# Cumulative Impact of Wind Farm Noise
## 4 Results  
The effects of noise are modeled on the noise receptors (R)--the existing facilities, permanently or temporarily used, in the zone of possible wind farm impact. A total of eight receptors are identified. The consensus is reached that, since identifying receptors below 35 dBA for individual wind farms is becoming more common, the noise contour of 35 dBA would also be appropriate for a cumulative assessment. Figure 2 outlines the 35 dBA impact area for individual wind farms, while Figure 3 shows the changed 35 dBA contour in the case of a cumulative effect.  
Receptors R1 to R7 are positioned in the border areas so as to detect the extension of the 35 dBA outline, while the R8 receptor is placed in the central impact zone of both wind farms.  
Although the change in the 35 dBA contour in the case of cumulative impact is only slight, it is easy to notice that the receptors R2 and R6, which were outside the impact zone of individual wind farms (as shown in Figure 2), are now affected. It can also be seen that the receptors R4 and R8 are within the 40 dBA noise contour when it comes to the cumulative impact, although still within the limits of legally prescribed values. In addition, a slight increase in the area with the predicted levels of noise of 45 dBA is perceived without impacting the identified receptors.  
Figure 2: Noise value outlines for individual wind farms (Cibuk Wind Farm (**left**), Vetrozelena Wind Farm (**right**)).  
Table 3 shows the quantitative results of noise value modeling for individual wind farms as well as a cumulative noise value for all the receptors.  
The modeling results shown in Table 3 and Figure 3 outline the increase in noise in the case of cumulative effects, on the one hand, and the greater spatial propagation of the same effect, on the other. The last column shows the percentage of noise increase in the receptors due to the cumulative effect of farms as compared with the noise values of the existing Cibuk wind farm. In practice, criteria for determining limit values of noise prescribed by the national regulation are stricter than World Bank recommendations (Tables 1 and 2). Here, however, the noise values are still within the allowable World Bank range (Table 1) but also within the acceptable values stipulated by the national legislation (Table 2), since the values are the same. It has a value of 45 dBA at night (Figure 4). In that context, there is no need for additional planning solutions that would command the change in position of certain wind turbines or envisage measures for the reduced work of wind turbines in  
Figure 3: Noise value outline for the cumulative effect of Cibuk and Vetrozelena wind farms.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Noise Receptors** & **Cibuk Wind Farm** & \
\begin{tabular}{c} **Vetrozelena Wind** \\ **Farm** \\ \end{tabular} &
\begin{tabular}{c} **Cumulative** \\ **Effect** \\ \end{tabular} & **\% Increase** \\ \hline R1 & 32.8 & 33.9 & 36.4 & 11\% \\ \hline R2 & 37 & 37.1 & 39.7 & 7\% \\ \hline R3 & 34.1 & 33 & 36.3 & 6\% \\ \hline R4 & 37 & 40.2 & 41.7 & 13\% \\ \hline R5 & 32.5 & 36.1 & 37.7 & 16\% \\ \hline R6 & 29.5 & 34.6 & 35.8 & 21\% \\ \hline R7 & 26.8 & 33.8 & 34.6 & 29\% \\ \hline R8 & 41.5 & 39.6 & 43.3 & 4\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Quantitative results of noise value modeling in decibels (dBA).  
certain conditions. This was the exact conclusion of the SEA process in the part that refers to the noise impact.