We are getting double glazed PVC windows 4-20-4 and filling the air gap with Argon gas cost $640 extra.Does anyone have any suggestions whether the money would be wisely spent?
Thanks,
double glazed windows
(52 posts) (23 voices)-
ghostgum
MemberSee if you can find the WERS ratings for the windows with and without Argon.
http://www.wers.net/
http://www.wers.net/residential/certified-productsFor the windows on my house, double glazing reduces the heat loss/gain through the windows by about 25%. Adding Argon would improve this by about 2%. The aluminium windows frames are a significant path for heat transfer. PVC has less heat transfer through the frames.
Posted Thursday 29 Jan 2009 @ 1:14:03 am from IP # -
cameron
MemberTo throw an additional option into the mix, I went for low-e glass (low-e = low emissivity) when I bought double glazing. I concluded this was more cost effective than argon fill for an equivalent U-value gain. My glazing provider also suggested that argon will need refilling after 10 years or so; low-e glass at least wont have this ongoing maintenance requirement. Sometimes from certain angles the glass has a slight blue tinge to it, but nothing you'd notice.
As ghostgum points out though, the frames are an important consideration as is general sealing around the frames.
Posted Sunday 1 Feb 2009 @ 12:46:29 am from IP # -
The extent to which one should chase window performance is always interesting. The PVC frames fix the Thermal Bridging issue - how far to go on the glazing? Your supplier should be able to give you comparitive U Value figures for air or Argon fill. I'm assuming that they aren't Viridian ThermoTech IGUs (insulating glass unit) you're considering, because they seem to be typically 12mm gap. As an example though, the Viridian Glass info is all on their website, and a 4-12-4 plain glass with air IGU has a U Value of 2.7, Argon fill lowers it to 2.6!! Since U Value is the inverse of an R Rating, this gives us R0.37 with air or R0.38 with Argon.
Of course, these are centre of glass only figures. Any double glazed PVC framed window is tons better than a plain single glass window, particularly if the single glass was in an unbroken metal frame. Note though, that the IGU is about as insulating as an uninsulated weatherboard/plasterboard wall - R0.4.
Posted Friday 6 Feb 2009 @ 5:56:12 am from IP # -
Slightly off topic, because it's not a retail window, but I'm upgrading an existing small East facing, fixed, plain glass/timber framed window in my office.
IGUs are quite expensive, and perform quite well, but only block UV if coated or laminated glass is used.
Coated or laminated single glass costs less, but only gives a moderate performance improvement.Because I've got plenty of frame depth to play with, I'm going to a novel triple glazed solution.
12-16mm behind the existing outer glass will be a piece of 3mm flat Polycarbonate. It's 99% UV proof.(The trial piece cost about $80 per sq m at the hardware shop, probably less in big sheets for big windows from a proper supplier.) Polycarbonate has quite high thermal expansion, so instead of being puttied into place it'll be mounted in a soft rubber channel from the foam shop - $8.50 per m)
12-16mm behind the poly is plain 4mm toughened glass, to suit the floor depth window and the rules (the illegal plain glass lower pane is currently protected by 10mm plywood) 4mm toughened also retails for about $80 per sq m, lead time 1 week from a local window supplier.
The resulting triple glazed UV proof window should easily exceed the thermal performance of standard IGUs, but the trial is to check for other issues like condensation, thermal stress cracking of either glass etc. The easily scratched poly should be OK in the middle, as long as I don't put any dirty marks on it during assembly. If it works I'll write it up for ReNew.
Posted Friday 6 Feb 2009 @ 8:31:15 am from IP # -
burtons40
MemberIf adding argon is only going to reduce heat loss by 2% it may make more sense to look more closely at roof and wall insulation. You don't say where you are so I'm not sure how much insulation is required. However, even the best window treatments are not much better than an untreated wall. What about reducing the size of the window by 2%? Does the window face north and have good solar access or is it on the south? Maybe it's something that needs to be looked at on a window by window basis.
Posted Monday 16 Feb 2009 @ 10:28:28 pm from IP # -
norbert
Memberburtons 40
We live/build in cooler climate (Woodend Vic)and we've put a lot of effort in getting the insulation part right.We use PVC panels for the external cladding and R5.5 ceiling batts in combination with thermacell roof insulation.The house/living is facing north and so do most of the windows.For the sake of 2% less heat loss I don't believe the extra cost is justified.
Thanks to all of you for your help.Posted Wednesday 18 Feb 2009 @ 5:59:02 am from IP # -
lbpoulton
MemberNorbert I wonder if you're able to tell me the approximate quote you've been given and for what size windows?
I am just after a ball park figure as I've often thought about getting double-glazed windows but haven't gone as far as getting a quote yet - just curious.Posted Monday 23 Feb 2009 @ 2:17:59 am from IP # -
ghostgum
Membernorbert, I'm not saying that the difference is 2% for your windows. It was 2% for my windows with aluminium frames, and the frames are likely to affect the figure, since they couple heat from outside to inside, and from the outside glass to the inside glass. With PVC frames, argon fill might be worth more than 2%. Hence my suggestion that you look at the WERS site and look for your windows with and without argon.
Posted Monday 23 Feb 2009 @ 4:42:15 am from IP # -
johnny
MemberI just have to add a note to those who are considering commercial grade double glazing.
Think of utilising a separate window of plain glass, more that 25cm (1") from the original, and be sure that the second window is of a wooden frame aka Canadian system 75% of all house have this system called storm windows with a small manual opening closeable vent to allow air exchange when the insulation is not of paramount imortance. (can swap in the summer for insect screens).
I lived in Falls Creek (The Ski Resort) for about 10 years using this system to great success. (lowered heating bills by arround 15%) Also double insulated the flat and pine lined ALL of the exterior walls.Posted Monday 23 Feb 2009 @ 9:52:40 am from IP # -
norbert
Memberghostgum
I've looked at the WERS site under Eurotech (tilt & turn) that's the brand/type of windows we get and to me the windows the site refers to doesn't make sense.Our windows are 4-20-4 but this configuration doesn't seem to show on the website.Maybe you could have a look, perhaps you understand it better then I do.
ibpoulton
Our windows cost $ 21,300,that includes glazing on site and fly screens.
We get a total of 13 windows and the price also includes one slide door and two other doors, main entry and laundry all double glazed.The 4 windows facing north are floor to ceiling measuring 2400x2100 so pretty big.I did a lot of research and quotes varied from around $ 20,000 to as high as $ 37,000.There is now much more competition in regards to PVC windows then 5 years ago so shopping around pays off.If you need more details then please let me know and I can forward you our window schedule and also the quotes we got.Posted Monday 23 Feb 2009 @ 11:03:27 am from IP # -
ABOTHE
MemberI tackled the problem from anoterh aspect. We originally had Aluminium framed windows and rather than junk them we added a new wooden framed 4mm glass section over the top with teh glass spacing 19mm. Then we added a fishpond air pump and a 4 litre container of Silica gell in a closed circuit. any new air pumped into the space between the glass panels has to pass via the silica gel as well as the recirculated air. It has been working for 10 years in Beechworth on a single circuit of 8 windows each 2 metres long.
Retrofitting is possible.
Posted Saturday 7 Mar 2009 @ 9:11:54 am from IP # -
lbpoulton
MemberGot a quote today for retro fitting "double glazing" to exiting windows. They install a second frame inside your windows with a glass panel in it. For example I have a lounge room window that is 3 panels wide, two high and two wind out sections. What they would do is install a new frame inside the existing, all the way around the 6 panelled window. Then have three top to bottom sliding secondary glass panels - sliding so that you can still open the wind out sections.
I thought the best reduction in heat transfer came from the two layers of glass having next to no air, or a gas like argon in the middle of them.
It seems that this second layer that can be openable and is not completely or vacuum sealed wouldn't get anywhere near the same energy/heat transfer reduction that would make it worth while.The quote was approximately $395 per square meter of the stuff - $4500 for only three window units on one side of the house!
Anyone else had experience with this system rather than the traditional double glazed units that would replace the existing glass?
Posted Wednesday 1 Apr 2009 @ 5:28:43 am from IP # -
lbpoulton
The system that you had quoted sounds very expensive and not very effective. You don't mention whether your existing windows are timber or aluminium framed. Aluminium framed may need some fiddly retrofit, timber framed is potentially easy as I outlined earlier. (No I haven't assembled it yet, though all the parts are now here)The 'air space' in double glazing is just that, filled with air. Glass is surprisingly flexible, and normal glazing could not withstand the external pressure of a vacuum without the panes touching. This would totally negate any beneficial effects.
The reason that a 'thin' film of air (typically 12-20mm) is used between the panes is to prevent the formation of convection currents. As in a conventional single pane window, convection currents are the enemy.
If on a cold Winter evening the warm air in a room is allowed access to the top of a cold pane of glass, the air cools quickly and drops down between the curtain and the glass. This movement sucks more warm air in at the top, and with low performance windows and 'unsealed' curtains the resulting cold draught is easily felt at the bottom of the curtain. That is why simple sealed pelmets and heavy floor length curtains are such a benefit to thermal performance. They don't help much in cold daytime though.
If the 'secondary glazing' is too far from the existing glass the warm inner glass will make some of the enclosed air rise to the top while the cold outer glass will make the outer 'half' of the air sink. Once a convection current is established the widely spaced 'secondary glazed' window is just acting as a 'heat exchanger' to send your energy outside. The benefit is simply the time lag taken to achieve the inevitable.
If a space that wide was filled with an insulating batt (ie a wall) it would work very well because all the trapped air is kept still.
When the air film is thin enough to avoid convection currents, the still air acts as an insulating layer. It's just that it's a very thin film of insulation - like sleeping under one blanket in Winter.
In places where it gets really cold multiple layers are used. There are some beaut windows in the States with 4 layers,(eg Superglass Quad - see http://www.alpeninc.com/windows) the inner and outer ones are coated glass and the inner 2 are simply 'energy reflective' films (like window tint film) suspended in between. Four layers of Low E 'glazing' and three Krypton filled 'air spaces' must give brilliant results. (It's hard to tell, US ratings still involve Fahrenheit Degrees so their numbers are hard to relate to.)
Once the 'air film' is the right thickness to stay still, the only other advantage that can be obtained is using a less conductive gas instead of air - which is where Argon and Krypton come in.
As shown in my earlier post though, the actual change in U Value is comparitively small (in simple double glazing anyway), like sleeping under one 'better' blanket in Winter!If your 6 panel window was timber framed the 4 fixed panels could be very easily upgraded yourself, and since the three lower ones sound like they may be floor level they are required to be safety glass anyway. If you use laminated glass instead of toughened (about the same cost, roughly $80 per sq m) you'll stop UV into the bargain, and the risk of dangerous breakage during assembly is eliminated. Ask the supplier for 'rough arris' edge treatment and you can't even easily cut yourself.
Posted Tuesday 7 Apr 2009 @ 12:57:18 am from IP # -
petanque
MemberI have no experience with double glazing but I do have roller shutters. They cam make a huge difference to the comfort and energy consumption.
I live in Adelaide and the payback period about 10 years ago was 5 years.
$600.00 for Argon and a 2% saving sounds like if you have a heating bill of $5,000 a year it may be worth it if you are spending that sort of money on heating I would imagine that there would be all sorts of energy savings that should be investigated.
Posted Tuesday 7 Apr 2009 @ 3:24:11 am from IP # -
Peter147
MemberHello All , Newbie Here.
Dear JohnB, great post.
It is hard to cut through the myths and marketing and your post seems to be right from my investigations. The gap cannot be too big of too small. The still air does the work. I think 12mm is best. I have also ofund you only imprve the R value from 0.1 to 0.5 with good curtains bringing it to R1.0. When you consider batts can easily be R3 for minimal cost you see why return for $ is important.
I am looking to retrofit wooden heritage double hung windows with double gazaing. Being wood the loss via frame is minimal. Keeping moisture out seems an issue. Any with experience thay can post here?
thanks Peter
Posted Wednesday 29 Apr 2009 @ 11:36:21 am from IP # -
Months ago I mentioned the proposed Triple Glazed window upgrade I was planning, using clear 3mm polycarbonate as the inner 'glazing' because of it's low energy conductivity and UV exclusion.
I finally installed all the bits yesterday, and while it doesn't yet have it's internal timber trim (or exterior paintwork in the 'new' colour) it's now a sealed unit. Because it's a prototype it has to be able to be pulled apart, which is a nuisance, when simply puttying the inner glass to the frame would be so much easier.
Overnight it has passed it's first test, being free of condensation this morning. The inside face of the inside glass feels cold to me, but I guess it's not as cold as the other window in the same room, which has condensation over most of it's surface.
Initial thoughts are that the poly, and the allowance for it's thermal expansion, are a headache probably not worth the effort. Giving the poly 'room to move' basically means that the two internal airspaces aren't airtight, so I expect that any benefit gained from the material's lower conductivity is squandered by the small possible airflow between the airspaces.
Probably just better off with a glass centre layer puttied in place, at least it's sealed, and it's cheaper, easier and less fiddly too.
Most people I mention the concept to want to have all the windows in their project looking the same from the outside at least.
The next idea is to use a fixed laminated glass (blocks UV if it's the good stuff) aluminium framed window as a basis, because it's the cheapest option from the window supplier. The extra panes can simply be retrofitted behind, within the timber reveal, again giving low frame conductivity and multiglazed performance (hopefully) at reasonable cost.
Satisfying Basix here in NSW that a window is 'double glazed' is as simple as the window having two layers of glass, there is as yet no stipulation that it be a 'retail' IGU.There are some pictures of the window and it's components on the Sunergy Design page on Facebook, feel free to check it out. (It would be good if we could post images here)
Posted Monday 8 Jun 2009 @ 10:43:02 pm from IP # -
linda
MemberI have aluminium framed windows (2 double hung and 3 wind-out) and 2 large window-doors which open on to a courtyard and a balcony. I'm interested in retrofitting double-glazing or replacing the current glass with a more efficient glass. Is it worthwhile on a cost basis to retrofit? If so, does any one have any recommendations for products to follow up? Or, is it better to source replacement double-glazed windows?
Posted Tuesday 9 Jun 2009 @ 10:16:13 pm from IP # -
Linda,
It's hard to know whether your frames can be upgraded or not - it depends what the frames are. The frames in my place are first generation aluminium ones from the late 70s. They are so small in the glazing channel that they wouldn't even be able to fit anything bigger than the 3 or 4mm glass they currently contain. Frames like that can only be replaced with whole new units.
If you have quite modern windows and doors they will most likely be able to fit something like ComfortPlus (Low E coated 6.38mm laminated), and some modern frames will fit IGUs as well in their standard form.(Some also have adaptors that allow IGUs to be added, though that means more badly conductive aluminium around the edges.)
If you consider that standard window glass has a U value of about 5.9, and standard double glazing is about 2.7, the 3.6 of ComfortPlus is a good improvement, particularly if you can retain the otherwise perfectly acceptable windows and doors, and save the labour of removing and replacing frames etc.
It's probably worth asking a local glass supplier first (who wants to sell you glass) rather than a window supplier (who wants to sell you new windows).
A friend of mine has a similar situation, and his frames were modern enough to allow glass replacement with something better, but it added up to many thousands of dollars for the whole job so it hasn't happened.
Another factor is the orientation of the windows and doors. While all glass areas should ideally be of reasonable performance, a Southern window or door that never lets any warmth into the building (and in fact is a constant Winter daytime energy drain) is a greater liability than a Northern one that floods your place with Winter sunshine.
Any window can be easily and effectively covered in the evening, and much more cheaply than replacing bad glass with better, so the first goal should be to determine whether it's daytime, nighttime, or all the time performance that needs attention.
Posted Wednesday 10 Jun 2009 @ 11:11:45 am from IP # -
bundy
MemberHello all
I am considering double glazing for some West facing Windows in our soon to be renovated house for some summer heat protection . (Not a Fan of LowE as I have been told the inside coating scratches easily and looks terrible when that happens)
As all the Window frames for our extension will be custom built in Timber I was thinking is it as simple as having the Joinery company build the Frames so they can be double glazed or is it more complicated than that? ie Do we need special seals and the like as part of the frame?
I understand the concept of double glazing with the Air gap and all but I just am not sure on the specifics of how a double glazed window is put together and where the extra cost factors comes into play.
Is it the extra cost involved based on the simple fact you are using twice as much glass or is it more complicated than that?
Finally will double glazing help with protection from summer heat gain as well as it does for heat loss in Winter?
Posted Sunday 19 Dec 2010 @ 9:43:01 am from IP # -
ghostgum
MemberDouble glazing will help reduce heat gain by conduction. That is, it reduces the heat gain from hot air on the outside warming up the glass on the inside.
It does not reduce (to any significant amount) the radiant heat through a window. For that you still need to put a blind outside the western windows.
As far as the window is constructed, the frame just needs to be thick enough for the thicker insulated glass unit (IGU). A single pane might be 4mm, while a double glazing IGU might be 20mm (4mm glass, 12mm gap, 4mm glass).
I have double glazed aluminium frame, and the difference is just the thickness of rubber strip on the outside. These are far from the most efficient double glazing windows on the market, but better than single glazing.
Posted Sunday 19 Dec 2010 @ 10:14:05 am from IP # -
termite
MemberI second ghostgum on the DG structure. Most DG units are sealed with an inert gas between the panes. They may also have a size limit to prevent the middle of the panes touching in cold weather. Note that it must be produced in dust-free conditions as you can't open it up to clean the glass on the inside. They are quite heavy.
What style of window is this going to be? Fixed, sliding, double hung, awning, hopper or casement? I got the latter, in western red cedar (WRC), about 8 years ago, and I found that combination greatly limited my choice of supplier, and thus my price options. Perhaps things are better now, as double glazing is much more easily available and cheaper as a total of the job than it was then.WRC is the best timber for window frames as it is highly rot-resistant (though for better impact resistance, sills should be made of hardwood). Timber also is a better insulator than metal.
They don't use hinges on casements like they used to. They use a kind of pivoting stay, supposedly for wind loads. Mine were painted zinc-coated steel, and started to rust within a year. If you get casements, make sure the stays are stainless steel. Zinc coating is worse than useless.However, for cool on that side of the house, I think that a retractable awning would be more effective, though - and cheaper - if you have the space...
Posted Sunday 19 Dec 2010 @ 11:24:34 am from IP # -
bundy
MemberHmm thats very interesting and helpful. So Radiant heat (Which is my main reason for considering this due to harsh westerly afternoon sun in Perth) will still be an issue through the windows. (Walls will be protected with Glareshield)
My other thing is I will need to use Laminated glass for safety reasons on both sides of these potentially double glazed windows so they would be quite thick at 6.2/ 12mm / 6.2
I am thinking then that double glazing has most effect for keeping heat in rather than keeping heat out and may not be worth the added cost and trouble in my situation.
Installing a good blind or shade may achieve the same if not a better result.
Posted Sunday 19 Dec 2010 @ 11:45:53 am from IP # -
hamish05
MemberHi bundy. My Daughter, was at her wits end renovating her 100 y/old house with similar problems to you. In the end she chose to replace the glass only in her sash windows (north facing) with glass 10mm thick, and a verandah/blinds combination. She claims the improvement has been very noticeable, with a big reduction in noise, as front windows are close to the street.
Not sure what the science would say about this approach, but she is now very happy.
Posted Sunday 19 Dec 2010 @ 11:58:10 am from IP # -
bundy
MemberHi Hamish - exactly my situation too. A 90 year old house which we wish to keep to the original style but also make as liveable and enviro friendly as possible (Within reasonable cost/reward scenarios)
So that means Timber detailing and floors (No concrete) Lots of big sash windows areas and lots of detailing.
It's sometimes very hard to be sympathetic to both our heritage and the environment at the same time.
Posted Sunday 19 Dec 2010 @ 12:10:37 pm from IP # -
cool at home
MemberBundy, for west facing windows I'd definately go for a retractable awning in cotton canvas (note that most canvas you buy today is 'acrylic canvas' and doesn't block nearly as much light - and I presume heat - as cc). You don't need to have dark colours or a dark backing; a light colour will be more reflective of course. I have both acrylic and cotton canvas retractable awnings on my house in the same colour ('sand' or something like that... beige/light coffee kinds of colour) and the difference is very noticable. Price was the same - I didn't realise I was getting acrylic canvas with the first awnings - although apparently the acrylic will last longer. Can't vouch for longetivity, but as I really need to keep the western sun out, I really need awnings that work.
Incidently, we have low-e glass throughout our house - no scratches on the inside coating after 7 years, but I have to say I'm not overly fussed with performance. I presume they give us 'more' than ordinary glass, but awnings and thermal curtains (properly fitted) are still essential.
Posted Sunday 19 Dec 2010 @ 1:20:32 pm from IP # -
Eco
MemberDouble glazing is not effective against radiant heat - that is predominantly sun shining directly through the window (and also indirect radiation). So the top priority in summer is to keep the sun from hitting the glass - so outside shade structures, such as blinds or trees - refer Your Home Technical Manual for options.
However double glazing is effective at stopping *conductive* heat flows - it is just as effective in summer at limiting this type of heat transfer as it is in winter. However double glazing retrofit is still expensive. A similar result could be achieved with good quality lined curtains - so long as there is some level of edge sealing to prevent convective flows past the curtain.
Also gap sealing to prevent air leaks into the house.
Posted Monday 20 Dec 2010 @ 3:38:23 am from IP # -
Benny
MemberI agree with the others that if you're problem is incoming sunlight - ie radiation and not conduction, then double glazing will not help much. The whole idea of double glazing is to still be "clear" so it will let through all the radiation unless its special glass to absorb/reflect IR. So you have to have either a shade system to block the light from the window or a reflective film on/outside the glass. For late westerly sun an awning can be tricky since the sun is so low it can come under it so a blind is the only solution.
Or what a bout a reflective film/blind ? The renshade product has been talked about a lot on this forum but I have no idea how good it is...
http://www.enter-shop.com.au/catalogue/c37/p327There's a canadian version of this too but I can't find the link at present.
Posted Monday 20 Dec 2010 @ 4:48:12 am from IP #
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