By combining parametric planning with simulations and digital manufacturing methods, it is possible to create aesthetically and functionally completely new types of components. The "acoustic walls" in the new extension building of Basler & Hofmann in Esslingen show how it was possible to optimise room acoustics with the aid of this interplay.
To begin with, only one thing was clear: acoustic elements were to be used in the new cafeteria in the office building of Basler & Hofmann in Esslingen that would be created with innovative digital planning and fabrication methods. The elements were to be aesthetically eye-catching, but also to help ensure excellent acoustics in the room at the same time. The shape, material and method of production were open. In an iterative design and planning process between Gramazio Kohler Research, the Chair of Architecture and Digital Fabrication at ETH Zurich, Erne Holzbau and the acoustics engineers of Basler & Hofmann, the idea of the "acoustic walls" gradually started to take shape. These are three walls made up of over 8,500 identical wooden elements. They are arranged in such a way that the gradual progression of light through the room constantly creates a new pattern of shadows on the wall as the day passes. And the extraordinary nature of the walls was matched by the process by which they were created.
The effect of the "acoustic walls"
The acoustic walls were designed parametrically by researchers at ETH Zurich – which means that they were not drawn as they would have been in a conventional design process, but were instead programmed based on the relevant parameters. In this way, it is possible to generate countless design variants within a very short space of time. But which design and which shape offers the best acoustic properties? In a cafeteria, it is important to be able to hear and understand what other people are saying who are only a short distance away. At the same time, it was important to avoid flutter echoes between the large flat glazing units. The walls influence the acoustics by means of carefully designed “gaps” between the wooden elements. The sound waves are absorbed by the hollow space behind. In addition, the surface structure of the wall also provides diffuse scattering of the sound. The acoustics engineers simulated these effects on different design variants, and by doing this they were able to determine the ideal arrangement of the wooden elements – both in terms of aesthetics and in terms of functionality.
Building with augmented reality
With just a conventional, two-dimensional plan hardly anybody would be able to build such a complex pattern. Instead, an augmented reality application developed by researchers at ETH Zurich was used to visualise the exact position of every construction element for the installation engineers, enabling accurate layering of the wooden elements. The cafeteria was opened in June 2019.
Parties involved in the project
Building owner: Basler & Hofmann AG
Project management: Basler & Hofmann AG
Architecture and parameterisation: Gramazio Kohler Research, Professorship for Architecture and Digital Manufacture, ETH Zurich
Development of the AR installation system: Robotic Systems Lab, Institute of Robotics and Intelligent Systems, ETH Zurich and Gramazio Kohler Research, Professorship for Architecture and Digital Manufacture, ETH Zurich
Specialist acoustics planners: Basler & Hofmann AG, Strauss Elektroakustik GmbH
Architecture office extension: Stücheli Architekten