Traffic noise in atrium courtyard

During the design phase of a combined office and housing project, the noise and vibration expert Claus Backalarz from DELTA calculated the load from traffic noise on the open atrium courtyard from two adjacent streets. The opening from the streets into the courtyard is approximately 6 x 11 m2. Inside the courtyard, walkways with glass railings reflect and screen traffic noise.


It was the first time Claus Backalarz from DELTA used the Odeon extrusion modeller, when he created this geometry. The traffic lanes of the adjacent streets are simulated as line sources. Point receivers are placed in appropriate places in the courtyard and at the facades of the building.


In Denmark, the recognized method for calculation of traffic noise is the Nordic calculation model (NBV96). The traditional modelling tools for traffic noise calculations could not handle the complicated transmission paths of the building project, and therefore Odeon 9 was used as the only possibility to perform the detailed calculations.


Danish environmental law requires a noise contribution from road traffic at maximum LAeq,24h = 55 dB re 20 Pa (year mean day). When the construction project finished, measurements were made at the facades, in the courtyard and on the walkways. Compared to measurements Odeon 9 generally overestimated the values with 3-5 dB. At this moment there has been made no attempt to analyze why this deviation appeared.


With the use of ODEON, DELTA had a much better foundation for evaluating the use of sound absorbing materials and possibilities of screening. DELTA will continue to use Odeon as a supplementary simulation method for external noise, where the geometry is too complicated for the traditional calculation methods.