- Net-zero architecture uses circular economy principles to reuse or recycle building materials, boosting sustainability by saving materials and landfill space.
- Adaptive reuse projects using advanced technology showcase the potential of net-zero architecture, including Battersea Power Station in London.
- Creating a net-zero mindset will require commitment from the building industries and legislative action to enforce and incentivize better practices.
Plastic is a plague. Since the 1950s, humans have created more than 8 billion metric tons of it, according to researchers from the University of Georgia. In a 2017 study, the school reported that in the past 60 years, only 9% of plastic has been recycled; 79% has ended up in landfills or the natural environment. If these trends continue, roughly 12 billion metric tons of plastic waste will be in landfills or the environment by 2050.
To save the planet from pollution and climate change, it’s time to get serious about recycling—not only bottles, boxes, and bags but also buildings, says Pete Collard, exhibitions curator at the United Kingdom’s Royal Institute of British Architects (RIBA).
“Like many other industries, architecture, engineering, and construction has followed a linear path: We consume materials; we make a product; then, we throw that product away and buy a new one. That’s not sustainable,” says Collard, whose exhibition titled Long Life, Low Energy: Designing for a Circular Economy debuted at RIBA’s London headquarters in November 2022. The collaboration between RIBA and Autodesk, which is sponsoring the exhibition through April 1, 2023, demonstrates how circular economy principles can help create more sustainable, net-zero architecture.
“Land has value, and there increasingly is great financial gain in knocking down existing buildings to build new ones,” Collard says. “We’re proposing that your starting point should always be to reuse. You can always build something new, but it’s so much better to use the existing building or components and materials found within it. In doing so, you can stop the use of virgin materials and avoid filling landfills. When you knock down buildings, you create a hell of a lot of waste.”
Adopting circular economy principles isn’t just sustainable—it’s strategic. The global population reached 8 billion in November 2022, according to the United Nations, which expects that number to reach nearly 10 billion by 2050. This increase will require the global construction industry to build an average of 13,000 new buildings every day. Facing challenges like supply chain interruptions and labor shortages, it’s unclear how the industry will keep up.
Relying only on new construction, it might not. “Circular” design and construction—restoration, renovation, retrofit, and reuse—is an economic and environmental imperative.
“Obviously, there are serious climate issues happening right now,” Collard says. “The world is waking up to the harmful legacy of previous generations … as a result, we as an industry need to put more thought into what materials we use and the ways we design and build.”
As RIBA’s exhibition illustrates, a growing number of architecture firms are doing exactly that. Using technology solutions that make reuse increasingly viable, they’re forging a new legacy with innovative projects showcasing the potential the circular economy offers the built environment.
Phoenix House Rises From Storied Ashes
Among the projects featured in Long Life, Low Energy is CSK Architects’ Phoenix House in Windsor, England. Set for completion in 2024, it’s located on the historic site of an 18th-century mansion, home to two former British prime ministers. One former owner, Sir Frances Barry, acquired the house in 1872 and called it St. Leonard’s Hill. When Barry died in the 1920s, his disgruntled son—with whom he had a thorny relationship—wanted to sell the house but couldn’t. So he peppered it with dynamite and blew it up. Its scattered remains have rested on a picturesque hill overlooking Windsor Castle ever since.
Current owner Andrew Try commissioned CSK to build on the foundations of the old structure, using reclaimed materials salvaged from the carcass of St. Leonard’s Hill. The finished product will be a net-zero courtyard house with a U-shaped design incorporating the historic stone portico—the only part of the original mansion still intact.
“The bit that’s left from the original house is like a fragment of DNA, and in a weird sort of Frankenstein way, we’re taking that fragment of DNA and using it to regrow a new house,” says architect Matthew Barnett Howland, director of research and development at CSK. “You have this site where there have been a couple of buildings over a few hundred years, and it’s blown up by dynamite. You come along and collect all those bits, and you put them back together to build something new. … It’s quite an unusual project.”
Working with the Bartlett School of Architecture at University College London, CSK excavated stones from the site, cleaned and numbered them, and made 3D digital scans to create a “digital quarry” of salvaged materials. Using design software, architects can mix and match stones from this digital inventory, determining how to reassemble them for aesthetic and structural integrity as if playing a game of virtual Jenga. The team used this process to design and build a prototype: a trabeated stone portal that mixes rough, organic stones with smooth ones cut into six-sided blocks.
“Our stonemason said they typically work on a 30% reuse proportion” Howland says. “So if they receive a ton of stone, they can hope to use one-third of a ton in the final building. Through this more careful process, we were able to increase that to 50%.”
“Without modern technology, you’d have big stones lying in front of you, but you wouldn’t be able to envisage and move them around to work out which stone goes best with another one,” he continues. “With a digital inventory of parts, you can create bespoke elements that would be impossible to build otherwise.”
Howland says it would be “easier, quicker, and probably 10% cheaper” to build from scratch instead of utilizing existing materials. “For some people, it’s about the vintage aspect of it—the memories and the history,” he says. “For others, it’s about reducing resources and carbon. In the case of Phoenix House, it’s a little bit of both.”
Battersea Power Station as Net-Zero Prototype
Also showcased in Long Life, Low Energy is the Battersea Power Station. Located on the River Thames in London, it’s a coal-fired power station built in the 1930s, expanded in the 1950s, decommissioned in 1983, and reopened in 2022 after several failed redevelopment attempts. Once dingy and derelict, it’s now a mixed-use building that includes a large public park, high-end offices, flats, restaurants, shops, a health club, and a chic hotel.
Encompassing 42 acres, the project has attracted high-profile office tenants such as Apple and retailers including Calvin Klein and Ralph Lauren. Architects, historians, and environmentalists have applauded the decision to reimagine the Battersea Power Station instead of razing it.
Led by architects at WilkinsonEyre, the vision was to create a modern space while respecting the substance, style, and scale established by the building’s original architects, Sir Giles Gilbert Scott and J. Theo Halliday. The results are evident at every turn.
Take the four iconic white chimneys. They were structurally unsound, so crews painstakingly dismantled them and then carefully rebuilt them to the original specifications using the original construction methods from the 1930s and 1950s. Now, visitors can view them from inside through a giant glass ceiling in the South Atrium, or they can take Lift 109, an innovative glass elevator, to the top for exquisite views of London’s skyline.
Or there are the 6 million bricks that constituted the building’s original structure, many of which were weathered and damaged. To restore them, Battersea Power Station Development Company (BPSDC) located the two brickmakers of the Power Station’s original masonry and commissioned 1.75 million new hand-thrown bricks to match.
Other highlights include Turbine Halls A and B. Turbine Hall A has been fully restored to its original art deco glory, featuring an old gantry crane, as well as footprints of the old turbine machinery laid in brick on the floor. In Turbine Hall B, the dials and switches in an old control room have been turned into decor for a 1950s-themed bar, Control Room B.
“We reused as much of the existing fabric within the Power Station as possible,” says Sebastien Ricard, project director at WilkinsonEyre. “Where new materials were required, we sourced these from the UK, where we could help reduce the carbon footprint. In many cases, the existing fabric was kept in an ‘as found’ condition, albeit strengthened with the necessary structures, to keep the quirks and abnormalities that tell the building’s history.”
To successfully execute the project’s many elements, the team conducted an extensive 3D point cloud survey of the existing structure, created 2D and 3D models using CAD software and Autodesk Revit, and overlayed the newer elements of construction on top of its models.
“Technology has the advantage of putting all the various parties in construction in simultaneous receipt of information, working in parallel rather than in series,” Ricard says. “[Building information modeling] BIM is transformative because it allows coordination of information during design stages, evaluating the impacts of different scenarios, and meaningfully testing sustainability strategies during the development process.”
In a 2019 interview with consulting firm McKinsey & Company, Simon Murphy, CEO of the BPSDC, echoed that BIM was crucial to the complex project, coordinating hundreds of architects and engineers and more than 80 trade contractors—as many as 3,000 personnel onsite. The contractors, architects, and engineers worked from a 3D digital model of the whole project for every stage of construction.
A Rather Significant Shift in Mindset
Collard hopes that Phoenix House, Battersea Power Station, and similar projects will inspire a new generation of architects to build differently—starting with materials.
“The idea of the circular economy is not new, but the materials used in modern construction don’t traditionally lend themselves to the process of dismantling and reusing,” he says. “Funny enough, the older the building is, the more recyclable or reusable it can be. If you go to Rome, for example, there are so many buildings from the Roman Empire still standing because they were built with blocks of stone, and stone lasts forever. … In ancient European cities, it was common for those stone blocks to be disassembled and reused in new buildings.”
Or consider Asian design. “Far Eastern architecture uses timber structures, which in many cases are put together without any joints or fixings at all,” Collard says. “There’s a culture where buildings are designed to be taken down and rebuilt—looking exactly the same but with slightly newer materials.”
Implementing circular-economy principles requires a forward-looking approach to building that references those ancient examples. “We need to design and build with the idea that buildings will not be demolished at the end of their life, but rather will be taken apart carefully,” says Collard, adding that architects and engineers can use tools such as Revit to document materials and methods to make it easier for successors to reuse them. “That will require a rather significant shift in mindset to consider the longevity of materials and who might want to use them next.”
Environmental regulators can help by creating laws and policies to manage the carbon that buildings emit through their use of energy and the carbon that’s embodied in their materiality.
“We still have the major problem that adaptation and reuse is generally more expensive than building the same footprint from new—so unless a price is put on embodied carbon, effectively penalizing demolition, the impact on cost has to be sold to the client,” Ricard says. “Why build to a 30-year design life if we can build to 60 or 90 with a 30-year interim upgrade? This is the approach being adopted by many of our corporate clients in the assessment of their estate.”
In the meantime, technology gives architects increased knowledge, accuracy, and collaboration, bridging the gap between the wasteful building of yesteryear and the more efficient building of tomorrow.
“Particularly with reuse projects, where you’re inheriting a building or materials from someone else, you need to know what you’re working with, and you need to be able to share that information with all the other people who are working on your project,” Collard says. “Technology is an integral part of that. It translates the old into the new.”