A Method for Design of Sound Insulation of Glazed Balconies Against Traffic Noise

The maximum allowed values of the noise levels issued by the Council of State in 1992 are applied to balconies in several cities in Finland. There are no generally agreed methods for design of sound insulation of glazed balconies. The object of this work was to develop such method. The developed design method for the selection of glazing is based on the laboratory measurement values of airborne sound insulation of the glazing. The method also takes into account the noise field inside the balcony (sound absorption), balustrade and its slit-shaped apertures and the surface areas of these building elements. The design method was validated by comparing the calculated sound insulation of balconies with corresponding field measurements. Measurements were done in 5 new buildings from which 10 glazed balconies were measured (2 balconies each). The average difference between measurement and design values was found to be -5 dB, which is used as a correction term in the final design method. After the introduction of the correction term, the differences between calculated and measured single-number values were found to be ±1 dB for traffic noise and ±2 dB for railway or air traffic noise.