heating bill

[normanwisdom]

What is a typical average home heating cost and what is a typical saving by DG installation? I googled this but there is loads of misinformation from DG companies.

cheers Norman

[Andrew Gabriel]

Double glazing is usually the longest payback of just about any insulation improvement measures you might take, and in many cases it will never payback. Without giving a lot more information about the age, construction, size and insulation in your home as it currently stands, this is just impossible to even guess.

[Handy]

Double Glazing (Low-E Glazing is best) - COST: Around > £3,000 - SAVING: Around £20 - £35 Source:

takes years to recoup the cost of installation of DG. But less heat lost is only one of several benefits.

[Brian Sharrock]

Without challenging any of Andrew's observations regarding 'pay-back'; double-glazing _does_ improve the 'comfort' feeling of any room into which it's installed. Typically one 'finds' square-metres of rooms that previously were draft/cold/uncomfortable habitable. . What vale you personally place on this comfort is your affair.

[Jeff Mowatt]

Now I'd like to replace the glazing in my house built around 1860 with double glazed wooden panes, though these have multiple panes, thin side panels with small corner panes.

I'm told by the would-be maker that 25mm spaced glazing panes are incompatible though he could glue the appropriate moulding on to a single pane and had been persuaded to by another customer in the past.

I know there are firms promoting these window styles as replacements Would anyone know if this glue-on approach is considered satisfactory?

Jeff

Handy wrote:

[The Natural Philosopher]

somewhere between £200 and £2000 per annum.

not nearly as much as you might suppose.

If you have fairly small draught free wooden windows, its not worth doing.

If you have rotten, old and draughty ones,huge picture windows, or those dreadful Crittal steel things that invite condensation, bin them ;-)

In general the most cost benefit is draught proofing doors and windows and old suspended wooden floors.

Then do roof insulation, because its really cheap and its a major heat loss on older houses.

After that, cavity wall insulation nets you more than windows, unless your rooms are mainly windows. Its probably similar in price too.

Floor insulation comes next, but its expensive and not the worst cause of heat loss..suspended floor are though. They are well worth insulating.

Then if uoi have an old boiler, get a better one..a 10% risee in efficiency can be a 10% or more fuel reduction.

Whats left to do? Oh. Double glazing. Nah. Thick lined curtains is better and more attractive.

[normanwisdom]

Sounds like the original windows are well worth keeping - possibly a disaster to spoil them. Stick on bits etc is totally crap bodge don't do it. If you want to save money take another look at Handy's link

[The Natural Philosopher]

The biggest benefit is usually in case where the original winbodws are

- draughty

- Critall steel

- Really large

My mothers 1953 house had all three, and it benefitted from DG units enormously.

Conversely I have fitted SG lead lights to this new house, and the windows are small, draught free, and oak framed, and were good enough with extra insulation elsewhere, to get past the building regs 2000..

Fitted with thick lined curtains, I have 8 " of air insulation now behind the curtains..just as good as DG with the curtains closed..

[The Natural Philosopher]

Yes, there is a problem with DG and small panes, in that the edges of DG panes have to be a certain side, and you need fairly chunky frames to hide them.

I had the same probs with my leaded lights - the 'glazing' bars' looked fake and naff, so I went single glazed instead.

You are allowed to replace like with like, or slightly better, so I'd get some more draughtproof single glazed ones..if the BCO gets stroppy install demountable secondary glazing, and remove it when he has gone.

I'd simply get a joiner to make up replicas of what you have, in a decent wood..Iroco is nice, stable and not too expensive, and if you don't like the red color, paint it.

[Ian Stirling]

Indeed. My current windows (13 of, overall area of 15m^2) lose about 700w at an average of 10C delta.

At best, double glazing might take this to 200W, for a total of maybe

500W of energy saving.

This is perhaps 5000Kwh/year. Or at 4p/Kwh, 200 quid or so a year. Going to take a long time to pay back several thousand pounds.

[Dave Plowman (News)]

It depends on what type of double glazing. New windows with double glazing might never recoup their cost. Secondary glazing might quite quickly.

[Weatherlawyer]

If the present windows are in good condition there is little need to replace them to get double glazing. Just pop down to a glazier that makes DG units and ask how much rebated panels would cost.

You will need to take care with opening lights as the weight in the sashes will double, triple if you have older, thin glass (unlikely but possible. In the good old days 3 mm -or rather its imperial equivalent, was used mostly characterised by poor clarity as it might predate float glass.)

You can get around this with an extra hinge and by ensuring a couple of packers give the pane a diagonal bearing that transmits the weight from the top outside corner to the bottom inside one.

Stepping the glass allows the inside section to rest on top of the frame's profile. In other words the outer glass panel will sit in the rebate and the inner will come into the room by the thickness of the inner glass panel and the gap in the unit.

Prices for DG glass panes are typically =A350 to =A3100 each depending on the size of the pane and the thickness of the gap in them.

[Ian Stirling]

Very true.

I'm considering doing either:

A) Secondary glazing of 2mm polystyrene with slow air feed of dry air from an aquarium pump mounted outside, to avoid condensation.

B) Making up new window 'tops' - with better sealing to the bases, and putting in completely new units.

C) Obtaining 3 or 4 8*4 sheets of glass, and making up my own sealed units. (or mostly so, with the aid of the aquarium pump)

The existing wooden windows are _mostly_ in good condition, and those that are not, I imagine I could without too much difficulty replace - the section is not that complex.

D - splash out thousands on new windows simply isn't on the cards.

[normanwisdom]

I was asking for "typical average" figures. It seems that =A3500 pa for heating and =A325pa for saving by DG would be about right. There was an oft-quoted rule of thumb that window lost 10% and DG halved that. Interestingly although the % loss would be higher for a well insulated house the actual heat lost would be the same AOTBE i.e. a bigger cut of a smaller bill, and the value of DG still dubious.

cheers Norman

[David Hansen]

On 23 Nov 2006 06:46:03 -0800 someone who may be "normanwisdom" wrote this:-

Like many things, it depends on what someone wants to do. If they want to look at in terms of simple payback period then double glazing is usually not a good investment. However, there are many other reasons for doing something.

[Dave Plowman (News)]

If it were 25 gbp pa then there would be tiny if any saving after loss of interest on the capital was taken into account - even less if finance was involved.

I dislike rule of thumb quotes for this sort of thing - many take them as gospel.

[Tony Bryer]

I did a quick 'what if' on our SuperHeat program and it suggests that changing single glazed windows to low-E double glazed (U-value

2.1) will save about £2/m2/yr. That's on a SAP-2005 standardised fuel price of 1.63p per kW so you would need to multiply this by the current cost of the energy used.

[Andrew Gabriel]

20 years ago, I bought a packet of sellotape secondary glazing film. It was the type that you stick to the frame with double sided tape, and then shrink with a hair drier to form a tight almost invisible film. I did a few windows with it, and it lasted a couple of years, usually until someone/something poked a hole in it or tore it. However, I still have one piece left after 20 years, on the window above the front door, where it's out of harm's way. It's still as good as the day it was fitted. As someone pointed out when I mentioned this here a while back, that's longer than some real double glazing lasts.

[The Natural Philosopher]

E - spend a very little money on very good quality draughtproof strips and spend rather a lot more on lined, and INTERLINED curtains. They look better than secondary glazing - and indeed double glazing IMHO and if they are thick, heavy and extend a fair bit below the sill, will trap a lovely insulating wedge of air behind them.

They WILL lead to a bit of condensation on cold days tho..the windows themselves will be a tad colder.

I haven't data to back it up, but I reckon they are as good as triple glazed units..SG with thick curtains.

[Dave Liquorice]

Agreed, people these days don't appreciate that decent curtains can make a considerable difference to the heat lost through a window when they are drawn closed.

Two pairs is even better. May only be practical if you have deep reveals though. One thick lined pair close to the actual window and a second pair possibly over the entire reveal opening.

I think that would be pushing it a little bit but certainly on a par with double glazing, *provided* that the SG is well draft proofed.