The ultimate problem for architects is that the most sustainable building is always the one that is already there. There is a huge amount written about green buildings, much of it nonsense. There is some confusion about buildings layered in vines and living walls, stacked high with plant pots, and buildings that actually are green.
Contemporary architecture’s issue is mostly embodied in one material: concrete. Some 8 per cent of all CO₂ emissions are attributable to concrete, the most used material on Earth after water. The rate at which we are still using it is astonishing: half of all the stuff manufactured by weight is concrete. From 2011 to 2013, China used more concrete than the US had in the whole of the 20th century. The construction industry has become helplessly addicted to the protean grey sludge that can be so easily formed into almost anything.
There are signs, however, that architects are beginning to shake things up.
The first credible alternative is, perhaps a little ironically, that oldest of building materials, timber. The pioneering use in Austria in the 1990s of cross-laminated timber (CLT), in which layers of lumber are built up, their grains running in opposing directions, into a very tough laminate, led to a new sustainable direction.
The flexibility of CLT has led to the “tall timber” movement and “plyscrapers” — towers constructed entirely of wood. There has had to be some significant adjusting of fire regulations for the new wonder-material (long avoided in high-rise situations precisely because of its flammability), but the problems are being overcome.
One of the first significant CLT buildings was a research centre into the material itself, the Bautechnikzentrum (building technology centre) at Graz University of Technology in Austria (2001), an impressive, industrial-scale structure.
Subsequently, British architectural practice Waugh Thistleton has been a pioneer in the field with its nine-storey Murray Grove housing block in Hackney, east London, in 2009. More recently, its Black & White Building in nearby Shoreditch (2023) is an unusual mass timber office building, with everything from floors to facade in wood, with an intimate, warm feel throughout — a building that performs as well as any other, but far more sustainably.
For an even more extreme example you might look to Hermann Kaufmann’s 2013 IZM building, perched over a lake for a hydroelectric dam in Vandans, western Austria, an elegant wooden structure both sustainable and beautiful.
Japanese architect Shigeru Ban has been working in wood for decades but also employs the even more sustainable, fast-growing bamboo in his buildings (his Blue Ocean Dome at the Osaka Expo 2025 is impressive). He has also employed his characteristic cardboard tubes for emergency shelters at disaster sites around the world.
Wood has become popular in part because it is familiar and obviously sustainable but also because of a kind of sleight of hand. The capacity of trees to absorb carbon during their lifetimes gives timber buildings a head start, in theory at least, beginning with a negative carbon count.
Another familiar material making a return to the sustainable arena is stone. You might think it never went away, with big, self-declared sustainable blockbusters such as Foster + Partners’ Bloomberg Building in the City of London being clad extensively and extravagantly in the material. Stone used to be employed as both structure and finish but today is more likely to be applied as a veneer of cladding over steel and concrete.
Architects have more recently been questioning this approach and returning instead to stone as a structural material, cutting out the other, far less sustainable materials.
In Mallorca, where stone is a genuinely local material, architects have been attempting to revive disused quarries and revitalise local material supply chains to create extremely fine new social housing.
One practice, IBAVI, was responsible for a raft of small housing projects, modest but well designed and crafted, and responding to local need on an island where so much construction caters for tourism. Its housing on Salvador Espriu (2022) emulates the vernacular in scale and style using local timber and stone, much as builders would have done centuries ago. The architects have had to redefine local supply chains to get here, stimulating local economies — a long and involved process but one with admirable results.
Rammed earth has also been proving popular recently. Suphasidh Architects’ mixed-use building in Chonburi, Thailand (2024), is a remarkable demonstration of the richness of the material in colour and texture. French architects Déchelette even used it on a Paris apartment block in the suburb of Boulogne-Billancourt (2024).
Long decried as rural and primitive, compressed earth and mud-brick are being revived as a super-sustainable material (no need for carbon-intensive firing) that bonds the building to its site in a very visual manner, creating a sense of place through material — architectural terroir.
Yet it remains the case the building that is already there is the most sustainable.
Paris-based architects Lacaton & Vassal, whose motto is “never demolish”, have become known for imaginative and elegant reuse. At the Tour Bois le Prêtre (2011) on the edge of Paris, they took an unpromising social housing slab of a tower and allowed the residents to stay inside during the works, thus maintaining continuity — something so often lost with big construction projects. It reminds us that sustainability ought to apply to communities as well as materials.
Rather than demolish, they clad the tower in a layer of extra space, cheaply wrapped in polycarbonate (with sliding sections), to create new terraces, winter gardens and balconies, expanding living space and allowing residents to customise their new areas with greenery. The result is elegant and economical, isolating the apartments while expanding and allowing them to breathe.
We also need to consider Rotor. This unusual practice tends to get a little left out of sustainable architectural discourse because it builds little itself. But what it has achieved is nevertheless remarkable.
Based in Brussels, it began by disassembling buildings about to be demolished or refurbished, salvaging what was reusable, from doors to marble tiles and bathroom fittings and, in a perfectly circular manner, sold these on to architects who wanted a little more texture and character inserted into their buildings.
The practice has also undertaken extensive studies of waste in the industry and defined strategies for reuse and repair. Its Brussels warehouse is a truly remarkable place, rammed with hardware, 1970s bathroom tiles, marble panels and huge glass partitions. A whole, remarkable circular world in itself.
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