Issue 03: Reuse in Japan

Sou Fujimoto’s Grand Ring for Expo 2025 was superlative. With its approximately 2km-long circumference, it was recognised as the largest wooden architectural structure by the Guinness Book of Worl Records in March 2025. Aside from its dominating size, the Grand Ring’s beautifully rhythmic structure became emblematic of the expo and was hugely popular with visitors. It was also interesting for international designers as it showcased modern versions of traditional joinery techniques and demonstrated what timber connections for disassembly could look like.

It was a surprise for many, then, that only a 200m length of the Grand Ring was earmarked for retention. There were some rumblings that a portion of it will used as part of disaster housing, but Expo 2025 officials stated that the majority of the 27,000m³ of timber used for the structure would likely be chipped to create wood fuel. All the works for the expo were to be temporary so there was no original intention to retain the Grand Ring. However, the chipping proposal is lamentable considering significant parts of the structure could have been reused or repurposed where retention was not possible.

Figure 1: The Grand Ring at Expo 2025 Stephane Aboudaram

Reuse would have been preferable to recycling. It requires relatively less processing as this is often limited to cleaning and repair which spares the energy recycling needs. Reclaimed material also has a better chance of retaining its market value. As a quick estimation, the cost of spruce glue-laminated timber (glulam) imported to the UK for a project I recently worked on was approximately £535/m³. In contrast, a cursory internet search showed wood chips sell for variable amounts depending on desired quality, but we will assume an average of £70/m³. This constitutes an 86% loss in market value.

Figure 2: Hierarchy of circular economy strategies Circularise

Design for disassembly (DfD) is an emerging theme in Japanese construction. It is a key preceding step for reclamation as structures deliberately designed with this in mind simplify the reclamation process. Three of Japan’s five so-called super general contractors: Obayashi Corporation, Takenaka Corporation and Shimizu Corporation, each developed their own modern versions of traditional connections for the Grand Ring. The distinguishing feature of the beam-column connection, known as a nuki detail, is beams are threaded through column openings to form a frame. The nuki system has had something of a resurgence in recent years as it can be designed to be moment-resisting, so minimal or no bracing is needed to resist lateral loads.

Each contractor’s proposal is mechanical and avoids adhesives specifically so the structure can be easily dismantled. It is easy to imagine how the frame can be parcelled following deconstruction. The beams are continuous and are of a good size and could be imagined as structural members in other buildings. The columns are better repurposed as the clear sections in some areas are unusably short due to the close vertical beam spacing.

Figure 3: Nuki details developed by Takenaka Corporation for the Grand Ring Takenaka Corporation

However, despite the many possible futures that can be imagined for these members, Japan has no established distribution networks dealing in reclaimed material for structural reuse. Nor are there any regulatory frameworks to support this. When timber is removed from the context of its original building, it loses its Japan Agricultural Standards (JAS) certification which is required for structural timber. Without clear recertification guidance, the current easiest way to reuse timber may be to treat it as ungraded. The codified strength of ungraded timber is lower than that of graded timber for the same species so more material would be needed for the same configuration and loading. Though this is less ideal, it may still save timber from downcycling and disposal.

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The Value of Reclaimed Material

The lack of reuse systems is not accidental. It reflects how much the country values reuse. Like any other commodity, the value of reclaimed material is determined by its desirability. In economic terms, desire is complex. It does not solely rely on a product’s fundamental value, its practical functionality or its scarcity. It is also sociological – value is relative because of our cultural understanding of a commodity – and it is temporal – what we value and by how much changes over time.  

To fully reflect value, desirability is diluted by risk and uncertainty. This principle can be illustrated by the image below. From this we see that high desirability and low risk result in high value. Conversely, high risk and low desirability mean value is reduced. Japan’s assessment of reclaimed materials is towards the bottom end of this image.

Figure 4 : Relationship between desirability and risk

The low desirability of reuse is informed by a variety of factors, namely: high seismicity’s impact on design and the perception of safety, the outlook on construction promoted by the financial implications of earthquakes, and the ascribing of religious meaning to the use of new material. Increased risk stems from the practical challenges relating to realisation of reuse buildings. The complexity involved can disincentivise clients, especially when overcoming these also requires deviation from construction industry norms.

Let’s inspect each element closer.

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Desirability

Newer is safer

Of course, safety is an important criterion when renting, buying or selling property. Modern Japanese buildings are designed to the Building Standards Act. This outlines the minimum seismic design requirements to prevent collapse. Several amendments have been issued since it was first established in 1950. Each amendment has reflected lessons from major earthquakes and seismic research.

The Miyagiken-oki earthquake of 1978 was consequential. The research sparked by the extensive building damage observed culminated in the 1981 revision of the Act. This revision is often referred to as the new seismic standard. It was a large departure from its antecedent: designs now had to resist earthquakes of minimum seismic intensity 6 rather than the previous limit of 5. This change ushered in the use of ductile/inelastic design and the introduction of Level 1 and 2 seismic categories. Though other revisions have also been significant, the 1981 Amendment remains notable and is commonly understood as the turning point for modern seismic safety.

Figure 5: Key earthquakes impacting design codes

Buildings predating 1 June 1981 – when the new standards came into effect – were not required to be rebuilt to align with the amendments. It is deemed impractical to ask that buildings be updated to meet current building ordinances each time there is a change, so these older buildings, known as existing noncompliant buildings, are legally permitted to be used provided their use and size remains the same. A seismic evaluation is required where major alterations are proposed. Noncompliant areas should then be retrofitted. Where retrofitting is too complex or not possible, rebuilding is necessary.

Figure 6: Timeline of key seismic events and standard changes

Figure 7: Examples of seismic retrofitting Top: Apartment building Hagirawa Masaki Bottom: Building in Osaka Trevor Mogg/Alamy Stock Photo

Following the devastation of the 1995 Great Hanshin-Awaji Earthquake (Kobe earthquake), regulations were put in place to encourage retrofitting of buildings of certain scales and uses to meet modern standards. Buildings presently implicated by the regulation include: hospitals, fire stations and other emergency services, places of congregation like large stores, apartment blocks and theatres, and socially important buildings like schools.

So, when people are looking for property, they can opt for older, non-compliant buildings that are cheaper, may be at risk when large earthquakes strike and are harder to insure, or they can opt for more modern, compliant buildings that give peace of mind but are more expensive. While ‘old’ can be valuable, in instances like this, it can also be understood as precarious and unsafe.            

Here today, gone tomorrow?

The perceived long-term value of buildings has been impacted by high seismicity. A telescope view of history on the islands shows us buildings are not always the permanent markers of place or mascots of neighbourhood character we may be used to them being in Europe. Tokyo alone has seen several incarnations in its 400-year-or-so history. War, earthquakes and fires have all had their turn at almost erasing the city. Each time it has been rebuilt.

Of course, the reconstructed urban fabric has been important in its role of sustaining demanding city life, but it has a certain impermanence. Your home, your place of work, the train station where you start and end your commute can all unpredictably cease to be, either by man’s hand or nature’s. Buildings therefore don’t easily fall into a class of assets that can reliably be passed down through the generations, accruing value as they age. The ground they sit on is different. More often than not, it is there ready for the next reconstruction and makes for a more stable asset.

With buildings being treated as the more malleable component of urban infrastructure, they can be replaced as needed with less sentimentality. The catalyst for change may be an earthquake, but the general acknowledgement that buildings may have short lifespans means other factors such as loss of functionality, change in architectural fashions and sociopolitical considerations can also more easily encourage demolition.

Figure 8: View of major construction site which is part of the Shibuya Regeneration Project taken during a visit in January 2025

Whenever I visit Tokyo, no matter how much time has passed, I feel I’ve caught the city in a moment of flux with each arrival. Construction is constant and the city has never felt quite finished. This made it an exciting place to be a designer because the pace of construction provides opportunity to experiment with and refine design thinking. It is becoming clearer with time that this way of constructing is a reaction to place to a degree, but it can be at odds with wider conversations about climate change and modern construction.

Forever young

Geography and economics contribute to the ecosystem where newness is more sought after, but there is also another unique approach that argues its power and necessity. In Mie prefecture to the west of the country, there is the important Shinto site of Ise Jingū. It is home to two important gods: Amaterasu, the goddess of the sun, and Toyouke-hime, the goddess of grain and food. Every twenty years, a sacred ceremony is held here where each goddess’s shrine and their associated buildings are rebuilt.

Figure 9: Old and new shrine buildings standing side by side on the east and west shrine grounds Ise Jingū

The rebuilding process is seen as necessary for divine perseverance as explained by the principle of tokowaka. It is the belief that physical change is essential as by inhabiting the new, the divine can continue into the future. The principle also serves to remind us of the cyclical nature of life in general – everything must make way for its eventual rebirth. Save for the interruptions of war, this rebuilding process has been repeated on this schedule over the site’s 1,300-year history.

The 8,500m³ of hinoki needed is harvested from specially designated forests. The timber is used unseasoned, so it needs to be stable for use in large members. Mature trees are best for this, and the ideal trees are ancient by modern standards: many are over 100 years old and some can be as old as 400 years.

Figure 10: Shrine rebuilding at Ise Jingū  Ise Jingū

Over the ceremony’s history, hundreds of thousands of trees have been used for rebuilding and some Japanese argue that such rare mature trees should be preserved. However, others see the felling as part of the rebirth cycle as conveyed by tokowaka. They also argue that the timber is put to good use as it makes homes for the earthly and holy alike.

There is also a wider ecosystem for the hinoki used at Ise Jingū. The traditional techniques used to erect the shrines allow for easy disassembly (similar to the Grand Ring structure). The tradition of rebuilding is not unique to Ise and is practised across the country. Once the old buildings at Ise Jingū are deconstructed, the timber is sent to be reused in other religious sites in the country. It’s not clear, though, how much of the original timber is sent for reuse, how long the timber is in use in secondary sites or how many times timber is exchanged. Ise Jingū is at times cited as a historical precedent for sustainable approaches in Japan but because of this it is difficult to say confidently to what degree the system is circular.

The rebuilding ceremonies also have social value. They are an integral part of local Ise culture. The 20-year process is marked by several local festivals that celebrate the various stages of rebuilding. In general, festivals are important in Japanese life. They are social lubricant that helps to foster community spirit and are a major form of religious expression.

Figure 11: Traditional timber-pulling event where wood is brought by Ise residents to the sacred grounds  Ise Jingū

It is often said that the most sustainable action we can take is to not build at all. This does away with the need for new material. In Japan, newness is not treated as an extravagance. It is why people feel of security in the spaces where they spend most of their time. Quick acceptance of it also affords the flexibility needed to begin again, and it can be spiritually nourishing.

Newness is engrained in the economies around the built environment and in the social understanding of the materials that make up the built world. On these islands, desirability is skewed in favour of it and creativity is needed if reuse is going to stand a chance. This may come in the form of engaging the global supply chain to circulate reclaimed materials further afield to places with more appetite. Material resource can also be shared with other disciplines. New works could create new social associations between reuse and legacy, for instance by using reclaimed material to create artistic pieces that let people to own a slice of urban history. By looking a little to the side, Japan’s current position about reuse in architecture can benefit others in unexpected ways.

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Risk

The risk with reclaimed materials comes from uncertainty. Fundamentally the lifespan of buildings is unpredictable because destructive earthquakes strike without warning. Key code changes are also unpredictable, and these can drastically and quickly change the seismic risk profile.

Figure 12: Damage from the 2024 Noto earthquake KYODO/Reuters

The practical challenges surrounding reuse also exacerbate risk. Steel is a good example that illustrates this. Examples of Japanese steel reuse seen so far have mostly been of buildings that have been deconstructed and rebuilt wholesale in new locations. (This is similar to the architectural tradition of kaitaishūri. Historical timber buildings, much like Ise Jingū, were constructed with details that simplified disassembly using kigumi which is where timber members are joined without metal fixings. Kigumi buildings could be deconstructed (kaitai) in part or wholly and repaired (shūri ) or transported as necessary.) These cases are not reuse in the way we have been discussing it here where one structure is cannibalised to provide material for an entirely separate structure. However, they illustrate how a building can live in a more direct way.

Reuse as we are thinking of it would require special permissions. Two years ago, I attended a lunchtime talk by a local reclaimed steel stockist who explained the steps necessary for the recirculation of existing steel. As can be expected, careful disassembly is necessary to minimise damage and maximise the volume of useful material. This volume is further whittled down through assessments that determine suitability.

Though guidance is being developed, steel produced before 1970 does not align with modern chemical and mechanical standards so it is not currently reused. Radioactively contaminated matter, steel that has suffered fire damage or irredeemable toxic chemical contamination is also not viable. Degraded or damaged members, for example where excessive rust is present, are similarly discounted. The remaining stock is then tested using non-destructive methods to determine mechanical properties. The members that pass this testing can then be reused.

Figure 13: Steel sourcing for London reuse project Elliot Wood

Apart from the categorisation of pre-1970 steel, these considerations also apply to steel reuse in Japan but there is an additional consideration. The introduction of inelastic design was crucial in increasing the absorption of earthquake energy. This is a critical mechanism for preventing collapse, particularly in large and complex buildings. Inelasticity also means that irreversible changes (yielding) that permanently alter mechanical behaviour can occur in structural elements. Yielding in members or connections means they cannot be candidates for reuse, so steel is checked for this.

There may be some technical intricacy required but the steps are theoretically feasible. Nevertheless, ‘feasible’ is not the same as ‘practical’.  In this case the technical challenges exacerbate the perceived risk. The foregoing process can be esoteric for clients which can disincentivise them. To gain the special permissions required, the process needs to be rigorous and thorough which intimidates. There is also no guarantee that permissions will be granted even after all the technical hurdles have been overcome, so overall, the idea can be off-putting.

Lowering the barrier to entry would likely require a joint effort between researchers, designers, contractors and policymakers. Reclamation can be better controlled to increase material yield by more carefully considering connection details as done by the contractors on the Grand Ring. Buildings can be designed to have localised areas that absorb seismic energy so the remainder can be harvested for materials. Researchers can contribute to this effort by helping designers understand collapse mechanisms more deeply. International collaboration could also be possible here: countries that are vulnerable to earthquakes could share knowledge about the specific difficulties of their regions.

Reducing risks requires creativity in the same way increasing desirability does and there may be something vital in not trying to tackle it alone.

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Selected Bibliography & Further Reading

Blok R, T. P. (2019). Demolition versus transformation, "mortality of building structures” depending on their technical building properties . IOP Conference Series: Earth and Environmental Science. IOP Publishing.

DISRUPT - Delivering Innovative Steel ReUse ProjecT. (n.d.). Policy Considerations for Reclaimed Structural Steel. Retrieved from ASBP: https://asbp.org.uk/wp-content/uploads/2023/03/Policy-considerations-for-reclaimed-steel-DISRUPT-Toolkit.pdf

Holland, O. (2024, January 6). How Japan spent more than a century earthquake-proofing its architecture. Retrieved from CNN Style: https://edition.cnn.com/2024/01/06/style/japan-earthquake-architecture-dfi-hnk/index.html

New Steel Construction. (2025, September 3). Embracing the circular economy. Retrieved from New Steel Construction: https://www.newsteelconstruction.com/wp/embracing-the-circular-economy/

Image Credits

Thumbnail image: AXIS

Figures 4-6, 8: analogs | this~that

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