Euroview 70 Technical Manual - West Coast Vinyl Windows

Chapter
7
58
Construction basics
Expressed simply, in the case of white PVC-U-windows, elon-
gations of ± 1,25 mm per 1m window width should be used
when calculating joint widths. In case of windows with
coloured surfaces, this value is doubled because of the dif-
ference in the surface temperatures attained (T = 60°C in-
stead of 30°C).
In case of windows with coloured surfaces, the vertical de-
flection to the window plane should also be taken into con-
sideration through the requirements concerning the window
size, the reinforcing, and the distances of fastening points.
This is due to the small heat conductance of the PVC-U-pro-
files.
7.3 Thermal insulation
Beside the energy saving, the legislator gives top priority to
the thermal insulation in building construction (see DIN 4108
and Energy Saving Decree (EnEV)) and constantly increases
the requirements on the building industry. The concentra-
tion on energy saving insulation values and decibel should
not lead to disregard of room climate comfort.
Measures for thermal insulation shall:
■ reduce heat loss,
■ avoid overheating in summer,
■ avoid hypothermia in winter,
■ avoid damaging condensation but also (a fact that is for-
gotten most of the time):
■ ensure comfort.
Both sets of regulations require:
“Joints in the building envelope are to be sealed
permanently air tight according to best practice.’’
DIN 4108 includes all the characteristic values concerning
thermal and humidity insulation, methods of calculation as
well as requirements and information about the planning and
execution.
The requirement of DIN 4108-2, that the change of air (stan-
dard ventilation rate s = 0,8 · h -1 ) is to be ensured in terms
of planning, takes some of the load off the window manu-
facturer and the installation company.
But for all that a hint about the importance of the correct
ventilation can’t do any harm and can help to avoid the for-
mation of mildew and humidity damage!
7.3.1 Heat conductance
The heat conductance of the building materials is an impor-
tant characteristic for securing these requirements. In sub-
stances, heat is transported from particle to particle by ther-
mal conduction, which is characterised by the heat conduc-
tance . This indicates the quantity of heat which is trans-
ported between two coplanar even surfaces each with an area
of 1 m 2 through a 1 m thick layer with a temperature differ-
ence of 1 K.
However, the heat conductance is not a constant value, but
dependent on:
■ temperature,
■ humidity content,
■ moulded density,
■ size, nature and arrangement of pores,
■ gas pressure in the pores,
■ nature of the gas in the pores.
Nevertheless, the heat conductance , mostly determined at
20°C, gives important information for the choice of suitable
building materials (see chart 12).
RAL-GÜTEGEMEINSCHAFT KUNSTSTOFF-FENSTERSYSTEME