The Conceptual Power to Connect Forests and Cities: A New Form of Construction Born of Resource Recycling126

The power of imagination to connect forests and cities: A new form of construction born from resource recycling

Updated by Obayashi Corporation on September 02, 2025, 8:45 PM JST

Can trees change the shape of cities? As a general construction company, Obayashi Corporation is seriously tackling such a question. The company's current focus on wood is not limited to simply aiming for a change in materials. The company is now looking at urban buildings as "second forests"-a concept that aims to make the city itself part of the environmental cycle.

OBAYASHI WOOD VISION is a vision of the Obayashi Corporation. The vision is to promote decarbonization by increasing the number of wooden and wood-based buildings in cities, to improve health and provide comfortable living environments by increasing the number of wood-based spaces, and to build a sustainable supply chain that encompasses the manufacturing and construction of building materials and the use of energy. This vision aims to realize a rich, recycling-oriented society centered on trees through these three pillars.

In particular, he said, the third important initiative for realizing a recycling-oriented society is the establishment of a sustainable supply chain.

As a general contractor, we are located in the downstream of building construction, but we cannot realize the future of wooden construction only by doing so. We believe that a cycle can only be established when we go from downstream to midstream, in other words, when we go into the cultivation of forests and lumber production.

This is the view of Mr. Hakuei Akamatsu, General Manager of the Environment and Energy Solutions Department of the Technology Division. For the past 10 years since his arrival at this division, he has been involved in local development projects such as recycling-oriented forest utilization and local energy production for local consumption.

Local energy, local construction materials, and local jobs go round and round. By adding our construction technology, the city itself becomes a living cycle. Our starting point was that we want to be responsible for the beginning and the end of the wooden construction process.

Circular Timber Construction" is the result of Akamatsu's and others' ideas on site. The idea is to incorporate the connection with forests from start to finish in the process of construction, where trees are born as construction materials, grow up, are used, and are then reused.

The "starting point" in this process is the "forestation" initiative. The company has developed a "hybrid sapling production system" that combines artificial and natural light, and has succeeded in shortening the time required to grow saplings to about one-third that of conventional systems and significantly reducing costs. In Nichinan Town, Tottori Prefecture, a pilot plant has been established to produce larch saplings, and a system is in place to supply approximately 10,000 trees per year.

In addition, the company-owned forests in Hokkaido are managed in a recycling-oriented manner, with repeated clear cutting and reforestation. The company aims to build a sustainable forest utilization model together with local communities. These efforts are aimed at incorporating the responsibility of not only "using trees" but also "growing trees" into the company's own operations.

In 2021, the company acquired Cypress Sunadaya, a company that specializes in the manufacture of CLT (laminated laminated laminated timber) using domestic timber, as a group company. This is intended to establish a stable supply system for structural members, which are essential for medium- and large-scale wooden buildings, and at the same time, to realize integrated operations with the downstream construction division.

By being on the production side rather than just the buying side, we can reduce the risk of procuring lumber and smoothly link it to the building project," says Akamatsu. A system that allows us to utilize the needs of the users in development is a great advantage in realizing rational and lean wooden construction," said Akamatsu. He also says that it will lead to increased transparency and traceability of the entire supply chain, as well as the visualization of information that will enable the company to understand where the wood comes from, when it was harvested, and the processing process, and will broaden the scope of the construction industry to create a system that supports the sustainable use of forest resources.

The trees are grown and further processed efficiently into building materials for use in the company's own buildings. The finishing touch in the development of the timber route is the "end point" after it has been used. As an outlet for timber that has finished its role as building material, the company has also prepared a wood biomass power generation system to recycle it as a resource. Currently, a power plant using thinned wood as fuel is under construction in Otsuki City, Yamanashi Prefecture. The energy produced here is used as electric power. This is truly a model for "using up every last bit of wood.

Wooden buildings built in cities will continue to be recycled as resources and energy even after they have finished their role. I think we are gradually beginning to see a form of construction that takes into account not only design and construction, but also the generation and reuse of materials.

Within this tree cycle, the company has been introducing unique wooden structures to the world. A prime example is "Port Plus," completed in 2022. This is the first project in Japan to clear the restrictions of the Building Standard Law and to be realized as a high-rise, pure wooden fireproof building with all of its main structural components made of wood.

Port Plus" also served the purpose of verifying the extent to which wooden structures could be built to meet fire resistance, earthquake resistance, and durability requirements under current regulations. The project was intended to serve as a "demonstration building," from construction to data collection and feedback, with an emphasis on accumulating the know-how needed to make a high-rise pure wood-frame building viable in urban areas.

Although the project was meant to be an experiment," recalls Akamatsu, "we were able to share within the company the knowledge and issues unique to wooden structures through the entire process from design to construction. This kind of steady effort has helped to convince us that wooden structures can be used in urban areas as well.

Currently, Obayashi is applying the knowledge gained from Port Plus to subsequent projects, and is working to create a system that can handle a wide variety of wood construction projects, including mid-rise non-residential buildings and public buildings. The company's vision for the future of wooden construction is to refine wooden construction as a technology and at the same time incorporate the concept of circulation into it.

And as an extension of this project, "LOOP50. This is a grand concept that aims to synchronize the cycles of buildings and forests by designing a set of approximately 20,000 hectares of forest and a town with approximately 15,000 inhabitants. The design concept is very unique: a portion of the building is demolished every 50 years and extended using trees grown in the adjacent forest over the next 50 years as building material. By continuing this process every year, the two cycles, the growth of the forest and the renewal of the city, will move at the same "rhythm.

LOOP50 is one of the future forms of circular timber construction. It is one of the future forms of Circular Timber Construction," says Mr. Yu Oka, General Manager of the Carbon Neutral Wood Solution Department of the Sales Division. This compact city was designed with an eye toward the amount of timber needed in 50 years and the size and growth of the forests that will provide it. And it also incorporates the use of wood from demolished buildings as biomass and reused materials. The cycle of growth, use, and regeneration of the forest is synchronized with the cycle of renewal of the city. I think this is the ideal form of a recycling-oriented city."

Of course, LOOP50 is still in the conceptual stage, but the company, in cooperation with local governments, has begun a demonstration project to realize a recycling-oriented forestry business. One such initiative is in Hanno City, Saitama Prefecture. The city is known as a production center of Nishikawa lumber, a brand-name material, and has long been a region where forestry and urban life coexist. In this area, Obayashi is studying urban development through the introduction of smart forestry technology and the creation of a model for utilizing local resources. The visualization of forest data, the study of the introduction of cutting-edge operation systems, and the concept of a timber industrial complex - each of these down-to-earth initiatives will lead to the realization of LOOP50.

Not just "use" trees, but "nurture, utilize, and use again. Obayashi's efforts are not limited to the mere promotion of wooden construction. The company's perspective of extending the forest cycle, which begins with saplings, to construction sites and the urban form itself, offers a glimpse of the construction industry of the future.

Tags.

• Wooden and woody construction in the town
• woodworking industry
• recycling-oriented society