Windows

What is the modern window? Even today we have twin or separate wooden window blocks with plate glass. The majority of modern high-rise buildings are supplied with notorious woodwork which is pervious to cold air and dust, which needs constant tinting, sealing and unfastening during washing.

But the modern window is a complex construction which consists of a double-glass pane and profile (window sash and case). Such a construction along with high aesthetic characteristics possesses excellent heat and sound insulation, durability and stability against environmental activity. Profile may be made of plastic, wood, aluminum or combined materials. The leaves of the modern window may be opened in different ways: flinging open and folding, window frames are furnished with airing devices and other sophisticated arrangements. Finally, in contrast to "woodwork" they can become a perfect decoration for the facade of a building and the interior.

Thus, regardless of the type of a house - wooden or stone - one should mean only modern windows with double-glass panes since they secure the necessary standard of thermal protection.

Some words about double-glass panes

Double-glass pane is an impermeable construction which consists of two (one-chamber), three (two-chamber) and three (three-chamber) panes between which there is a thin-walled frame with perforation. The double-glass pane is filled with dried or inert gas (to improve the energy-efficient characteristics). The frame contains special granulated material (silica gel) which absorbs residual moisture from the air inside the double-glass pane and protects the pane from sweating. An ordinary one-chamber double-glass pane has thickness of 24 mm (4-16-4). The resistance coefficient of heat transfer of such a window is 0,34 m² °/ВW, while according to the standard it must be 0,56 m² °С/W. It means that at least two-chamber double-glass windows must be applied in our climatic conditions. At present special energy-efficient glass with low-emission coating (K-glass and I-glass) can be applied.

Which profile is better - wooden or plastic?
Hidden drawbacks and evident advantages

The debates about which profile is better have been going on. Some people claim that windows must be made of wood, others say that plastic windows are the most practical. But these debates make no sense because the both kinds of the window profiles have their own advantages and disadvantages. And in order to win the competition one should respect one's competitor and know his strength.

Plastic windows have proved their justifiability. Consumers have appreciated plastic windows since their advantages are well-known. Such windows are more manufactureable than wooden ones; during operation they do not need tinting and repairing, they are easy to wash, they are moistureproof during repairing. Moreover, plastic windows are cheaper than wooden windows of high quality. By the way, the last argument is much weightier for the majority of our customers.

And what about the drawbacks? First of all, plastic windows do not breathe. After proper assembling plastic windows are almost absolutely hermetic, that is why if you do not open them, there will be short of oxygen in the room. If there are many people in the room moisture increases and mould appears. Natural wood in contrast to even the most quality plastic breathes, that is it slowly lets air in through microvoids. On the average for 24 hours the standard wooden profile lets in approximately 2,7m³ of air, which secures constant airing of the room and prevents sweating.

The second drawback of plastic windows, which is little talked about, is more important. The point is that the thermal expansion coefficient of plastic is rather high and it differs from the similar characteristics of glass. In practice it means that plastic profile changes its linear dimensions under the influence of temperature and during operation buckling of the window leaves occurs due to low temperature. In theory, the steel infilling in the profile must compensate this, but if the technological process was not kept properly (for example, the infilling with thin walls was applied or it was not applied at all) the window changes its form. Thus, it is not advisable to apply plastic windows with large glazing area.

But there are such characteristics which are peculiar only to wooden windows. Wooden windows perfectly match the interior and they are considered to be the part of the interior (for example, as furniture). Plastic windows will never meet this requirement, even if high-quality polymer films are used (exactly as furniture made of natural wood is better than that of synthetic substitute). That is why well-off people tend to install good wooden windows. Unfortunately, people of average income ca not afford wooden windows due to their high price, that is why they often prefer cheaper plastic windows.

But the preponderance of plastic windows is on the wane. Besides, some trouble points of plastic windows are revealed themselves . Moreover, some tests have proved that the characteristics of resistance to heat transfer of plastic windows are overrated. That is why in many European countries the production of plastic windows becomes less and less popular, for example, in cold Norway, Finland and Sweden about 70% of all windows are made of wood.

Modern wooden windows

There are two kinds of modern wooden windows: windows made of whole timber and of glued timber. Windows of the first kind are much cheaper, but less practical. With the lapse of time they change their form; even if they are treated with antiseptic they need constant service, they are very susceptible to moisture change and cracking. And the best wooden windows are made of glued timber. The price of such windows is rather high as the production of such constructions requires a number of complicated processing steps:

• bucking logs skillfully, and sawing boards to lamellas
• drying
• calibrating
• sorting out
• jointing
• machine-processing
• gluing together
• again machine-processing.

After that the timber is processed, then cases and leaves are assembled. At last, they are surfaced several times, treated and covered with antiseptic, base coating and stop-off lacquer. Then double-glass pane is installed, furniture and sealants are adjusted. The whole complicated process is described in details here.

For window production various kinds of wood are used, fine wood including, which affects the price of the end item. However, due to skillfully matched toning colour even inexpensive wood may look like fine wood (for example, a window made of pinewood may look like one made of oak).

Wood-aluminum window systems

To prolong life service of the wooden window made of glued timber combined constructions are produced from wood and aluminum. In this case the interior part of the window is made of wood and the outer part is made of aluminum. Such constructions have quite good prospects. But there are also some difficulties.

Nowadays there are several ways of wood-aluminum window system production. Our market is generally under the influence of the "Italian system" which means that the double-glass pane is to fasten straight to the aluminum strip. This system is not functional because of sweating on the inner surface of the double-glass pane. The "Finnish" variant of the wood-aluminum window implicates two separate windows made of wood and aluminum, which are not fastened together. Their main drawback is that such windows can be opened only in the traditional way, they can be flung open but not folded).

"German" system is the best kind of wood-aluminum windows. In this construction the double-glass pane is protected with wooden window rabbet on the outside, and aluminum profile is put on the wooden window rabbet. This profile is fastened in such a way that water does not leak inwards. It is noticeable that aluminum and wood have different thermal conduction. If we put them together cold areas will appear between them. That is why there must be air chamber between aluminum and wood. This construction is more expensive but it is the most manufacturable. This is the technology which is applied by "Variant Ltd." for wood-aluminum window production.