Talk:Insulated glazing

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I would like to see a close-up image of the different types of panes (particularly double panes), as many people have trouble telling if their panes are well insulating double panes or single panes.

Contents

[edit] definition

When isn't glazing referring to glass? Isn't that the whole definition of glazing? Civil Engineer III 18:24, 2 March 2006 (UTC)

It can refer to certain plastics, e.g. polycarbonate. See Glazing. --Singkong2005 (t - c - WPID) 06:30, 16 July 2006 (UTC)

[edit] Sound insulation

I don't know if the term "Insulated glazing" covers sound insulation, but the two are closely connected. I've made a number of edits (see changes) and referred to sound a number of times. If someone knows a more suitable place and wants to move it or suggest a move, that's cool, but it should be at least linked from this article.

Likewise for films/coatings and "secondary glazing" - I don't know if these are covered under the term "Insulated glazing".

[edit] Common term?

I've never heard the term Insulated glazing before - I wonder if it's a UK term? Double glazing and triple glazing are more common in Australia - compare 52 google results for "insulated glazing" site:.au compared to 36,400 for "double glazing" site:.au and 305 for "triple glazing" site:.au. Similar comparisons results are found searching without the restriction to .au sites, but not quite as extreme (still about 150 times as many references to double glazing).

Having said that, insulated glazing may still be the better term, as it's a broader term (at least covering double glazing and triple glazing). --Singkong2005 (t - c - WPID) 06:30, 16 July 2006 (UTC)

Googling for "insulated glazing" gets about 21,400 hits; Googling for "double glazing" gets about 2,900,000 hits! "Triple glazing" gets 63,500 hits, i.e. three times as much as "insulated glazing". - Eyeresist 02:33, 4 August 2006 (UTC)

In the US, the technically correct term is "Sealed Insulating Glass." "Double galzing" can apply to things like storm windows which do not provide the sealed spce between the lites of glass. I left the title of this article along, but added a re-direct from "Sealed Insulating Glass." Newell Post 15:46, 16 June 2007 (UTC)

[edit] Title of the article

Insulated glazing unit is most commonly known as "IGU" in North America and as a "DGU" in Europe. I think the abbreviation "IGU" should have a 'disambiguation' page, with "International Geographic Union", "International Gas Union" etc. included. I dont know how to create something like that. IGU should then be added to the title of the article.

I would also like to focus the article on primarily Glass IGUs. The reason for that is that this is the most common reference for the term and because there is a vast amount of information specific to glass IGUs that needs to be added, which I would love to undertake.

I have started some work already and am wondering if I should wait for any feedback on this comment before I start modifying the article more radically. This is my first attempt at editing on Wikipedia. I am an architect specializing in matters of glass and curtain walls.

Thanks. Sarega 01:13, 29 August 2006 (UTC)

Thank you for your efforts and enthusiasm. This article could use some radical transofmation, so go ahead and be bold. If you make a mistake, it's easily fixable, and there are certainly enough experienced editors watching out for and and the articles. So have fun! (And I certainly agree that it should focus on glass) Civil Engineer III 13:05, 29 August 2006 (UTC)

[edit] Scientifically unsound explanation

Removed:

Argon (Ar) has an atomic mass of 39.9, which is much more than [[nitrogen]] (N<sub>2<sub>) and [[oxygen]] (O<sub>2<sub>) [[molecule]]s, which have a molecular mass of 28.0 and 32.0 respectively. As a result, argon atoms move significantly slower than nitrogen and oxygen molecules at the same [[temperature]]. This reduces [[convection]] and decreases the energy transfer between one side of the glass and the other.[http://www.windowinfo.co.uk/double-glazing.asp] {{Fact|date=February 2007}} <!--need a better link on the technical side --Singkong2005-->

Thermal conductivity is the relevant factor, not atomic mass. As an example, what has higher thermal conductivity: H2O (18.0152 amu) or Cu (63.546 amu)? Or O2 (31.9988) compared to Cu? 144.5.224.144 12:11, 1 March 2007 (UTC)


Another point on the science of double glazing. I recall being taught during my physics degree course that 3/4" was the maximum (therefore thermal optimum) air gap before it gave rise to convection. I doubt whether the figure or 10mm in the article is correct.

Many commerical units are available with 16mm air gap which tends to confirm the optimum is larger. Practicle constraints on the construction may often lead to a compromise, smaller value.

Substituting more elaborate explaination from : http://www.doubleglazing4windows.co.uk/sealedunits.html

The optimum dimension of the air-space in an IGU depends on the gas in the air-space. For example, while 1/2 inch (13.2 mm) is standard and effective for air filled air-space, an argon filled air-space is most effective at 16 mm. The reason this difference exists is because of the different densities of the gasses. Keep in mind that the issue is to keep the gasses from circulating in the cavity, thereby preventing transfer of heat through convection. Of course, some flexibility is employed when sizing the air-space for architectural reasons or convenience. The spacers are available in various dimensions, though, 12 mm is the standard in the US market, 16 mm the standard in European market.
I will sooner or later add this information to the article. Sarega 13:06, 5 April 2007 (UTC)

[edit] Claim that evacuating the airspace "drastically reduces heat transfer"

From what I know about kinetic theory, thermal conductivity is independent of pressure, making this claim untrue. That is unless the airspace is evacuated to such a low pressure (of the order 10-4atm) that the assumptions behind the kinetic theory model no longer hold. If this is the case then it might be helpful to mention what the pressure is between the panes in evacuated glazing.

Pagw 14:19, 14 September 2007 (UTC)

Evacuated Glazing Units (EVUs) are actually known for their superior insulating properties as opposed to IGUs. When the space does not have any medium (i.e. vaccuum), the heat transfer through both conduction and convection could theoritically be eliminated. This is the principle behind the advent of the EVUs. But in practice, achieving an efficiently performing EVU (and being able to mass produce it keeping the costs down) has been a huge challenge for numerous reasons. That is why, even after over 20 years of the advent of the theory, only one Japanese manufacturer offers EVUs as a product in limited sizes and for a huge cost premium.
Sarega 04:12, 11 October 2007 (UTC)
Can you give a source which says that evacuating the space between the panes will actually reduce heat transfer? As I said, as far as I know unless the pressure is reduced to very low levels the heat conductivity of the gas shouldn't be affected, although I could be wrong.
Pagw 15:00, 13 October 2007 (UTC)
But we are not talking of the conductivity of any gas... rather about the absence of any gas! See here. As it says, Conduction does not occur at all in a perfect vacuum. Or in other words, vacuum is a really bad conductor of heat. Moreover, absence of any medium would also eliminate convection as that too is directly dependent on the existence of a medium (some fluid). The only mode of heat transfer that is left is radiation which is independent of the existence of a medium. I hope this clarifies it!
Sarega 15:57, 22 October 2007 (UTC)
But my point is that you will never get a perfect vacuum between the panes, so there will still be some molecules in there to conduct heat. According to kinetic theory, with the assumption that the mean free path of the molecules is significantly smaller than the gap between the panes, the heat transfer will not be affected by the low pressure [1]. The formula given at the linked page says the thermal conductivity is proportional to n and also proportional to the mean free path (which is proportional to 1/n), so therefore there is no dependence on n and therefore there is no dependence on pressure.
Now kinetic theory is far from perfect, so this analysis may not be right in this case. But I still think it's necessary to have a citation for the claim that evacuating the space between the panes reduces heat transfer, or a calculation showing that the assumptions of kinetic theory aren't reasonable in this case (e.g. because the mean free path is greater than the distance between the panes), or something else along those lines.
Pagw 10:47, 23 October 2007 (UTC)
Please see here. The abstract says: low pressure greatly reduces the conduction and convection of gas within the space. Therefore, heat transfer through vacuum glazing is significantly lower as compared with double glazing unit with inert gas. If you see the attached PDF document (may need registering), you will find further references to the same idea: If there are no gas molecules, conduction and convection can be liminated. Therefore, it is possible to achieve high levels of insulation in a double glazing by evacuating the gas from the space between the two glass sheets. This leads to the concept of vacuum glazing. There are comparative thermal conductance values included in the paper for different types of composite glazing.
Window Conductance
(Wm-2K-1)
Vacuum glazing (6.2 mm) 0.8
Single glass sheet (4 mm) 5.6
Double glazing (10 mm) 2.6
Triple glazing (15 mm) 0.7
I believe that this satisfies your requirement for a source, Pagw. The writers of this article, based in University of Sydney, are the authority on evacuated glazing. Sarega (talk) 17:13, 29 November 2007 (UTC)
Just found another article here. Sarega (talk) 17:19, 29 November 2007 (UTC)
Yeah that's good!
Pagw (talk) 12:17, 13 December 2007 (UTC)

Less molecules available for heat transfer. —Preceding unsigned comment added by 125.238.252.246 (talk) 21:32, 19 October 2007 (UTC)

[edit] First Sentence

I do not think that the first sentence of this article is appropriate. It makes no attempt to explain what Insulated Glazing is but rather states some facts about the role of windows in heat loss from buildings. This may be a valid point to make even in the top paragraph but the first sentence should introduce to the reader the subject of the article. Even in cases where the subject matter is complicated the first sentence should still able to give a bit of information about what is about to be described and into what categories it falls - is it a person, a product, a brand, a concept, does someone own it etc.

I thought someone who takes an interest in this area might like to change this section. —Preceding unsigned comment added by Mark Neilan (talk • contribs) 17:59, 9 April 2008 (UTC)