The energy required to construct and run buildings is responsible for nearly 40 per cent of global carbon emissions. Can the green-architecture boom slow the tide?

In May 2019, many of the UK’s leading architecture practices released a statement declaring that humanity was in the midst of a climate emergency, and that architects urgently needed to address the subject. “The twin crises of climate breakdown and biodiversity loss are the most serious issue of our time,” the statement read, responding to the 2018 Intergovernmental Panel on Climate Change (IPCC) report, which declared that humanity had just 12 years before the situation became irreversible.

The group, calling itself “Architects Declare,” published an 11-point manifesto. Its goals ranged from modest ones (minimising construction waste, monitoring energy use) to loftier ambitions such as adopting “regenerative” design and minimising “life-cycle” footprint—from the amount of CO₂ it takes to make concrete or quarry stone to the energy expended by demolition. One suggestion, particularly controversial for an industry used to getting rid of old buildings and starting afresh, was that existing structures should be repurposed and retrofitted rather than knocked down.

Initially, 17 firms signed up, among them “starchitects” such as Norman Foster, Richard Rogers, David Chipperfield and the practice founded by the late Zaha Hadid. Within weeks, nearly 500 firms were on board. The Royal Institute of British Architects (Riba) joined, followed by American and Australian firms. In October, the UK’s most prestigious architecture award, the Stirling Prize, went to an unglamorous council house scheme in Norwich built according to a standard known as Passivhaus (literally “Passive House” in German), which encourages ultra-low energy buildings. 

One veteran I spoke to couldn’t believe how rapidly things had changed. “For a long time,” she said, “people saw sustainable architecture as bird-watching sanctuaries in Norfolk. Now everyone’s talking about it.”

No one doubts that architects and the construction industry have a lot to answer for. According to the World Green Building Council, the energy required to construct buildings and run them is responsible for nearly 40 per cent of global carbon emissions—far more than all the world’s cars, planes and other vehicles. If the cement industry were a country, it would be the third-largest emitter of CO₂ after China and the United States. Concrete, the most widely used human-made material, is astoundingly carbon-intensive—a cubic metre produces enough CO₂ to fill a detached house. It is also a so-called “threat multiplier”—worsening flooding, increasing pollution, and smothering biodiversity under a thick crust of grey.

But when the problem is so enormous, where do you start? And given that it often takes years to design buildings, acquire planning permission and construct them—especially in conservation-conscious Britain—the IPCC’s 12-year deadline (which has already fallen to 10) is horrifyingly soon.

For all the bright-eyed idealism of Architects Declare, it hasn’t taken long for accusations to emerge that it is greenwashing or, to borrow an architectural phrase, “reskinning”: reshaping a façade to make a building look more attractive than it is underneath. In November, Zaha Hadid Architects announced that it would be designing a £2.9bn airport in Sydney, a city recently under siege from devastating wildfires. A few days later, Foster + Partners—whose plane-mad founder Norman Foster once declared that his favourite building was the Boeing 747—revealed that it would be building a “sustainable” luxury airport on Saudi Arabia’s Red Sea coast. No irony was apparent.

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Part of the problem is that few people agree what “sustainable” architecture actually means. Look up the word in the online design magazine Dezeen and you get a bewildering range of interpretations. The surprise renaissance of an ancient building material called cob (a mixture of soil and straw) is lauded; so too is a luxury hotel in Amsterdam, constructed partly from recycled concrete and with an “intelligent” façade controlling internal temperature. Is a sustainable building one that lives in harmony with its surroundings—local timber, mortar, stone—or one that uses gee-whiz technologies such as solar panels and geothermal heating? Should sustainable buildings aim to be durable, in order to maximise the energy it takes to construct them, or quietly biodegrade once the need for them has passed?

Many of these tensions were on display at the inaugural Sharjah Architecture Triennial in the United Arab Emirates, which I attended in early November. Held in a dusty city on the outskirts of Dubai, its theme was “Rights of Future Generations”—a clarion call for architects to design the path to a cleaner, greener future. As has become fashionable, architecture was being interpreted in its broadest sense. One strand of the triennial featured the Ngurrara, a group of aboriginal people from western Australia, who brought a gorgeous room-sized painted tapestry, which forms part of their battle for land rights.

The climate crisis—and architects’ guilt about their role in it—was a low background hum, like the omnipresent air conditioning (even the old souk was artificially cooled). As I wound my way through an installation portraying how the Middle East had become unsustainably built up, and into one exploring how plastic waste and invasive plant life go “feral,” the challenges seemed stark. What was missing were fixes.

When I raised this point with Adrian Lahoud, the triennial’s curator and dean of architecture at the Royal College of Art, his answer was vague: “The solution is the political empowerment of people,” he said. When I suggested this was beyond the remit of architects, even ones with well-developed god complexes, he replied: “We can’t have sustainability within unsustainable societies. And the political economy of the [architectural] profession is unsustainable.” It felt somehow appropriate that we were talking in his SUV, stuck in Sharjah’s appalling traffic.

Other contributors, though, were thinking in more nuts-and-bolts terms. The London-based artists and “spatial practitioners” -Daniel Fernández and Alon Schwabe, who operate under the joint name of Cooking Sections, had dug a modest desert garden next to a repurposed former school. Filled with drought-resistant plants, it employed ancient desert-cultivation techniques—no need for water-guzzling irrigation.

Elsewhere, the Bangladeshi architect Marina Tabassum had created a courtyard installation from several lightweight houses made in the Ganges delta, which had been crated up and transported to the UAE. Constructed from locally sourced, damp-resistant hardwood frames and available as off-the-peg flatpacks, they perch on stilts and are designed to be moved when the waters rise—as, in Bangladesh, they invariably do.

“Over its lifespan, each house might sit in seven or eight different locations,” Tabassum explained. These houses were designed by local craftspeople, who are forced to think about architecture as something responsive to the environment; indeed, literally mobile. An elegant answer to the reality of a world in which flooding will become more common, it made many developed-world solutions—higher flood barriers, multi-billion-pound drainage schemes and tidal tunnels—seem wrong-headed.

“We’ve been thinking about it from the very beginning,” said Tabassum. “Sourcing materials locally, recycling elements. The buildings we design need to function on their own, without extra resources. Not to be sustainable is a luxury.”

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For all that non-professional architects have been addressing sustainability for millennia, the modern green-building movement is a relatively recent invention. The American architect Frank Lloyd Wright was a pioneer as long ago as the 1930s, advocating structures that operate in harmony with their surroundings—think Fallingwater, Wright’s graceful house in rural Pennsylvania, which straddles a waterfall. But it wasn’t until the 1960s that architects began to think intensively about how to work with nature, rather than seeking to master it. As a replacement for the modernist maxim “form follows function,” the Norwegian architect Kjetil Trædal Thorsen has suggested a new catchphrase: “form follows environment.”

In 1994, the US Green Building Council introduced its Leadership in Energy and Environmental Design (LEED) ratings—a labyrinthine certification system that aims to improve design and construction. Use top-grade insulation plus recycled “grey water” and you gain LEED points; build on wetland or far from existing services and you shed them. The British Building Research Establishment Environmental Assessment Method (BREEAM) is similarly comprehensive, covering everything from energy and water-use to health, well being  and transport. If your office block is close to a bus stop or train station, say, it has a better chance of being rated “excellent” or “outstanding” than one with a large car park. Depressingly, fewer than 1 per cent of new non-domestic buildings in the UK are rated “outstanding.”

By contrast, the European Energy Performance Certificate—the one you’ve encountered if you’ve bought or sold a property in the UK since 2008—provides a summary of energy usage so pitifully watered-down as to be essentially homeopathic: a rapid once-over of elements such as insulation and glazing, made using standardised assumptions about how these will operate. “Truly awful,” said one architect I spoke to.

“Net-zero” buildings, which are currently making the headlines, are problematic in a different way: they gain their “zero” status by generating as much energy as they use day to day. But that doesn’t include the energy required to build them, which is significant. And given that, as things stand, Britain only manages to replace a small fraction of its housing stock each year—less than 1 per cent—it seems unlikely, to put it mildly, that this will help address an imminent climate emergency. Some architects believe that net-zero misses the emergency point entirely, and might push up emissions in the short term.

The issue with many ratings systems is that they are tick-box—tweaks to conventional approaches rather than a new design philosophy. For genuine greenness, you have to travel to mainland Europe. Back in the early 1990s, Wolfgang Feist, a professor at the University of Innsbruck, formulated the “Passivhaus” system. The aim was to make buildings “passive” by cutting their reliance on “active,” energy-hungry heating and cooling systems, and instead make better use of the sun, body warmth and even the heat emitted by household appliances. A prototype apartment block was finished in Darmstadt, Germany in 1991. Feist and his family were among the first residents.

The key is insulation. Passivhaus buildings are rigorously engineered thermal boxes, as airtight as possible, with the temperature inside regulated by built-in fan ventilation and “heat-recovery” systems. The best Passivhaus structures claim a 95 per cent reduction on typical heating bills—a significant dent in emissions, if you consider that around three-quarters of the energy expended by buildings over a lifetime comes from day-to-day use (the remaining 25 per cent is the “embodied carbon” within materials emitted during construction). Rather than a set of aesthetic principles, Passivhaus is regarded as a “fabric-first” approach: form is up for grabs, function everything.

A week after returning from Sharjah, I went to a substantially chillier site in Camden, north London, to see Passivhaus in action. The largest Passivhaus scheme so far in the UK, Agar Grove has been created by the specialist practice Architype, working with the firm Hawkins\Brown. This scheme is architecture at the sharp end: a large council estate draped around a grimy 1960s concrete tower. Altogether, nearly 500 homes will be built, largely in medium-rise blocks, to Passivhaus standards. The tower will stay, but undergo a “deep retrofit,” overhauling everything but the core structure.

Architect Ann-Marie Fallon whisked me past the completed section, a seven-storey block that welcomed its first residents last year. Devoid of ornament and finished in sober dark-grey brick, it looked smart but unremarkable, like a thousand other apartment buildings erected during the last decade. But Fallon drew my attention to the Passivhaus detailing: triple-glazed windows, tight seals, ventilation panels. Looking across to one of the unfinished blocks, I could see hefty blocks of insulation attached to the bare carcass, with silver tape masking every crack to ensure no air or heat seeps in or out.

Fallon explained that constructing to Passivhaus standards costs around six per cent more than using traditional techniques, though of course the finished building will be far cheaper to run. She was modestly proud of Agar Grove: after a year of use, smart meters were reporting fuel bills at least 70 per cent lower than similar conventional housing. Most tenants hadn’t used any heating for six months of the year. “A great start,” she said.

The building’s most crucial design feature was defiantly low-tech, she explained: its aspect to the sun. The south-facing side had large windows shaded by balconies (blocking summer sun, yet allowing winter sun to penetrate), while on the north side the windows were smaller, to limit heat loss. “There’s a lot of technology involved, but in the end you’re designing with the elements,” Fallon said. “I find it constantly surprising that more of us don’t do that as a matter of course.”

This was obviously a pioneering project: how did it compare to the identikit houses being built up and down the UK? “House building is often of inherently poor quality,” Fallon said. “There’s no incentive to be more efficient.”

According to evidence given to a select committee in 2019, the rules are so lax that major housebuilders are permitted to build to outdated regulations, some a decade old. Though many new homes are granted a “B” EPC rating (OK, if hardly stellar), individual properties are rarely tested. Instead, a standardised design will be certified, with little attention paid to whether a finished building truly meets that standard.

While we warmed up in a nearby pub, Fallon revealed the real scandal. In the UK, BREEAM and other ratings are admirably tough. But how buildings perform in real life, once the architects are finished and the contractors hand over the keys, is almost never measured—a problem known as the “performance gap.” Other countries have tried to grasp the nettle: in Australia, commercial buildings are rated on how much energy they use in practice, which means that architects and developers compete to find solutions that endure. But in Britain, if you get the certificate you’re allowed to call a building “green.”

“It’s crazy,” Fallon said, shaking her head. “If you bought a car and it didn’t perform as advertised, you’d take it back. But with buildings in the UK we never do that. We just accept bad quality as a matter of course.”

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But is Passivhaus even the right approach? If the aim is to make form follow environment, why construct a triple-glazed box where opening a window to hear the birds sing disturbs the building’s energy flow? Passivhaus standards might make sense in, say, Saxony, where temperatures are regularly in the high 30s during summer, and plunge to -10C or lower during winter. But Britain’s climate is coastal and temperate. Is it worth all that insulation and airtightness—which involve significant amounts of “embodied” carbon to build—when we could be living more harmoniously with the environment? Energy sources are rapidly switching to renewables: for the first time ever, for three months last summer, the UK generated more energy from windfarms, solar panels and biomass power plants than it did from fossil fuels. Is Passivhaus the answer to the wrong question?

In the green-architecture boom of the last few years, all sorts of cunning solutions have been mooted, many as replacements for CO₂-spewing concrete. Some have called for buildings to be constructed from mycelium, a dried fungus “grown” in moulds to create lightweight bricks with impressive insulation properties. Cork is being touted as another wonder material: impressively sustainable, it is lightweight (and so not polluting to transport) and surprisingly durable. A house in Eton made almost entirely from cork—some of which was, yes, recycled from the wine industry—was recently shortlisted for the Stirling Prize.

There are all manner of wonderful and sometimes weird ideas: buildings that regenerate themselves, or actually “repair” the environment; techniques for sucking CO₂ out of the atmosphere and turning it into bricks; a certification called the “Living Building Challenge,” which aims to harmonise sustainability with aesthetic beauty and inhabitants’ happiness. Yet it’s hard to see any of these innovations being employed at a scale that will make a difference within the IPCC’s 10-year deadline—still less pop up in the average Barratt box.

A more realistic and compelling option is cross-laminated timber (CLT), a sort of industrial plywood, with thick layers of lumber glued together at right-angles to increase strength. Although CLT involves cutting down trees, it uses a tiny fraction of the carbon emitted by cement, and can replace steel in low and medium-rise buildings (and because trees absorb CO₂ from the atmosphere, CLT can be carbon-positive).

The world’s tallest CLT building was recently completed in Norway, a mixed-use block containing homes and a hotel. At 85m and 18 storeys high, smartly finished in local spruce, it seems to offer a genuine alternative to concrete-and-steel edifices. In the UK, however, CLT is controversial: because of the fallout from the Grenfell Tower fire, the material is banned from use in high rises because of flammability, and might start to become harder to use because of the insurance risk, even in smaller projects.

Phineas Harper, curator of the recent Oslo Architecture Triennale, is critical of Passivhaus, which he described when we spoke as “an architectural strategy predicated on the assumption that humans and nature are two different things.” And he’s in two minds about Architects Declare. Harper suggested to me that part of the issue is the way in which much new architecture still works in the developed world. “If you were designing a phone or a car, you’d spend an extraordinary amount of time doing R&D,” he said. “In the building industry, we design it once and then move on.” Instead, he argued that we should think of buildings as more like products: intensively prototyped, standardised, modular.

One example on display in Oslo was an ingenious system designed by the Canadian practice YYYY-MM-DD: super-strong, reusable bags that can be filled with gravel or old concrete to make columns. As soon as the building is no longer needed, the gravel can be poured out and used elsewhere. Another model might be the Great Mosque at Djenné in Mali, built in 1907, which has mud-brick walls that are repaired annually (scaffolding is permanently built into the structure).

Cambridge Heath by Waugh Thistleton Architects. Photo: Jim Stephenson 2018

Even in the developed world, the concept of the “hundred-mile house”—every material sourced from within 100 miles—has gathered impetus. Architype’s recent Enterprise Centre at the University of East Anglia not only uses materials such as hemp, reed board and nettle fabric, but also managed to source most of these components from within 50 miles.

Harper argues that architecture needs to rid itself of its obsession with durability and permanence, and make far more use of recycling and retrofitting. “Architecture shouldn’t just be about putting new fabric into the world; it should be about reconfiguring the fabric that already exists,” he said. “The art of subtraction, not addition.” This was true on a global scale, he added: architecture needed to confront what some theorists have called “degrowth,” the notion that unending economic development, no matter how carefully handled, is inherently unsustainable, for both humans and the planet.

Instead of seeing this as a death sentence for architects, Harper argues that there are radical possibilities here, if we have the courage to grasp them. He cited the Japanese practice of kintsugi—the art of repairing broken porcelain with gold-dusted lacquer, to make the repairs not only obvious, but beautiful. Instead of fetishising the flawless blueprint, we should reacquaint ourselves with the kind of architecture that is easier to modify and adjust in use—fewer white modernist lines, more a rough and tumble aesthetic that reflects how buildings change and evolve. “That philosophy is very new, but it’s also very old,” Harper said.

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Can architecture firms adjust to a philosophy of building less? How do you persuade clients not only to take sustainability seriously, but shell out for a design whose cost benefits might only pay off in 20 years’ time? How to negotiate the brain-bending thicket of calculations needed to ascertain a building’s whole-life footprint?

Lurking beneath this is an issue of which designers are keenly aware: their own insignificance in the wider built environment. According to Riba, only 6 per cent of new homes in Britain are created by architects, with the overwhelming majority using off-the-peg designs created by big developers. Most “vernacular” projects—from big-box supermarkets to storage depots and health clinics—are put together by engineers, or rely on cookie-cutter templates. Although our culture elevates the starchitects, they are largely irrelevant to the buildings that most of us live and work in.

Perhaps Phineas Harper is right, too, that our culture needs to move away from its obsession with novelty. That goes for government, too: new homes and some other new builds are currently VAT-exempt, but there are few comparable incentives to restore existing buildings. The Conservative election manifesto pledged £9.2bn for extra insulation in schools and hospitals. But critics point to the last Tory government’s record in office, which included junking Labour’s “green homes” initiative, increasing VAT on home solar panels and abandoning any commitment to zero-carbon building, despite the UK having passed laws to bring greenhouse gas emissions to net zero by 2050. Scotland may do better: Nicola Sturgeon’s SNP government has announced its intention to spearhead a “green new deal,” focusing on renewables, and to lobby for the UK government to follow suit.

Astonishingly, south of the border, we seem to be going backwards. If new building standards currently being consulted on by the government go through, in the future British homes might be built to lower standards than they are right now. Architects are resisting—but how much impact will they have, with a Conservative government with a large majority?

When I asked Ann-Marie Fallon if she felt positive about change, she “wasn’t optimistic”: the construction industry has too many lobbyists, too many vested interests.

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One November morning, I visited an office block in east London, which opened earlier this year as a home for charities and social enterprises (one of its tenants is Extinction Rebellion). Entitled the Green House and masterminded by the Waugh Thistleton practice, it recently won an Architects’ Journal award for retrofit. Few aesthetes would sigh over its appearance: a bulky block, angular and hulking, squatting on a busy main road. But beneath the skin the building is a thing of subtle beauty.

Andrew Waugh, one of the partners, gave me a high-speed tour. On to the existing 1962 concrete edifice, the architects had strapped an extra storey, plus an extension behind increasing the amount of office space to 50,000 sq ft. This “lean-to” is largely built from CLT, and there’s a new glass curtain facade acting like a blanket, helping heat-proof the original structure. Plus there are shrewd details: solar panels, lime-render walls, a wild meadow “green roof.” Even the steel joists are bolted together rather than welded, so they can be reused. Altogether, 1,600 tonnes of CO₂ had been saved compared to traditional construction methods: roughly half of what might have been expended.

Patting the concrete skeleton, left exposed in the ceilings and harmonising with a wall now covered in rough wood bark, Waugh conceded that it helped that brutalism is back in fashion—“but then these buildings were massively overengineered to begin with. All those filing cabinets they had to hold were heavy!”

When I suggested that one room we walked through seemed chilly, he shrugged. “Yes, sometimes in this building you need to wear a jumper. Strange how we’ve forgotten how to do that.” Far more important was the fact that, in this project, very little had to be demolished. “If you’re thinking about embodied carbon, that has to be the main focus,” he said. “You need to make such a strong case to demolish. It’s like when my daughter asks for new pyjamas: have you really outgrown the old ones? Really?”

One of the founding signatories of Architects Declare, Waugh admitted to the challenges, in particular persuading larger practices to shift their business models away from carbon-guzzling schemes. But he seemed fired up by the possibilities. “Oh, I sense opportunity here, not crisis. And we have to start somewhere.” Given the scale of the challenges, many architects were fearful about the future and daunted by how to change it, I suggested. Waugh flashed a smile, and quoted the Dutch designer Rem Koolhaas, often regarded as contemporary architecture’s patron saint: “You can only be an architect if you’re profoundly and foolishly optimistic.”