SRDA
ICA SAS
FEI STU
Tubular Skylights
Svetlovody
Project APVV 0264-07
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Calculation
Calculation of the tube efficiency
Date and locality:
Date:
Day
Month:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
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23
24
25
26
27
28
29
30
31
1
2
3
4
5
6
7
8
9
10
11
12
Time:
Geographical latitude:
φ [deg]
Geographical longitude:
λ [deg]
GMT:
Light-guide parameters:
Diameter of the tube:
D [m]
Length of the tube:
H [m]
Reflectance of inner surfaces:
ρ [%]
Other parameters:
Luminous solar constant:
E
0
[klx]
Cloud ratio:
D
v
/E
v
0.15
0.16
0.17
0.18
0.19
0.20
0.21
0.22
0.23
0.24
0.25
0.26
0.27
0.28
0.29
Transmittance of the cupola and diffuser:
Maintenance factor for horizontal cupola:
0.75
0.76
0.77
0.78
0.79
0.80
0.81
0.82
0.83
0.84
0.85
0.86
0.87
0.88
0.89
0.90
0.91
0.92
0.93
0.94
0.95