Introduction

The pilot project in Hohenmölsen, Germany, represents an innovative step toward circular and sustainable construction. The city plans to construct a youth center utilizing precast concrete elements reclaimed from a donor building—a five-storey residential block built in the early 1980s as a “P-Halle” precast system used in the former GDR.

The ‘P-Halle’ series, like other GDR prefabricated buildings, uses cross-wall construction, where vertical loads are transferred through internal transverse walls. The structure is stabilized by the stairwell walls, transverse walls, and floor slabs. The lightweight concrete exterior walls act as self-supporting facades, while the gable walls are structurally reinforced. Its design is based on a 1200 mm modular grid, defining its main dimensions. 

With this initiative national and international building and environmental policy goals, such as reducing climate-damaging emissions and conserving resources will be met. By reusing components, the project aims to conserve embodied energy, reduce CO₂ emissions by over 90%, and lower construction costs by up to 30% compared to conventional methods.

The donor building’s partial deconstruction (May–July 2022) provided reusable elements for this circular approach. The project is scientifically coordinated by the BTU Cottbus Senftenberg. It seeks to demonstrate the feasibility of component reuse while showcasing the historical and cultural value of GDR-era precast systems. Local stakeholders, including city officials and housing associations, support the project, which aims to inspire sustainable practices and spotlight Hohenmölsen as a pioneer in circular construction. The youth center’s design will include diverse functions across two floors with an 835 m² gross floor area, integrating outdoor facilities and reinterpreting GDR building heritage.

Deconstruction and Storage

The donor building, located at Otto-Nuschke–Straße, underwent partial deconstruction in 2022. The project involved removing two storeys from the five-storey precast concrete structure, owned by WOBAU Hohenmölsen GmbH, under Managing Director Ronald Luckanus. Ecosoil Ost GmbH, led by Axel Bretfeld and Dietmar Gottschling, managed the dismantling, focusing on component-oriented deconstruction.

BTU Cottbus Senftenberg, under Prof. Angelika Mettke, provided scientific oversight, analyzing the suitability of components for reuse. Structural evaluations were conducted by the Cottbus engineering company ‘Ingenieurbüro Jähne’ situated in Cottbus, ensuring compliance with safety standards. Local stakeholders, including housing associations and city officials, supported this collaboration, are crucial for a big sustainable construction project as this one.

As for the process of deconstruction, the building’s surroundings were cleared, and the balconies were deconstructed before the whole building was scaffolded.

During the whole deconstruction process a mobile crane was used to lift all elements and necessary equipment and materials onto and off the building.

The two upper storeys were taken down in a terraced way, meaning that different deconstruction processes can be executed parallel (taking off roof elements, deconstruction of floor elements and reconstruction/retrofitting the new roof). Depending on the purpose deconstructed elements were stored or crushed on site.

Testing and Digitalisation

The testing process for concrete elements followed a structured decision-making methodology based on Brandenburg’s Building Code and local guidelines. Prior to deconstruction, in-situ investigations assessed the structural condition and suitability for reuse. Visual inspections identified cracks, spalling, and other surface issues, while metrological assessments evaluated concrete compressive strength, carbonation depth, and reinforcement cover using tools like Schmidt-Hammer and Hilti Ferroscan. Computational analyses calculated load-bearing capacities due to the lack of original data sheets.

After deconstruction, inspections focused on new defects, such as edge spalling, and further assessments confirmed minimal damage. Laboratory tests using drilled cores provided detailed data on compressive strength and elasticity. Carbonation depth tests showed no corrosion risks, and reinforcement properties were validated through destructive testing.

Results indicated compressive strength classes between C20/25 and C35/45, surpassing original estimates. The modulus of elasticity ranged from 20.7 GPa to 26.5 GPa, suitable for reuse. Hazardous substances, primarily asbestos-containing Morinol sealant, were safely removed by specialists before dismantling.

Digitalization tools streamlined assessments, enabling accurate structural analysis using software like BauStatik. The findings highlight the viability of reused concrete elements in sustainable construction while ensuring compliance with safety and environmental standards.

Precast concrete reuse in the design and construction of new buildings

For the design phase a new way of architectural thinking and planning had to be implemented. The design of the new youth center had to be adjusted according to the available elements deconstructed from the donor building. In total 162 prefabricated concrete elements in nine different types and dimensions were reassembled in the construction plans.

The elements were deconstructed, thoroughly stacked on site, transported and stored a second time at their final storage facility close by the future (re-)construction site. 

Because of the aforementioned fixed dimensions of the elements, especially the grid of the ceiling plan is predetermined. Hence, new additional elements, such as steel beams and columns or wood stud walls need to be installed to meet modern space and floor requirements. Further the interior and exterior walls of the donor building were placed on an extra wall strip to achieve appropriate room heights.

Due to longer than expected planning and realization of this construction project, the stacked elements on the intermediate storage facility will be covered for weather protection reasons. Meanwhile, the necessary funds are currently being requested by the City of Hohenmölsen. By the middle of 2025 the building permit and hence the tendering and execution phase are expected.

Check out the YouTube videos showcasing the disassembly and deconstruction of the German donor building

German Country Cluster Partners