Bronze Architecture, Building and Structure Design · 2026
Sumu Yakushima Residence
by Tsukasa Ono
- A' Design Award 2026 Bronze Winner in Architecture, Building and Structure Design
- Awarded April 15, 2026
- CLIENT: tono Inc.
- Estimated Number of Design Views: 5,417
- Verification code 98CB03E4D2 · Verify this award
About Sumu Yakushima Residence
Sumu Yakushima applies Regenerative architecture, a new approach developed that combines traditional Japanese civil engineering with contemporary technology. 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 and decks are raised, dispersing wind flowing between the mountains and the sea without blocking it.Off grid energy from solar power and firewood.
Sumu Yakushima Residence by Tsukasa Ono represents a compelling contribution to the evolving discourse surrounding contemporary interpretations of timber architecture within ecologically sensitive forested environments, drawing upon deep regional traditions of wooden construction while addressing present-day aspirations for spatial openness, environmental transparency, and material authenticity that characterize much progressive residential design throughout the temperate forest zones where such building cultures have flourished for centuries. The architectural gesture captured here reveals the essential structural system at a particularly eloquent moment in the construction sequence, where the primary load-bearing timber framework and elevated deck platform achieve maximum legibility before subsequent layers of enclosure and finish obscure the tectonic clarity, allowing viewers to appreciate the rigorous geometric order underlying the composition, the systematic spacing of vertical supports rising from individual concrete pier foundations that elevate the structure above grade in response to topographic conditions, moisture management considerations, and the symbolic tradition of lifting dwelling spaces into proximity with the forest canopy while maintaining respectful distance from the earth plane. The technical execution demonstrates accomplished understanding of timber frame design principles, with square-sectioned posts of substantial dimension supporting the platform structure through what appears to be mortise-and-tenon or similar traditional joinery methods, the horizontal decking boards laid with consistent spacing that creates visual rhythm while providing functional surface, and the careful integration of the glazed building volume behind the deck, where dark-framed windows and doors establish geometric punctuation across the vertical timber-clad facade and suggest thoughtful modulation of interior illumination and prospect. The chromatic accomplishment lies in the harmonious orchestration of warm natural wood tones ranging from pale honey to deeper amber across the structural elements, creating tonal unity while celebrating the inherent color variation within the timber itself, complemented by the cooler neutral concrete foundation elements that provide chromatic grounding and material honesty, and the crisp black window frames that sharpen the overall composition and establish clear threshold between interior and exterior realms. Thematically, the residence appears to explore the enduring human aspiration to dwell within nature rather than merely beside or against it, seeking integration through material sympathy, where the choice of local timber species and traditional construction methods acknowledges regional building wisdom while the spatial openness and transparency suggest contemporary desires for visual and experiential continuity with the surrounding landscape, the elevated platform creating a threshold condition that is neither entirely of the forest floor nor completely separate from it, but occupying an intermediate zone that offers both prospect and refuge. The architectural language evokes vernacular precedents throughout forested regions where timber construction developed sophisticated responses to climate, topography, and available materials, while the refined geometric order and careful proportional relationships suggest engagement with modernist principles of clarity, honesty of materials, and functional expression that have enriched architectural discourse for more than a century. One might observe in the rhythmic spacing of vertical supports a potential reference to traditional modular planning systems that organized domestic space through standardized intervals, creating flexible frameworks within which daily life could unfold with both order and adaptability, while the transparency of the glazed envelope invites contemplation of how contemporary life might maintain connection to seasonal cycles, diurnal light variations, and the subtle transformations of the forest throughout the year, positioning the dwelling as instrument for heightened environmental awareness rather than barrier against natural forces. The composition invites viewers to consider how architecture might serve as mediator between human habitation needs and ecological sensitivity, demonstrating through material restraint, structural legibility, and spatial openness that dwelling need not require domination or transformation of site, but might instead achieve presence through careful attunement to existing conditions, celebrating the particular qualities of place while providing shelter, prospect, and contemplative repose for those who inhabit these thoughtfully conceived spaces.
Press Kit
- 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. - 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. - 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 - Image Credits
- Photo: Rui Nishi
Colors of Sumu Yakushima Residence
Grand Interview about Sumu Yakushima Residence
Before moving to Yakushima, I had already begun to feel uncomfortable with the way sustainability was being discussed.Of course, reducing environmental impact is important. However, whether we install solar panels or reduce carbon emissions, we are often still talking about minimizing damage rather than creating positive change. I kept asking myself: even if we succeed in reducing harm, will the planet truly become healthier? What does the end goal actually look like?At the same time, environmental issues were increasingly being translated into numerical indicators and market mechanisms. Carbon trading, certifications, and sustainability metrics all had their place, but I often felt that the original purpose was being overshadowed by the pursuit of measurable targets. I found myself struggling to distinguish genuine ecological improvement from symbolic gestures.The answer came from Yakushima's natural environment.Nature does not argue through theories; it reveals its answers through outcomes. Where water flows well, life flourishes. Where circulation is blocked, vitality declines. The forest taught me that healthy ecosystems are built not on efficiency but on relationships and cycles.While participating in the restoration of degraded land on Yakushima, I began to see nature itself as the ultimate environmental textbook. Through direct observation, I realized that the most important question was not how to reduce environmental damage, but how to restore and strengthen the cycles of life.Sumu Yakushima emerged from this realization. It became my first attempt to explore whether architecture could move beyond minimizing harm and instead contribute to the regeneration of ecosystems. The project was born from a simple but profound question: can a building help life thrive?
What troubled me most about contemporary environmental discourse was its tendency to rely on a single metric.For example, when carbon reduction becomes the primary measure of success, we risk overlooking other consequences such as biodiversity loss, monoculture plantations, or large-scale deforestation associated with certain renewable energy developments. Nature does not operate through a single indicator, and neither should architecture.Forests, water, soil, plants, animals, fungi, and microorganisms exist within an interconnected system of relationships. When one element is isolated from the whole, we often lose sight of what truly creates ecological health.This is why I place great importance on the concept of the watershed.Rain falls on mountains, flows through forests and rivers, and eventually reaches the sea. Human settlements exist within that journey. Architecture is not separate from this system; it is part of it.For me, a building is not an isolated object. It participates in the movement of water, the health of soil, and the vitality of ecosystems. Its responsibility extends beyond its walls.What Sumu Yakushima proposes is not simply a low-impact building, but an architecture that actively participates in the cycles of life.If human beings are part of nature, then our homes should be capable of enriching nature as well. I believe this shift in perspective represents one of the most important challenges facing architecture today.
While observing Yakushima’s forests, I became fascinated by the immense network of fungi and microorganisms that exists beneath the ground. Healthy forests are supported not only by what we see above the surface, but also by invisible relationships within the soil.At the same time, Japan has a long tradition of using charcoal within landscapes and agricultural systems. Inspired by both ecological observation and traditional knowledge, we incorporated carbonized wood beneath the foundations and used charcoal-based materials throughout the project.Charcoal is highly porous. It retains moisture, air, and nutrients while providing habitat for countless microorganisms. Yet the charcoal itself was never the goal.What we were truly trying to create was an environment that could support biological activity and strengthen the living soil system beneath the building.The results were encouraging. Microbial diversity on the site was measured at levels exceeding those found in the surrounding untreated forest.For me, this finding suggests that architecture does not have to be a force of depletion. Human-made structures can potentially contribute to the enrichment of ecological systems rather than their degradation.I see this not as a construction technique, but as the beginning of a new design philosophy—one that reconnects architecture with soil ecology and recognizes that the health of a building site cannot be separated from the health of the living systems beneath it.
Around the world, we are witnessing accelerating biodiversity loss, deforestation, soil degradation, and the disruption of natural water cycles.In this context, architecture is often discussed as part of the problem. Buildings consume resources, alter landscapes, and contribute to environmental pressures. While this is true, I also believe architecture can become part of the solution.Although Sumu Yakushima was developed within the unique environment of Yakushima Island, its core principle is universal: understanding the ecological characteristics of a place and supporting their regeneration.I believe the role of architects will change significantly in the coming decades.Traditionally, architects have been responsible for designing buildings. In the future, I believe we will also be asked to design relationships—between water and land, between people and ecosystems, between communities and the natural processes that sustain them.The future of architecture is not simply about creating structures that blend into their surroundings. It is about creating places that contribute positively to the health of those surroundings.If Sumu Yakushima can offer any lesson beyond Yakushima itself, I hope it demonstrates that architecture can become a participant in ecological restoration rather than merely a consumer of ecological resources.
One of the greatest challenges during the development of Sumu Yakushima was implementing an approach that had very few contemporary precedents.However, it would be inaccurate to describe it as entirely new. Many of the strategies we employed—such as elevated floors, independent foundations, and respect for underground water movement—were inspired by traditional Japanese building knowledge that had existed for generations.The real challenge was that I was still learning.At the time, I did not yet have complete confidence in all of the answers. Could architecture truly support ecological regeneration? Could a building coexist with underground water systems and microbial networks? These were questions I was actively exploring myself.Whenever local craftspeople asked difficult questions, I often found myself reaching out to researchers, traditional builders, soil specialists, and practitioners from many different fields. Rather than visiting them, many generously came to Yakushima, walked the site with me, and shared their knowledge directly.What remains most memorable is not the difficulty itself, but the generosity I encountered.These experts spoke passionately about their fields of expertise, and I found myself constantly inspired by the new worlds they revealed. Each conversation opened another door. Each question led to another discovery.Of course, there was uncertainty and experimentation. Yet rather than feeling burdened by it, I remember that period as an exciting journey of continuous learning.Without the knowledge and support of those people, Sumu Yakushima would never have been realized.The experience taught me that regenerative design is not the product of a single architect's vision. It emerges when diverse forms of knowledge connect and collaborate, much like the living networks found within nature itself.
The Japanese word “Sumu” means “to live” or “to reside.” At the same time, it shares its pronunciation with another word, “sumu,” which means “to become clear” or “to become purified.”The name was chosen because it expresses a relationship that I believe modern society has largely forgotten.Since industrialization, human settlements have often been created by clearing forests, extracting resources, and importing energy from distant places. In many cases, the more we live somewhere, the more the surrounding environment is depleted.Yet I began to question whether this condition should be considered normal.For most of human history, people lived within the cycles of nature rather than outside them. Human habitation and ecological health were not necessarily in conflict.Today, I believe it is possible to rediscover that relationship without abandoning modern technology.At Sumu Yakushima, elevated floors and independent foundations help preserve underground water flows and ecological continuity. Carbonized wood and locally sourced materials support biological activity within the landscape. At the same time, solar energy systems, battery storage, and high-performance thermal design provide contemporary comfort and resilience.The goal is simple: to create a place where living and ecological clarity can coexist.A place where people live, and the environment becomes healthier.A place where a healthier environment, in turn, enriches human life.This reciprocal relationship is the philosophy embodied in the name Sumu.I do not see it as a radical idea. Rather, it is an attempt to remember something very old—that human beings are not separate from nature, but part of it.
People often ask whether Sumu Yakushima could only exist on Yakushima Island.Certainly, the specific techniques would differ elsewhere. A desert, a mountain forest, and an urban environment each require different responses. Regenerative architecture should never be reduced to a universal formula.However, what I believe is transferable is not the technique itself, but the way of thinking behind it.One of the most important concepts for me is the watershed.Wherever people live, rain falls, water moves across the land, and ecological systems develop around those flows. Human civilization has always evolved within watersheds.I view architecture as part of this larger living system.The role of a building is not simply to occupy land, but to participate in the movement of water, support healthy soil conditions, and contribute to the vitality of local ecosystems.The specific design solutions may vary from place to place, but the principle remains consistent.What matters is not the regeneration of buildings themselves, but the regeneration of the living cycles that already exist within a landscape.If we begin from that perspective, regenerative architecture can evolve into countless forms around the world while remaining rooted in the unique conditions of each place.
What I most hope people take away from Sumu Yakushima is a reconsideration of humanity's relationship with nature.For a long time, modern society has tended to frame human prosperity and environmental protection as opposing forces. We often speak as though we must choose between economic development and ecological responsibility, between human comfort and the well-being of the natural world.I do not believe this is the only possible future.Human beings are not separate from nature. We are participants within it.The goal of Sumu Yakushima was never to prioritize nature over people, nor people over nature. Instead, it was to explore whether both could thrive together.In that sense, the project is not simply an architectural proposal. It is a question.Can we create places where human well-being contributes to ecological well-being, and where ecological health enriches human life in return?I believe this question will become increasingly important as we confront the environmental challenges of the coming century.If there is one aspect of the project that has not yet received sufficient attention, it may be the idea that architecture should be evaluated not only through the experience of its human occupants, but also through its impact on the living systems around it.Comfort, beauty, and functionality remain important. But perhaps we should also ask whether a building contributes to healthier soil, cleaner water, richer biodiversity, and stronger ecological relationships.To me, that is one of the most exciting possibilities for the future of design.
When we confirmed measurable electrical activity connecting trees on opposite sides of the building site, I felt a profound sense of wonder.Of course, those networks already existed within the forest. We did not create them.What mattered was the possibility that the building had not interrupted them.Throughout the project, we tried to avoid treating the site as an empty canvas. Instead, we viewed it as a living system that already possessed its own relationships, flows, and intelligence.This perspective influenced many design decisions, including the use of elevated floors and independent foundations that help preserve underground water movement, airflow, and ecological continuity.The evidence suggesting that biological communication may have remained active beneath the building was deeply meaningful to me.It reinforced an idea that had been developing throughout the project: architecture is not simply the arrangement of materials in space.Architecture is also the design of relationships.Relationships between people and place.Relationships between water, soil, plants, and microorganisms.Relationships between human activity and the larger living systems that support it.The experience strengthened my belief that buildings do not need to dominate nature in order to be successful. They can instead support the conditions that allow life to flourish.
I have never wanted architecture itself to be the protagonist.At Sumu Yakushima, many of the architectural elements were intentionally simplified so that the surrounding landscape—the forests, mountains, sky, and sea—could become the true focus.The building acts as a frame through which nature can be experienced more clearly.At the same time, the project integrates contemporary technologies such as solar power generation, battery storage systems, high-performance insulation, airtight construction, and radiant heating and cooling.Some people see a contradiction between advanced technology and a close relationship with nature. I do not.In fact, I believe the opposite is true.The more secure and comfortable people feel, the more open they become to experiencing the natural world around them.If you are worried that a storm might break your windows, it is difficult to appreciate the beauty of the wind, the rain, and the forest. But when you feel protected, you can observe those forces with curiosity and wonder.Likewise, when a warm and comfortable interior exists, people are often more willing to step outside onto a deck, feel the changing weather, and engage with the landscape.Human beings explore because they feel safe enough to do so.The use of local cedar, regional soil, and other place-based materials further strengthens this connection. The building becomes part of the landscape rather than an object imposed upon it.Ultimately, I believe that people become healthier when the environment around them becomes healthier.And I believe that the environment can become healthier through the way we choose to live.This idea is reflected in the name Sumu itself.A place where people live, and nature becomes clearer.A place where nature becomes healthier, and human life becomes richer.If visitors leave Sumu Yakushima with a renewed sense that they are not separate from nature, but part of its ongoing cycles, then I would consider the project a success.Because perhaps the most important form of sustainability is not a technology or a metric, but the feeling of belonging once again to the living world.