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REUSE on the European architectural scene

14 of September '23

The article is from A&B issue 9|23

Reuse, from English, literally "secondary use," in architecture refers to building materials and components. This is the kind of activity we have always known. What is new is that in recent years reuse has become the focus of avant-garde architectural circles that design, teach and write, thus shaping trends. The European reuse architectural community is diverse, with almost every country having its own specialists. The common denominator of their experiments is environmental motives.

While the reuse of cladding or objects is relatively easy and popular, the reuse of entire building components or load-bearing elements is difficult and as yet little recognized. However, increasingly interesting and bolder examples of such implementations are appearing on the European architectural scene, often taking the form of experimentation. The architecture resulting from such developments can influence design and aesthetics. In the coming years, we, the citizens and citizens of the European Union, are faced with the need to adapt the law, the construction market and the way we design not only to new standards, but also to changing social expectations. The first signs of this are already visible and promise interesting times ahead.

what is it and what is it for?

I first encountered the term reuse in architecture around 2010 in the context of the popularization efforts of the then young Belgian research and design studio Rotor. To quote one of their definitions of the phenomenon: reuse "means the fact of recovering building elements during demolition work or during reconstruction and finding them uses in other projects. [...] Reuse is different from recycling, which involves the thorough transformation of the acquired building elements. [...] Recycling activities typically involve milling the acquired components, resulting in the component being turned into a raw material: solid wood into chips, plastics into pellets, gypsum board into dust, glass into silica. These raw materials can then be used to produce new components. Reuse, in turn, seeks to maintain the integrity of the shape and functionality of the components involved. In general, however, many steps are needed to ensure correct and secondary use. "1 In turn, the Swiss pioneers of circular architecture gravitating around the In Situ studio explain why reuse is interesting from an environmental perspective this way: "Every time components of buildings that are serviceable for several more decades are not destroyed, but are reused in buildings, there is not only a saving of resources. It's also a drastic reduction in energy consumption and greenhouse gas emissions during the construction process. "2 The scale of the construction industry's environmental impact is significant. Danish architect Anders Lendager, author of spectacular realizations using circular material strategies, risks the following estimate: "We need to move away from a linear economy with a cradle-to-grave approach, in which materials have an expiration date, and return to viewing waste as a resource. The construction industry plays a key role as a catalyst for change. In a world that consumes more than twice as many raw resources relative to what the planet can provide, the built environment absorbs up to 70 percent of these raw materials and 40 percent of CO2 emissions. "3 To put it simply: using new building materials (except those with a negligible carbon footprint, such as earth, straw, some wood) is inherently a heavy burden on the environment, recycling is good because we don't extract more raw materials, but reuse is much better because it doesn't require another energy expenditure for processing.

old as the world

All of us architects know plenty of examples of reuse from our own cities, villages, history or personal lives. My grandfather, after being resettled in Masuria, built a summer house out of planks and boards after boxes of UNRRA4 donations. But did you know that the monumental stone pedestal of the former Central Committee headquarters in Warsaw (designed by the Warsaw Tigers) was made from stones recovered from the Hindenburg mausoleum near Olsztynek? And from more contemporary examples: did you know that a prefabricated bathroom excavated from a German plattenbau was inserted in Arno Brandlhuber 's wonderfully designed artist's studio in the West Pomeranian town of Ninikowo? In this article, however, there will be no mention of my family, war spoliation or other beautiful anecdotes. The rest of the text will focus on contemporary projects and innovative realizations that push the boundaries of an architect's professional practice, and therefore, in my opinion, are inspirations worth making public.


TheRotor organization consists of two main business entities. The first is a design and consulting cooperative with unique expertise in reuse issues. The second, Rotor DC5 (from deconstruction), was founded in 2016 and is an online and physical store for materials and items harvested from demolition. The store is the most well-known part of their business, and provides a great entry point into the world of reuse. The ability to select building components and Rotor's curated expertise on dismantling, identifying authorship and technical properties of the components in question sets the store apart from the usual antique markets. Access to technical information as early as the design stage makes it possible to buy or reserve components and integrate them into a project6. Rotor as an organization has been operating since the 2000s, having been founded by a group of young architects. Already in 2010 it was recognized and a monograph was dedicated to it in a series devoted to "emerging" studios. In the pages of this modest publication, the young founders surprise with their knowledge and maturity, describing themselves as follows: "Rotor is an association of people who share the conviction that the secondary use of materials can be a correct ecological strategy, and concede with some surprise that it is so rarely considered, especially in the circles of professions that make choices that affect how material resources are used. "7 Today, the Rotor studio is an organization that employs more than twenty people, functions on a cooperative basis, and has numerous exhibitions8, lectures9, publications, as well as projects of which they were the main designers or consultants from reuse to external architects.

An example of Rotor's operating model is its cooperation with other architectural studios as design support, i.e. as reuse industry professionals. Together with Brussels-based studio OUEST, they developed a headquarters project for the NGO Zinneke. In remodeling and combining several Brussels houses, nearly 95 percent of the mass of materials found on site was left behind. 12 percent of the new materials were recycled. Secondary uses included steel sections obtained from other buildings as lintels, windows, insulating wool, steel stairs, exotic wood for the terrace, oak parquet floors, radiators, doors (including fire doors), and an entire mechanical ventilation unit obtained from an office building.

In the interview,Michaël Ghyoot, co-author of the project, cites examples of the many difficulties encountered during the project. One of these was applying for a building permit at a time when the dimensions of the windows that would be obtained were not yet known. After negotiations with the authority, it was agreed that these "unknowns" would be marked on the elevation drawings with a dotted line and a fork of minimum and maximum dimensions would be provided. As independent designers, the Rotors mainly do interiors and temporary pavilions. In this field, they achieve very high reuse rates, with up to 80 percent of their workmanship made from recycled materials.

In Situ

In Situ is a Swiss design studio with a staff of fifty or so, with offices in Basel and Zurich and smaller offices for individual projects to be closer to construction, which is the ambition of these architects, as the studio's name indicates. The studio was formed around a handful of pioneers and pioneers of circular design, including charismatic architect Barbara Buser, who, after studying in Zurich, lived in Sudan and Tanzania, where she learned to see the potential of reusing materials that would be considered waste in Europe. Upon her return to the country in 1995, she founded a secondary building materials exchange (German: Bauteilbörse), which she personally ran for more than a dozen years. In 1998, she founded a design studio with Erik Honegger. Buser, her partners and associates, in characteristic fashion of those associated with reuse, are engaged in extensive educational activities. They teach classes at universities, give lectures, publish articles, exchange information and experience, and advise.10 In addition, In-Situ and its partners conduct scientific evaluation of the projects they participate in, which allows them to build databases and evaluate implementation. The studio's flagship building is the K.118 erected in Winterthur, Switzerland. The design and realization were evaluated by an expert consortium consisting of academics and academicians, NGOs and the design studio itself. A great book has also been published on the subject - "Reuse in Construction: A Compendium of Circular Architecture." The title is just a bit over the top, since the specific data is mainly about this one project, K.118. Nevertheless, in my opinion, to this day it is the best position on the market on this subject.

The K.118 project concerns the reconstruction and superstructure of an existing warehouse and industrial building. The resulting building is experimental and intended for an understated function, loosely defined as office. The project's investor was a Swiss pension fund, which made it a condition to conduct a thorough evaluation of the entire design process and implementation in order to draw conclusions and assess circular architecture and reuse. The superstructure of the three-story building is made of brick, with ceilings on a steel structure. The additional three floors were designed with steel framing, which was obtained from nearby buildings slated for demolition. So were the exterior stairs, the planks used for the floors, windows, insulation, photovoltaics and numerous smaller elements. Much of the new elements were designed from materials with a negligible carbon footprint (wood, clay or straw). The façade was planned from trapezoidal profile sheet metal obtained from another building, the found red color was left; the paint was in good condition, avoiding the not-so-environmental secondary painting. During the search for structural components for secondary use, the architects worked on an ongoing basis with structural designers, who verified that the components had sufficient load-bearing capacity. The architects looked for components from nearby demolition sites so that long-distance transportation would not be required, which would involve emissions and increase the carbon footprint. What sets the project apart is that as components were sourced for the project, detailed drawings were created - it was the dimensions of the steel sections that dictated the final geometry, the dimensions of the terraces and the distinctive overhang of the superstructure. Because of the large number of unknowns involved in sourcing the various components, the architects used design solutions that allowed some flexibility in design and construction. While in new office construction everything seeks to cohere components into a single grid of modules into which the structure, facade, parking lot or partition walls fit, in this case the designers worked on separate modules for the structure, facade, windows. Separating the project into macro-components allowed the differences in sourced materials and their combination to be absorbed into the design. For example, it was only after the sheet metal for the facade was sourced that the dimensions of the individual trapezoidal profile sheets were different, which was not apparent before the measurement after disassembly. In the K.118 project, the sheets of the superstructure's facade overlap with a gap on successive floors, allowing the differences to be lost and, on occasion, covering up the hidden exterior louvers (also recycled).

A publication accompanying the realization of K.118 compares the costs of the various secondary materials versus new. Steel structures, stone slabs and wooden floors come out more expensive, all other items - cheaper. According to calculations by expert Katrin Pfäffli of ZHAW, who undertook a detailed evaluation of the realization, the K.118 building saved 59 percent of carbon dioxide emissions (about 500 tons of new materials) compared to the construction of a new building with similar parameters.



The Lendager Group design office, founded by Danish architect Anders Lendager, has been successfully implementing circular design ambitions in large commercial projects. After a frustrating professional experience, Lendager came to the conclusion that in order to convince investors of pro-environmental solutions, one must speak their language. In his opinion, investors will not choose innovative solutions if they are not assured of their cost and effectiveness. Therefore, he decided that his projects would be accompanied by calculations proving effectiveness against environmental parameters and implementation costs. Like Rotor and In Situ, Landager also released a manifesto on his research and implementation - "Solution: Circular Buildings." Unlike the aforementioned publications, it is less scientific and more marketing in nature. What sets Lendager's projects apart from other more nerdy reuse implementations is their accessible aesthetic. Observing their buildings, it's easy to imagine that certain reuse solutions could quickly penetrate the mainstream.

A project for new communal housing in Copenhagen's Ørestad neighborhood featured upcycled walls. This is a proprietary technique that involves reusing meter-by-meter squares cut into the brick walls of nearby buildings slated for demolition. To obtain the bricks, the designers decided to cut them in groups instead of excavating them individually, since they chose buildings that used cement mortar to bond the bricks - it is often more durable than the brick itself. The squares of bricks are then placed in the formwork, rebarred and poured with concrete on the back side. The load-bearing functions are provided by the new reinforced concrete, not the old bricks. According to the architects, such a wall generates 38 percent less CO2 emissions compared to a classic wall made of new analogous materials. It is not entirely clear how this comparison was calculated, and it can be assumed that after implementation such a wall will not be able to be dismantled again and used in another building.

In the neighboring development of Upcycle Studios row houses, Lendager used many materials and components partially sourced from reuse. They used concrete with recycled aggregate, recycled wood and so on. But most spectacular are the large glass front walls. To make these partitions, sheets of glass were obtained from abandoned nearby buildings. This made it possible to obtain repeatable dimensions of the panes in sufficient numbers. In order to achieve the required heat transfer coefficients, these partitions were designed as double-layered, meaning double-glazing was installed twice. The new frames were made of wood to achieve a smaller carbon footprint than if the new ones were made of aluminum or plastic. The whole building looks like a patchwork irregular curtain façade made using the box window technique. Only selected windows are openable. After analyzing their own implementation, the designers estimate that the upcycled windows made were about 13 percent more expensive compared to using new windows, but it reduced CO2 emissions by 87 percent. The designers point out, however, that having learned from this experience, they know how to act to optimize these costs in future projects.

news reuse

In the past few years, those in the fields of architecture, research, activism and engineering, working with universities, have been making bold experiments that seek not only to enable reuse on a larger scale, but also to design so that new buildings are easier to demolish and reuse.

Established in 2016, the Structural Xploration Lab at Lausanne Polytechnic University, led by Corentin Fivet, is exploring the possibility of using reuse materials as structural elements. One of their projects is a ten-meter-long concrete pedestrian bridge11, the construction of which did not require the pouring of a single drop of new concrete. The project was made using elements cut from existing concrete walls and ceilings in buildings slated for demolition. The retrieved blocks were cleaned, inventoried, drilled and then placed on a temporary arched wooden frame, after which they were tied together with tensioned cables, and the frame was removed. The authors of a scientific article about the experiment calculated that a bridge made with this technology is about 70 percent less emissive than an equivalent structure made of recycled concrete or steel, and only 8 percent more emissive than a bridge made of wood. The structure was initially not intended for outdoor use, but more as a laboratory experiment. It came out so well, however, that after minor adaptations it was adapted to outdoor conditions and exposure to the elements and approved for public use. It is currently serving the residents of the small town of Conthey.

A similar technique is being implemented by young architects from Swiss studio Maclver-Ek Chevroulet in collaboration with engineers from 2401 in the design of a boules building to be built in 2024 in the Swiss town of Renens. Sections cut from the concrete ceiling of a nearby building will be used as vertical support elements in the new development.

Another project, conducted jointly by Lausanne University of Technology and the aforementioned 2401 engineers, is a school building under construction, where the load-bearing structure consists of individual reinforced concrete cup columns that were cut from the same building slated for demolition.

paradigm shift

The common denominator of all the projects presented is that they are being built in a legal and economic environment unsuitable for such activities. They are experimental and, for the time being, require an excess effort on the part of all stakeholders. Reuse is one way to reduce the carbon footprint of new buildings, and this reduction will be required of investors and designers by lawmakers. In the coming years, there will be a demand for consulting, engineering, economic or insurance services to facilitate the implementation of circular design. The first such services are emerging, one of which is the emerging BUDO12 store and consulting service, inspired by Belgium's Rotor DC. The spread of design with reuse elements will also affect aesthetics13. Domestic projects with recycled facades by Piotr Kuczia are already known. There are rumors of emerging projects by other young studios in Mazovia, where reuse will be on a larger scale. Will reuse change architects and their aesthetic ambitions the way, for example, reinforced concrete influenced modernists? Anthropologist Michel Massmünster, who deals with this topic, describes the paradigm shift in design as the advent of sampling: "Designers are becoming like DJs, who do not compose new music, but rather use selected fragments of existing pieces, analyze them, understand what use they might have, and incorporate them into a new composition. "14 Time will tell whether reuse will influence aesthetics, or merely enrich the palette of available ways to build less damagingly, which will already be a success.

Michal Sikorski


1. quoted in Rotor, Déconstruction et réemploi, EPFL Press 2018 (quoted in M.S. transl. article).
2. quoted from the cover story: Reuse in Construction. A Compendium of Circular Architecture, eds. Institute Of Constructive Design, Design And Civil Engineering Zhaw School Of Architecture, Eva Stricker, Guido Brandi et al., Parks Books 2022.
3. the end of "end of life", in A. Lendager, E. Pedersen, Solution: Circular Buildings, Danish Architectural Press 2000.
6. This is possible with smaller private projects, but difficult with public projects.
7. rotor - coproduction. Jeunes Architectures, CIVA/A16, 2010.
8. recently one of their exhibitions - "99%" - was hosted in Poland at the invitation of the Institute of Design in Kielce.
9. For those interested, I refer you to the transcript of a conversation with Michaël Ghyoot from 2022 organized by the Warsaw Branch of SARP and the ZODIAK pavilion, in which Michaël explains in detail the history and advantages of recycling building materials,
10. Those interested are encouraged to watch a conversation with Kerstin Müller, an architect from the In Situ studio,
13. For those interested in the subject, I refer you to the conversation with Barbara Buser published in English in the catalog of our exhibition "Poetics of Necessity".
14. k.118 Reportage, in Reuse in Construction, op. cit.

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