While the circular economy as a concept is no longer a novelty in the European building industry, the path to genuine circular construction, including the comprehensive reuse of building materials, is still a bumpy one. How can you build using reused materials in a way that can be easily dismantled for future reuse, yet still comply with all building standards and regulations? Who has the expertise to dismantle tiles or windows, clean and repair them for reuse in another building? Heck, where do you even source used building materials in sufficient volumes?
In Germany we have so far seen only a few pioneers of circular architecture. One of the latest examples can be found in Berlin, where the 20,000m2 site of a former brewery in Neukölln is currently being redeveloped. The building was vacated in 2005, but interest in developing the property – located in one of the poorest areas of Neukölln – remained low until 2011, when a Swiss-French art collector couple bought the architectural set-piece at the centre of the site: a large, slightly Expressionistic-style dark-brick building, which originally housed the machine hall, brewing house and water tower.
Built between 1926 and 1930 and looking more like a cathedral than an industrial plant for making something as prosaic as beer, this was transformed by the couple and reopened in 2015 as KINDL – Centre for Contemporary Art (its name derived from the original brewery). Just two years later, the rest of the site was acquired by a Swiss charitable foundation, the Stiftung Edith Maryon, which specialises in buying primarily city-centre property to hand over on long-term leases to social, cultural or creative business users. This ensures the property is protected from commercial speculation and secured at low rents for the long term. To date, the foundation has protected over 100 such sites, primarily in Switzerland and Berlin.
For the brewery site, the foundation set up an interdisciplinary team, which included existing users and neighbours of the site, to develop a concept around an arts centre, transforming the existing buildings into artists’ studios, affordable apartments and offices for organisations whose work fits with the foundation’s policies. From the start, the idea was to densify the site by adding new buildings and expanding existing ones.
To date, four projects have been completed. A former utility building was transformed into offices and studio spaces in a retrofit by Berlin-based architects Hütten und Paläste. This was deliberately minimal, adapting the interiors with sustainable materials and adding simple balconies. To the west, a historic brick building became the One World Center and to the north, a new timber-and-concrete hybrid building – Haus Alltag – has been built by Berlin-based Carpaneto Schöningh Architekten. This now offers short-term apartments for people in rehab, as well as those seeking temporary refuge, such as girls and women fleeing domestic violence. On its ground and first floors, a health centre offers medical and pediatric services and a small communal kitchen also doubles as a café.
These projects were already testing the water of an architecture taking economical, ecological and social responsibility seriously in creating affordable and functional spaces. But none has taken these ideas further than the most recently completed: CRCLR-Haus.
The CRCLR-Haus – or Circular Economy House – is designed by Berlin-based architects Die Zusammenarbeiter. To match the ambitions of this pioneering project, they brought in ZRS architects and engineers from Berlin, who specialise in sustainable construction using timber and adobe, plus Basel-based practice baubüro in situ, which brought its expertise gained over more than 20 years in building circular architecture in Switzerland.
The CRCLR-Haus combines the retrofit of the former brewery’s barrel-loading hall on the site’s southern edge along Rollbergstraße with two and three-storey rooftop extensions providing workspace and housing. The original building is about 70m long and 18m wide. Yet, because it sits along the edge of an artificial plateau on which the brewery was built, its ground floor is only accessible from the street, whereas from the plateau on the north side the entrance is at first-floor level.
The retrofit of the existing building was all about a sustainable transformation using as minimal means as possible. All exterior walls were insulated internally with softwood fibre and lightweight panels made of either wood fibre or clay. For structural reasons, part of the northern exterior wall towards the plateau had to be completely replaced. This was externally insulated and clad in metal façade sheeting taken from the original building’s southern façade. At ground floor level, the interior remained largely untouched and is occupied by a couple of DIY workshops and start-up offices. However, the first floor has been entirely redesigned by LXSY Architekten, in co-operation with client TRNSFRM, along circular economy lines. They have installed a large wooden mezzanine and created 500m2 of new office space, including meeting rooms and team kitchens, with 70 per cent of the project’s materials being reused. This is now home to Impact Hub Berlin, part of a global organisation providing co-working spaces for socially, environmentally and financially sustainable businesses and initiatives.
The old roof – a simple but robust construction of steel girders, timber and metal sheeting – was fully replaced by reinforced concrete in order to make the extension above possible. The wood was reused and about 25 tonnes of the steel girders were put aside for reuse in the new addition. In order to reduce weight and maintain the idea of circular sustainability, the architects decided to construct the new storeys using a timber frame with straw insulation. With an eye to easy future dismantling, all the wooden joints are screwed or wedged instead of using glue or nails. To comply with some of the stricter fire protection laws for timber construction, the new volume was cut in two. To the east, two new storeys provide additional co-working spaces, while a three-storey element to the west offers cluster apartments of up to 390m2 for collective living. These are run by Campus Cosmopolis, which is bringing together a mix of refugees and local people as residents of the flats.
Since the aim was to start construction without a fully finalised plan and with many materials still needing to be sourced and dismantled from existing buildings, it proved very difficult to find a contractor willing to take on the risk. Instead, around 30 skilled and unskilled workers were brought together through the networks of the users, architects and the foundation to form an experimental building company: The Collective Construction Site, whose work included searching demolition sites for possible materials and components. Indeed, the CRCLR-Haus is a bit of a Frankenstein building. Fire doors came from the refurb of a hotel on Alexanderplatz, washbasins from a demolished youth hostel in Brandenburg. The biggest find was in Switzerland, where 106 windows from a residential building were saved from demolition: the price – including transport, reglazing and storage – came in below that for new windows.
Unfortunately, there wasn’t always such luck. Often appropriate materials or elements couldn’t be found in time and every delay in construction meant rising costs. Much of the know-how needed for circular construction had to be acquired in parallel to the construction process. A certain trial-and-error rate could not be avoided and caused delays in the building process again and again. On the other hand, the experimental construction site developed some positive dynamics, too. When no company could be found to construct the timber and straw structure, the workers of the collective took over and were trained on site by members of the Fachverband Strohballenbau Deutschland, a small private club promoting building with straw in Germany.
All in all, the circular ambitions of this project and the many difficulties in harmonising these with building regulations, as well as the harsh reality that most building materials are still simply being thrown away, has led to a rather pragmatic design. The floor plans, with their dark middle zones, are far from being innovative in the field of cluster apartments. The façades are more the result of a very straightforward construction than of any higher aesthetical ambition. In the end, many parts of the CRCLR-Haus were built rather conventionally in order to find a compromise between budget, building regulations, mandatory warranties and technical standards.
For the time being, two of the more ambitious ideas had to be cut entirely. The western façade was to include large balconies made from the reused steel girders. But since there are no assembly regulations in Germany for reused steel girders, extra static tensile tests and chemical analyses were necessary for official approvals. These were done, but in the end, no money was left for cutting and mounting the girders as balconies, so they are now stored in the building, in the hope they will be installed in the future. Similarly, an idea to wrap the gap between the two new volumes entirely with reused windows, creating a kind of glasshouse, or large, communal winter garden had to be put on hold due to budget. If both these elements had been realised, the building wouldn’t look quite as pragmatic as it does now.
In the end, we see a simple building with an extremely complex genesis. And this is exactly where its importance lies: in making visible the many obstacles to holistic circular construction. Architect Christian Schöningh of Die Zusammenarbeiter believes that this highlights the fundamental structural problems of a circular building industry still in its infancy: the availability of second-hand materials on the one hand; the problems with finding a company to actually build it and gain the necessary official approvals on the other. With building costs of €15 millionf for a gross floor area of 6,100m2, the project has ended up more expensive than a comparable conventional building – mostly because of the additional planning and logistics needed.
But all over Europe, we see young companies building up databases for second-hand materials, setting up specialised demolition and transport companies to save, restore and reuse them – from baubüro in situ in Switzerland, Rotor in Belgium to Material Cultures in the UK. Once there is a reliable ecosystem for this, the bumpy path of circular construction will gradually become more comfortable to travel, making it an easier and eventually cheaper way to build than conventionally. The collective workers who built the CRCLR-Haus already firmly believe this fundamental change is coming and have turned their experimental collective into a ‘real’ building company: Heap59, specialising in circular construction – and at your service.
Florian Heilmeyer is a Berlin-based editor, curator and writer on architecture
Impact Hub Berlin at CRCLR-Haus by LXSY Architekten
This co-working space is designed for use by entrepreneurs working in the circular economy, sustainable food, diversity & inclusion and green tech sectors. Resource-saving construction informed LXSY Architekten’s interior design, which uses recyclable materials and elements designed for easy disassembly and repurposing with the help of product and material passports.
The former warehouse is split into two levels by a wooden gallery with accessible multifunctional rooms and team spaces placed above and below it. Telephone booths, meeting rooms and seating niches are distributed throughout the levels, with studios, workshop rooms and labs in the basement.
Materials and products used in the design originated from demolition sites, trade fairs, museums and company stockpiles. The sliding doors of the telephone boxes, for example, were taken from a previous Impact Hub Berlin. The black MDF comes from a Berlin club. Local carpentry workshops were regularly canvassed to recycle wood offcuts and leftover pieces. Much of the furniture from old Impact Hub Berlin was kept and complemented with a mix of vintage pieces or furniture rentals. Functional elements such as cables, sanitary installations, ventilation pipes and heaters were also second-hand.
The use of new materials, in the form of hemp walls, for example, provides a healthy indoor climate as well as sound insulation. Felt and straw panels also serve to boost the acoustics.
Circular construction manifesto
The principles of circular construction that guided the project were:
1. Build robust and adaptable buildings that can actively adapt to the changing needs of users over their lifetime.
2. Think of buildings as temporary material storage facilities, with the aim of long-term preservation of identity of individual materials/elements and value of the resources used.
3. Use simple standards and modular components so that individual elements can be
easily replaced.
4. Build only what is necessary, using as few resources as possible.
5. Choose high-quality materials so that they can last a long time and handle multiple cycles of use.
6. Document the materials you use to make future reuse easier.
7. Choose simple, reversible, mechanical and accessible connections which can
tolerate repeated assembly and disassembly.
8. Prefabricate building parts beforehand to minimise assembly time and last-minute changes on site.
9. Sharing comes before owning: components and installations should where possible be purchased as services and not as a product itself.
10. Promote cycles (material, economic, social) among different users of the building.
11. Create a passive, resource-saving and decentralised means of supply and disposal – technical standards should be based on need and not a maximum specification.
Detail design guidelines
The rules of construction followed in the design were:
1. Simple, robust and visibly joined structural elements.
2. Avoid/minimise projections or recesses.
3. Keep clear separation between functional components in the building construction (reducing need for extra fixing components).
4. All usable areas to have two escape routes.
5. No internal firewalls.
6. Components to be joined additively and not integratively (eg no use of glue).
7. Avoid fire protection cladding if possible.
8. All mechanical/electrical fittings to be surface-mounted and visible.
9. The design to provide for shared rooms and uses.
10. Reuse existing components for the following components: timber-aluminium windows; steel truss and I-beams; curtain wall and cladding elements; sheet metal and glass; sanitaryware.
Project data
Start on site 2020
Completion 2023
Gross internal floor area 6,100m2
Construction cost €15 million
Architect Die Zusammenarbeiter and Gesellschaft von Architekten with baubüro in situ
Architect (tenant fit-out) LXSY Architekten
Client TRNSFRM building cooperative
Leaseholder Terra Libra Immobilien
Structural engineer ZRS Ingenieure
Fire consultant Brandkontrolle
Energy consultant eZeit Ingenieure
M&E consultant Solares Bauen
Life cycle assessment Benedikt Kurz, TU Berlin
Financing partner Umweltbank
Project manager TRNSFRM
Main contractor TRNSFRM