In view of the amount of grey energy embodied in buildings, CO2 reduction is an increasingly pressing issue in demolition, new construction and refurbishment. Up to now, however, consistent concepts and methods for tackling the problem have been lacking. With an eye on achieving highly climate-neutral construction processes by 2030, Swedish architectural consultancy White Arkitekter have been developing a data-driven solution since 2020. ReCapture allows all the components of an existing building to be mapped and identified.
The architects first perform a 360° laser scan of the building to be demolished or transformed. Drones are used to obtain views of the building from all angles. The resulting point cloud provides the dimensional framework to which further data from other sources, including as-built records, are added to create a three-dimensional BIM model. Laser scans and drones, however, capture only the surfaces. Other experts, such as structural designers, toxicologists, building physics engineers, historic building specialists, recycling and environmental technologists, also inspect and evaluate the data. Their assessments complete the 3D model, which then contains all the relevant information about the materials: from weights and dimensions to costs, locations and degree of reusability. The next step is to generate a component catalogue documenting all the information about the materials and the condition of the individual components, an essential step before their potential reuse.
Evaluation
The architects can then estimate the percentage of reusable components in the old building. This forms the basis for the decision about where to place the focus in identifying components for feeding back into the value cycle and the possible forms of reuse. Architects and clients evaluate which elements are most worthwhile recycling, such as those with the highest embodied energy from raw material extraction and manufacture, for example, metal doors or windows. To this are added elements that, because of their high quality or special functions, are suitable for reuse, which could be in their original condition, in modified form or after disassembly into individual parts. This method can positively impact on the carbon footprint of the new building by saving primary materials.
The 3D model also allows virtual tours of the building. This does away with the need to physically visit the site because the project stakeholders can read all the information they require from the model. To a large extent, the market currently lacks the appropriate arrangements for construction component reuse. But even today, there are purchasers for second-hand construction elements and materials, primarily in the metal and glass sectors, where raw material extraction and manufacture require high amounts of energy. Various Internet exchanges for second-hand construction components and materials provide the basis for a rough estimate of their value. For the strategy to succeed, component reuse should be considered as early as possible in the planning phase. Early involvement of the demolition company is also important and the anticipated profit from reused elements and materials can be included in the tender for the project. This approach also reduces disposal costs.
Heinzelmann Areal
ReCapture is currently in use on the Heinzelmann Areal project in Reutlingen. This former factory complex manufactured textiles over many generations. The oldest building dates from 1890, the youngest was built in 1959. On behalf of the client, Gieag Immobilien AG, White Arkitekter is planning a car-free district with a diverse mix of residential and commercial uses. The existing buildings, some of which are listed, will be renovated. Only two buildings will be demolished and their sites enhanced by stand-alone timber structures.
The project is intended to be as carbon-neutral as possible, achieve DGNB certification and be part of the IBA 2027 Network. White Arkitekter was commissioned with the 3D scan, which was paid for as a special service in support of an innovative design process. Using this method, the architects quickly and efficiently documented and assessed the condition of components such as windows, doors and interior fittings that characterise the project site’s industrial buildings, which are up to a century old and listed, at an early planning stage. The majority of these construction components can be upgraded, reconditioned and put back in their original positions.
White Arkitekter see ReCapture in its current form as the first step towards climate-neutral construction by 2030. In the coming years, the architects intend to improve the process through “learning by doing” and continual technical and digital development. The 3D models will soon incorporate even more detailed information. In the longer term, White Arkitekter would like to create a digital model that evaluates projects based on CO2 savings through component reuse.
