Green Building Forum - Triple glazed windows

Triple glazed windows

Arnold — Fri, 07 Nov 2008 07:33:29 +0000

this is most interesting i had 6 windows & a door from Fibertec (Canadian co) 5 yrs ago they were supposed to have a U value of 0.8!

were 2G argon filled with (kglass type) coating can't remember actual spec. at moment and don't know where paperwork is.

the knowledge-able people on the forum reckoned they could not be that good.

I am very pleased with there thermal Qualities they were insulated inside the frame which are made from Fiberglas.
The door frame had a wood liner to go up to brickwork. to allow for cock-ups?

However they are excellent with noise we have had a brick crusher out side hardly heard it, got more noise in house from a Velux in bathroom

every body else who lives here were complaining about the noise they have plastic 2G windows

My windows cost Â£5000 which included transport tax and ?????

It cost me in all Â£1000 to have them fitted but that included a bricky who spent 5 days on site. modifying kitchen.

I'm in Chester. uk

Does fibertec still exist I sent them e mail recently yet to get a reply

Arnold

Triple glazed windows

Stephen T — Sat, 08 Nov 2008 17:23:24 +0000

As proud as i might be of Canadian buidling products, as far as i know, the laws of physics are basically the same here as they are in the UK.

So, depending on the type of low-e in Arnold's windows the casements, would have a Uwindow,americas of either 1.65 or 1.54 W/m^2K . (This is based on a window size of 600x1500mm, North American temperature differences, 90% argon gas fill and Edgetech's SuperSpacer). So my guess at Uwindow,european would be no lower than 1.4 W/m^2K . In fact, the suppliers website suggests their best 2G casement is Uwindow,americas 1.6 W/m^2K

So i agree with the knowledgwable people on the forum, a 2G window with U 0.8 is unlikely, to say the least (at least until vacuum glazing is commercialized and maybe not even then)

As far as sound attenuation goes, i am at least equally skeptical. Canadian windows are typically 3mm glass. Only switching to 4mm glass when glass areas exceed 1.5m^2. (some USA windows start at 2.5mm!) Whereas UK windows start at 4mm. Thicker glass attenuates sound better than thinner glass. I work for a company that also makes a GRP window with polystyrene insulation in the frame, and i've not seen any independant reports that would lead us to believe that we offer superior sound attenuation to our PVC framed competition.

On the other hand my skepticism may be misplaced. As compelling as anecdotal evidence maybe, i need to see independantly measured data to be convinced that Canadian style insulated GRP window frames offer better sound attenuation than their UK PVC counterparts.

By the way, all of our in-house calculations show that the effect of filling otherwise hollow frames with polystyrene insulation, makes very little difference to Uwindow of a 2G window. However, in a 3G window the effect of filling otherwise hollow frames with polystyrene insulation, does make a difference to Uwindow.

Triple glazed windows

fostertom — Sat, 08 Nov 2008 18:04:53 +0000

Stephen T, what do you think of

Posted By: fostertomRadiant transfer is proportional to the difference between two fourth powers, not the the fourth power of the difference. And over the narrow operating band say 253K to 313K, that works out close enough to proportional to the first power of the difference, just like conduction and convection.

So the U value difference you're finding must be due to something else - any ideas?

Triple glazed windows

Stephen T — Wed, 12 Nov 2008 03:08:51 +0000

Stephen T, what do you think of
Posted By: fostertom
Radiant transfer is proportional to the difference between two fourth powers, not the the fourth power of the difference. And over the narrow operating band say 253K to 313K, that works out close enough to proportional to the first power of the difference, just like conduction and convection.

So the U value difference you're finding must be due to something else - any ideas?

Went back and checked my textbooks and i think you are correct, its not radiation between the panes that accounts for the difference.
So i think the next most likely culprit is the roomside convection co-efficient
I'll try to track down some people more on top of this topic.....

Triple glazed windows

fostertom — Wed, 12 Nov 2008 08:58:58 +0000

Thanks Stephen T. This was the same mistake made by people 'proving' why multifoil insulation couldn't work, on this forum

Posted By: Stephen Tnext most likely culprit is the roomside convection co-efficient

or the size assumed for the 'typical' window?

Triple glazed windows

Stephen T — Thu, 08 Jan 2009 15:01:18 +0000

Re: differences in Uwindow,european and Uwindow,americas

Looks like i was not only wrong about the difference being do radiation heat transfer, but also about the roomside convection coefficient. yikes.

After some discussions w/ more knowledgable people it seems that the roughly 10% difference in U is due to the difference in outside air temperature used to calculate Uglass. In North America we use -18C, i believe Europeans use ?0C?

It was explained to me that this means the temperature of the gases between the panes of glass are different in the each of the two approaches. Different interspace temperatures mean the gases have slightly different thermal properties. This means there are differences in the amount of heat transfer across the interspace by convection and conduction. And apparently this is enough to create the difference....

There can of course be differences in Uwindow, due to size differences. This is particularly true of windows where the glass insulaltes significantly better than the frame.

hope this helps

Triple glazed windows

fostertom — Wed, 21 Jan 2009 19:49:20 +0000

Time for another 3G price/availability survey. Meanwhile, I'd like advice ...

On p3 of this thread, 21 Dec 07 I published 3 best quotes received - Â£300-330/m2 delivered (which seemed remarkably gd value) - for pine Scandinavian-style 3G windows, 4-12-4-12-4 - Uw (whole-window U-value) typically 1.0 to 1.1 - so these were not the new breed of Passivhaus-grade super-3Gs.

15mths on (from quote invite time) the game's moved on and we're now looking at
a) those PH-grade pine 3Gs (a far bigger selection of them now available, than were for the 'old' 3Gs); also possibly
b) alu-wood ditto i.e. pine frame as before but all external surfaces formed of aluminium extrusions.

Can anyone suggest %age price-level difference, for each of a) and b), compared with the 'old' 3Gs? Note that Â£300-330/m2 was probably a low base for comparison - Â£375/m2 might have been more generally available; plus there may have been price cuts since then - or maybe not, as they say materials continue to rise while labour falls.

Triple glazed windows

Monty Gerhardy — Sat, 24 Jan 2009 21:09:34 +0000

Posted By: fostertomTime for another 3G price/availability survey. Meanwhile, I'd like advice ...

I think it would be helpful to set a specification as there are huge variations in triple-glazed windows. To be more exact there are significant variations in the properties of both the glazing units and the framing materials.

As an example in order to get a window beneath the 0.8 PH benchmark many people, Rationel for example, are supplying glazing units with a 0.4 W/m/k u-value. What they negelect to mention is that such a unit will typically also have a low g value and relatively lowish light transmission. Another very significant issue with such glazing will be external condensation. It is a problem with glazing units at 1.2 and it is going to become even more prevalent with glazing units at 0.4

Another question that should be asked is why go to triple-glazing. What u-value are looking at and what sort of solar factor? On another thread I saw a reference to a Nordan window with a u-value of 1.2 for a double-glazed window. I spoke with one of their reps before Christmas and he told me that they could probably go even lower then that if the customer was prepared to pay extra for krypton and take a hit on the g-value and light transmission with coatings on both panes.

If you tell me what performance level are you looking to acheive I might be able to help with a specification ?

Monty

Triple glazed windows

fostertom — Sat, 24 Jan 2009 21:33:49 +0000

'PH-grade' does describe it - the Uw (whole window) benchmark (.8 or .9. I forget) that manufacturers need to hit, to compete in the new Passivhaus market. They will do it different ways, some having high-insulative frames, others relying on extreme Ug (centre-pane), with attendant low-g (light and solar gain transmission) disadvantage.

Triple glazed windows

richy — Sat, 24 Jan 2009 22:24:39 +0000

You draw it we'll make it! Seriously I think someone with the knowledge should tell a small time joinery manufacturer like me how to build a window! We are pre programed by tradition into making more of the same. Re-program me!

Triple glazed windows

johnz — Sun, 25 Jan 2009 08:52:36 +0000

I was wondering what peoples thoughts were regarding a couple of related points.

Given Fostertoms, building regs/glazing situation (which highlights something we find alot as equally keen glass fans) and which shows that even with relatively underperforming glazing elements, shortfalls can be made up elsewhere, and given the increasing complexity, and financial/manufacturing energy cost, of glazing units (be they 2G, 3G, krypton, Argon, vacuum etc) What do people think of the potentially short lifespan of the intricate units before inevitiable breakdown and the subsequent need to basically 'start again'? Does not this call for a high quality, but simplified, approach such as 2 or 3 x 1G? Where is the energy pay off in the wider scale regardless of the 'efficiency' of individual house windows?

Triple glazed windows

fostertom — Wed, 28 Jan 2009 09:39:59 +0000

johnz, don't you think that quality 3G units properly installed shd last a gd long time? Just because the typical UK cheaply-fa'bd 2G unit bedded in mastic has limited/unknown life.

Another question is how long the gas filling stays in even the best of units - no one seems to know. Seems to me we can rely on multiple panes and their coatings, but only regard gas fillings as an initial performance bonu, if dead cheap, that may not last forever.

Doing it as 2x or 3x 1G - hard to imagine how that could be developed to be as cheap as 3G, reliable and not requiring constant condensation-wiping. Any ideas?

Posted By: johnzFostertoms, building regs/glazing situation .... which shows that even with relatively underperforming glazing elements, shortfalls can be made up elsewhere

I'd say, in this more highly glazed case, glass performance is more important than wall/roof - makes the biggest difference to overall loss. It's cheap and easy to get to BldgRegs wall/roof min standard, and progressively harder to do significantly better. But BldgRegs window min standard is so very low, that it's cheap and easy to do twice as well, which has a big impact on overall loss, even tho of smaller area than the walls/roof.

Triple glazed windows

fostertom — Wed, 28 Jan 2009 10:07:06 +0000

About to go for another round of window quotes, and would appreciate any more suggestions.

I have a long list of suppliers, prev unknown to me, that have been suggested on this forum - thanks - any last minute additions?

Any guideline %age comparisons between
a) all-solid-wood Scandinavian-style 3G apx 1.0 Uw, as I previously reported @ Â£300-330/m2 delivered on this thread p3 21 Dec 07
b) ditto but aluminium faced externally
c) as above but Passivhaus-grade 0.8 Uw

Triple glazed windows

Peter Clark — Wed, 28 Jan 2009 10:21:15 +0000

Are you including some local wood working businesses?

That would be greener than importing, or can they not compete in this market?

Triple glazed windows

fostertom — Wed, 28 Jan 2009 11:02:43 +0000

I doubt it - these are really technological, developed products, the quality/lamination of the timber, the complicated machined profiles, the seals, the hardware, everything. Hard to just copy. Also the glass - hi tech glass seems so very much cheaper in Europe. Of course, current exchange rate doesn't help.

I think it's a case of petrochemicals well spent, shipping such things in from efficient factories, if their use (because so effective) can save umpteen times more petrochemicals over their lifetime. Also, is it better to transport bulk timber from Estonia to UK, and machine it away to waste here; or to do the wastage near to the forest, and only ship the finished product to UK?

Triple glazed windows

Jo — Tue, 03 Feb 2009 17:12:43 +0000

Hi .. I'm new to the forum and fairly new to the whole issue of energy efficiency in construction .. but I've been reading and am learning fast. What brings me here is a building project due to start in a couple of months .. a garden room/entrance/WCcloakroom extension (5m x 6m single storey) which faces north-east and has mucho glass. I've really had to work on all the energy factors as I want to use the room all year round, and it will join our kitchen via a wide linking space (ie it won't be considered a conservatory for B regs). I have been working with an energy consultant and we now have the building better than B Regs. BUT, this relies on me being able to source windows with U-values of around PH levels. (I am not at all concerned with solar gain - there won't be any.) I want windows which will hang on to whatever heat we put in there - which will be via UFH wet system. So .. all you people who've been thinking about this and researching for years .. I've read your info from a year or so back .. where should I be directing my attention for prices now? I'd really value up-to-date advice.

Triple glazed windows

ralphd — Wed, 04 Feb 2009 15:09:57 +0000

Posted By: Stephen T
By the way, all of our in-house calculations show that the effect of filling otherwise hollow frames with polystyrene insulation, makes very little difference to Uwindow of a 2G window. However, in a 3G window the effect of filling otherwise hollow frames with polystyrene insulation, does make a difference to Uwindow.

Hi Stephen,

Good to see you still commenting online.

I have hollow PVC framed windows, double-glazed lowE, argon fill & superspacer. I found at cold temps (<10C outside) I was getting condensation not only at the sightline but on the sash & frame too. I used some foam in a can to fill the cavities & fixed the problem. I still have a problem with my casements as I can't foam fill the cavity where the rod for the cam locks goes.

If I could do it again I'd go for foam-filled fiberglass frames at a premium of up to 5% vs hollow PVC. Besides the better insulating qualities I believe the fiberglass frames are more rigid which helps with compression seals in an operable unit.

Triple glazed windows

Jo — Thu, 05 Feb 2009 09:30:33 +0000

Hello again ..

Another issue re my NE facing extension and 3G windows - 3 of which are floor to ceiling jobs. I'm debating what to go for re the glass - ie whether toughened or laminated.

We live in a fairly isolated position so security is an issue .. laminated is reckoned to be better from the security angle. But .. toughened is, well, tougher, and we have a lot of grass (quite rough) alongside two of the windows. One firm told me that stones flying from mowers accounts for a fair amount of their business in spring when the mowing season gets going. I'm inclined to go for toughened on the basis that 3G windows are more difficult to break through anyway (ie without worrying too much about the glass). What say you?

Also .. given that solar gain isn't going to be either an advantage or disadvantage .. what arrangement of glass and coatings do you think would be best? I've asked companies about this but got some confusing (or confused) responses. I'm not sure whether they're trying to sell their pet products and/or think that being female I won't understand anyway (I do get this sometimes). So - what glass/coatings arrangement do you think would best suit my situation?

Triple glazed windows

Peter Clark — Thu, 05 Feb 2009 09:58:08 +0000

Posted By: ralphdI used some foam in a can to fill the cavities & fixed the problem.

Hi Ralph,

You mean you filled the cavities in the PVC frames?

It has crossed my mind to try this with our aluminium frames, but I dismissed it as a mad idea. Can you say how you did this? Were the frames in place in the building?

Peter

Triple glazed windows

rogerwhit — Thu, 05 Feb 2009 09:58:39 +0000

Jo, what is the glass rebate depth of the window frames??

Triple glazed windows

howdytom — Thu, 05 Feb 2009 10:07:25 +0000

Peter,
if your alloy frames are a one piece extrusion, ie no thermal break,

then the alloy will still conduct the heat around any infill insulation.

you could drill 6mm holes then after foaming fit grommets

Tom

Triple glazed windows

Peter Clark — Thu, 05 Feb 2009 10:18:23 +0000

Posted By: howdytomif your alloy frames are a one piece extrusion, ie no thermal break,

then the alloy will still conduct the heat around any infill insulation.

you could drill 6mm holes then after foaming fit grommets

Thanks Tom,
The frames have a thermal break in, i believe, so maybe filling with something insulating would not be possible, or useful?
I am having trouble visualising it, I have never seen a window frame other than installed into a wall, so i don't understand how they are constructed.

peter

Triple glazed windows

Jo — Thu, 05 Feb 2009 10:31:12 +0000

Hiya Rogerwhit

The (3) companies I've got quotes from so far don't say, however, they are each quoting for 4-16-4-16 (argon filled) .. does this answer the question?

Jo

Triple glazed windows

Jo — Thu, 05 Feb 2009 10:37:24 +0000

Roger .. I meant 4-16-4-16-4, of course! .. J

Triple glazed windows

Peter Clark — Thu, 05 Feb 2009 11:27:49 +0000

Hi Ralph and Tom,
I moved my questions to:

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2963&page=1#Comment_46312

Where they seem more appropriate.

Peter

Triple glazed windows

rogerwhit — Thu, 05 Feb 2009 11:51:01 +0000

Ok Jo - 4-16-4-16-4 then, with the argon. Toughened.

2 upgrades worth thinking about: warm-edge spacers (generic term) especially if a vented dry-glazing system is used; maybe a low-E soft-coat rather than the normal hard coat.

Triple glazed windows

Jo — Thu, 05 Feb 2009 12:31:44 +0000

Hi Roger .. warm edge spacers are included in the quotes .. but can you tell me what difference soft coat makes? Also, on which face (or faces) should this go?

I've seen earlier that fostertom has listed companies he has obtained prices from but he seems to be awol at present .. so I wonder, do you know of any good (and inexpensive) companies worth trying for prices? Or is asking for that information really frowned upon on the forum?

Many thanks.

Triple glazed windows

ralphd — Thu, 05 Feb 2009 13:24:08 +0000

Posted By: JoHello again ..
We live in a fairly isolated position so security is an issue ..

If your house is wood framed (i.e. not ICF or brick facade) then the window security is a moot point.
A crook with a cordless circular saw & recip saw can easily cut a hole through the wall.

-Ralph

Triple glazed windows

rogerwhit — Thu, 05 Feb 2009 14:07:20 +0000

Each improvement - eg using soft-coat not hard, should improve the U-value of the window by 0.1 or 0.2, something like that. And the bees' knees windows have an insulated frame too (something sandwiched in the wood, if they're wooden).

Prices have been mentioned on various threads.

Triple glazed windows

James Norton — Thu, 05 Feb 2009 14:07:57 +0000

Some criminals have no respect for the finer points of airtight construction....

J