Sumu Yakushima 住宅 by Tsukasa Ono is a highly esteemed winner of the very prestigious 2026 A' Design Award 銅獎 in 建築、樓宇及結構設計 Competition Category.

銅建築· 2026

Sumu Yakushima 住宅

by Tsukasa Ono

Client: tono Inc.

A' Design Award 銅獎 Winner in 建築 Category

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The Design

About Sumu Yakushima 住宅

Sumu屋久島採用再生建築嘅設計手法，將日本傳統土木工程同現代科技結合，係一種嶄新嘅設計方向。呢個項目透過設計地底環境，並將建築物融入人工構建嘅菌絲網絡，從而提升生物多樣性。建築物同露台採用架高設計，保持空氣同水流嘅自然流動，令山海之間嘅風可以自由流通。呢座住宅完全離網運作，以太陽能同柴薪作為主要能源。

The Recognition

About the A' Design Award 銅獎

Sumu Yakushima 住宅是 A' Design Award 銅獎得主，這是授予以創造力、獨創性和敏銳見長的傑出設計的極具聲望的認可。銅獎得主是技藝嫻熟、創意驚人的作品，印證了其設計師豐富的經驗、想像力與機智。預計Sumu Yakushima 住宅將成為一件備受推崇、令人欽佩且被珍愛的物品，兼具顯著的專業性與創新性。這件贏得 A' Design Award 銅獎的設計融入藝術、科學、設計和技術領域的最佳實踐，並因注重細節而出類拔萃。Sumu Yakushima 住宅出色地滿足需求，觸動渴望，迷住情感，並吸引好奇心。

Behind the Design

Press Kit

Credits, team members and technical details provided by the designer.

Unique Properties: 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.
Dimensions & Packaging: The building area: 162m2.
Tags: Regenerative, Sustainable, Nature positive, Environmental
Production Technology: Burned wood is placed under the foundations, and carbonized surfaces promote the growth of mycelium, joining the buildings to the soil network. This promotes a symbiotic effect whereby tree roots grow under the buildings and support the soil.
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.

The buildings are raised, dispersing wind flowing between mountain and 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.

The off-grid kitchen made with local cedar features a solar-powered radiant heat cooker, while water is drawn from the river basin, then cleaned and returned to nature after use.
Lights made from local soil fill rooms with light embodying the color of the surrounding earth, and plaster made from a hemp charcoal/EM bacteria mixture provides healthy, comfortable spaces by preventing putrefactive bacteria.
Design Challenge: While the global pursuit of sustainability is highly commendable, in architecture it is generally understood as an effort to reduce negative impacts rather than to generate positive ones. This assumption stems from viewing architecture as an isolated object. In reality, every building site already contains an existing ecosystem. The project sought ways for architecture to connect with and contribute to the regeneration of that ecosystem.

It was an unprecedented challenge, and until measurable results began to appear, the process relied on careful observation, research, and repeated trial and error. In Japan, very few practitioners have direct experience with this construction method. Drawing from their knowledge, the team gradually developed its own methodology. Communicating appropriate instructions to local craftspeople was also a significant task.

After completion, however, positive outcomes began to emerge, as described earlier, and verification of the method is still ongoing.
Research: Regenerative architecture is a method of building that works with soil microorganisms, supporting healthier conditions for surrounding plant life. It applies, in a contemporary way, traditional Japanese civil engineering knowledge that has largely been forgotten.

To examine the effectiveness of this approach, three methods were used.

First, the construction site itself was deliberately selected. The building was placed on the most degraded and depleted area within the property. The land was overgrown with weeds to the point that it was difficult to enter, mosquitoes were abundant, and the trees were weak, with thinning trunks and falling leaves. The structure was positioned in close relationship to these struggling trees. After construction, the trees showed clear signs of recovery and renewed vitality.

Second, in order to visualize the underground mycelial network, experiments were conducted that identified the presence of electrical activity within the soil. Evidence indicated that trees on either side of the building were connected through electrical signals transmitted underground.

Third, microbial diversity was analyzed. Soil samples were collected both from the surrounding forest—where no intervention had taken place—and from the center of the Sumu site. The results showed that microbial diversity at Sumu was nearly three times greater than that of the surrounding untreated forest.

These findings suggest that human involvement can contribute to ecological enrichment. Beyond architectural technique, this approach may also influence how humanity understands its role within the Earth’s living systems.
Inspiration: Sumu is a place for tending to nature while reflecting on values.
It applies Regenerative architecture, a new approach developed by the designers that combines traditional Japanese civil engineering with contemporary technology.
Going beyond simply preserving nature, key considerations in the design are:
1. Designing the underground environment
2. Orientating buildings based on in-depth understanding of water and air flows
3. Creating an ongoing connection with nature through architecture
Project Duration: Duration：
The project began in 2020, with the first phase of construction expected to be completed in 2022. Since then, the project has continued to expand its scope of activities, including the expansion of the deck, regenerative activities, and soft aspects such as education.
Location: Yakushima island, Kagoshima, Japan
Operation Flow: 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.
Image Credits: Photo: Rui Nishi