Innovative concrete roof celebrates its Zurich premiere

The prototype was built over the course of six months in the Robotic Fabrication Lab of the Federal Institute for Technology (ETH) in Zurich, according to a statement. The shell is part of a rooftop apartment unit called HiLo, which will be built next year on NEST, the living lab building of the Federal Laboratories for Materials Science and Technology (Empa) and the Aquatic Research Institute (Eawag).

The researchers built the formwork out of a net of steel cables, which supported a polymer textile on which the concrete was sprayed. This technique enabled the researchers to save a great deal on material for construction and opened the door to completely new kinds of design. Another advantage: concreting of the roof can in theory take place at the same time as the interior building work.

The building technique was developed by the Block Research Group led by Philippe Block, Professor Architecture and Structures, and Dr Tom Van Mele, together with the architecture firm supermanouevre. Numerous industrial partners contributed.

The prototype, which has since been dismantled to make space for new experiments, consisted of a self-supporting, doubly curved shell roof with multiple layers. Heating and cooling coils were installed over the inner concrete layer, thin-film photovoltaic cells on a second, exterior layer. 

The roof will be built once again at the NEST building in 2018 over the course of ten weeks. The individual components of the roof structure can be reused as often as needed, explains ETH Zurich.