As construction costs escalate and sustainable development becomes a no-brainer, recycling - and circular construction - are taking on a new significance.
Circular construction strives for an efficient and effective use of resources, with a view to creating or at least maintaining economic, social and ecological value. As resources become more scarce, the importance of creating buildings with recycled and recyclable components has never been higher.
However, if you want to build a new building with reused materials, you face three major hurdles: how to find the materials in an appropriate condition and sufficient quantity, how to be sure that these reused materials will meet all the technical and engineering demands of contemporary building standards and, perhaps most difficult of all, how to find a builder who is willing to use these unconventional materials.
That’s not to say it can’t be done. Germany’s first recycled house was built in Hanover in 2019. The architects came up with creative solutions to reuse as many materials as possible, including radiators, stairs and several walls consisting of sauna benches. The façade insulation is made of recycled jute sacks for cocoa beans, with the windows coming from a former youth club. The project planning took three years, due to the time-consuming search for recyclable building materials and firms that were able to install the recycled material. Nonetheless, it set an important new standard, proving how different materials can be reused in new buildings.
These obstacles are part of the reason why recycling has not become a bigger part of sustainable building, although that is now starting to change. The recycled house in Hanover got underway in 2015 when local real estate and construction company Gundlach decided to try and build a 100% recyclable house. The concept of the local architecture office cityfoerster was to construct a house entirely of recycled and recyclable components. For example, the gluing together of elements was avoided, so that all components and materials could be dismantled and reused in the future.
Construction and demolition waste accounts for more than a third of all waste generated in EU
It is easy to see the appeal of recycling in construction, also in a broader context: according to Interreg Europe, a platform that brings people together to share innovative and sustainable solutions to regional development challenges, construction and demolition waste (CDW) accounts for more than a third (35%) of all waste generated in the EU. It contains a wide variety of materials, such as concrete, bricks, wood, glass, metals and plastic, including hazardous materials like asbestos. About 450 – 500 million tonnes of CDW are generated annually in the EU. It contains all the waste produced by the construction and demolition of buildings and infrastructure, as well as road maintenance. Technology for separation and recovery of construction and demolition waste is well established, readily accessible and generally inexpensive. Nevertheless, the level of recycling and material recovery of construction and demolition waste varies greatly across the EU, ranging from less than 10% to over 90%.
Developers are getting in on the act. In Munich, developer GWG Städtische Wohnungsgesellschaft München announced earlier this month that it wants to repurpose elements of apartment buildings set for demolition across 900 new apartments being built or in other projects.
However, to do this, a material flow analysis is needed, which essentially tracks the path of a material from its extraction to processing, to its reuse or eventual disposal. This enables GWG ‘to assess which components we can reuse in our own new building projects, which materials are suitable for a building materials exchange and whether it even makes sense to take them back from the manufacturer’, according to Rositsa Doneva, team leader for climate protection at GWG.
Epea, a consulting firm specialising in the circular economy, has been tasked in cataloguing door frames, window glass, metal, wood and also waste bins, among other things, and identified possibilities for reuse: ‘As long as they do not contain any harmful substances, almost all building materials can be reused or at least recycled to a higher value,’ said Andrea Heil, an expert in recyclable building at Epea.
For its part, GWG has ambitious plans for 2023, announcing last month that its goal is to complete around 1100 new flats, commercial units with different uses and social facilities this year. In addition to the new construction, it is engaged in 24 modernisations of existing stock. The guiding principle is to implement a sustainable and energetically high-quality construction method in combination with special forms of housing, mobility stations for the GWG tenants and infrastructure measures.
‘I am very pleased about the high new construction figures of our municipal subsidiary GWG München,’ said Verena Dietl, chairwoman of the Supervisory Board of GWG München and Mayor of the City of Munich. ‘As a housing company, GWG stands for a socially just Munich that is also committed to implementing sustainability issues for the future and the next generations.’
For developers who have been squeezed by rising construction costs, recycling makes economic sense. According to Epea, it costs around €400 to dispose of a five-cubic-metre container with mixed construction waste, whereas selling it actually generates income. Similarly, tiles can typically be sold for around 50 cents each, processed concrete rubble is worth €8.50 per cubic metre, and a kilo of scrap steel is worth about 20 to 30 cents, according to Epea. As such, raw materials used in buildings, roads and civil engineering in Germany likely add up to 29 billion tonnes.
Another building material that is increasingly being recycled is aluminium - the most commonly used metal on earth, according to the Council for Aluminium in Building. As with cement, the production of aluminium is also very energy-intensive, yet recycling it requires 95% less energy than its original production. Something else that can easily be recycled is broken bricks: ‘With the help of our recycling plant at the Puttenhausen site, we have now been able to recycle more than 5,000 tonnes of broken bricks,’ said Thomas Bader, head of the building materials manufacturer Leipfinger-Bader. Start-ups are also muscling in. The Swiss company Holcim is working with the start-up Neustark, which has developed a process to bind CO2 in the production of recycled concrete.
In 2013, four founders launched Restado, the first online marketplace for reclaimed building materials. Restado’s findings led to the launch of Concular, a platform for circular construction, in 2020. The platform records used building materials and its database is used by architecture firms, construction companies or developers who want to reduce the carbon footprint of their buildings with recycled materials, but also by manufacturers who recycle their building materials, according to Dominik Campanella, co-founder of Concular: ‘In order to establish circular value chains, we network local deconstruction companies, testing centres as well as project and architecture offices.’
Government to launch building resource passport
However, in order to preserve recycled materials and their value, the relevant data must be recorded and documented, not only in new buildings but also in existing ones. In its coalition agreement, the federal government has stipulated the introduction of a building resource passport. This does not yet exist, but in addition to Epea, the German Sustainable Building Council (DGNB) has developed such a digital product.
Over in Gehlberg, Polycare is developing innovative construction technology that makes sustainable habitats affordable with its CO2-reduced modular construction system poly-blocks. Polycare's aim is to replace concrete as far as possible because it releases so much CO2 in the production of its key component, clinker, that it is responsible for 8% of the world's carbon dioxide emissions, making it one of the reasons why the building sector is breaking its climate protection targets year after year. At the same time, entrepreneurs were looking for a way to reuse existing building materials instead of sending them to landfill. Poly-blocks look like very large play bricks, consisting of a shell nestled around a filling of demolition bricks, replacing the binder cement with polyester resin: ‘This creates a material that is even stronger than concrete,’ according to Polycare CTO Robert Rösler.
And while recycling in commercial construction is a relatively new trend, moves are afoot to make it easier to recycle materials such as concrete, bricks, tiles and ceramics, which will no longer be considered waste if they are recycled during construction. The Federal Ministry for the Environment is preparing a separate legal regulation whereby mining-grade building materials will be given product status.
The Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV) is working on criteria that will determine when certain mine-related substitute construction materials will no longer be considered waste. The necessary legislative procedure is to be completed before the end of this legislative period. In the coalition agreement, the federal government already set itself the goal of releasing quality- waste products from waste legislation and giving them product status. A key point paper is being prepared, which will then serve as the basis for a draft amendment. Such a regulation would achieve more for the circular economy than a discussion about product-specific recycling quotas, according to Felix Pakleppa, managing director of the Central Association of the German Construction Industry (ZDB).
As of 1 August this year, the Waste Management Ordinance will come into force, the core of which is the Substitute Construction Materials Ordinance, which was introduced by Article 1. This will regulate how and where construction waste and excavated material may be used as recycled construction material. More than 220 million tonnes of mining-related construction waste is produced in Germany every year, although almost 90% of this is recycled in an environmentally sound manner, according to a recent report by the initiative Kreislaufwirtschaft Bau, of which the ZDB is a member.
Ultimately, for recycled buildings to take off, developers, investors, architects and renovators need to work together. As Clive Nichol, CEO of Fabrix, a real estate investment platform specializing in bringing value to underutlised and overlooked urban spaces, notes: ‘Lots of people have been advocates of urban mining for many years but it’s those controlling the development who must make the decision and take the perceived risk. It took us a lot of work, not everyone is interested in doing that.’
