The glass part of the window occupies about 90% of its area, therefore, for the most part, the heat and noise insulation of the entire structure depends on it. If you want a really warm and quiet window, then it is not enough to buy a profile from a well-known manufacturer - it is also important to choose a suitable double-glazed window, and here some difficulties await us, associated with a huge assortment. Manufacturers offer double-glazed windows that differ in the number of chambers, the type of glass and many other parameters, and since technology does not stand still, every year new and more advanced solutions appear. To choose the best double-glazed window, you need to carefully study all the offers on the market and determine your own requirements. Let's break it all down.
Even the simplest modern double-glazed window will be many times warmer. This was achieved through the implementation of a number of design features. A double-glazed window today is called a complex structure, consisting of several glasses connected to each other by a distance frame. The space between panes is called camera, it is in most cases filled with air, but can be filled with inert gases to increase thermal insulation. Two glasses form one chamber, three glasses form two chambers, and so on.
There may be a desiccant inside the spacers to absorb excess moisture and prevent fogging. Double-glazed windows are inserted into a profile from, or: a palm tree that holds a plastic profile for a year in a row. 
If multi-chamber double-glazed windows are used, then distance between panes within the same design may differ, but it will still not be more than 20 mm. Reducing the distance allows you to nullify the thermal convection between the panes, and as a result, it is possible to save a significant part of the heat of the inner glass and not let it out into the street. This is the basis for more effective thermal insulation of double-glazed windows compared to old windows. To create the most warm and quiet window, manufacturers are introducing many other technologies, such as the use of special glasses, seals, filling the chamber with argon and xenon.
In warm Europe, single-chamber double-glazed windows are considered the most popular, and double-glazed windows are rarely installed there. In the conditions of a harsh domestic climate, you can not even look at single-chamber structures - two-chamber double-glazed windows will be optimal in most regions, and in some especially cold areas - three-chamber ones.
The more chambers in the design, the warmer the window will be, and physics explains this very simply: in several chambers it is possible to conclude a larger heat-shielding layer of air, and it prevents convective heat transfer. So, for example, an average single-chamber double-glazed window has a heat transfer resistance of about 0.3 m 2 K / W, a two-chamber one - 0.5 m 2 K / W, and a three-chamber one - 0.7 m 2 K / W or more. But a large number of cameras have their drawbacks, so it is not appropriate to insert a three-chamber double-glazed window into every window. 
Consider the advantages, disadvantages and areas of use of double-glazed windows with a different number of cameras:
Double-glazed windows with four or more chambers are considered exclusive, and their necessity is a big question.
The classic option is the use in a double-glazed window ordinary float glass 4-6 mm thick. The technology makes it possible to obtain glass that is perfectly even and of the same thickness, which perfectly transmits light from the street. The standard is glass with a thickness of 4 mm, thicker (5-6 mm) is recommended for use in noisy areas and on the upper floors, where gusts of wind have a decent force. An ordinary double-glazed window has good heat and sound insulation properties, it resists fire well, but there is no limit to perfection - today glasses have appeared where certain characteristics are significantly improved.
In addition to the usual ones, they can also be used special glazing:
Some manufacturers offer even more modern and "smart" double-glazed windows. For example, in Japan they invented dirt-repellent coating, thanks to which there is no need for constant washing of windows, and this is a significant savings when it comes to high-rise buildings. Dirt almost does not stick to such glass, under the action of sunlight it is destroyed and washed off by rainwater.
Some manufacturers offer double-glazed windows that allow you to easily change the level of glass transparency and if necessary turn it matte to keep prying eyes out. To solve the problem of ice formation, double-glazed windows with electric heating. Heating the glass makes snow and ice melt, and at the same time acts as an additional source of heat in the apartment.
In addition, today you can choose double-glazed windows with decorative glass, which can have any desired color or even mimic . Such products are made according to an individual project.
Modern double-glazed windows allow you to effectively solve not only the issues of thermal insulation, but also the absorption of street noise. City dwellers should appreciate this property.
Noise isolation characteristics depend on the following parameters:
The wider the double-glazed window, the better its sound insulation, and a double-glazed window with a width of 42 mm will be much “quieter” than a two-chamber double-glazed window with a width of 28 mm. With an increase in the chamber by 3 mm, the sound insulation increases by an average of 10%, and a two-chamber double-glazed window is already 40-45% more effective in terms of sound insulation than a single-chamber one. At the same time, the thermal insulation characteristics increase with an increase in the chamber up to 16 mm, stabilize in the range of 16–24 mm, and then deteriorate due to convective heat transfer.
Distance between panes should not be more than 20 mm, but, as a rule, it is 6-16 mm, and the more glasses are used, the smaller the distance between them, since the total width of the double-glazed window should not exceed 60 mm. And then the manufacturers go to the trick, and make chambers of different thicknesses, achieving the destruction of the symmetry of the system, leading to resonance. 
Excellent effect in terms of sound insulation and has use of glass of different thicknesses. When a sound wave collides with barriers of the same properties (glasses of the same thickness), it easily passes through them. If the barriers have different parameters, then it will be more difficult for the sound wave, and it will lose a huge part of the energy. Glasses of different thicknesses do not enter into resonance and make the apartment quieter by about 30%. In a double-glazed window, only one glass should be 6 mm thick, let the rest be ordinary, 4 mm thick, so that the structure is not overweight.
If, in addition to everything, triplex type glass is used in the double-glazed unit, which dampens noise well, then it is possible to achieve the highest results. 
The insulating glass chamber can be filled with one of the following gases:
A promising direction is the production double-glazed windows with vacuum inside. Vacuum does not conduct heat at all, therefore it will provide maximum thermal insulation, only the manufacture of such double-glazed windows differs in a number of technical difficulties, therefore it costs a pretty penny and is not widely used.
On a remote frame in a double-glazed window, literally everything is kept. It holds the glass and sets the required distance between them. It is better to choose a double-glazed window with a frame not made of aluminum, but made of steel, because its thermal conductivity is lower, but even better is to use a full fiberglass or plastic frame.
Glasses are connected to the distance frame by means of butyl and thiokol, which isolate the entire structure and give it the necessary physical properties. In fact, all well-known manufacturers of double-glazed windows use a similar connection method, but there are also unfortunate companies that glue the entire “pie” with double-sided tape.
Additionally, thin decorative frames can be installed inside, which form an interesting layout. 
The characteristics of a double-glazed window are often presented in the form of a formula, which it would be nice to be able to read correctly so as not to fall into the possible tricks of sellers. The formula is presented in the form “glass thickness and its type - chamber thickness and its filler - glass thickness and its appearance ...”, and they start with the outer (street-facing) glass.
For example, double-glazed window, which is described by the formula 6M1-16-4M1-12Ar-4I, consists of three glasses and two chambers. The outer glass is normal 6mm thick, followed by a 16mm air-filled chamber, then 4mm regular glass, a 12mm argon filled chamber, and 4mm low-emissivity i-glass. Such a double-glazed window will perfectly retain heat and provide good sound insulation.
The specialist of the company that manufactures windows must choose the appropriate option, but it’s better to be aware of such subtleties yourself in order to choose the right double-glazed window. 
When choosing a double-glazed window, first of all, it is necessary to proceed from the weather outside the window and personal requirements put forward to the design. For warm regions, a single-chamber or single-chamber low-emission double-glazed window will be enough. In other cases, it is better to look towards two-chamber structures. 
Each type of double-glazed window is characterized by its own heat transfer resistance index: for a conventional single-chamber this indicator is at the level of 0.3-0.37 m 2 * C / W, and for a wide two-chamber it is already 0.5-0.62 m 2 * C / W. In order not to overpay, it is important to take into account the real needs for heat saving. So, for example, for the Moscow region, according to building codes, it is better to use window blocks with a heat transfer resistance of at least 0.55 m 2 * C / W. This requirement is met by a two-chamber ordinary double-glazed window and a single-chamber with i-glass and argon filling. 
In pursuit of high-quality double-glazed windows, don't forget your profile: if it is thin, and there are gaps in the structure, then the house will still be cold and noisy.
There are many factors that affect the cost of double glazing.
You can save on buying double-glazed windows if carefully consider the requirements that are put forward to the window block in each room. Companies often force a customer to choose one type of construction for all windows, although this is often not necessary. For a bedroom, for example, sound insulation and thermal protection are important, and in the kitchen you can put far from the “warmest” and “quiet” window - it is important here that it skillfully open both completely and slightly, and forming a small gap. For the first floors, a tinted or burglar-proof window would be appropriate.
However, it is important not to overdo it with savings. Too cheap offers are immediately rejected, as well as frankly inconvenient options. For example, a deaf window block will be inexpensive, but it is inconvenient to use. On the other hand, too intrusive offers of a costly feature manager should also not be credible.
When the double-glazed window is ready, it is necessary to inspect it. There must be a marking indicating the date of production and the manufacturer, some companies assign each product its own individual number. There should not be any chips and cracks, the glass should have a smooth smooth surface, and the double-glazed window should have the correct geometry. It does not hurt to measure the diagonals of the structure and compare them: with a discrepancy of more than 3 mm, we can talk about a poor-quality product. 
Windows are installed for at least 10-15 years, so when choosing them, it does not hurt to spend a little time collecting information and studying the market.
