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.

ReUse Hub Kolkwitz

The implemented German ReCreate pilot is the ReUse Hub Kolkwitz, an extension to the clubhouse of the sports club SV Kolkwitz 1896 e.V. at the Jahnstraße sports grounds in Kolkwitz near Cottbus (Brandenburg). The project comprises: 

• a two-storey extension with storage and technical space on the ground floor (~88 m²) and new fitness and office space on the upper floor (~73 m²); 

• two separate single-storey buildings at the entrance to the sports grounds: a ticket office with storage and a carport for the club’s minibuses. 

Including these ancillary buildings and public-use facilities, the project covers approximately 290 m². Kolkwitz is the first site in Germany where the reuse process developed within ReCreate has been put into practice on a real public building. 

The project continues the club’s long-standing commitment to component reuse. The existing clubhouse was itself built in 2009 from 80 reclaimed precast concrete panels in an earlier research project led by Prof. Angelika Mettke. Once completed, the new building will serve the whole community, not only the sports club: the local council, associations, and educational, cultural and sports activities. 

The extension was commissioned by the Municipality of Kolkwitz on behalf of the sports club. The partners and their roles were: 

• BTU Cottbus-Senftenberg under Prof. Angelika Mettke developed the reuse concept and architectural design. The first drafts were drawn up by Sevgi Yanilmaz and developed further by Christoph Henschel. 

• Ingenieurbüro P. Jähne GmbH (IBJ) acted as lead building designer. 

• Ingenieurbüro für Baustatik, Dipl.-Ing. Wolfgang Lehmann carried out the structural calculations on behalf of IBJ. 

The shell construction was financed through ReCreate. The interior fit-out and equipment are funded with more than €521,000 from the State of Brandenburg’s structural development funds for Lusatia. 

According to BTU’s calculations, reusing the existing elements can save up to 97% of the CO₂ emissions that would result from producing new ones, and significantly reduces primary energy demand compared with conventional new construction. 

Deconstruction and Storage 

All reused elements originate from a single donor building: a WBS 70 series precast concrete corridor-type apartment building (Mittelganghaus) in Großräschen, built in 1988 and originally six storeys tall, about 40 km from Kolkwitz. To reduce housing oversupply, its owner had the top two to three storeys partially deconstructed in winter 2023/24. The work was carried out by ReCreate partner Ecosoil Ost GmbH and scientifically observed by BTU. 

The campaign shows the difference between theoretical reusability and what is actually recovered for a specific project. Of 707 deconstructed elements, 211 floor slabs, 224 interior wall elements and 104 exterior wall elements were classified as technically reusable. For Kolkwitz, 88 elements were carefully reclaimed, including interior wall panels, exterior wall panels, floor slabs and frame elements. Some are up to six metres long and weigh almost six tonnes. They were transported to an intermediate storage yard in Kolkwitz. 

All elements were inspected for damage before and after transport, and 8 elements were set aside as reserves. The remaining 80 were allocated as follows: 

Testing and Digitalisation 

The structural reuse of precast concrete elements is not covered by the technical building regulations in Brandenburg, and no general technical approval (allgemeine bauaufsichtliche Zulassung, abZ) was available. Their use therefore required a project-specific approval (Zustimmung im Einzelfall, ZiE). In Brandenburg this is handled by the Technical Building Inspection Authority (Bautechnisches Prüfamt, BPA) of the Brandenburg State Office for Building and Transport (LBV). 

Extensive pre-testing of the elements following the LBV (2012) guidelines formed the technical basis for the approval. Prof. Mettke prepared the supporting expert opinion (gutachterliche Stellungnahme). The scope of testing and verification was first defined in February 2026 at a meeting between the BPA and the pilot team (IBJ and BTU). Later requests for additional information expanded the required investigations, which also affected the project schedule. The material properties documented in the ZiE process provided the design values for the structural calculations. 

Before the pilot, the German cluster tested the construction method in a full-scale test building on the former Cottbus airfield in April 2024. It used 12 elements from the same donor building. The test covered: 

• newly developed flat-steel connectors fixed with concrete screws; 

• the combination of reused concrete elements with timber stud walls; 

• the SysCompound joint mortar based on fly ash and recycled aggregate; 

• sawing of elements to new dimensions. 

The lessons learned were to plan for larger dimensional tolerances, keep concrete sawing to a minimum, and expect more joint grout where edges are uneven. 

Precast concrete reuse in the design and construction of new buildings 

The architectural design responds to the spatial and functional needs of the sports club, rather than simply reproducing the grid dimensions of the standardised donor building. This increases the effort of examining possible component arrangements, but allows the reclaimed elements to be accommodated meaningfully in a new spatial context. Storey heights in GDR-era precast buildings were typically very low. Setting the reused, only nominally reinforced wall panels on masonry plinths therefore allows greater storey heights than the original panel dimensions would permit, which extends the design freedom of reuse. 

The load-bearing structure is formed primarily from reclaimed donor elements: 

• Supplements and foundation: masonry in wall sections, plinths and parapets, all supported on a foundation slab. 

• Larger spans: where these exceed what the reclaimed floor slabs can provide, additional steel beams and columns were introduced. 

• Horizontal stability: provided by the wall cross-sections together with floor diaphragms, which are formed by the slab elements and an in-situ peripheral tie. 

• Building corners: the vertical wall-to-wall connections are dowelled with steel anchors to ensure shear stiffness, since the panels bear on the plinths. 

• Change of use: some former interior wall panels are reused as exterior walls. The increased concrete cover they now need is achieved with a lime-cement render. 

Construction began in late April 2026 with site preparation. The first reclaimed elements were installed at the end of June 2026, shortly after ReCreate partners from all four country clusters visited the site during the final Annual Meeting. The load-bearing frame, with all reused elements in place, was completed in early August 2026, and the topping-out ceremony was held on 20 August 2026. Completion of the whole project, including parking, landscaping, the extension, ticket office and carport, is expected in early 2027. 

Lessons learned 

The pilot gave valuable insight into the administrative effort of reuse. The ZiE process required substantial resources and proved difficult to predict in scope and duration. This confirms that the absence of standardised procedures remains a key barrier to wider structural reuse. BTU is therefore pushing for a revision of the LBV (2012) guidelines to simplify and standardise approval by better defining the required scope, and efforts are under way to adapt Brandenburg’s building regulations. 

The pilot also confirmed that transport is a major source of cost and organisational effort. Reuse appears particularly viable when the new application is close to the donor building, while longer distances can significantly reduce practical and economic feasibility.

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

German Country Cluster Partners