New Double Glazing, Energy Saved?

jelliot

If I replace my 30 year old 12mm gap wooden double glazing windows with 20mm gap Upvc windows with energy efficient glass how much energy could I save and would it even be noticeable?

Though there is nothing wrong with the old windows other than they need painting.

Ebe_Scrooge

You'd save 73.649 KWh per year.

Seriously, it depends on a lot of factors, not least the size of your house and the number of windows. You would save some energy, but it's going to be a tiny amount if, as you say, the existing windows are basically sound. Certainly not enough to offset the cost of replacing them. Even replacing knackered old single-glazed windows with shiny new double-glazing takes many years to pay for itself, so your payback period would be several decades.

If you want to replace them because they'll look better, or the old ones are starting to deteriorate, then that's a different matter. But doing it purely in the hope of saving money is not worth it.

FreeBear

jelliot wrote: »

If I replace my 30 year old 12mm gap wooden double glazing windows with 20mm gap Upvc windows with energy efficient glass how much energy could I save and would it even be noticeable?

Replacing some of my 40+ year old DG windows this month - These will be 28mm sealed units, which I believe are the current standard. The return on investment (i.e. the amount I will save on energy compared to the cost) is going to be negligible. But as the frames are starting to rot, hinges failing, and units misting up, I figure it is worth doing.

phill99

If you are looking for a payback calculation, based on energy savings alone, you will be very disappointed. It will be in the many multiples of 10 years, even maybe a hundred years. However, when you take into account the reduced maintenance costs etc, it will be a shorter payback.


Windows, as they don't take up a lot of wall space, don't have a major impact on energy savings. It is roof and wall insulation where you see the big savings.

ashe

The above is all true, but factor in that soon seals are likely to start going plus the visual factor of new windows. Once they start to fail you would probably notice it more, but its not going to reduce your gas bill by £20 a month.