Wood For Good
After over a century in which concrete has become the go-to material in construction, cross-laminated timber has emerged as the most viable solution to make architecture and the building industry more sustainable.
ÁLVARO TAVARES RAMOS
Words
CLT Park Harumi pavilion
by Kengo Kuma & Associates
Photo: © Kawasumi · Kobayashi Kenji
Since the beginning of the 20th century, concrete has been a favourite of most architects. This was true of Oscar Niemeyer and his enormous project for Brasília. It was also the case for Le Corbusier, whose fascination for the potential and beauty of béton brut led him to create the famous Unité d’Habitation, influencing generations of fellow professionals until now. This assertion is exemplified by the list of Pritzker Prize winners, most of whom are well known for using concrete, and the fact that 70% of the world’s population live in a building made of this composite.
That said, the climate emergency and the building industry’s CO2 emissions have meant greater scrutiny of concrete as a polluter. With continued growth in the sector, especially in markets like China, there is a need to find alternatives to cement, which currently represents 8% of global carbon dioxide emissions. Despite the launch of ‘green’ concrete, which significantly reduces carbon footprint compared to the regular type, this industry has other issues, such as huge energy consumption during construction and excessive mining of minerals like sand, an essential ingredient in concrete production.
Some architects are determined to turn this situation around using innovative solutions, such as cross-laminated timber (CLT), which involves the gluing of different wood layers, arranged per-pendicularly to achieve great rigidity and resistance. In addition to its use for walls or floor slabs, it also boasts excellent acoustic properties, is relatively light and reacts well to earthquakes and fire, refuting many of the reasons given for preferring concrete over wood.
More importantly, it offers the chance to move from a construction model based on mining to a system founded on renewable raw materials that naturally absorb carbon, which is key to making the sector more sustainable.
CLT Park Harumi pavilion
by Kengo Kuma & Associates
Photo: © Kawasumi · Kobayashi Kenji
One of the world’s most enthusiastic proponents of CLT is the Japanese architect, Kengo Kuma, who was chosen to expand the Gulbenkian Museum’s Modern Art Centre, using another innovative wood-based raw material, laminated veneer lumber (LVL). Kuma was also responsible for the cross-laminated timber features of Tokyo’s new Olympic stadium, and the Park Harumi project, a pavilion initially located in the Japanese capital, then transported to a national park in Okayama. The trees used to produce the pavilion panels came from this southern region of Japan, demonstrating the versatility of local CLT.
Created in the late-20th century, CLT may just change the face of architecture. High-profile examples of its use include the Forest Green Rovers stadium (Zaha Hadid Architects, England), the Vestre furniture factory (Bjarke Ingels Group, Norway) and the Dutch Mountains multi-use towers (Studio Marco Vermeulen, Holland).
Waugh Thistleton Architects, a London practice that has focussed on sustainable architecture for over two decades, has become a major pioneer of CLT internationally. Founded by Andrew Waugh and Anthony Thistleton, this firm has been responsible for some of the most impressive projects using CLT, such as the Murray Grove building (2009), which is the first residential, tall urban housing project to be constructed entirely from cross-laminated timber. “At the time, we didn’t realise the importance. We were primarily answering our own question, as to whether mass timber was a viable alternative to concrete and steel”, says Andrew Waugh from London. With this project, which was entirely built using load--bearing walls and floor slabs made from prefabricated CLT, it was possible to demonstrate the material’s potential to be a financially viable, environmentally sustainable and beautiful replacement in high-density housing. “We work to reduce the environmental impact of our architecture as much as possible. We do that both in the energy efficiency of the buildings that we build and how and what we build them from. Currently the only low carbon structural system that we know of is mass timber – therefore we start every project with the principle that we will design it for timber. This was the same for Dalston, as for every one of our projects”, reiterates Waugh.
MultiPly
American tulipwood cross-laminated timber
Waugh Thistleton Architects
Forest Green Rovers Stadium
Zaha Hadid Architects
In addition to environmental benefits, CLT offers various other advantages for people using such buildings. “There is increasing data showing how much more relaxed we are. Lower heart rates, better concentration, and it smells so good. It’s fast, light, efficient, solid, and easy to prefabricate. You build it quietly, quickly and non-toxically.”
Convinced that CLT is the only sustainable alternative for the construction industry, Waugh states that “the planet is burning, we have millions of homeless people that desperately need housing, and concrete and steel are major contributors to carbon emissions. It’s inevitable that we build increasingly in timber. We just need to keep shouting about it! We need help from governments and some better estate agents.”
With this in mind, Waugh Thistleton decided to join forces with Folkhem, a Swedish property developer that only builds with wood. What they came up with was Årstafältet, one of the most ambitious projects of its type. The proposal for this part of Stockholm includes 14 blocks of dense and mixed-use buildings, with a total of 220 homes entirely built in CLT. “It’s the future. It’s always been our ambition – the level of ambition for sustainability in the Nordics is inspiring”, says Waugh.
Despite some of the challenges that CLT still offers, and the necessity “to collaborate with engineers, contractors, and clients from the beginning”, Waugh has no doubt regarding CLT’s future and how important architects are to the process. “We need to be resource efficient. So, leave the cantilevers in the history books and get on with saving the planet.”
Forest Green Rovers Stadium
Zaha Hadid Architects
