Environmental Engineering Reference
In-Depth Information
250
208
200
Cooling load
Ventilation gain
185
150
94
100
78
74
71
69
54
47
50
36
35
25
25
11
0
Figure 2.17 Ventilation gains from the double fa¸ade for varying ventilation strategies together with
the total daily cooling load of the office
When extrapolated to the complete month of August, the total ventilation heat gain
with varying air exchange rates and two tilted windows is about 2 kWhm 2 per month.
This value is not that high in absolute terms, but three times higher than ambient air
ventilation.
2.3.2 Parameter Study Using Simulation
Further studies on the total heat gain of double and active fa¸ades were done with
TRNSYS, into which the newly developed fa¸ade model was integrated (type 111).
A schematic description of the room in the office building described above, as well as
of the wall constructions used for the building model, is given in Figure 2.18.
At first the influence of window sizing for a single fa¸ade system was investi-
gated. The air change rate was set to 0.7 h 1 , and all internal walls as well as floor
and ceiling areas are boundary walls where the adjacent room temperature was as-
sumed to be identical to the zone temperature. The external fa¸ade faces south and
the ambient climatic conditions used (temperature and solar radiation) correspond to
the standard reference climate for Germany as defined in DIN 4108-6 (2003). The
internal loads were set to zero.
In Figure 2.19, the yearly heating and cooling loads of the office are shown for
different window areas (given as a percentage of wall area). The monthly heating en-
ergy balance method from the European standard EN 832 implemented in the software
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