Active facades to reduce the noise immission in buildings

The BMBF project “Active facades to reduce the noise immission in buildings” explored possible uses of multifunctional materials and active counter controls as a means of reducing noise pollution. Together with Schüco International KG, the Research Group SzM developed active systems that fight against unwanted vibrations and oscillations before they are able to cause airborne sound to radiate from structures.

Hotels, skyscrapers, airports, etc. – facades are being used everywhere as an outer layer for buildings. They dominate cityscapes all across the globe. In addition to providing static support, facades serve primarily as an architectural aid. If facades were planned appropriately, they could also be adapted to reduce the sound radiation in buildings and thus the noise pollution.

Double or triple glazed windows, insulating mats, and sand-filled profiles are among the classic passive methods for noise protection. Each of these methods brings with it a crucial disadvantage – the use of this extra material increases the weight. Since in facade engineering it is a requirement to build light facades, such weight increases can oftentimes not be tolerated.

A new approach was more closely examined in the framework of this project. Several actuators distributed on the structure produce vibrations that are inverted to the unwanted vibrations in the facade, such that they cancel each other out. In conjunction with an appropriate control system, broadband noise radiation can be reduced. The applied principle here is referred to as Active Structural Acoustic Control (ASAC) by the scientific community.