HiLo Unit at NEST

Dübendorf, Switzerland

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HiLo Unit at NEST

Dübendorf, Switzerland

Firm

ETH Zurich, Block Research Group

Type

Commercial › Office

STATUS

Built

YEAR

2021

SIZE

1000 sqft - 3000 sqft

BUDGET

$1M - 5M

Photos

Roman Keller (6), Juney Lee (4), Nick Krouwel (1)

The HiLo unit of the Next Evolution Sustainable Building Technologies (NEST) platform in Dübendorf, Switzerland, demonstrates the potential of digital concrete construction to lower embodied emissions in the structure of buildings, reduce construction waste and minimize resource consumption. It also shows how the integration of advanced building systems in lightweight structures allows for energy-efficient operation and enhanced user comfort. HiLo stands for High Performance and/with Low Emissions. The unit is designed as a two-story collaborative, flexible workspace with two closed offices and multiple shared, open office areas. HiLo’s innovations have been developed at ETH Zurich: the construction and structures (1-3) are by the Block Research Group (BRG), headed by Prof. Philippe Block and Dr. Tom Van Mele, and the building systems are by the Chair of Architecture and Building Systems (Prof. Dr. Arno Schlüter) (4-5), with collaborations with the Chair of Digital Building Technologies (Prof. Dr. Benjamin Dillenburger).

Concrete sandwich shell built with a flexible formwork (1-2)
HiLo’s roof is a doubly curved “sandwich” shell, containing a layer of insulation blocks between two sheets of reinforced concrete of only 5 and 3 cm thick (2 and 1.2 inches). The concrete layers are connected by thin compressive stiffening ribs and vertical tension rods to activate the entire depth of the section. Instead of using a custom, costly and wasteful formwork, the HiLo roof structure was built using a reusable flexible formwork, consisting of a tensioned cable-net covered with a thin fabric membrane onto which the concrete was sprayed. The roof structure and its formwork system were developed and realised through a flexible design-to-fabrication workflow implemented with COMPAS, the open-source computational framework for research and collaboration in Architecture Engineering and Construction, providing an effective research-to-practice transfer.

Rib-stiffened funicular floor system (3)
The HiLo floors use a thin, doubly curved funicular shell with vertical stiffeners to transfer loads to the supports through compression only. The resulting forces are accumulated in the corners, where their outward thrust is absorbed in post-tensioned ties. By placing material only where it is structurally needed (following the flow of forces in compression and tension) the HiLo floor system developed by the Block Research Group saves 70% of concrete and 90% of reinforcement steel compared to the standard reinforced concrete slab, and, by keeping all materials separate, allows for easy recycling at end of life. Furthermore, the funicular geometry of the floors results in low stresses in the structure allowing low-strength materials, which typically have a low carbon footprint, to be used as well as high percentages of construction and demolition waste instead of our scarce natural resources.

Building Systems and Adaptive Solar Facade (4-5)
HiLo is equipped with a set of state-of-the-art heating, cooling, solar shading, and ventilation systems. Different control strategies and machine learning approaches are explored to provide optimal indoor temperature, lighting, and ventilation conditions. Occupants can also learn from the building. For example, through visualizations, they can learn which behaviors help to reduce energy consumption without compromising their comfort. The embedded heating and cooling networks inform the contours of the 3D printed concrete ceiling while introducing an innovative architectural feature. This approach provides a highly efficient radiant panel due to the thinness of the concrete structure. The thermal performance is further enhanced by coupling with the ventilation system.

HiLo, moreover, features the Adaptive Solar Façade (ASF): 30 lightweight modules equipped with efficient thin-film solar cells, move on two axes acting as shading and solar tracking devices. As an interface, the ASF can regulate the thermal environment by controlling the solar intake, either by allowing the sun to enter the room for passive heating or preventing it to reduce overheating and cooling demand. At any time during the daylight hours, the ASF produces electricity through its photovoltaic cells. Through learning mechanisms, the ASF learns optimal behavior based on its location on the building, the changing weather, and the presence of the inhabitants and its interactions with them.

Credits

Innovations:
- Block Research Group, ETH Zurich
- Architecture and Building Systems Group, ETH Zurich
- Digital Building Technologies, ETH Zurich

Architecture:
- ROK Architects
- Block Research Group, ETH Zurich

Selected Planners and Contractors:
- Buergin Creations
- Dr. Schwartz Consulting AG
- Marti AG
- Pletscher Metallbau AG
- Künzli Holz AG
- Kaufmann Spenglerei & Sanitär AG
- Holcim Switzerland
- Mitsubishi Electric