| Annex A4.2 |
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| Calculation
of Noise Level Due to Operation of Wind Turbine |
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| NSR Location: |
Hei Ling Chau Addiciton
Treatment Centre (Annex) (N2) |
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| Horizontal Distance= |
382 |
m |
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| Vertical Distance= |
120 |
m |
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| Slant Distance= |
400 |
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| Frequency,
Hz |
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25 |
31.5 |
40 |
50 |
63 |
80 |
100 |
125 |
160 |
200 |
250 |
315 |
400 |
500 |
630 |
800 |
1000 |
1250 |
1600 |
2000 |
2500 |
3150 |
4000 |
5000 |
6300 |
8000 |
10000 |
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| SWL(1), dB(A) |
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66.5 |
68.8 |
72.2 |
78.9 |
78.3 |
80.6 |
84.9 |
84.9 |
87.3 |
91.2 |
90.5 |
92.5 |
92.5 |
93.4 |
94.7 |
93.8 |
93.5 |
93.4 |
93.6 |
91.5 |
89.5 |
87.7 |
86.8 |
83.5 |
76.5 |
69.8 |
62.4 |
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| Distance,
m |
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400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
400 |
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| Distance correction |
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-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
-60 |
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| Screening
correction(2) |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
-5 |
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| Atmospheric
Absorption(3) |
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0.0 |
0.0 |
0.0 |
0.0 |
-0.1 |
-0.1 |
-0.2 |
-0.3 |
-0.4 |
-0.7 |
-1.0 |
-1.5 |
-2.1 |
-2.9 |
-3.7 |
-4.6 |
-5.6 |
-6.6 |
-7.7 |
-9.2 |
-11.3 |
-14.4 |
-18.8 |
-25.3 |
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| Predicted Lp, dB(A) |
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1 |
4 |
7 |
14 |
13 |
16 |
20 |
20 |
22 |
26 |
25 |
27 |
27 |
27 |
28 |
27 |
26 |
25 |
24 |
21 |
18 |
15 |
13 |
7 |
-3 |
-14 |
-28 |
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| Lp, dB(A) |
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1.5 |
3.8 |
7.2 |
13.8 |
13.2 |
15.5 |
19.8 |
19.8 |
22.1 |
26.0 |
25.2 |
27.0 |
26.8 |
27.3 |
28.2 |
26.7 |
25.6 |
24.6 |
23.9 |
20.9 |
17.9 |
14.9 |
12.5 |
7.1 |
0 |
0 |
0 |
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| A-Wt
Sound Pr. Level = |
36.9 |
dB(A) |
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| FACADE CORRECTION= |
3 |
dB(A) |
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| PREDICTED FACADE
NOISE LEVEL AT NSR = |
40 |
dB(A) |
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| (1) Reference has been made on a test report of a wind turbine
with all measurements and analysis were done in accordance with the IEC 61400-11: Wind Turbine Generator Systems - Part 11:
Acoustic noise measurement techniques, and |
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| with adjustment to represent the worst case
scenario of a maximum sound power level of 104dB(A). |
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| (2) Some buildings in N2 may have line of sight to a small part of
the swept area of the blades but most part of the wind turbine will be
screened off. |
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| (3) Basing on the equation Aab(fm) = Aat(fm) [1+0.00533[1-0.2303 Aat(fm)]]1.6 from Handbook of Acoustics (where Aab(fm) is the atmospheric attenuation for broadband at frequency fm, and Aat(fm) is the atmospheric
attenuation for |
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| pure tone at frequency fm) and ISO 9613:Part 1
for Atmospheric Absorption at 30°C and relative humidity of 100% as the worse scenario (see Annex
A4.3). |
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| Note: The average atmospheric condition in
Hong Kong was 23oC
and RH 79% as per the Weather Report 2005, "The Year's Weather -
2005" by Hong Kong Observatory. |
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1
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2
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5
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24
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21
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36
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96
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95
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163
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395
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329
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502
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476
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542
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656
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463
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363
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291
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247
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122
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61 |
31
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18
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5
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1 |
1 |
1 |
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4948
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36.944 |
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