Wood learns to cope with difficult conditions during its growth.

Wood windows, especially those that are industrially manufactured, have high durability. They are resistant to high degrees of temperature and physical loads.

uPVC windows need to be supported by steel profiles. uPVC profiles tend to deform when they face a constant load. Since steel profile does not usually follow corners, sash may change shape in unfavorable conditions. As a result, the sash opens and closes badly. It is impossible to fix a deformed sash.

It is obvious that materials with bad insulation values cause more energy loss. Wood is one of the least conductive materials since it is a cellular and porous material and since the lack of free electrons required for energy to be transferred from one molecule to another like metals. It is beyond discussion that wood has a better insulation value than uPVC (thermal conductivity is 0.13 W/mK on average). This value is 5.9 W/mK in aluminum whereas it is around 0.8 W/mK in PVC. The reason why wood is used on the handles of hand tools is because of this low heat conductivity property.

The fact that upto 85% of residential buildings in Scandinavia are made using wood is the best example that shows how wood can resist against the harsh climatic conditions. Wood is extremely strong even though it is a very light material. For example, tensile strength of wood is 100 N/mm2 and specific gravity of wood is 0.6 N/cm3 whereas tensile strength of steel is 500 N/mm2 and specific gravity of steel is 7.89 N/cm2. Tensile strength divided by specific gravity, gives the breaking length and quality of the material. While the rate of tensile strength to specific gravity of the wood is 166 N.cm3/g.mm2, the same rate of steel is a very low value like 63 N.cm3/g/mm2. This shows the breaking length when the material is hung under its own load. The breaking length of steel used in construction is 5.4 km, chromium molybdenum steel 6.8 km, hardened curved steel 17.5 km, spruce 19.8 km and beech 28.3 km. Similarly laminated woods are up to 5.5 times superior to some steels. All these explain why wood is frequently used in sports and healthcare centers.

Wood is a complex material in terms of its behavior against sound. The sound transmission speed of wood is close to metals but on the other hand it also has surprisingly high sound absorption values. Thus, it absorbs reflected sounds and noise. That is the reason of common use of wood in concert halls.

Wood does not loose considerable physical strength until reaching burning temperatures. Its artificial alternatives weaken and soften depending on the temperature they are subjected to. The difference of wood and its alternatives in case of fire are discussed in the relevant link.

Wood windows are not affected by hazardous materials in air when maintained correctly. Those with aluminum cladding provide even more protection. uPVC is easily damaged by external conditions, its surface gets pale and brittle with time.

Wood windows and doors have been favorite products for architects because they fit any facade and integrates with it.

Compared Value	Wood	uPVC
Mechanical strength		-
Deformation by the effect of heat		-
Thermal insulation
Noise insulation
Resistance against chemicals		-
Fire safety		-
Architectural use