yes, except where there are restrictions that prevent you doing so, such as planning restrictions. Before you do any work, make sure you check with your local planning office, particularly if you live in a conservation area, have an Article 4 direction on your property or have a listed building.
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