Windows are a suitable case for treatment on which you can spend a little or a lot. There are also solutions for listed or conservation areas. You can make considerable gains by installing good windows, though it can be expensive.


The starting point is how much heat you may be losing from what you currently have. Some estimate that 18% of heat will be lost from windows, but of course it all depends! If you have solid walls you will be losing heat at the rate of 2.2 (this is a U value and is measured in watts per sq metre per degree of heat difference over the wall or window – the lower the better). It may be that you cannot do much about your walls, but you can address your windows. Single glazed windows will be losing heat at 4.8 (U value), i.e. you are losing more heat through your windows but they occupy less of the external wall. Curtains could take this down to 3.6 (U value), secondary glazing to around 3 (U value); basic double glazing to 2 (U value), which is better than the walls; and triple glazing to 0.6 (U value)! Each of these steps adds cost.

Geek says

  • If you are in doubt about your windows you could get a thermal image which often shows how good or bad they are. LCON and other CAGS often arrange for a camera team to be available during the winter.
  • Don’t forget the value of “old fashioned” solutions such as installing good curtains or blinds.
  • Make changes when you are doing other building work: it makes the pain easier to bear!
  • Finally, don’t be fooled by your builder or architect: the standard to match is now triple glazed reaching U values well below 1 (watts per m 2 per oC).

Local experiences

One of the draught-proofing products Brenda Boardman particularly likes is V-seal from Stormguard. This is available from at least some of the local hardware chains, for wooden and metal hinged doors and windows. Only one half of one-side of the V is adhesive and this is stuck to the frame, so the V faces to the outside. When the wind blows the V is forced open and becomes more effective. It is reasonably durable.

Judith needed to get her single PVC glazing replaced with double glazing to get maximum benefit from further energy saving initiatives. She used Oxford Double Glazing (now reverted to their original name of Jack Brunsden) and was pleased with the results. They do a range of products – she had PVC, but timber frames were also available. She particularly liked the fact that they employed direct labour – so proper employees rather than self-employed operatives. She felt that the workmen took their time and get the job done really well rather than having to make their money by rushing off to the next job.


Useful links

Thermal imaging of windows

2 thoughts on “Windows

  1. Thanks so much – we’re currently making a decision about replacing our current single glazed, plus secondary glazed windows in a Victorian semi with no possibility of being able to insulate the walls in or out. I have two quotes in front of me and have been able, thanks to you to make a decision on what’s worth doing and which company is offering best value. Hurray. Will get back to you when we’ve had the work done – but our choice is a local builder with great skills so we are hopeful of a good outcome.

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