Talk:Insulated glazing

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WikiProject Glass (Rated B-class, Top-importance)


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)

Sound insulation[edit]

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".

Common term?[edit]

I've never heard the term Insulated glazing before - I wonder if it's a UK term? Not used in the UK' at least not by the general public! Is it a US term? Double glazing and triple glazing are more common in Australia and the UK - compare 52 google results for "insulated glazing" compared to 36,400 for "double glazing" and 305 for "triple glazing" 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." But it may not be glass?! "Double glazing" can apply to things like storm windows which do not provide the sealed space 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)

I think Insulated Glazing Unit(IGU) is the accepted term in the US.--Grooney (talk) 09:23, 16 June 2009 (UTC)

It depends on the context. In the US, if you are buying residential windows, you can get double glazed or triple glazed windows. If you are building a commercial building, and the architect specifies framing and buys just the IGU, then "IGU" is the term used.Ccrrccrr (talk) 12:06, 16 June 2009 (UTC)

Title of the article[edit]

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)

Scientifically unsound explanation[edit]


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.[] {{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? 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 :

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)

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

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
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 (talk) 21:32, 19 October 2007 (UTC)

Why are you giving up Pagw, you are absolutely right conductivity doesnt depend on density untill you reach a very good vacuum, I want to know too which levels are reached in practical glass. The results shown in the table demonstrate that the regime is a hibrid regime, give us some real info, possibly a graph of conductivity vs pressure. — Preceding unsigned comment added by Omblauman (talkcontribs) 02:37, 22 January 2012 (UTC)

First Sentence[edit]

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 (talkcontribs) 17:59, 9 April 2008 (UTC)

Photo requested[edit]

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.

...erm, one of them has one piece of glass and one of them has two. that simple enough?? Paulmallon (talk) 14:17, 20 November 2008 (UTC)

Condensation inside units[edit]

Is it just me or does this whole section sound like a load of pov from someone who runs a company that drills holes in double glazing?? The comment about the glazing industry not recycling glass from failed dgu's is certainly not true in the uk. Paulmallon (talk) 14:17, 20 November 2008 (UTC)

Yes, it is POV. The solution is to add other POVs to make it balanced. I think the point that desiccant can become saturated is worth mentioning, especially if it's really impossible to exchange that then IGUs are not sustainable, which defeats the intention of many people who install them. If you know more about the subject, please help improve this section. — Sebastian 19:30, 20 November 2008 (UTC)

Capicalization of chemical elelmements[edit]

An IP editor keeps insisting that chemical elelmements be spelled with capitals, which is of course not supported by Wikipedia:Naming conventions (capitalization) or by any publication outside of Wikipedia. Since that editor also did some marginal improvements, I manually only reverted the capitalization and patiently explained the situation at user talk: However, my edits were immediately reverted (this time from IP address ), again with some marginal improvements. I now went through the changes manually again, but I will not have the time to be that thorough next time, and next time, I (or any other editor here) may simply undo any such edits altogether. — Sebastian 07:51, 7 December 2008 (UTC)

Thanks. And noting that you are certainly correct.Ccrrccrr (talk) 05:18, 10 December 2008 (UTC)

Sealants and stuff[edit]

The component section needs to have a subsection on sealants. I will add that shortly. Some of the references I used (i.e Southwall) are there simply because no one else in North America or elsewhere is doing this kind of work and is NOT POV content nor is it intended as such. I do not have any dealing with this organization. Hschlarb (talk) 23:19, 8 December 2008 (UTC)


This entry tells me nothing about what I really wanted to know - when and where did double-glazing originate and how did it spread and become popular. Furthermore, how did attitudes to it develop, such as class distinction and humourous or satirical references? —Preceding unsigned comment added by Nikteacher (talkcontribs) 20:46, 9 December 2008 (UTC)

There may be a point in including some history. However, I'm not sure what you expect to read about attitudes, and why you'd expect there to be any class distinction and humourous or satirical references. It's just a simple variation of a window. For "window", you may be able to find some such references, but I doubt that there even exist any for insulated glazing. Can you find any other article on a similarly specialized item, in any encyclopedia you like, that provides such information?
Regarding history, though, I can tell you some anecdotal history: I lived in a house that was built in Germany around 1930; it had double windows, each in its own frame. Since everything you do with them, like opening, closing, and cleaning, takes twice as long, the step to combine them into one frame seems pretty straightforward to me. — Sebastian 06:02, 10 December 2008 (UTC)

I'd also like to know a bit more about the history of double glazing, specifically in the UK - when it started to become popular, for example.

I'd also like to know how long it takes the average house to recoup the cost of installing double glazing, and how this has changed over time. — Preceding unsigned comment added by (talk) 21:35, 24 September 2011 (UTC)


Did anyone else notice that reference 7 and 9 are the same? Should this not be adjusted, or is there a special reason to do this? —Preceding unsigned comment added by NickVdBroeck (talkcontribs) 20:28, 18 March 2010 (UTC)

Secondary Glazing[edit]

This article is the redirection destination for 'Secondary Glazing' but it only covers sealed units: secondary glazing as the term is understood in the UK involves adding a second pane of glass or plastic behind an existing single-glazed window, used where cost or heritage issues prevent replacing the original windows.


At my workplace we got sent a notice not to stick anything to our double-glazed windows (like posters or even post-it notes) because they would cause "differential heat stress" which could lead to the glass shattering. I did a little googling, and it seems that double-glazed windows may implode / explode in some situations. Does anyone know any more about this? (talk) 03:18, 17 November 2010 (UTC)

thermal section[edit]

Obviously this is a critical piece of the article, and the values given are seriously wrong. This mislead me, and it can be verified by the unit conversion factor between the two. There seems to be a serious problem with confusion on this issue. The R-value article says the conversion between U value and R value is 1 h·ft²·°F/Btu = 0.176110 K·m²/W. From this it is apparent that the 5.6782 W/m2·k= btu/h·ft2·f . And yet the part here says the u value of a double glazed window unit is 0.35 w/m2·k and yet 2 btu/h·ft2·f. The table in one of the comments above says the u value for a double glazed unit it 2.6 w/m2-k. someone should recheck this from the basic units, and if I have timee I will hunt down more accurate u values for windows... —Preceding unsigned comment added by (talk) 10:04, 22 January 2011 (UTC) Having a table for the values of different types of double/triple glazing units with a column for SI units and another for American units would be a clear way to display this information allowing easy comparisons.