A robot as construction worker: ETH Zurich's Arch_Tec_Lab
Architecture: Arch_Tec_Lab AG
Location: Zürich (CH)
ETH Zurich regards the Arch_Tec_Lab, which has been set up at the Hönggerberg campus after a six-year planning and construction process involving six professorships, as a real-world laboratory for integrated building planning, zero-emission technology and robotic building construction. The building, erected using lightweight construction technology on the roof of an underground car park, is devised to not release CO2 emissions once it is in operation. At the same time its ground floor is the location of the Robotic Fabrication Laboratory initiated and planned by Gramazio Kohler Research.
In comparison to conventional high-rise buildings featuring up to 400 kilograms of material per cubic metre, the average built volume in the Arch_Tec_Lab amounts to a mere 240 kilograms. Timber was chosen for the roof structure and steel for the structural skeleton as these materials have ideal stiffness-to-weight ratios. The steel framework does without supporting cores and shafts, making it possible to adapt the interior design to changing needs and thus enabling flexible use.
A total of 120 ventilation units known as airboxes are integrated into the building's double floor structure and connected to the Hönggerberg campus's Anergy Grid, thus providing the building with ventilation and serving to heat and cool it. The double floor houses the respective piping and ducts on the one hand and on the other creates slight positive pressure above the floor vents to draw air into the rooms.
The roof structure is a particular eye-catcher, consisting of 48,000 individual timber beams up to 3.10 metres long and spanning a distance of 15 metres without intermediate supports. One hundred and sixty-eight serially joined and robot-assembled nailed trusses transmit the loads to five panels on steel beams. The entire building services, ranging from fire protection to lighting, are integrated on the underside of the exposed roof structure.
The roof was produced using Europe's largest gantry robot, developed by Güdel AG in collaboration with Erne AG Holzbau, the company that executed the project. The robot, which is 50 metres long, can handle work pieces up to 48 metres long and 5.6 metres wide. Highly articulated thanks to its six or seven operational axes, it can saw, mill, screw, nail, lift, glue, weld and perform various other processes; in this respect Erne compares it to an oversized 3D printer. The company names time-savings as the main advantage of robotic construction; indeed, each truss integrated into the roof would have taken about 60 hours to fabricate if produced in manual labour.