Is double glazing worth it?
The short answer
- about 56 years to pay back: around £4,800 for a semi, saving about £85 a year
- Lasts 20 to 35 years, so the energy saving alone never repays it
- Comfort, noise and condensation are the real reasons; about 6 EPC points in our model
Not for the energy bill. Replacing single glazing with A-rated double glazing in a semi costs around £4,800 and saves about £85 a year, according to the Energy Saving Trust: about 56 years to pay back, longer than the windows last. Comfort, noise, condensation and windows that need replacing anyway are the real reasons to buy it.
The energy payback
About 56 years on £4,800 saving £85 a year, longer than double glazing lasts.
| Price source | Cost | Saving a year | Payback |
|---|---|---|---|
| Energy Saving Trust, A-rated windows for a semi | £4,800 | £85 | about 56 years |
| Checkatrade, 3 bed house, low end | £8,000 | £85 | about 94 years |
| Checkatrade, 3 bed house, high end | £15,000 | £85 | about 176 years |
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On energy alone, no. Replacing all the single glazing in a semi with A-rated double glazing costs around £4,800 and saves about £85 a year, according to the Energy Saving Trust: about 56 years to pay back. The Trust says double glazing lasts 20 to 35 years, so the windows wear out before the saving repays them.
Costs from the Energy Saving Trust and Checkatrade's May 2026 guide, saving from the Energy Saving Trust for an entirely single glazed semi in Great Britain. The saving is for replacing single glazing; we have no sourced figure for replacing old double glazing.
The real reasons to buy it
Comfort, less noise and less condensation, or windows that need replacing anyway.
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The Energy Saving Trust names three benefits beyond the bill, and they are why most people buy new windows:
- Comfort: less heat lost through the glass, so fewer draughts and cold spots near the windows.
- Noise: double glazing insulates the home against outside noise, and triple glazing more so.
- Less condensation on the inside of the windows, which can lead to mould. Our condensation and mould guide covers the other causes.
Rotten or failing windows have to be replaced anyway. Then the question is not whether double glazing pays, but which windows to buy.
EPC points
About 6 points from single glazing, at about £800 a point, one of the dearest ways to gain them.
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Going from single to double glazing adds about 6 points in our EPC points model, at about £800 a point on the Trust's £4,800. That is one of the dearest ways to gain points: loft insulation, heating controls and LED lighting add points far more cheaply. Our guide to improving an EPC rating ranks every measure, and the EPC calculator finds the cheapest route for your home.
When double glazing is worth it
When the windows need replacing anyway, or for noise and comfort, not to cut the bill.
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It is worth it when the windows need replacing anyway, when the home is on a noisy road, when cold, draughty rooms are going unused, or when condensation on single glazing keeps coming back. It is not worth it as a way to cut the bill: insulation pays back much faster.
If the windows are sound but draughty, draught-proofing them costs far less, and secondary glazing keeps the originals.
Secondary glazing instead
Often cheaper, and it keeps the original windows.
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Secondary glazing adds a pane inside the existing window. The Energy Saving Trust says it can be cheaper than new windows, depending on the type, and suits homes with restrictions such as listed buildings. Permanent secondary glazing can be more energy efficient than replacing the windows. Our double glazing cost guide compares the options.
Planning rules
Similar looking replacements need no planning permission; listed buildings need consent.
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Replacement windows that look similar to the existing ones on a house do not need planning permission: they are permitted development, according to the Planning Portal. A listed building needs listed building consent for significant work, and a conservation area or an Article 4 Direction can add restrictions, so ask the council's conservation officer first. The Energy Saving Trust notes that double glazing can be made to look like a building's original windows, and reversible secondary glazing does not usually need listed building consent.
Frequently asked questions
Is double glazing worth it for the energy saving?
Not on its own. Around £4,800 for a semi, saving about £85 a year, is about 56 years to pay back, longer than the 20 to 35 years double glazing lasts.
What are the benefits of double glazing?
Comfort, with fewer draughts and cold spots, less outside noise and less condensation on the inside of the windows, according to the Energy Saving Trust, as well as a smaller energy bill.
Does double glazing improve an EPC rating?
Yes, by about 6 points from single glazing in our EPC points model, but at about £800 a point it is one of the dearest ways to gain points.
Is secondary glazing a good alternative?
Yes, especially for listed buildings and conservation areas: it keeps the original windows and can be cheaper, depending on the type.
How long does double glazing last?
20 to 35 years if it is good quality, well installed and maintained, according to the Energy Saving Trust, and it can last longer.
Data sources
The Energy Saving Trust and Checkatrade for costs and savings, the Planning Portal for the rules.
Show every source
- Energy Saving Trust, Energy efficient windows and doors (last updated 20 May 2026): £4,800 for a set of A-rated windows for a semi-detached house, £85 a year saved replacing single glazing, triple glazing around 20% dearer, a life of 20 to 35 years. Checked 5 October 2026.
- Checkatrade, Double glazing cost (updated May 2026): ballpark prices per double glazed window and for a 3 bed house, checked 5 October 2026.
- Planning Portal, Doors and windows: planning permission, checked 5 October 2026.
- Heat pump cost from our heat model, js/heat-model.js: the median installed price under the Boiler Upgrade Scheme for a heat pump of the size the home needs (DESNZ statistics, August 2026). EPC points from our EPC calculator model.