Help needed with u values and double glazing quote calculations

lardconcepts

Living off the mains gas grid, heating with LPG is expensive. Twice the price, if I've read this table correctly: http://www.nottenergy.com/energy-costs-comparison3

We've done all we can with insulation, but the current double glazing on the windows is old and incredibly thin (4mm or something).Last winter, the snow remained on the roof all the way through until the melt, but the velux windows were melted off in about an hour!

We had a quote from a local manufacturer, and actually, it's not as bad as I thought it would be.
This is for replacing the glass into the current, sound, traditionally shaped wood frames, including curves at the tops (so glass needs to be shaped)
I've turned his paper quote and u-values into a spreadsheet for my own info - does all this look right?

https://spreadsheets.google.com/ccc?key=0AmkhuHmI5mk1dF9WLU5IbkJHNjVGTXhMOXI0b3JWZXc&authkey=CIzSz7wL&hl=en_GB

In particular, note the decreases in u-values regarding the filler gas vs the increase in price. Is it actually worth going for Krypton?

We're hoping to get a fair bit of passive solar gain through the south facing patio doors and windows.

The company come well recommended locally and by neighbours, and to be honest, the bloke doing the quote was so pleasant and un-pushy, if you think this looks fair I don't think I'll even bother with a second quote.
The last time I got a glazing quote at my old house, it was a thoroughly unpleasant and pushy experience and came to a stupidly high price so I didn't bother.

Anyway, whaddya reckon? Do my sums make sense? Googling around here and elsewhere seems to show that having a gas fill is definitely noticeably worth it, but would you bother with the krypton?

Thank you.

sashman

check out http://www.ggf.org.uk/energy-savings-calculator

C rated is the new minimum A and B are better performers, some need aron or krypton to get the rating

http://www.doubleglazingcompanies.com/knowledge/product-accreditations/WER/?3 explains more about window energy ratings

sashman

lardconcepts

Thanks, Sashman.

Since making the first post, I found a couple of things out, the first of which has made me have a major rethink about the whole thing. The guarantee on the sealed units, ie, the double glazing that goes inside my frames, is 1 year. Which is about 9 years less than I was expecting! I'll probably get the worst two units done.

Also, I asked about Kyrpton vs Argon, and also Planitherm, which was mentioned but not quoted for. When I googled it, it seems that Planitherm is actually better than Pikington K.

The reply from the company is:

"The thing to remember is Krypton is more efficient the narrower the airspace where as argon works the opposite way. We can do planitherm which is the same price".

So should I forget about the Pilkington and go for the Planitherm?

One thing I maybe should mention is that it gets cold where we are in Wales. Very, very cold. Like, -16c last winter. And for 3 days running, the accurate, well-placed outdoor thermometer never registered a daytime high of less than -6c for 3 days running.

So every therm/Kw counts!

Incidentally, for anyone interested, here are a couple of pics:

Here's how thin the patio door currently is: http://goo.gl/7nTK6

And here's how foggy the fogged up old glazing with 5mm gaps which makes up most of the rest of the windows are. http://goo.gl/PKh9R

sashman

Dont over complicate it!

Why does it matter to you if its krypton, argon or air (other than it is what it claims it is and that you have got what you have paid for). Why does soft coat or hard coat glass, pilks, guardian or st gobain matter? An A rated window will perform better than a C rated. Thats it, if heat loss/retaintion matters, buy a rated product, then make sure it blends into your home, is secure, and that you have the additional backing of the GGF protection or DGcos etc

If you really want to get detailed then the energy performance number (14 in this case, bottom right of the bfrc certificates) http://www.doubleglazingcompanies.com/knowledge/product-accreditations/WER/?3 tells you the number of units the window will lose in a year, if the number is + (A rated) it means the windows will gain more energy than it loses over the course of the year.

As for 1,5,10 yr guarantees. I know Anglian and Everest get bad reviews but to their credit they do offer lifetime guarantees and been known to honour sealed units 25 years later! most offer 5 to 10 years but units dont perform well if they sit in water. If a PVC window does not have adequate drainage or if a timber window is putty glazed the sealed units tend to blow within 5 years.

I installed Maghogany PVC windows in my parents home in '86 two have blown but the remainder are as perfect as the day they were fitted. They were excellent windows made correctly (i knew how they should be made and they were) unfortunately the company I bought them from failed 3 years after I fitted them!

sashman

lardconcepts

sashman wrote: »

Dont over complicate it!

Why does it matter to you if its krypton, argon or air (other than it is what it claims it is and that you have got what you have paid for). Why does soft coat or hard coat glass, pilks, guardian or st gobain matter?

Because I have a certain budget, the current frames have a limited rebate to put the new glass into, and I want to focus the maximum energy saving onto one particular room. When getting DG custom made to put into current frames, I was told that a certain "rating" couldn't be guaranteed, so how can I go for a rating? Sure, if I have £10,000 floating around, I'd have brand new everything to the highest rating possible, but I don't, and there's other things that need doing, too.
Gotta balance the finance with the savings/comfort!

docmatt

Lard what size sealed unit can you fit in the framework? Have you done other stuff you can do to your home like loft insulation and cavity wall? (providing there is a cavity). Cheers.

By the way i know a cheap glass manufacturer in Birmingham, even though you miles away may be woth the drive if u save a few quid.

lardconcepts

docmatt wrote: »

Lard what size sealed unit can you fit in the framework? Have you done other stuff you can do to your home like loft insulation and cavity wall? (providing there is a cavity). Cheers.

Loft insulation: loft is a tiny triangle at the top of an overshot roof!
Roof: Re-done at great expense with the thickets kingspan you can get - really good, snow stayed on all winter, where it had melted off within a day before.
Walls - previous owner said they were told they were already done.
Might be worth me drilling a hole and having a look though...

docmatt wrote: »

By the way i know a cheap glass manufacturer in Birmingham, even though you miles away may be woth the drive if u save a few quid.

Do you want to PM me the details? (I'll PM you anyway).
Thanks!

missprice

i just earlier this year had some triple glazing done and the price difference was not worth arguing about
for 8 windows to be double glazed some are really large others tiny (odd little house) was iirc £3800
for the same 8 windows to be triple glazed was £4000

so if your just doing one or two windows i think the cost may be worth looking into

am so dim sometimes
guarantee is 20 years (although how long the company is around if diff thing)
argon filled (i think maybe a different gas)
aluminium clad
u value of less than 1 cant remember if 0.9 or 0.8

they aint that wide and they well fitted and i do so love them
and i will so love next wintewrs gas bill

sashman

lardconcepts wrote: »

Because I have a certain budget, the current frames have a limited rebate to put the new glass into, and I want to focus the maximum energy saving onto one particular room. When getting DG custom made to put into current frames, I was told that a certain "rating" couldn't be guaranteed, so how can I go for a rating? Sure, if I have £10,000 floating around, I'd have brand new everything to the highest rating possible, but I don't, and there's other things that need doing, too.
Gotta balance the finance with the savings/comfort!

You won't get a rating by just changing the glass. WERs window energy ratings, are ratings on the whole window. You may have great sealed units but if the frames are steel they will lose heat badly, alternatively modern frames have extra insulation added to them to make them the highest rating possible.

Don't think you need fensa certificate because it's reglazing or repair not replacements.

Sashman