Sumu Yakushima by tono inc. posits visions of symbiotic living

Sumu Yakushima is an experimental housing co-op, conceived and designed by Tsukasa Ono of tono inc. Situated on Yakushima island, a natural paradise in southern Japan, that is flanked by the sea on one side and mountains on the other, the project sits amidst a forest that is home to millennium-old Japanese Cedar. The residential architecture is carefully positioned considering the river basin, existing flora and fauna, and the flows of air and water in and around the site. As described in the project brief, the name Sumu means both ‘to live’ and ‘to become clear,’ expressing its core concept of living in a way that positively impacts the landscape. It is a laudable venture in regenerative architecture as it sets out to create a ‘nature-positive’ cohabitation system. 

The project’s idea was initiated during the recent pandemic on a very small scale and only got bigger and better with a group of friends joining in to create a community, in the quest for an alternate living. Various professional skills brought together by different people like project management, environmental consulting, energy consulting, sleep tech and more, proved to be integral in the conception of Sumu.

In an exclusive interview with STIR, talking about the distinction of Sumu; Tsukasa Ono, one of the eight owners and the only architect in the team establishes that, “Our regenerative way of thinking is to look not only at the construction site itself, but also take a bird's-eye view of the entire watershed from mountain to ocean, and think about improving nature better than the current situation where we build. The environment in which we live cannot be considered by ignoring the circulation of water and air in the air and ground. Therefore, we especially focused on the underground environment that spreads under the building and built it with the intention of improving the natural environment through the work of microorganisms. It was learned from traditional Japanese civil-engineering methods, but we designed it by combining it with modern technology." 

The discourse on 'regenerative design' is not a recent one but it goes a step beyond 'sustainable design' in realising the scope and potential of the design process. It sees architecture as an extension of the site, the place, the flora and fauna, and the ecosystem at large. Buildings are treated as part of a larger system, helping to produce and share resources like clean water, energy, and food. Regenerative architecture insists on a forward-thinking approach and considers designing and operating to reverse ecological damage and achieve a net positive impact on the surrounding natural environment. Integral to this is a systems approach to thinking, wherein all relevant agents and contributing entities must be taken into account, assessing the complex networks in which they interact and function.

This careful approach is reflected in the philosophy of Tsukasa Ono, the project architect. tono inc.'s website describes tono as a word that means ‘with’ or ‘relationship’ in Japanese and it further reads, "We will create a good relationship between nature and people through buildings."

Aliased as the ‘bacteri-architect,’ Ono further elaborates on this, "The first thing you should know is that microorganisms are keeping this natural world healthy. The human body consists of 37 trillion cells, in which 100 to 1000 trillion microorganisms live. We cannot survive without their help. In forests and in the sea, nobody can live without coexistence with microorganisms. Rather, I believe that they are the main players on this earth. Most architecture does not live in harmony with nature. They damage the earth. Architecture and the environment coexist symbiotically means that the work of microorganisms should not be hindered. When it works, a regenerative cycle that enriches the environment can be activated. For this reason, I am investigating ways to connect architecture and the environment with microorganisms, so I am not an ordinary architect but a Bacteri-architect.”

Sumu posits a sense of community that creates a symbiotic relationship with the local environmental conditions. It does so in various ways. The conception of the built environment that Sumu incorporates entails several separate buildings to enable a layout that respects the original landscape. The buildings and decks of the landscape architecture are raised, dispersing wind flowing between the mountains and the sea without blocking it. This facilitates the forest to breathe, promoting healthy air and water circulation. Despite the humid climate, this ventilation prevents moisture accumulation that may damage the buildings. The building protects the tree roots and reduces the impact of the winds. Naturally derived persimmon tannin is applied to the wooden structures near the soil to prevent erosion by insects. The design also extends underground. Burned wood is placed under the foundations of each building, and the carbonised surface promotes the growth of mycelium (fungal threads) that join them in the forest’s soil network. The mycelium encourages tree root growth under buildings, strengthening the soil.

It functions with 100 per cent off-grid energy from solar power, storage batteries and local firewood. It creates comfortable living spaces that leverage architectural expertise to achieve effective airtightness and insulation. Fermented materials such as plaster made from a mix of charcoal and effective microorganism (EM) bacteria provide a healthy, comfortable space by preventing mould and other putrefactive bacteria. Spatially, the separation of buildings creates public spaces that are connected by outdoor paths. In this way, the building program promotes walks through the forest into daily activities to consistently stimulate the sensation of life in harmony with nature. 

As argued by the architect, Sumu's design changes our relationship with nature. It enables residents to discover new possibilities for interacting with nature and adapt the way they think and act, building relationships with nature that transcend generations. Its unique approach has the potential to accelerate environmental initiatives if more widely applied. Sumu is exemplary in the way it takes ‘the path of least resistance’ and embraces the idea of ‘living lightly on the earth.’

Project Details

Name: Sumu Yakushima
Location: Yakushima island, Kagoshima Japan
Lead Architect: Tsukasa Ono / tono Inc.
Year of Completion: 2022
Area: 162 sqm
Environmental consultant: Yuki Imamura/ Moss guide club
Off-grid energy consultant: Shizen Energy Inc
Landscape consultant: Tomonari Waku/ Wakuworks
Lighting designer: Hisaki Kato/Hisaki Kato Lighting & Design Inc.