Sustainability in Architecture Sustainable Building is Not a Top-Down Principle
Photo (detail): © picture alliance / IPON | Stefan Boness
The German Pavilion at Expo Osaka was themed around the circular economy: a pavilion built with the highest possible recycling rate and a low ecological footprint. But its implementation was met with criticism in the German media. Our author Julia Shimura spoke with professor and curator Axel Sowa about the importance of the circular economy and the challenges of sustainable construction.
Your question touches on the relationship between goals and the methods used to achieve them. In building science, however, people like to think in terms of the “longue durée”. In Western culture, we expect buildings to endure – or at least to retain their beauty as ruins. And with this comes the expectation that the materials themselves are durable.
In Japan, the approach is different. The country’s most important shrine is dismantled every 20 years, and its parts are reused in other, less significant shrines. Japan has long embraced a cyclical understanding of construction. Yet the questions remains: what methods should we use to build sustainably, and what levels of energy efficiency, recycling and other practices are appropriate? I believe we’ve reached a point where we must ask what the natural cycles of buildings are, and how long they should last.
The German Pavilion faced considerable criticism for precisely these reasons.
I want to look at the bigger picture here, rather than focus on the everyday political debates. In architecture and construction, we are at a critical juncture. I’d say that a great deal of research has been done, and we have a reasonably clear understanding of how we should proceed.
In the past, people were often convinced buildings would be used in a certain way forever. But circumstances can change rapidly. Today, we also have to consider how predictable a building’s use will be over time – in other words, how permanent or sustainable its function is. Architecture must respond to this reality, and in that sense, the Expo serves as a real-world laboratory.
Nevertheless, repurposing Expo pavilions has always been difficult. In Hanover, the Dutch Pavilion from Expo 2000 stood largely neglected for over 20 years. Even back then, there were plans to build sustainably. So what has really changed?
Not much has changed, and it’s important to remember that in construction, buildings that are 50 years old can feel fairly recent. That’s why I mentioned the concept of longue durée and cycles. For a long time, there has been a discussion about at least two approaches to designing buildings that can adapt to changing uses – about how to do it better.
And what are they?
They design the architecture so that different infill structures can be used within the skeleton. These constructions are reversible, like the Centre Pompidou, which has open floor plans that can be refigured for different exhibitions.
The other approach is to continue building with solid, heavy structures, while considering how a building designed for specific uses can be modified or remodelled over time.
However, this also raises the question as to how we should deal with the legacies of the 1950s and 1960s. Each year, millions of tons of construction waste are generated, and the construction industry is a major contributor. Indeed, this is the big elephant in the room when it comes to sustainability.
The German Pavilion focused on the circular economy as a building approach. The pavilion is designed to be 90 to 95% reusable.
The challenge is that industrial-scale construction always involves tendering processes, building regulations, specifications and detailed planning. The problem with reusing existing materials is that they’re always very heterogeneous. Take recycled windows, for instance – you still have to deal with warranty periods. But who accepts responsibility for outdated thermal insulation? Issues like this radically alter the design process. You can never be certain which components will be available. We are now at a point where we must carefully consider which methods, recycling techniques and which logistics we use when we build from reclaimed materials. This is the challenge of construction today. And it was also the theme of the Expo. It’s actually a smart idea to tell people to consider deconstruction from the very start of the design process.
“Circular economy” is the key concept here. You curated an exhibition on this topic in Japan called Material Flows, which took place not far from the Expo in Osaka. What did you do differently?
My partner Murielle Hladik and I approached this exhibition as a commentary on the Expo. In architecture, you can’t just critique the absurdities; you also have to propose solutions. We aimed to be constructive by bringing together everyone who is currently making interesting contributions to building research using renewable materials, such as mycelium, clay and others. We also demonstrated ways in which buildings can be sensibly dismantled or converted.
Fungal mycelium was also showcased at the Expo. What exactly is this?
Mycelia are the fine, fibrous roots of fungi, which grow very quickly. Essentially, they are the answer to the question of how to create compostable components that can be returned to the natural cycle when they are no longer needed.
So, these panels could simply be composted?
Yes, everything is compostable. Their density is roughly the same as that of insulating foams or mineral wool, making them suitable as insulation material. Researchers are also exploring how mycelium can be used to create or reinforce load-bearing elements, and some truly exciting results have emerged. We were able to showcase these innovations in our Material Flows exhibition in Osaka. For instance, mycelium could be used to retrofit thermal insulation systems in older buildings to improve energy efficiency. Conventional insulation systems are likely to become hazardous waste within the next two to three decades.
Climate control will also become increasingly important. The German Pavilion had no air conditioning during the extremely hot Japanese summer. A passive airflow was used to cool the space by six degrees.
We see this in traditional Japanese architecture. The idea of living in spaces that are always 20 degrees Celsius with perfectly controlled humidity is relatively modern. Traditional Japanese buildings, however, resist such uniformity and embrace seasonal fluctuations. In winter, for example, you might warm yourself at a localised heat source, such as a charcoal brazier or a heated table, or simply put on a second jumper.
We’re rediscovering ways to work with different climate control systems to significantly save on energy. These solutions are not a top-down approach like at an Expo, which is commissioned by a federal ministry. Problems like climate control are more persistent and far-reaching than the Expo. The exhibition merely makes them visible.
But the Expo was also built on an artificial island made from construction waste, where a casino is now being planned. That doesn’t sound very climate-friendly. At the same time, lots of buildings in Japan are empty. Wouldn’t it have been better to focus on existing buildings?
That’s exactly what we thought when we chose not to go to the Expo and instead focus on a disused shipyard in Osaka – where the processes of transformation are visible. Today, the site hosts artist studios and spaces that have been converted and repurposed, including a particularly clever redesign by Dot Architects. In our “mini Expo”, we exhibited projects related to the Japanese principle of “kaitai” – constructions that can be easily dismantled and reassembled elsewhere. Visitors could learn traditional techniques, such as clay plastering. One exhibit highlighted a village in Chiba with thatched roofs, which had been adopted by a group of architects. If you connect all of this intelligently, you’re no longer dealing with an Expo built on methane-saturated reclaimed land with space for a casino and cruise ships – you’re engaging with the urban context.