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How to choose the right WINDOW?


wood aluminium windows
The odds are that majority of us remember the time when to add on the room temperature we simply had to turn up the heat from the heater, and when it got too hot, we threw the windows wide open without thinking how much this heat actually costs. 


Now that we have understood the real price of warmth in our homes and started looking for possibilities to get the rooms warm and save the money. Although the thermal resistance of the walls often requires improvements, yet much the largest source of thermal loss are windows.


The most affordable replacement for old windows was plastic windows that were the first on the market. After a while the product range was augmented by wooden and wood-aluminium windows. Some more time passed and the window-buyers already had to answer questions, whether to prefer windows of German, Finnish or Danish type; whether to order ordinary or selective window panes; whether the windows should be provided with two- or three-fold glazing units; whether the three-fold glazing unit should include one or two low-energy panes; whether to order argon gas between the glazing units, or does the standard air filler suit as well; whether to choose 18mm glazing bead between the glazing units or to settle for narrower ones etc? For certain many people’s wish to acquaint themselves exhaustively with the psychology of windows ended soon, and simply „good and cheap” windows were ordered. Unfortunately those people are now likely to face the same questions as 10-15 years ago, because the investment is not about to pay off. So that it wouldn’t go as far as this, herein we attempt to make it a little clearer and hope to thereby ease your window selection process.




wooden windows
First you have to decide which window materials to prefer. As said, the choice of materials at large divides into three, so that you have to choose between plastic, wooden or wood-aluminium windows. The architectural design of the building certainly matters, when choosing the material for windows.


As the price disparity is large, you will have to decide whether you want the windows for your home for decades, or for a temporary stopover that you would gladly leave, hoping that new windows will boost the price of the real estate.


Plastic windows are twice as cheap as wooden windows. Unfortunately this is their only advantage. You can read about the advantages of wooden windows in this article here.


Wooden windows are usually made of finger-jointed Pine wood. Certainly also Okoume, Meranti, Eucalyptus, Oak and Mahogany offer exciting possibilities that guarantee an exclusive appearance for the windows, if natural finishes are used. You can acquaint yourself with windows and balcony doors made of tropical Okoume wood here.


Contemporary paint industry’s top technological wood finishing products and wood paints guarantee the preservation of wood’s physical properties as well as excellent appearance during long years. Hereby we direct your attention to the fact that the task of a high quality finishing material is not only to protect the wood from mould and humidity, but it also has to guarantee an ideal bonding of finishing paint to wood.

Quality wooden window paints are especially designed high elasticity products that guarantee the crack-resistance of paints in window profile joints and surface of frames even in case of intensive sunlight. This way humidity does not get between wood and paint, and the wooden window will be truly durable.


wooden windows
Wood-aluminium window is a product in which the outer side of a wooden window is covered with aluminium profiles. Like this the window will be even more weatherproof.

If the Sun bleaches a dark colour wooden window on the southward and westward sides of the building, you can simply paint it over. But if on the outer side of the window there is an aluminium profile that is painted dark, then using a brush to paint the smooth surface of metal over, you will not necessarily achieve a good result. Thus each window buyer should consider if more than 30 percent mark-up when ordering wood-aluminium and aluminium windows is justified enough. Contrarily, light powder-painted and anodized aluminium cover tones (natural aluminium, light and dark bronze) will sustain well even on facades with large UV-load. If the facade of the building presumes more modern use of materials, we especially suggest those solutions.


It is also useful to know that adding aluminium to the exterior surface of wooden windows does not improve their thermal and sound insulation properties.

Aluminium windows are preferably used in glass facades of large office buildings, but we also see them in more modern-architecture villas and apartment buildings. Aluminium windows are usually of German type and their thermal insulation level is generally the lowest. Aluminium windows are also the most expensive.


As we know, the market share of plastic windows totals 45-50 per cent, and the market share of wooden and wood-aluminium windows also 45-50 per cent. The market share of aluminium windows is less than 5 per cent.

Considering the pros and cons of wooden and wood-aluminium windows, 75 per cent of inhabitants of Estonia prefer wooden and 25 per cent wood-aluminium windows.




wooden windows
Once we have chosen the material, we should make a decision about the window type. On our market there are represented German, Finnish and Danish window types. Infrequently we also encounter American type sash windows that are horizontally divided into two parts, and the lower part can be moved up and down. Immediately said, as a standard solution the thermal and sound insulation properties of those window types are more or less equal. Thus, when choosing the windows, one should take into account their appearance, compatibility with the environment, ease of use, and demands about durability.


German type “tilt and turn” windows have one important advantage in front of competitors – their construction allows to easily achieve excellent thermal and sound insulation properties, which guarantees an excellent price-quality ratio. Since German type windows open entirely inward, they can be used rain or shine in micro- as well as ordinary ventilation position. Additionally, inward opening windows are very easy to clean. Thanks to their airy design, the German type windows are a perfect fit for decorating the facades of new as well as renovated buildings.


If a window of German type generally has one sash with two- or three-fold glazing unit in it, then Finnish type windows have two separate sashes, inner one with two-fold glazing unit and outer one with a single glass pane. Outer and inner sashes are united by a clamp so that the window can be opened just up to a score of centimetres, and only sideward. Assuredly you will notice the cons of this construction; if not earlier, then during the first window cleaning. Thanks to their more archaic construction, windows of Finnish type are better matched with more rustic buildings.


Danish type casement windows have sashes that are just 60mm thick, which does not allow using a three-fold glazing unit with a proper thermal insulation. A client can also decide in favour of a thicker sash and three-fold glazing unit, but in that case the price of only outward-opening Danish type windows significantly exceeds the price of German type windows. Although Danish type windows have a jamb width of even 90-100mm, it does not add to their thermal insulation. It is though worth to know that the vertical and horizontal piers between windows are as thick as jambs, and these jut out to the interior far from the window surface, so not everyone likes them. When leaving home, you should definitely close Danish and Finnish type windows, because failing which an unexpected rainfall may cause you an unpleasant surprise.


Almost 90 per cent of European window buyers prefer German type windows and that many people cannot be wrong. In this the choice of an appropriate window type should also be relatively easy for you.


Worth to know! No matter the type of windows, it is possible to order window frame integrated ventilation valves. Kalesi does not recommend such solution because when milling the ventilation opening, the thermal and sound insulation of the window frame will be irrevocably damaged. To direct the ambient air into the rooms, we suggest the use of micro ventilation position or the ventilation system.




wood aluminium windows
Window panes play the most decisive role in thermal and sound insulation. Glazing unit usually comprises of two or three glass panes and they are bound together by an aluminium or plastic spacer profile to form an air-tight whole. Connecting spacers are glued between the glasses using butylated mastic, and to guarantee the air-tightness, the edges of the glazing unit are covered with the same material. Customary glazing unit, one that conforms to the construction norms currently valid in Estonia, is glued together from two 4mm thick glass panes between which an 18mm aluminium spacer  is installed. Inside the spacer is a filling that absorbs the humidity in the air or argon between glass panes.


The inner side of the room-facing glass pane of the glazing unit is usually coated with low-energy glass surface layer that reflects the room warmth from the glass pane back to the room, and the cold back outside. Implementing low-energy glasses is undoubtedly the crowning achievement of contemporary glass industry. Using one low-energy glass in a dual glazing unit increases the thermal insulation of the window by 100 per cent. In a triple glazing unit it is possible to use a maximum of two low-energy glasses. Using a second low-energy glass adds another 30 per cent to the thermal insulation of the glazing unit.


Gas filler of the glazing units


To improve the thermal insulation it is possible to fill the space between glasses with argon or crypton gas. Crypton-filled glazing unit has better thermal insulation but unfortunately it is difficult to find glass producers in the adjacent countries that would use the more expensive gas in glazing unit production.


Argon gas is relatively cheap and conducts heat less than air. Using argon in a two-fold glazing unit with an 18mm spacer improves the thermal insulation of the unit by approx. 22 per cent. It is important to note here that in a three-fold argon-filled unit with just 10mm spacer beads the result does not improve. However, the thermal insulation of a three-fold, argon-filled glazing unit will rise as much as 30 per cent if the width of spacer beads is 15mm.


Important to know! Often clients doubt the consistency of argon in glazing unit, and rightly so. Such a situation may indeed arise, if the window producer has ordered the glazing unit from a producer that cannot guarantee an air-tight production process.


Sound insulation of glasses


To improve the sound insulation of windows, the glazing unit is made of glass panes of various thicknesses, or partly laminated glasses are used. Glasses of dissimilar thickness let different sound frequencies pass, and the external noise will not get inside as easily.


Avoiding the condensate


wooden windows
The coldest part of a window is the edge of glazing unit. To stop the condensate appearing on the lower edge of the inside of the glazing unit, plastic or other composite material spacers are used that conduct heat significantly less. This minimizes the probability of humidity condensing, but during the cold period the spacers cannot entirely prevent the appearance of condensate without the help of heating and ventilation systems.


If such a problem arises, it requires an instant solution because due to the influences of long standing condensate mould can appear on the frames of plastic as well as wooden windows. Wooden window frames can get irrevocably damaged due to the excess humidity and this up to corner pins expanding open. Internal climate of the rooms should be especially monitored during the construction period, when the relative humidity of the air should not exceed 60 per cent. After all, excess humidity is harmful not only to windows, but to all other parts of construction as well, not to speak of finishing and furniture more generally.


Choices of glass panes


In addition to ordinary glasses, for compiling the glazing unit it is possible to use toned, high-tempered or laminated glasses to meet your needs for beauty and security.




When you have come to terms with yourself considering the material, type and glasses of the windows, it only remains to order the windows. For this you have to measure your window openings and come to a store that sells the windows of your choice. Together we can choose the suitable modes of opening, colour tones, glass pane types and the rest of essential things to guarantee your peace of mind for long years.


The owners of homes with passive windows can sleep particularly peacefully because thanks to low heating expenses the investment will pay back soon, and the rest is already net gain. Passive windows also guarantee a warm and cosy presence near the windows during cold winter nights, because they do not give off waves of cold.


Worth to know! When installing windows, you should not forget ventilation! Winterizing an old house usually begins with replacing windows and improving the efficiency of heating systems. The next step should definitely be undertaking the concerns of ventilation, but people rarely get around to solving these issues. The result is constant ill-being due to close air that does not let you take a full delight in decreased heating bills. It does not help to curse the „excessive tightness“ of windows, since good windows are meant to be tight and thermal.


We wish you clever choices!