Green architecture…and the boom in building with wood

Green architecture…and the boom in building with wood

On the list of causes of climate change, architecture trumps many. According to the United Nations Environment Programme, the construction industries account for about 37% of carbon dioxide emissions worldwide, and three of the most widely used building materials – concrete, steel and aluminium – generate nearly a quarter of total global carbon emissions. But there is progress, as the use of renewable organic materials such as wood and bamboo is expanded.

Carbon-absorbing plants and trees are being more widely integrated into architectural design. Even concrete has begun to eliminate its harmful environmental impact with the development of low-carbon varieties.

Sustainability-conscious architects are embracing these materials in buildings that are not only more environmentally sensitive, but also look different from modern concrete and steel boxes. One of the most powerful symbols of the green building revolution – in the public imagination at least – is the tall building covered in plants. Plant-covered building designs can be found in the portfolios of international architects such as Jean Nouvel, Norman Foster, Thomas Heatherwick, and Kengo Kuma, to name a few. However, no one encouraged this type of construction more than the Milanese architect Stefano Boeri, who called his creations “vertical forests.” The original vertical forest — a pair of residential towers with facades featuring some 800 trees, 5,000 shrubs and 15,000 plants — opened in Milan in 2014. Boeri has since completed about a dozen more models, most recently in Huangang, China, and the Dutch city of Eindhoven.

“What we did was use plants, not as decoration, but as a kind of biological skin,” says Boeri. They provide greenery, shade and coolness, regulate humidity and absorb carbon dioxide and pollution. It also serves as a habitat for birds and insects and creates a direct and immediate connection between residents and nature.

Boeri, who has future projects – some of them entire villages – in various stages of development in locations including Cairo, Dubai and the Mexican resort of Canon, adds that the buildings are “always evolving and changing with the seasons.” Some critics have dismissed the vertical forest concept as green camouflage or eco-friendly embellishment, arguing that the environmental benefits are negated by the carbon-intensive concrete and steel required to maintain the trees and plants.

Boeri said that studies conducted by the engineering company Arup found only a 1% increase in carbon dioxide emissions associated with the construction of vertical forest buildings. He added that his company now typically uses precast concrete panels, and is looking to build with wood, where appropriate, to reduce carbon emissions. Boeri acknowledges the limited environmental impact of individual buildings, but stresses the importance of connecting “biodiversity hotspots to a network of other green systems.” He imagines that in the future there may “definitely” be cities made of vertical forests. One major city taking steps in this direction is Singapore.

Policies aimed at bringing nature into Singapore's urban center have produced a cityscape dotted with buildings featuring expansive green spaces, including several built by local company WOHA. Among Woha's most famous designs are the recently completed Pan Pacific Orchard, with its expansive garden terraces overflowing with plantings, and the Oasia Hotel Downtown, a 30-story tower surrounded by a red grid interwoven with… Nearly twenty types of vines. “The permeable living facade is part of the passive strategies we have implemented to cool the building, reduce energy consumption and create a comfortable living space,” said Wong Moon Som, co-founder of WOHA. Studies have shown the exterior is up to 68 degrees Fahrenheit cooler than nearby glass-walled structures, he said.

A large-scale infusion of green space could help repair so-called urban heat islands created by expanses of asphalt, concrete, glass and steel. Two years ago, Carlo Ratti, the Italian architect and director of the Senseable City Lab at MIT, who has been chosen to curate the Venice Architecture Biennale in 2025, unveiled a proposal to create what he described as the world's first farm. It extends over a skyscraper in Shenzhen Province, China. The 51-storey building, called Jian Mu Tower, will be wrapped in a vertical hydroponic farm.

Ratti estimated that his plan could produce enough produce annually to feed 40,000 people. Another tool for achieving net-zero carbon buildings is one of the oldest and most common building materials: wood. Given its value in sequestering carbon dioxide and keeping it out of the atmosphere for decades, if not centuries, wood is now being widely engineered into components of so-called block timber, made of compressed, fire-resistant layers. Architects are also turning to other natural materials that sequester carbon, such as linen and seagrass.

Henning Larsen, an international company based in Copenhagen, recently used reeds to create the first-ever thatched facade for a new primary school in southern Denmark. An equally dramatic effect, in a very different context, is being achieved at the new terminal of Kempegowda International Airport, in Bangalore, India, designed by Chicago-based Skidmore, Owings & Merrill, or SOM. The station, which was designed as “a model of sustainable development but also as a new experience related to connection with nature,” said Peter Lefkowitz, the company’s director. It is characterized by its use of engineered bamboo, which drapes the columns and is layered in grid spaces across the ceiling. The design also includes hanging plants, lush walls of greenery, and water features.

Stephen Wallis*

Journalist at The New York Times. Published by special arrangement with the New York Times Service.