Study On Noise Control Strategy Of Multi Unit On Public Building Roof

Since the reform and opening up,the rapid development of Chinese society has also brought a series of environmental pollution problems,in which noise pollution is one of the most serious environmental pollution.Because of the special building function of multi-storey public buildings,many large equipment will be installed on the roof of the building,which will produce a lot of noise.Therefore,the noise reduction of the roof of multi-storey public buildings is one of the most important parts to control the noise pollution.Through the actual case of noise pollution caused by public buildings,the most typical one is Hefei Rural Credit Union of Anhui Province.Because of its unique building function,there are many kinds of roof equipment,and they are in operation all the year round,so this paper takes the multi unit noise generating equipment on the roof of Hefei Rural Credit Union of Anhui Province as the research object.First of all,through the measurement of the relevant dimensions of the roof,and using the sound level meter to obtain the noise value of various types of sound sources on the roof,the relevant data of the building roof are obtained.According to the measured data,Auto CAD is used to draw the layout of the target building and its surrounding environment.According to the layout and noise value,the noise status of the roof is simulated in Cadna a software.The simulation results show that the maximum noise value of the roof multi unit equipment on the surrounding environment is 92 d B,which seriously exceeds the national acoustic environment standard.Therefore,through the analysis and comparison of the influence of roof noise source,the main noise source cooling tower adopts the way of installing muffler at the exhaust outlet and laying anechoic blanket in the drenching area to reduce the noise value,and adds a sound absorption cover at the top of the cooling tower to reduce the noise value and change its transmission direction;optimizes the sound insulation cover and muffler of air-cooled heat pump to reduce the noise value Through calculation,the noise value of multiple air conditioning units under comprehensive use is obtained,and the noise level is weakened by laying sound absorption board at the upper end.By simulating the roof,it can be found that the impact of noise on the surrounding environment is reduced to less than 78 d B.Although the noise value has decreased significantly,the noise of the office area near the roof is still close to 70 d B.Therefore,secondary noise reduction measures are taken for the roof,such as adding grid type ceiling above the roof and adding sound insulation barrier at the upper end of the parapet,which can not only change the transmission way of noise,but also optimize the roof effect,and reduce the subjective impression of noise visually,and finally reduce the noise The noise of the roof can be reduced to 68 d B.Finally,the roof equipment itself has requirements for natural ventilation,so in the noise reduction measures,whether the noise enclosure added on the roof will affect the ventilation,this paper uses PHOENICS software to simulate the secondary air environment before and after noise reduction,so as to verify the ventilation effect of the wind environment.It can be found that after adding grid type roof,the ventilation side of the roof changes reversely,but the change of wind speed is small,and the impact on the roof can be ignored.