Euroview 70 Technical Manual - West Coast Vinyl Windows

Chapter
7
54
Construction basics
Under these circumstances, the dew point is attained at
9,3°C. For practical experience the path of the 10°C-
isotherms is calculated for the building envelope. After that,
the installation plane of the window has to be chosen in
such a way that the 10°C-isotherm path doesn’t run at an
inner surface or in the interior of the building.
But if the dew point lies inside the building envelope or even
at an inner surface,
■ the condensed water must be able to condense to the out-
side
■ or to be drawn in such a way that the building won’t suf-
fer damage.
This is attained as a first approximation if the installation
plane is
■ in case of a monolithic wall: in the centre of the wall,
■ in case of a shell-like wall construction: in the range of
the insulation. 1)
inside
- 2°C
1°C
4°C
7°C
10°C
12,6°C
16°C
10°C
Examples of isothermal paths for typical installation situa-
tions are shown in fig. 36 up to fig. 39.
To reduce the risk of the formation of mildew – which exists
already with an air humidity of 80% or more – by means of
constructive measures, a surface temperature of si ≥ 12,6°C
should be maintained according to DIN 4108-2 (except win-
dows).
That means, that the temperature factor must be t Rsi ≥ 0,70.
It is imperative:
RAL-GÜTEGEMEINSCHAFT KUNSTSTOFF-FENSTERSYSTEME
t Rsi =
si – e
i – e
si = surface temperature inside
i = air temperature inside = 20 °C
e = air temperature outside
Fig 36: Influence of the fitting position on the 10°C-isothermal path
central outside
10°C
Condensate, because the 10°C-isotherm leaks out of the building component
outside -5°C
inside +20°C
10°C
Fig. 37: Concrete wall with pre-masonry and
rear ventilated insulation zone, plas-
tic window with case of windows in
the range of the insulation zone
1) The Gütegemeinschaft Kunststoff-Fenstersysteme (GKFP)
can be asked by distributors for special software for the calculation
of two-dimensional heat flows.