Advanced Building Simulation

S d (h)
80
60
40
20
0
–80
2
Uncertainty in building simulation 41
1 16 10 3
6
8 45 20
21 11
15 14 27 25 30 922
24 23 26 29 12 13 28 1718
19
31
33 34 32
35
36 38 37
39
78
43
76
82 6263 56 72 71 53 61 57 74 51 55 41 44 59 65 40 42
45
46 48 49 58 60 64 66 67 68 69 73 75 54 47 50 52 70 79
81 8077
83 –60 –40
7
85
84
–20 0 20
md (h)
40 60 80
Figure 2.7 Sample mean m d and standard deviation S d of the elementary effects on the performance
indicator TO obtained in the parameter screening.The numbers in the plot are the parameter
indices (see Table 2.2).The dotted lines constituting the wedge are described by m d�
�2 S d/√r. Points above this wedge indicate significant nonlinear effects or parameter interactions.
Table 2.2 Parameters that emerge from the parameter
screening as most important
Index Description
2 Wind pressure difference coefficients
1 Wind reduction factor
16 Temperature stratification in space under study
19 Local outdoor temperature
10 External heat transfer coefficients
of the total variance, leaving 10% for the remaining 84 parameters and another 5%
for interactions. These numbers confirm that the parameters in Table 2.2 are the
parameters of interest.
2.3.7 Discussion and conclusions
Three immediate conclusions can be drawn from the results in the previous sections.
First, the five parameters in Table 2.2, that is the wind pressure difference coefficients,
the wind reduction factor, temperature stratification, local outdoor temperature and
the model for the external heat transfer coefficients are the parameters that account
for the majority of the uncertainty in the model output.
Second, although several parameters of secondary importance line up along
the wedges in Figure 2.7, indicating the presence of parameter interactions or nonlinearity
of the model output in the parameters, these effects do not seem to play a
significant role. Lomas and Eppel (1992) report similar findings in their sensitivity