Wooden-aluminium windows are the most modern solution in the window industry, especially for regions with high humidity in the atmosphere, coastal climate and weather that’s characteristic for the northern part. Wooden-aluminium windows combine sound and thermal insulation that is characteristic for wooden windows and moisture resistance that is characteristic for aluminium windows. Flora offers two kinds of profiles:
Aluminium lining for wooden frames
Wooden-aluminium windows are made based with wooden frame and mounting aluminium linings on top of it. It would be more accurate to call these wooden windows with aluminium lining. Using this construction a good atmosphere can be established in the room, guaranteeing that the aluminium outside will ensure optimal window protection from the weather, which means that the windows will be durable. Because of this durability ease of care, wooden windows with aluminium lining are the best choice economy-wise. These factors provide a chance to reduce the costs of exploitation. Aluminium is lightweight, durable and almost non-corrosive material which has a high durability against the effect of environment. Their finishing perfectly integrates windows and doors with different facades. Aluminium surface also does not require painting. Aluminium linings are attached to wooden details with staples and are not in touch with wood. Therefore the wood under aluminium is ventilated and there is no threat of accumulating moisture. Since aluminium extends linearly, it has to be taken into consideration that after assembly aluminium should not be directly attached to plaster or facade frame, there must always be expansion joints.
Offered wooden-aluminium solutions
Flora offers wooden windows with aluminium lining based on two profiles that have the same thickness – 78 mm. It is possible to integrate both single-chamber and double-chamber glass in both profiles. See more about each profile and their differences and advantages in their descriptions:
Wooden window frame and sash
Wooden window frame and sash are made from laminated wooden scantlings consisting of multiple layers glued in thickness (lamellae). The middle lamellae of the scantling are usually finger-jointed, the external can be both jointed (the so-called “glued” or optimized scantlings) and solid unjointed (fixed scantlings). Windows are most commonly made from pine or oak scantlings; however, material of other wood species is also available, for instance, larch, meranti, sipo etc.
The width of frame and sash profiles is usually 80mm, thickness 68, 78, 90 or 98mm. Windows opening inwards. The bottom of the frame contains cuts for easy installation of internal and external windowsills.
For finishing of windows and other structures, we apply the water-based impregnant, primer, paints and varnishes produced by Teknos. We offer 54 tones of tinted varnish and covering paints according to RAL or NCS catalogues.
Thermal conductivity coefficient of a window
Thermal conductivity coefficient of a window Uw represents the heat loss through a square meter of the window area when the temperature difference is 1°C. The lower the number, the more energy-efficient is the window (saving heat). According to the standard DIN EN ISO 10077-1, it is calculated and also verified for turn-only windows with dimensions 1230*1480mm. Uw is mainly determined by thermal conductivity of the insulating glass unit and wooden frame and sash, as well as by the spacers of the insulating glass unit and sash seals. By choosing an insulating glass unit with the so-called “warm” spacer, Uw of the window may be reduced by approximately 0.1 W/m2*K. Since usually the thermal conductivity of an insulating glass unit is significantly lower than that of the wooden frame and sash, then Uw will be higher for a smaller window and window with divisions. This means that heat losses through a square meter of the window will increase. For wooden windows, Uw ranges from 0.7 to 1.8 W/m2*K depending on the profile system, the type, size and configuration of the insulating glass unit.
Insulating glass unit
An insulating glass unit consists of 2 (a single-chamber unit) or 3 (a double-chamber unit) glasses and separating slats or spacers, the whole structure is glued and sealed using a butyl sealant. Spacers usually are made of aluminium or aluminium combined with plastic materials (the so-called “warm” spacers). The space between the glasses is filled with argon. Energy-efficient insulating glass units feature a special (selective) coating on the glass surface, which reflects the infrared (heat) radiation back into the room reducing heat loss. This feature of the insulating glass unit is characterized by thermal permeability coefficient Ug (W/m2*K). The smaller the coefficient, the less heat is lost through the insulating glass unit. For a single-chamber insulating glass unit (with 2 glasses) the Ug value is around 1.1 W/m2*K, for a double-chamber (with 3 glasses) it ranges from 0.8 up to 0.5 W/m2*K, depending on the glass type, the type of selective coating and thickness of the insulating glass unit. For comparison – for a 4mm single-layer glazing Ug =5.7 W/m2*K.
The sound insulation
The range of human ear sensitivity is extremely wide, therefore in acoustics the sound intensity is measured in logarithmic units – decibels (dB). The quietest sound a human ear can perceive (threshold of hearing) is assumed to be 0 dB. Different volume levels can be roughly described as follows:
20 dB- rustling leaves (100 times greater sound intensity than 0dB)
30 dB- whisper (1000 times greater sound intensity than 0dB)
40 dB- peaceful classroom (10000 times greater sound intensity than 0dB)
50 dB- a passing car (100000 times greater sound intensity than 0dB)
60 dB- human speech (1000000 times greater sound intensity than 0dB)
80 dB- heavy traffic in city
100 dB- perforator
120 dB- rock concert
140 dB- pain threshold (100000000000000 times greater sound intensity than 0dB)
180 dB- rocket launch
Therefore, if the sound insulation of a window is 30 dB, which means loss of sound intensity by 1000 times, the human voice speaking outside the window we hear as a whisper. The change in volume by 3 dB people perceive as barely noticeable.