4.8 “VDN22” by Sedlak Immobilien: a pilot project for recyclability-oriented refurbishment

Partners: Sedlak / SCALE, Digital findet Stadt

The project for Van-der-Nüll-Gasse 22 – an older structure owned by the real estate company Sedlak Immobilien – is a pilot attempt to rehabilitate a building according to the principles of the circular economy, as detailed in the EU Taxonomy, by applying the technical screening criteria published in June 2023 as a delegated act of the European Commission. The plan is to arrive at the best possible economic and scalable solutions that can be implemented at moderate expense.

The object is a Gründerzeit building from 1885 that was already refurbished several times in the past. After conducting a first study, it is planned to accommodate new flats and offices on a gross floor area (GFA) of 1,650 sq m partly resulting from retroactive densification (three storeys gained through attic conversion). The project was launched in June 2023; construction is scheduled to begin in early 2025 and should be completed by early 2026.

The prerequisite for conducting a Taxonomy-aligned refurbishment project lies in compliance with the criteria of one of the six stated environmental objectives without doing significant harm to any of the other objectives. The environmental objective “Transition to a circular economy” is of immense importance especially for the construction industry, as this sector consumes over one third of worldwide resources; the savings potential is correspondingly huge.

Concretely, construction and refurbishment according to circular economy principles means to lengthen the useful life of a building through planning that comprises options for conversion and repurposing and ensures uncomplicated use as well as through employing long-lasting materials and technologies and forgoing the use of primary resources in favour of secondary ones, i.e. re-using existing or recycled materials and components and cutting down on construction waste that cannot be recycled. Moreover, a concept for dismantling the building at the end of its useful life must already be considered in planning. A full life cycle assessment for the building starting from the moment of renovation must also be prepared. The materials used in the building should be recycled at a later date; this requires a digital building resource passport as a materials database to clarify what materials were employed where and how.

The process is supported by new software by the company SCALE that allows for the simulation of the environmental impact of a building depending on the materials used. By means of the life cycle assessment calculated on the basis of a digital model, it is possible to optimise greenhouse gas emissions and other environmental indicators already during the planning phase (i.e. in the model) by comparing different construction materials.

The project receives funding through the WieNeu+ “Grätzlförderung” subsidy scheme.

Core interventions of the project:

• Waste management . The project minimises waste and aims to recycle construction materials for optimised resource use.

• Selection and use of materials . Environmentally friendly and sustainable materials are used for refurbishment.

• Construction design . The focus of planning is on flexibility, adaptability and dismantlability. The building should be well prepared, not only for the present, but also for the future.

• As-built model . A central database for relevant building information that allows for a precise documentation of the materials and components used.

• Documentation and transparency . Comprehensive reporting documents not only compliance with the EU Taxonomy criteria but also positive impact on the environment.

Outcomes

The project is considered a flagship intervention aiming to test the circular economy approach in building refurbishment on the basis of a concrete structure. This approach allows for a reality check of current framework conditions and offers an opportunity to obtain practically applicable know-how for future projects.

Taking a step towards circular economy-aligned construction methods calls for new, creative, open and, sometimes, out-of-the-box thinking.

The implementation of solutions that take account of the principles of a circular economy in refurbishment and rehabilitation is strongly dependent on building typology and age. Hence, a detailed on-site analysis of the status quo, specifically prepared for the respective project, is indispensable.

The economic efficiency and conformity of the interventions with the EU Taxonomy are essentially contingent on statutory and practical-technical framework conditions, which in their turn impact competitiveness and, hence, pricing.

The scalability of refurbishment solutions corresponding to the principles of a circular economy will only become reality with the – expected – arrival of commercially viable products and services geared towards a circular economy.

Further results as well as the progress of the project by Sedlak Immobilien / SCALE are published regularly in a blog on the website of Dipl. Ing. Wilhelm Sedlak GmbH.

The following projects focus on research and the formulation of innovative ideas for a preliminary exploration of their technical and organisational viability.