Recent studies show that environmental noise in urban environments continues to be a great health risk. This noise is especially further transmitted by the hard materials that are mostly used for façades. To predict these effects it is desirable to have a reliable prediction method. There are already several ways to predict sound levels in an urban context. This paper investigates two while focusing specifically on a practical approach to show that the methods are suitable to use during an actual design project. The impact of changing a façade at a specific location is investigated using both prediction methods. A façade which reflects
sound to a location where it has a smaller impact, a sound absorbing façade, and a façade which combines both are taken into consideration. These façade adaptions have the potential to improve the sound levels in the investigated area from 1.7 up to 9.3 dB(A).@en

The increasing migration into cities leads to an increasing number of people stressed by noise. More and more people are moving into urban settings comprised of multiple noise sources and hard reflective glass and steel facades. The omnidirectional arrangement of noise sources like airborne noise or car traffic noise and their reflection on the facades neither composes urban arrangements with silent indoor areas nor comfortable quiet areas outdoor. To come up with requirements for silent areas inside and outside of buildings further design parameters have to be introduced. The facade is not only a shelter for the inside. It can also provide comfort spaces outside the building. As engineers and architects we cannot change the noise source, but we can influence the impact on the surrounding urban space by controlling the reflection of noise emissions on the urban surfaces like facades. In a facade design the capability of reflecting noise can be tuned by modifying the surface. In order to come up with the acoustical needs no radical new way of facade design has to be introduced. Mainly a shift of attention to the acoustic parameters is needed. Based on acoustic measurements of basic geometry principles this research presents known facade designs and their acoustic parameters regarding the reflection capabilities and the functions in a facade.@en

Today’s city centres in European metropolitan areas are comprised of facades made of steel, glass and stone. These hard reflective facades are amplifying the perception of noise sources by human ears in their vicinity. Up to now in building designs this effect is neglected. Thus the number of people harmed by noise is increasing with the increasing noise levels on the streets caused by more and more hard reflective facades. To obtain control on urban acoustic spaces the focus of architects and engineers must be shifted to acoustics parameters. Several case studies in course of this research give evidence for the possibility of controlling the impact of noise sources on an urban space with modified facades. The experience and results of the case studies were merged to deliver a plot of a process chart for implementing the acoustical point of view in a building design process. Laboratory methods e.g. scale model measurements and impedance measurements were modified in order to be feasible in a building or facade design process. As with modified reflection properties of facade surfaces a sound reduction of up to 8 dB for specific frequency bands is feasible the building of quieter cities is in the responsibility of architects and engineers.@en

The increasing migration into cities leads to an increasing number of people stressed by noise. More and more people are moving into urban settings comprised of multiple noise sources and hard reflective glass and steel facades. The omnidirectional arrangement of noise sources like airborne noise or car traffic noise and their reflection on the facades neither composes urban arrangements with silent indoor areas nor comfortable quiet areas outdoor. To come up with requirements for silent areas inside and outside of buildings further design parameters have to be introduced. The facade is not only a shelter for the inside it can also provide comfort spaces outside the building. As engineers and architects we cannot change the noise source, but we can influence the impact on the surrounding urban space by controlling the reflection of noise emissions on the urban surfaces like facades. In a facade design the capability of reflecting noise can be tuned by modifying the surface. In order to come up with the acoustical needs no radical new way of facade design has to be introduced. Mainly a shift of attention to the acoustic parameters is needed. Based on acoustic measurements of basic geometry principles this research presents known facade designs and their acoustic parameters regarding the reflection capabilities and the functions in a facade.

@en

The representative high-rise facades of today's major cities are composing urban spaces out of glass and steel. With the reflection of one noise source on one hard reflective facade the noise level in an urban space can increase up to 3 dB. In the case of multiple reflections in a complex urban setting the level can increase up to 8 dB. Taking this effect into account, the surfaces of inner city facades have to be redesigned aiming for absorption of the sound energy. Due to the different functions of a façade, e.g. vista, light, energy and air, the complete covering of a facade in order to gain broadband absorption is not feasible. If the targeted broadband absorption is not feasible, the absorption effect can be tuned to several frequency bands in order to transform the uncomfortable noise perception into a comfortable one. During this research facade designs were developed with a focus on the acoustical effectiveness. It was demonstrated, that with a tunable acoustical facade construction, more than one frequency band can be influenced, thus achieving a comfort soundscape in an urban space.@en