Functionally integrated funicular floor for NEST HiLo, 2019

This prototype shows a ultra-lightweight, pre-fabricated, rib-stiffened funicular floor using recycled concrete. The floor is functionally integrated using an efficient hybrid cooling and ventilation system and realised using state-of-the-art 3D-printing moulds.

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By 2050, the rapid depletion of raw materials will leave the world without enough sand and steel to build in concrete. It is time to RETHINK the design and construction of buildings. In ETH Zurich’s pavilion in Davos, ETH Zurich’s Block Research Group unveils a “Functionally integrated floor system.” This novel architectural research demonstrates how historic geometrical designs and new technologies can result in lighter construction and significant savings in raw materials.

A team of ETH Zurich researchers at the Institute of Technology in the Department of Architecture is developing an integrated structural floor system to address and combat the building industry’s significant contributions to global greenhouse gas emissions and the rapid depletion of natural resources. The structural elements of a multi-storey building account for up to 50% of its embodied energy. In buildings with 10 or more storeys, up to 80% of the weight of that structure is contained in the floor slabs, most commonly built with steel-reinforced concrete. By introducing a materially efficient floor system, the embodied energy of the built environment in the planet’s rapidly growing cities could be reduced significantly. Furthermore, the integration of optimised heating and cooling systems could significantly reduce the operational energy demand in a building.

Core innovations

The Block Research Group develops rib-stiffened funicular floors, which are doubly-curved shells that carry loads efficiently in compression and absorb tension externally in ties rather than in embedded steel reinforcement. This offers a dramatic reduction of the amount of structurally unnecessary concrete by up to 70%. Additionally, the structural geometry results in very low stresses, even in the very thin sections, allowing for the use of weaker materials such as recycled concrete. By carving out the floor slab, leaving only the material that is needed for efficient force transfer in compression, pipes, wires and mechanical systems can be inserted and routed through volumes of the floor that were previously inaccessible.

In collaboration with the Chair of Architecture and Building Systems researches building energy and climate systems and their integration into structural elements in order to increase efficiency and reduce space and costs. This research specifically investigates the integration of an optimised, three-dimensional extension of a hybrid cooling and ventilation chilled-beam HVAC system into funicular floor geometries. Synergies with the structural design are achieved by utilizing cavities and geometrical properties of the floor for the efficient routing of air and water for heat transport and air supply. Such a design for optimal flow is made possible by the flexibility of 3D-printing.

Due to the complex structural geometry and high level of integration, the fabrication of such floors in concrete would typically result in wasteful and costly formwork solutions, furthermore requiring complex assembly and removal work. In collaboration with the Chair of Digital Building Technologies, new, efficient formwork solutions based on state-of-the-art 3D-printing technologies are being investigated to create bespoke, thin-walled moulds, used to form the internal duct system as well as the visible lower surface of the floor.


World Economic Forum 2019

The prototype of the functionally integrated funicular floor system exhibited in the ETH Zurich Pavilion in Davos during the 2019 World Economic Forum (WEF) Annual Meeting shows an efficient floor system, made possible through the use of structural geometry, building systems integration and feasible fabrication methods and collaborative research efforts within the National Centre of Competence in Research in Digital Fabrication (NCCR DFAB). It aims to demonstrate the vast potential of such new building components to address the grand challenges faced by the building today and even more urgently in the future.

Making-of movie

Check out how the unique concrete shell was designed, fabricated and constructed in this making-of movie!

Credits prototype

Project partners

Industry partners

  • BASF Schweiz AG
  • Holcim (Schweiz) AG


  • BASF Schweiz AG
  • NCCR Digital Fabrication
  • ETH Zurich


Rib-stiffened funicular floor system

Rib-stiffened funicular floor system

This research develops the structure for an unreinforced concrete floor consisting of a thin funicular vault stiffened by a series of spandrel walls on its extrados. The structural prototype is completed with tension ties, which link the supports and absorb the horizontal thrusts of the funicular shell. It is a prototype for the NEST HiLo project to be realised in 2019 on the Empa campus in Dübendorf, Switzerland.

3D-printed floor system

3D-printed floor system

This research develops and investigates the potential of a 3D-printed floor system consisting of a rib-stiffened funicular vault using discrete, prefabricated components. The study aims to take full advantage of the geometric flexibility of additive manufacturing processes allowing to realise structurally optimized, functionally integrated and economically feasible building components.


Block P. and Paulson N.E4: Efficiency, Economy, Elegance, and Ecology,Design - Tales of Science and Innovation,G. Folkers and M. Schmid (editors),Chronos Verlag, Collegium Helveticum and ETH Zurich,Zürich,2019.


ETH Zurich
Institute of Technology in Architecture
Block Research Group
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8093 Zurich, Switzerland

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