Paper ID: HOSHAN381 /p.1 ACOUSTIC PERFORMANCE OF HIGH RISE BUILDING FAÇADES DUE TO ITS BALCONIES FORM H. Hossam El-Dien CERMA, UMR CNRS 1563-Ecole d’Architecture de Nantes, 44319 Nantes, France, hany_e@yahoo.com In this paper we discuss the use of self-protecting buildings as a means of reducing traffic noise nuisance into the building facade. A three-dimensional, Pyramid Tracing numerical model is used to study the sound field over the balconies back walls in a tall building close to a roadway. Various inclined ceilings, inclined front walls, and combined forms are tested. The results obtained indicate that the protection increases with the increasing of the floor level by using an inclined ceiling. In this case, the sound pressure level reduction varies from 0.5 dB(A) to 4.5 dB(A). While the inclined front wall is more effective in the lower levels, where the reduction afforded varies from 0.5 dB(A) to 4 dB(A). The maximum protection due to the combined forms appears at the higher levels, where we can add from 0.5 dB(A) to 1.00 dB(A) to the protection gained by the other inclined forms. In general, the results can help the architects to design self-protecting building facades with respect to the external acoustics environment by adding slight modification to its elements form. 1. INTRODUCTION Surrounding landscape, nature or artificial barriers and soil composition can reduce the sound propagation when the distance between the sound source and the observer is in the vicinity of approximately a hundred meters 1 . When that distance is between 5-50 meters (our case) the external form of the building influences considerably the value of the noise level which propagates from the roadway and transmits through the external environment going to impinge upon the building facades located at the sides of the road. A balcony is an extension of an internal floor with access by means of windows or doors to an external environment. It provides view and weather protection and is a familiar element in buildings. Particularly, it can provide an acoustical protection by means of its elements forms. The acoustic protection afforded by an open balcony to a room open to the balcony has been investigated by Gilbert 2 , Gustafsson and Einairsson 3 by means of field measurements. The conclusion drawn is that the insulation of a building façade will increase if a balcony visually screens its back wall. Mohsen and Oldham 4 used one-tenth scale models and computer simulation in an assessment of open balcony performance for a wide range of conditions. It was concluded that a first floor open balcony of 1 m depth, without a ceiling, can provide an L 10 insulation of approximately 6 dB(A) to a room open to the balcony. Field measurements were conducted by May 5 of closed balcony performance with respect to traffic noise in high rise buildings. The results are, however, difficult to apply since there is no information concerning the insulation afforded by the balcony to the internal space or over the balcony back wall. In this paper the acoustic performance of building facades is simulated and assessed with respect to traffic noise. Two types of balconies forms will be tested using a Pyramid Tracing model (DISIPYR) developed by A. Farina 6 . The first is a balcony with inclined ceiling form and the second is a balcony with inclined front wall. The results will be expressed in terms of sound pressure level reduction, in A-weighted scale, into the balcony back wall for a high rise building. PDF created with FinePrint pdfFactory trial version http://www.fineprint.com