Architecture that enriches nature. Sumu Yakushima by tono

Project description by tono

Concept
Regenerative Architecture & Life Style
Yakushima Island is a natural paradise in southern Japan where abundant rainfall onto 2,000-meter peaks nurtures dense forests home to millennium-old Japanese cedar.

This innovative housing co-op applies "regenerative architecture" to reconceptualize the relationship between human habitation and this nature. 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.

Rather than being a discrete site, the design takes a holistic view of the entire river basin, from the mountains to the sea, making a positive contribution to natural processes.

Idea
Experimental Housing with a Sense of Community
Sumu is an experimental housing co-op jointly created by eight owners. Made for use by owners and trusted friends, it is a place for tending to nature while reflecting on values.


Sumu Yakushima by tono. Photograph by Rui Nishi.

Regenerative Experimental Housing with a Sense of Community Architecture
Sumu applies "regenerative architecture," a new approach developed by designers that combine traditional Japanese civil engineering with contemporary technology. Going beyond simply preserving nature as it is today, key considerations in the design are:

Underground design. Designing the underground environment and engaging the buildings in a constructed mycelial network promotes biodiversity in the soil.

Promoting the flow of air and water. The buildings are oriented based on an in-depth understanding of how water and airflow through the landscape. It is important to design the part considering the flow of the entire basin.

Dialogue with nature. The deterioration of buildings is a function of nature. As such, we regard
maintenance as a dialogue with nature through architecture.

Revitalized tree. A camphor tree (an evergreen tree) that had grown weak and lost its leaves was revitalized through this regenerative architecture.

Form
Architecture that bonds with nature
Sumu comprises several separate buildings to enable a layout that respects the original natural landscape. The buildings protect the tree roots and reduce the impact of the wind, while stones supply minerals to the surrounding soil and foster tree growth. Tree roots passing under the buildings support the soil, an act of symbiosis between nature and architecture.


Sumu Yakushima by tono. Photograph by Rui Nishi.

Buildings that help the forest breathe
The buildings and decks are raised, dispersing wind flowing between the mountains and the sea without blocking it. This allows the forest to breathe, promoting healthy air and water circulation. Despite the humid climate, this ventilation prevents moisture accumulation that may damage the buildings. Naturally-derived persimmon tannin is applied to the wooden structures near the soil to prevent erosion by insects. The result is a space that breathes together with the surrounding forest.

Function
Encouraging tree root growth to support the soil near the foundations
The design also extends underground. Burned wood is placed under the foundations of each building, and the carbonized 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.

Off-grid kitchen
The off-grid kitchen made with local cedar features a solar-powered radiant heat cooker, while water is drawn from the river basin, then purified by microorganisms, and returned to nature after use. The island layout of the kitchen encourages social gathering and communication.

Illuminating spaces with the color of the earth
Lights made by local potters using clay from under the buildings reflected illumination from the mirror bulb, whose light source cannot be seen, and fill the space with the color of the soil itself.

Local & fermented materials
Plaster made from a mix of charcoal and effective microorganism (EM) bacteria provides a healthy, comfortable space by preventing mold and other putrefactive bacteria.


Sumu Yakushima by tono. Photograph by Rui Nishi.

Differentiation
Sumu has developed a new methodology called “regenerative architecture,” whereby the buildings enrich nature. In addition to exploring modern applications of traditional Japanese wisdom, its features include:

• 100% off-grid energy from solar power, storage batteries, and local firewood.
• Comfortable living spaces that leverage architectural expertise to achieve effective airtightness and insulation, unlike camp-style accommodation.
• Modern spaces with stylish design.

A major departure from conventional nature experience facilities, Sumu encourages a wider section of society to engage in learning with the aim of bettering our planet’s future.

Impact
Regenerative Lifestyle
True to its concept of making a positive impact by living among nature, Sumu residents adopt a “regenerative lifestyle” that enhances the environment through everyday activities, from collecting driftwood for use as firewood to clearing grass to allow cool air to flow through in a way that benefits the landscape. 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.

Carbon positive cycle
The local lumber industry in Yakushima struggles to compete with cheaper wood from outside the island, and there is an abandoned plantation located upstream from Sumu. Sumu’s owners perform maintenance on this area and use wood obtained from forest thinning for the upkeep of its buildings. Going beyond simply using wood to also foster the forest at the same time, creates a carbon-positive cycle.