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New Lightweight Concrete Roof Designed to Harvest Solar Energy

Posted by on Nov 13, 2017 in Featured News | 0 comments

A prototype has been developed for an ultra-thin curved concrete roof that also generates solar power. Researchers at the Swiss Federal Institute of Technology in Zurich say the futuristic design will allow a residential structure that is part of the school to generate more energy than it uses.

The roof design is made up of several layers. An inner sheet made from concrete acts as a foundation for heating and cooling coils and insulation. Thin-film photovoltaic cells are then installed on the exterior of the building to harvest solar energy.

Philippe Block, a professor of architecture and structures at ETH Zurich, and Arno Schlüter, a professor of architecture and building systems, led the research team. Their goal was to combine adaptive building systems with the new lightweight construction.

The initial prototype design was 7.5 meters high, with a total curved surface area of 160 square meters. It has now been taken down, with plans to implement the same design next year in a roof-top apartment unit called HiLo on the NEST, the living lab building of the Swiss Federal Laboratories for Materials Science and Technology and the Swiss Federal Institute of Aquatic Science and Technology.

About four out of five homes in the U.S. have asphalt shingles and are constructed with non-reusable materials. However, this project used a net constructed from steel cables covered with a polymer textile, producing a form the concrete would be able to bond to. In doing this, the project had an unusual design, but was considerable cheaper in terms of material costs.

Another advantage of the flexible formwork solution is that the area underneath the roof remains open, so interior building construction can be done at the same time.

Due to a calculation method developed by the Block Researcher Group and their collaborators in the Swiss National Centre of Competence (NCCR) in Digital Fabrication, the cable net is designed to take on the desired shape under the weight of the wet concrete.

The scientists were able to determine the correct concrete mixture, which needed to be liquid enough to be sprayed and vibrated yet thick enough to not flow off the fabric shuttering.

The team built the prototype within six months. It represents a huge milestone for the NEST HiLo project.

“We’ve shown that it’s possible to build an exciting, thin concrete shell structure using a lightweight, flexible formwork, thus demonstrating that complex concrete structures can be formed without wasting large amounts of material for their construction,” says Block.