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The STEP2 unit drives innovation in the NEST focus areas circular economy, industrial and digital fabrication, building envelope and energy systems. Partners from research and industry work together consistently towards marketable solutions. The unit is currently in the planning stage. After its completion, scheduled for summer 2022, it will serve as an innovation workshop and office environment.

Industry and research partners are working together in an open innovation approach to realize the two-story STEP2 unit. The main partner is BASF. The interdisciplinary collaboration along the entire value chain is the key factor in ensuring the development of marketable solutions. One central goal of the innovations is, among other things, the sustainable use of energy and resources.

These are the central innovation objects of the unit:

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The innovation objects in the STEP2 unit

As symbolic building spines, stairs have a significant functional, aesthetic and representational role in architectural spaces. However, bespoke concrete stairs pose significant fabrication challenges when it comes to conventional formwork solutions. To address and minimize these challenges, the innovation object is a complex free-form concrete stair based on research in 3D-printed formworks. In this context, a streamlined digital design-to-production framework is established, enabled through the synergy between computational design and additive manufacturing. The vision is to broaden the design possibilities of concrete stairs and reduce the extra cost, material waste, and labor associated with customization and complexity.

In terms of architectural expression, new design opportunities with highly articulated qualities are built in concrete. Glossy or anti-slip surfaces, ornamental features, and functional conduits are integrated in the design and parametrically controlled. Beyond a radical new design, the stair also integrates features for human comfort and safety.

Ultra-high-performance fiber-reinforced concrete is used for its excellent structural properties that enable very thin, complex shapes, otherwise impossible with regular reinforced concrete. Even though the innovation object is perceived as one coherent sculptural element, it is discretized into individual steps. The lightweight and structurally efficient elements are prefabricated and assembled on-site. The assembly is enabled by a state-of-the-art shape memory alloy post-tensioning system that provides the necessary reinforcement.

The aim is to highlight the benefits of digital tools, not only for the fabrication of bespoke concrete stairs, but for architecture, engineering, and the construction industry in general. Embedded in research, the innovation object demonstrates that digital fabrication technologies are already a sustainable fabrication strategy for context-specific, efficient and performant design solutions. It offers a ready-to-use solution for individual designs and building tasks.

Partners: Digital Building Technologies - ETH Zurich, BASF Forward AM, SW Umwelttechnik

The floor slab of the STEP2 unit drives innovations in the NEST focus areas industrial and digital fabrication and energy systems.

3D printing technology offers an enormous potential for the construction industry. It combines the efficiency of industrial manufacturing with the design and engineering capabilities of new digital design tools. A well-known application focus for this approach lies on floor slabs for solid houses. In a preliminary study, an overall technical concept for a ribbed filigree slab was therefore developed in cooperation with architects and civil engineers. This concept can cover spans of up to 20 meters – while at the same time minimizing material usage. A business case analysis evaluated the marketability and made this concept transparent for potential industrial partners.

The floor slab is prefabricated by NEST partner Stahlton Bauteile AG. 3D-printed formwork elements are used to produce biaxially pre-stressed precast elements with integrated beams. Pretensioning significantly increases both the freedom of design and the erection span extending the possible application field to a wide range. Technical functional components are already integrated at the factory.

At the construction site, the elements provided with shear and connection reinforcement are placed on the columns by a crane and completed with mesh reinforcement for the upper reinforcement layer. The in-situ concrete is then applied – the result is a monolithic reinforced concrete slab with beams and material-efficiently thinned out in intermediate areas. The prefabricated slab elements function as lost formwork with defined surface quality.

The floor slab is complemented by acoustic elements of NEST partner BASF Forward AM. Furthermore, BASF contributes products and expertise for the direction and distribution of light. This further promotes the central comfort issue.

NEST partner ROK developed specialized digital parametric design tools for the design of the ribbed filigree slab. These tools provide the architect with a great degree of freedom of design in order to accommodate customer requirements. On the other hand, these tools allow very efficient optimization of technical and economic criteria such as material usage and building physics. In STEP2, some of such optimization criteria were the deployment of recycled concrete as well as the direct integration of acoustic absorption elements.

During operation, the floor slab serves as a thermal storage mass. NEST partner WaltGalmarini AG dimensioned this thermal mass within the context of a holistic, integrated energy and building physics concept for the entire unit. This concept relies on passive technologies to further reduce the energy consumption. The thermal exchange takes place via thermoactive component systems (TABS). This technology is particularly suitable for bivalent thermal operation and therefore ideally complements the Energy Hub (ehub) at NEST with its geothermal probes and thermal storage systems.

Partners: BASF, ROK, Stahlton Bauteile AG, BASF Forward AM, WaltGalmarini AG

The building envelope plays a central role in the energy performance and comfort of a building. The façade of the STEP2 unit will therefore serve as a development and testing platform for NEST partners and their innovation topics. Its design allows the replacement of certain façade modules with minimal effort. In a thermally separated innovation workshop, this will even be possible during operation without any loss of user comfort.

The NEST partner Aepli Metallbau AG will carry out the development and production planning, the manufacturing as well as the assembly of the façade. The following innovation topics with the responsible partners are planned for the initial operation:

  • AAC façade modules with controlled air supply and integrated shading system. Partner: Aepli Metallbau AG
  • Light-redirecting systems (special laminated glasses, lens- and micro-mirror-systems...) to improve user comfort and reduce energy consumption. Partner: BASF
  • Automated ventilation flaps as a central component of the unit-specific energy and ventilation concept. Partner: WaltGalmarini AG
  • PV panels with Swiss colored glazing technology. Partner: Solaxxes AG

A core topic of the façade is the shading system. Using different approaches, the project team will analyze functionality, effectiveness and durability of new shading systems and materials and evaluate their influence on the energy concept.

The modular façade design allows the offsite installation of completely new shading systems into façade modules under controlled factory conditions. These façade modules allow for an easy and straightforward on-site installation.

Innovative glazing systems complement the shading systems. These systems affect light and energy input into the building. For instance, newly developed float glass systems with micro structured polymer films direct sunlight into the building where needed, reducing energy demand for artificial lighting. Such systems can also be designed to reflect sunlight partially in summer to reduce building heat up, while allowing the light to pass in winter to harvest the thermal energy and therefore reducing heating energy demand.

Another focus lies on energy production. The façade plays a significant role in the building's energy balance. This research field foresees a set of PV technologies to be subject to efficiency and profitability investigations. During operation, the unit will also provide valuable data about effective user behavior.

The modular construction of the façade as a test and evaluation platform allows the integration of further partners and topics during the operation of the unit.

Partners: Aepli Metallbau AG, BASF, WaltGalmarini AG, Solaxess AG

Building envelopes are the essential construction element when it comes to ensuring a comfortable indoor climate, preventing structural damage and reducing energy, operating and investment costs. The development of facades towards optimal energy efficiency with high comfort requirements is complex and therefore a central element of the STEP2 unit. For this purpose, NEST partner WaltGalmarini AG developed a comprehensive energy and building physics concept for the unit.

The planning project started with comprehensive studies of the location, the environment, the intended use and the local climate. Using thermodynamic simulations, control strategies for an adaptive building envelope were developed, which keep room conditions within the thermal comfort range.

The energy concept uses only passive systems such as natural ventilation and lighting, passive heating and cooling to condition the building interior. Active systems will serve only as a supplement if the passive systems do not sufficiently meet the desired comfort requirements. In the STEP2 unit the following technologies, among others, will be validated:

  • High thermal insulation glazing with high spectral selectivity
  • Controlled, natural ventilation by using automated ventilation flaps
  • Adaptive sun protection systems
  • An exposed concrete ceiling that can be activated as an extra storage system for thermal energy. By means of integrated heating/cooling loops, this can be additionally activated if required.

Partner: WaltGalmarini AG

New innovative materials are the key to sustainability. Customized profiles of properties reduce the consumption of resources and energy in their production and application. This makes them a central component of the growing circular economy, which is a key topic of the STEP2 unit.

BASF is contributing its in-depth expertise in a wide range of materials to the project. This includes structural and functional materials, bio-based and biodegradable products, dispersions, additives, coatings, composites, hybrids and multimaterials. With this expertise, the company develops new material systems, formulations and applications, which are further developed with cooperation partners. BASF is implementing a number of innovations in the STEP2 unit:

Thermal insulation is crucial for the energy efficiency of a building. New mineral-based insulation materials such as Cavipor® or high-performance insulation materials such as Slentex® are considerably expanding the range of applications, offer advantages in processing and recyclability and are also non-combustible. Slentex® has significantly improved thermal transmittance compared to conventional systems. This allows the construction of very thin thermal insulation systems.

The innovative water-based dispersion acForm® is the foundation of a new manufacturing technology with a high degree of wood utilization for three-dimensionally formed wood fiberboards. Due to their thermoplastic moldability, these wood composites are perfectly suited for molding and embossing technologies. They offer completely new design dimensions for furniture and interior design, for example molded furniture, wall and ceiling panels, doors, room dividers or structured floor coverings.

New materials also open up fields of innovation in lighting management – for example microstructured optical films that redirect light without significantly reducing brightness. When integrated into windows, these light-redirecting films can revolutionize the daylight supply in buildings.

Further examples include materials for 3D printing processes, such as photopolymers, polymer powders or plastic filaments like the Ultrafuse® product portfolio. It includes a wide range of materials that offer a variety of advantageous material properties such as printability, dimensional stability, durability and flexibility. Therefore, they are used in engineering applications and as temporary carrier materials.

Partner: BASF

STEP2 Partners

Project Credits: Bespoke Stair

Stair Design and Fabrication System
Digital Building Technologies - ETH Zürich with ROK and industry partners BASF Forward AM and SW Umwelttechnik
DBT Team: Georgia Chousou, Angela Yoo, Matteo Lomaglio, Andrei Jipa, Prof. Dr. Benjamin Dillenburger

3D Printed Formwork Fabrication
BASF Forward AM
BASF Forward AM: Jörg Petri, Sufyan Rasheed

Precast Concrete
SW Umwelttechnik / BASF Holderbank
SWU Team: Klaus Einfalt
Master Builders Solutions: Stefan Miesel

Architecture of STEP2 Unit
ROK Architects
ROK team: Silvan Oesterle, Michael Knauss

Structural Design
WaltGalmarini Team: Wolfram Kubler, Tizian Haussener

Project supported by the ETH Foundation

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