## 2 Shopping Center Noise Predictions  
### Noise Impact Methodology  
In accordance with EU DIRECTIVE 2002/49/EC [16], strategic noise mapping has to be modelled and assessed at a height of 4 m that corresponds to the height of the first floor of a residential building. The height of the noise prediction is treated in different studies [17; 18; 19], where it was concluded that the measured noise levels of road traffic or railway noise increase with height. Considering that the noise sources from the present study are situated at a 6 m height, a noise assessment is made according to a VBEB method which is made according to German national legislation. The studied area is situated on the northeast side of Bucharest in a densely populated area. The location of the commercial centre is planned to be situated among the houses at a distance of just 16 m from the closest residential building facade. In the surrounding area of the commercial centre, residential buildings with 10 stories are found with an average height of 26 m. Due to the daily commercial centre activities, a large number of inhabitants can be exposed to high levels of noise, resulting in a large number of complaints. In accordance with the WHO (World Health Organization), in the Guidelines for Community Noise [20], and Romanian legislation [21], it is specified that local economic activities with noise and vibration sources should be placed at a distance from the protected territories such that the equivalent continuous sound level at the building facade is under 55 dB(A) in the day period (from 7:00 to 23:00) and 45 dB(A) in the night period (from 23:00 to 7:00). The numerical modelling of the studied area was made using the IMMI software from Wolfel, which supports the requirements of Directive 2002/49/EC with the calculation method from ISO 9613-2. For outdoor cases, the IMMI software supports different methods for sound reflections calculation: the mirror source method and the ray tracing method. The mirror source method gets very time-demanding when you have a higher order of reflections (2 nd, 3 rd or 4 th order) in combination with a lot of reflecting surfaces. IMMI analyses the desired reflection order and the number of reflectors in a first step and then decides which method should be used. For a simple project with the 1 st reflection order, the mirror source method will be used and for high orders of reflection, the ray tracing method will be used. In the present study, 2 nd order reflection was adopted using the ray tracing method. The ray tracing method consists of substituting the sound wave with a ray which is a straight line emanated by the noise source, carrying a sound energy, which is specular reflected by the walls with a reduction in the energy according to the imposed reflection coefficients of the walls. The prediction software requires different input data: land surfaces with their acoustic characteristics, the shape and the heights of the buildings, noise power levels of the noise sources, etc. The geospatial vector data of residential buildings, the administrative buildings and other buildings from the analysed area were modelled with the IMMI software. The numerical model needs data related to humidity and temperature in order to compute the sound waves propagation into the air. According to the yearly average of Romania's climate, a relative humidity of 70% and a temperature of 10 \({}^{\circ}\)C were introduced in the numerical model. Special attention was given to buildings modelling, which significantly influences noise propagation due to reflection. In this case, the attenuation due to reflection at the facades of the building was set at \(-\)1 dB and due to the lack of vegetation, the ground attenuation was set to G = 0 which represents reflecting ground. The main noise sources considered in this noise impact study were generated by the air conditioners, heat pumps and the loading and uploading activities performed on the supply ramp of the commercial centre.