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Triple glazing: superfluous or revolution?

While the use of double glazing is becoming more and more common in the individual housing to ensure comfort and tranquility superior to single glazing, triple glazing is also beginning to attract attention. The glazed spaces thus offer many possibilities of choice but also raise a lot of questions among the consumers notably in terms of efficiency and use. This week HandymanDuanche is the synthesis and reveals the underside of triple glazing.


The principle of multiple glazing.

The use of multi-glazing, formed by the addition of the constituent glass walls of the glazing, is intended to increase the insulation performance by creating hermetically sealed spaces between the outer face and the inner face of the window. More concretely, these glazings use the physical laws that imply that a closed space containing a dry and immobile air, in the sense that it does not allow any gas exchange around, naturally acquires an insulating power.

Triple glazing: superfluous or revolution?: revolution

The effect of the insulation then being directly a function of the amount of trapped air and therefore the thickness of the air space contained in the gap separating the two glazing walls. According to this method, the double glazings have an insulating space enclosed between two panes while the triple panes offer two successive ones, contained by three spaced walls. It is precisely this succession which is at the origin of the differences of performances which make that the triple glazing really brings a better insulation than double glazing with equivalent range.

The triple glazing association - rare gas.

Like double glazing, triple glazing can use a rare gas filling to improve its insulation qualities. Rare gases have properties that enhance the insulating power of glazing at the thermal level, by limiting the heat losses produced by the simple use of air space. They are not only less conductible than air but also heavier. This limits in addition to conductive losses, the losses due to convection by slowing gaseous movement inside the closed spaces of multiple glazing.

Argon is today the gas most used in the design of double and triple glazing, because it is the one that represents the best quality ratio of insulation - price. In addition to these glasses with argon blade, you can also opt for glazing krypton, more powerful but also much more expensive.

Other parameters playing on the quality of insulation.

Triple glazing: superfluous or revolution?: glazing

In addition to filling the spaces of the multiple glazings, another method makes it possible once again to increase the insulating power of the glazing by reducing its emissivity, that is to say, in this specific case, the thermal transmissions by infrared radiation. To limit this phenomenon, one solution: the use of low emissivity coatings. These transparent coatings are composed of a very thin layer of metal oxide that lets shortwave sunlight pass by shielding part of the radiation heat transmission, characterized by longer waves. Relatively fragile, this type of coating is preferably applied to one of the internal faces of the multi-glazing units and makes it possible to qualify the desired effect by choosing its position. Indeed, its application on the glass closest to the outside will limit the heat gains of the strong sunshine in summer while its application on the glass closest to the interior will restrict, on the contrary, the heat loss at night and in winter.

Anyway, the glazing does not do everything in the insulation. First and foremost, be sure to seal the surround connecting the glazing to the window frame and pay particular attention to the joints of the window itself. It is often here, at the level of the frames and the frame ensuring the closing of the window that are located the weak points. If framing and carpentry are not reliable, you can be sure to lose even by investing in the best triple glazing upscale. Do not forget either the good reflexes: by closing your shutters at night, you contribute to isolate.

Triple glazing and insulation performance.

The calculation of the insulation performance of triple glazing depends on a multitude of factors, including: the influence of the type and characteristics of the triple glazing in question (air gap, argon, space thickness, low emissivity or not, etc), the orientation of the window (north, south, east, west, etc.), the area where you live, the material in which the window is designed (wood, PVC, etc.). A calculation to customize, in short.

Nevertheless to give you an idea, it is possible to refer to the associated U value. This translates the thermal conductivity force. In other words, the more it tends to 0, the stronger the insulating power. Even if it is difficult to give exactly the U of a window with reference to all the variables that can be taken into account, we can give you an idea. A standard triple glazing unit with two 12mm air blades installed in good conditions should display a U of about 1, two or three tenths. Under conditions of design and equivalent environment, a standard double glazing will have a slightly lower U rather of the order of 2.7 - 2.9 and a single glazing of 5.7 - 5.8.

Based on these same ratios to distinguish between ordinary triple glazing and argon low-emissivity dual glazing, the U difference would show a slight advantage for ordinary triple glazing at around two to four tenths. Also the use of triple glazing, whose cost is almost 80% higher than double glazing at equivalent range, can be described as over-insulation. The use of efficient double glazing is therefore more likely to satisfy the majority of French homes in terms of insulation.

But where does the interest of triple glazing lie?

Triple glazing: superfluous or revolution?: superfluous

Undeniably the triple glazing ensures the best possible insulation that you can currently benefit to equip your windows. But as we have just stressed, this desire for maximum isolation, given its price, is not for everyone. Especially if it comes to gain a few tenths of extra insulation. In fact, its interest is more in a logic of optimal limitation of energy losses underpinned by that of an environment-friendly habitat that consumes so little that it is close to the idea of ​​the house "zero energy". Triple glazing is therefore more of a product intended to equip passive houses.

Also, triple glazing has a secure future. Some of these triple glazings have also been awarded the passive habitat label. And for good reason, the triple glazing is a bit the ultimate for those who are betting on low consumption and have already invested in this direction. But do not jump too fast, investing in triple glazing before ensuring the proper insulation of your entire home would be nonsense.

Finally, the small disadvantages of triple glazing.

The addition of a third wall to the glazing, although it provides better thermal and sound insulation, also causes some inconvenience. First of all, that of the additional bulk it entails, even if it is true that the solution of triple glazing krypton can limit it in a certain way. The krypton has indeed an insulating power strong enough to reduce the size of the spaces separating the windows while keeping performance equivalent to the use of argon, but the use of this expensive gas also has the effect of increasing an already high bill.

The induced weight is also a problem in the sense that a triple glazing is much heavier than a double glazing, which implies that it is not only more difficult to handle but especially that it requires a frame and a carpentry adapted. This additional load tends to fatigue the hinges of the opening.


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