Wooden buildings are rising across Tokyo, with the city piling investment into high-value timber production to replace steel and concrete-based mid-rise and high-rise buildings.
This includes AEAJ Green Terrace, which secured the “Grand Prize” in the Tokyo Metropolitan Government-sponsored “Wood City Tokyo Model Architecture Awards” last month.
Designed by Kengo Kuma – the architect behind Japan’s 2020 Olympic Stadium – the 3-storey hybrid building is the new home of the country’s peak body for aromatherapy – the Association Aroma Environment Association of Japan.
According to Mr Kuma, the complex timber structure – made from SGEC and PEFC-certified warm cedar and cypress forests – “reflects the very essence of the building’s mission – promoting well-being through the power of aromas.”
Instead of using concrete – responsible for 8% of the world’s carbon emissions – Mr Kuma said the timber and steel-braced building used cedar and cypress, sourced locally through a thinning process – whereby trees are selectively harvested to maintain the forest’s overall health.
Inside the building and behind the floor-to-ceiling windows lies an interwoven skeleton of wooden beams – bound together as part of a complicated latticework system. According to Mr Kuma, this is a throwback to traditional Japanese joinery techniques.
“This intricate framework evokes a sense of history and cultural connection and a powerful visual representation of the interconnectedness of nature and human well-being,” according to a statement from Mr Kuma’s studio.
The construction method is part of a traditional carpentry technique used to construct temples and shrines, requiring careful alignment and shaping of the timber to create a construction system that minimises the use of nails and metal fittings.
Inside, the web of wooden beams extends across the ceiling and walls – allowing light to filter through the building, like sunlight piercing through a dense forest—an effect known in Japanese as komorebi.
According to Mr Kuma, the building acts as a giant diffuser, “with the porous nature of the wood subtly releasing the essential oils used throughout the facility.”
Gentle ventilation systems also distribute aromas, “creating a multi-sensory journey, engaging the nose, the mind and body,” he said.
Inside the National Stadium: The Main Venue for the 2020 Olympic Games
Mr Kuma strongly supports timber-based construction and has drawn lessons from designing the country’s national stadium – the first major Olympic stadium using timber as a predominant construction material for decades.
Costing 157 billion yen ( or US $1.4 billion), the 68,000-seat stadium hosts the opening and closing ceremonies for both the 2021 Olympics and Paralympics.
Reflecting on the project, Mr Kuma, one of the world’s most outspoken advocates for natural materials in construction, turned to traditional Japanese architecture and the environment for inspiration.
His oval design features three tiers of seats beneath a partially covered steel and latticed wood roof, using more than 20,000 cubic metres of timber from each of the country’s 47 prefectures in the stadium.
“The Olympics always becomes a symbol for the era, so with the 2020 Olympics, we wanted to create something that captures the people’s thoughts on the environment or the Earth at the time,” he told CNN in June 2019. “So, we thought that the best material for this era would be wood.”
Timber Buildings to Surge After Changes to Building Standards!
Japan has revised its Building Standards Law to encourage the greater use of local timbers in developments – with new projects like the Osaka 2025 Expo turning to local cedar timbers to construct the next generation of Japanese timber builds.
Coming into effect in April, it will build on the country’s “Promotion for the Use of Wood in Public Buildings”, which seeks to increase the use of Japanese domestic wood in buildings up to 3 storeys and 3000 square metres in footprint.
As one of the most earthquake-prone countries, Japan is already leading the world in researching how mass timber high-rise construction can withstand high seismic activity.
Last month, Wood Central revealed that for more than 100 years, Japan has progressively changed its building codes and standards to make its buildings “quakeproof.”
It includes seismic dampers and base isolation, described as the “Cadillac of performance options when you protect buildings in high seismic locations,” according to California-based structural engineer Krista Looza, who remarked on the resilience of Japan’s timber buildings under heavy shock.
“They have almost three times as many earthquakes as we see here in California,” he said. “And California is considered a region of high seismicity. So you can imagine, in Japan, they are very prepared and aware of the hazards they live around.”
