The livMatS Biomimetic Shell at the FIT Freiburg Centre for Interactive Materials and Bioinspired Technologies is a pioneering research building. It offers space for the development of cross-disciplinary research ideas. Source: Timberbiz
The building brings together the different research approaches to achieve an architectural synthesis. Compared with a conventional timber building, the FIT Biomimetic Shell reduces the total environmental life cycle impact by 50%.
The distinctive and highly resource-efficient segmented timber shell construction is fully de-constructible and reusable. This is made feasible through the integrative development of computational design methods, robotic prefabrication, and automated construction processes, as well as novel forms of human-machine interaction in timber construction.
Embedded in the wood shell is the “Solar Gate”, a large-scale skylight which contributes to the regulation of the indoor climate by means of a biomimetic, energy-autonomous, 4D-printed shading system.
The design of the building envelope is based on the principles of the plate skeleton of sea urchins, which have been researched at the Institute for Computational Design and Construction (ICD) and the Institute for Building Structures and Structural Design (ITKE) at the University of Stuttgart for more than 10 years.
For this project, the segmental shell construction was further developed as a highly insulating structure for year-round and permanent use. The distinctive shape of the shell results from the deliberate branching of two partial shells of different shapes and sizes. This creates an opening skylight, which is rarely found in conventional shell buildings.
The innovative timber structure spans a floor area of 200m² and consists of 127 different hollow cassettes, which are joined by means of cross-screwed joints. In the assembled state, the curved geometry of the wood shell works as a form-active structure that achieves a free span of 16 metres with a weight of only 27 kg/m² of shell surface. The construction principle not only allows for the reusability of the entire building structure but also ensures the separability of all structural components.
Together with the structurally favourable shell form, the hollow cassettes show how new approaches to resource efficiency and sustainability can also be pursued in timber construction through the integrative use of digital technologies.
The hollow cassettes consist of a top and bottom layer of three-layer spruce boards as well as spruce edge beams, which are assembled as building modules. The additional effort in design and execution associated with this load-adapted and geometrically differentiated construction, which normally makes it uneconomical, can be compensated for by integrative computational design methods, robotic fabrication and automated assembly, leading to a significant reduction in resource consumption and environmental footprint.
A detailed life cycle analysis (LCA according to ISO 14040-14044 and EN15804) shows that the material consumption of the livMatS Biomimetic Shell has been reduced by more than 50% and the Global Warming Potential is 63% lower as compared with a conventional timber construction.
The material-efficient principle of the hollow cassette was already used in the BUGA Wood Pavilion Heilbronn 2019 as a temporary, open structure. Here, it was further developed for a permanent, closed building with year-round use.
The timber construction method was also optimised in that more sustainable timber materials were used and the component sizes were adapted so that as little waste as possible was produced during the robotic manufacturing process.
The basic idea of resource-efficient, bespoke components was also consistently pursued in the integration of acoustic elements, lighting, integrated insulation, façade connections and grip holes for automated assembly.
The associated high complexity in the component geometries and structures was countered with highly integrative computational design and fabrication. In regard to the production (LCA A1-A3), the hollow cassette system, due to its optimized robotic fabrication processes, reduces the GWP by 35% compared with the same system with solid cross laminated timber (CLT) cassettes.
The heart of the prefabrication is a newly developed, transportable 7-axis robot platform that allowed seamless integration in the factory of the industrial partner müllerbaustein HolzBauWerke GmbH within a few hours.
The 12m long robot platform enabled the simultaneous production of four components with lengths of up to 3.5 metres. The individual hollow cassettes were joined by the heavy-duty robot from individual, digitally pre-formatted wooden parts, glued and, in a further step, milled, drilled and finally cut by means of a saw blade in a time-efficient manner and with an accuracy in the sub-millimetre range.
In this way, the robotic production time could be reduced by 75% compared with the BUGA pavilion. In the digital fabrication of the hollow cassettes, manual partial assembly steps of special components such as lights and acoustic elements were directly integrated by means of augmented reality.
This form of human-machine interaction in the fabrication process, in which different actors can cooperate in a shared digital process chain and tasks are distributed in a targeted manner, enables effective, digitally augmented handcrafted fabrication of complex components with a high degree of precision.
Segmented lightweight timber structures are suitable for automated assembly on site due to the high precision in prefabrication and the low component weight. This was carried out for the first time in a real construction site situation within the scope of the project using several shell segments. For this purpose, two cyber-physical assembly platforms with end-effectors were developed, which were investigated as an automated assembly concept from the digital twin to practical integration into the construction process.
The assembly method consists of a robotic spider crane that picks up components with a vacuum gripper, automatically places them at the corresponding installation position and holds them in position until they are also automatically screwed together. For this purpose, a second spider crane equipped with a new type of screw effector automatically approaches the edges to be screwed and inserts all screws. For the important localization and precision of the construction robots, an automated real-time total station network consisting of four total stations was developed, two of which determine the position of each construction robot.
To be able to guarantee a smooth assembly of complex shell structures, quality assurance is of utmost importance. The aim was to accompany hollow cassettes through all production steps and thus to be able to detect possible deviations in the geometry. For this purpose, a digital scan of selected cassettes was created using a terrestrial laser scanner, which could then be compared with the target design geometry. These measurements were carried out both after production, immediately before assembly on the construction site, and in the installed state.
