Problem: The source of the noise are four chillers located in the yard space of a residential and administrative building in Varna. They are exactly under the windows of the residential spaces at 13 metres distance. At the initial measurement of the noise, the noise pressure is established from 80 dB at the chillers and 75 dB at the windows. Also, in the neighbourhood is located an administrative building at 10 metres distance, which is immediately exposed to the influence of the noise.
Solution: For sound reduction of the noise, who reaches the receivers (the residential parts and the administrative building), building actions are taken for soundproofing lining around and above the chillers. The main element is a metal perforated sound-absorbing panel with 50 mm thickness. Sound absorbing wings with 300 mm thickness are mounted in order to ensure the airflow from the ventilators above the chillers, without causing a "leak" of noise.
Result: After mounting all of the equipment it had been reached values from 60 dB at the two noise receivers, which is a half reduction of the noise.