First materials register for entire German building stock lays foundation for circular construction

Germany's first database of materials for the country's entire building stock could provide an important foundation for increasing the rate of reuse and recycling of construction materials, said researchers at the Leibniz Institute of Ecological Urban and Regional Development (IÖR). "If we could manage to use building materials for longer, and recycle them after buildings have been demolished – in other words, if we built in a circular way – then the construction industry could make a significant contribution to limiting the climate change it causes, conserving resources and reducing environmental pollution," said IÖR researcher Georg Schiller.

About half of the raw materials extracted in Europe every year end up in buildings and roads, and construction and renovation sites alone generate over a third of the waste that ends up in the European Union's landfills. Moreover, the EU estimates that greenhouse gas emissions from material extraction, the manufacturing of construction products and the construction and renovation of buildings account for 5 to 12 percent of the total emissions of member states.

However, a lack of information is one of the biggest hurdles to reusing and recycling more building materials: details on which materials are used, in what quantities and how they are distributed in the building stock disappear quickly after a building goes up. Applying circular economy principles to construction – keeping materials in use for as long as possible, then reusing them in the next project or recycling them – holds great promise to cut waste, reduce raw material requirements and slash greenhouse gas emissions.

Using 3D scans, the researchers at the IÖR replicated Germany's building stock, separating structures by their use – for example single family homes, offices and factories. Based on extensive research, they designated each building type with the make-up of materials that they are typically composed of and used that to estimate stocks across the country. The "materials register", used together with information on regional demolition and new construction projects, means stakeholders in the building sector can now estimate which materials will be available for recycling as structures are torn down and know how those materials could be used for new construction and renovation projects.

The researchers will continue to refine the data, saying the work is far from complete. "Greater accuracy would allow further differentiation of the buildings, for example, by taking into account their age," Schiller said.

The emissions impact of construction has mostly remained an afterthought in Europe's efforts to make its buildings climate-friendly, which has largely focused on heating emissions. However, as homes and offices become more energy efficient, the environmental costs of construction are pushed into the spotlight. In Germany, there are currently no legal requirements to either assess the potential reusability of materials inside buildings being demolished today or to document which materials go into new buildings or refurbishment projects in the long term.