How much does replacing double glazing windows realistically save?

drobe

If I replaced 2 wooden framed windows 8 feet by 6 feet and 5 windows 4 feet by 6 feet with a gap of 15mm between panes with 7 PVC windows with a gap of 22mm between panes and heat reducing/reflective glass and special gas, how much, in % terms, would the heat loss reduce with an indoor temp of 22 deg C and an outdoor temp of 0 deg C?


In other words, would I ever save enough in my gas usage to pay for new windows, considering I use about 14,000kW of gas per year for heating?


I also use about 3,000kW of gas per year for cooking and hot water and pilot lights but I don't expect that to reduce.

Smiley_Dan

You need to know the U values for the windows in question.

Depends on how much you want to invest, but you can also get wider gaps.

Also, consider how much energy is brought *into* the house through the window. This is where wood windows win, because you can have smaller frames and therefore more glass.

Clueless101

I very much doubt the windows would ever pay for themselves, but obviously it depends how much you pay for the new ones and how much it reduces the amount of gas you need for heating (this won't be a massive amount though). For example, our new windows and doors cost around £6000, but our gas bill was only about £600 a year - some of that is hot water and even if we could cut back by £200 a year (unlikely - we've had one winter with them so far and used £180 less than last year, but this will be mostly due to much milder weather) the windows/doors would take 30 years to pay for themselves, by which time they would probably be considered ready for replacement! We got new windows and doors because the old ones were single glazed, rotten timber with poor locks, so the benefits were aesthetics, less maintenance, security as well as making the house less drafty.

Cardew

The Energy Saving Trust has had a stab at estimating savings; see:


http://www.energysavingtrust.org.uk/Insulation/Windows


I think most people would be lucky to get a saving of £100pa and probably less if you use heavy curtains.


When I had my house built 26 years I did some research and specified the best(supposedly) DG on the market. Some of these windows started to blow after about 20 years and I have already spent several hundred pounds on replacement glazing, and have another few also needing replacement.


My pal had his fitted by one of the leading firms(if advertising expenditure defines 'leading'!!) and they all needed replacement at around the 10 year mark.

Smiley_Dan

Yes, and the other thing you need to remember about uPVC v wood is that there's a difference between maintenance and durability.

uPVC is lower maintenance, but they're less durable in the sense that once they go, they go and it becomes increasingly difficult to fix them.

Whereas with wood... plane a bit off (I simplify).

captainhindsight_2

It will take you a lifetime for any double glazing to pay for its self in savings in heating costs, so if that's the only reason your getting new windows don't!

There are other benefits, better sound proofing, draft proofing etc. Double glazing is more of a luxury comfort thing rather than saving you any significant amount of money.

If you looking to reduce your energy consumption, their are other cheaper and cost effective methods. Insulation, condensing boiler, Solar pV (not so cheap, but better than windows), etc...

These advert on tv for double glazing saying they will save you loads of money, are just a complete con IMO,

Robwiz

We replaced the original 1960s windows (double glazed downstairs and single upstairs) with aluminium/triple glazed. Our motivation was the hardwood frames were beginning to rot and the seal/varnish on them was blistering, looking unsightly and was almost impossible to strip off.

Replacement made a massive difference to the warmth and comfort of the house, which now retains heat much better with overnight temperatures not dropping below 16º C. With the outlay there was a big motivation to see savings on our heating bills – for us it was the missing piece in the insulation jigsaw helping us to get the benefit of our cavity wall and loft insulation.

Our central heating failed in February and we were able to keep the whole house warm using our 8 kW wood burning stove plus a small 500W electric skirting heater in the kitchen. We haven't used any heating since the end of March, and looking at the temperatures, we could probably have turned it off earlier.

Knowing what I know now, I should have bought the windows from a manufacturer and paid an independent fitter to install them. I would also have gone for wood instead of aluminium.