Annex A4.1      
Calculation of Noise Level Due to Operation of Wind Turbine    
   
NSR Location: Hei Ling Chau Correctional Institution (N1)    
Horizontal Distance= 740 m  
Vertical Distance= 40 m  
Slant Distance= 741  
 
Frequency, Hz   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   0.0
SWL(1), dB(A) 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   0.1
  0.1
Distance, m 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741 741   0.1
Distance correction -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65 -65   0.2
Screening correction(2) -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10 -10   0.3
Atmospheric Absorption(3) 0.0 0.0 -0.1 -0.1 -0.1 -0.2 -0.3 -0.5 -0.8 -1.2 -1.9 -2.7 -3.9 -5.3 -6.9 -8.5 -10.3 -12.1 -14.3 -17.1 -20.9 -26.6 -34.9 -46.9    
  1.1
Predicted Lp, dB(A) -9 -7 -3 3 3 5 9 9 12 15 15 16 16 16 17 15 13 11 10 6 2 -2 -6 -13 -25 -40 -60   1.5
                                                             
  2.6
Lp, dB(A) 0 0 0 3.5 2.9 5.1 9.4 9.4 11.7 15.5 14.6 16.3 15.9 16.1 16.6 14.5 12.8 11.1 9.7 5.8 2.0 0 0 0 0 0 0   3.2
A-Wt Sound Pr. Level = 25.5 dB(A)   3.8
  4.5
FACADE CORRECTION= 3 dB(A)  
 
PREDICTED FACADE NOISE LEVEL AT NSR = 29 dB(A)  
 
(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    
    with adjustment to represent the worst case scenario of a maximum sound power level of 104dB(A).     
(2) N1 will be totally screened off by the natural topography.     
(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    6.6
   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). blank space,blank space,blank space
  0.0
   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.   
 
 
 
  1 1 1 2 2 3 9 9 15 35 29 43 39 41 45 28 19 13 9 4 2 1 1 1 1 1 1  
  355  
  25.5  
 
 
 
SWL(1), dB   65.2 67.5 70.9 77.6 77 79.3 83.6 83.6 86 89.9 89.2 91.2 91.2 92.1 93.4 92.5 92.2 92.1 92.3 90.2 88.2 86.4 85.5 82.2 75.2 68.5 61.1   0.0
  ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### #####  
  #####  
  102.74 dB(A)  
1.3   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  
  ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### ##### #####  
  #####  
  104.04 dB(A)