Preserving Kyoto Before Damage Becomes Loss

Kyoto has spent decades trying to protect one of the things that makes the city immediately recognisable: its traditional wooden townhouses.

Kyo-machiya were never monuments in the conventional sense. They were homes, shops, workshops and places of business. Merchants and craftspeople lived and worked beneath the same roof. Their narrow facades, deep interiors, latticework, earthen passageways and small gardens formed part of an urban pattern that developed over centuries.

That ordinary usefulness is part of their importance. A machiya was not built to sit behind a rope.

It was built to be used.

The World Monuments Fund recognised this when Kyoto's machiya were placed on the World Monuments Watch. Its subsequent work with local organisations did more than restore individual properties. Projects were intended to demonstrate sustainable preservation methods, provide resources for owners and encourage the continued use of these buildings within contemporary Kyoto.[1] More than a decade later, the problem has not disappeared.

Kyoto City's latest survey found 34,580 Kyo-machiya remaining in fiscal 2024. In the 2008-09 survey there had been 47,735. The city estimates that the present rate of loss is still around 800 buildings a year, roughly two every day.[2] That is an extraordinary rate of attrition for a form of architecture so closely associated with the identity of the city.

Why machiya continue to disappear

There is no single explanation.

Development pressure matters. So do inheritance, changes in family circumstances, vacant buildings and the economic value of land. But maintenance is a persistent part of the problem.

Traditional buildings require care. Roofs deteriorate. Drainage fails. Timber remains vulnerable when moisture persists. Plumbing and services age. Repairs may need specialist materials and specialist tradespeople. Seismic work can add another substantial expense.

The Sugimoto Residence shows how large that burden can become. The nationally designated Important Cultural Property underwent major work beginning in 2021, including extensive roof repairs and seismic reinforcement. The final project cost was reported at approximately JPY 250 million. Public subsidy covered a substantial portion, but its preservation organisation still had to meet roughly JPY 50 million itself and turned to donations and crowdfunding. [3] Sugimoto is an exceptional building, so its costs should not be treated as typical of every machiya.

The example nevertheless demonstrates something important about heritage conservation: once major intervention is required, the sums involved can become considerable.

Kyoto City has recognised this problem.

Its second Kyo-machiya Preservation and Inheritance Promotion Plan was adopted in 2026. The city allocated JPY 462.329 million to the programme for fiscal 2026, around five times the previous year's budget. Importantly, the measures extend beyond major renovation. A new support scheme is intended to reduce the burden of everyday maintenance for particularly important machiya. [4] That change in emphasis deserves attention.

Preservation does not begin when a roof needs rebuilding. It begins years earlier.

The gap between inspections

Most buildings are still cared for in a familiar way. Someone notices a problem, an inspection is arranged, the cause is investigated and repairs follow.

For many faults this works perfectly well.

The difficulty is that buildings do not deteriorate according to an inspection calendar.

A leaking pipe can begin the day after somebody leaves. A drainage problem may appear only during unusually heavy rain. Moisture beneath a floor can rise without producing an obvious stain in an occupied room. An area that appeared dry during an inspection may behave quite differently through the humid part of summer.

This is one reason monitoring has become increasingly useful in conservation practice.

Historic England's guidance on damp in historic buildings discusses a range of methods for assessing and monitoring moisture and stresses the importance of diagnosis rather than simply reacting to a reading. Its broader guidance makes the same point: moisture exists naturally within building materials, and the objective is to understand when excessive moisture is accumulating, where it is coming from and how it is moving. [5] That distinction matters for traditional buildings.

Wood, earth, plaster and other permeable materials interact continuously with their environment.

A single high humidity reading does not necessarily indicate failure. What becomes more revealing is the pattern: whether conditions are normal for that building, whether something has changed, whether an unusual increase follows rainfall, and whether the affected area subsequently dries.

This is where continuous monitoring can contribute something that a periodic inspection cannot.

Giving owners a history of their building

KyoSensa is being developed around that principle.

Sensors installed in selected locations can create a continuous record of conditions within a property. Rather than treating every reading as an alarm, the system can establish a history for the building and look for changes that deserve attention.

That history matters because old buildings are individual.

Two rooms in the same machiya can behave differently. A subfloor space will not have the same normal conditions as an upstairs room. Seasonal changes matter. Occupancy matters. Ventilation matters. Rain matters.

KyoSensa is designed to combine sensor data with local weather information and, where relevant, seismic events. The purpose is to provide context.

A moisture increase during several days of wet weather may need to be interpreted differently from an abrupt rise during otherwise dry conditions. A reading that stays elevated after surrounding areas have returned to normal may warrant investigation. A change following a significant local earthquake may justify closer inspection even where obvious damage has not been reported.

The technology does not determine the cause by itself. Nor should it.

Its role is to make change visible.

Better information for the people who actually preserve buildings

Traditional conservation depends on expertise.

Carpenters, architects, building specialists, owners and property managers understand things that a sensor cannot: how a building was constructed, where previous repairs have been made, how materials should behave and which interventions are appropriate.

Monitoring becomes useful when it gives those people better evidence.

Instead of saying, 'This area seems damp,' an owner may be able to show when the change began, how quickly it developed, whether it coincided with rainfall and whether conditions are still worsening.

After repair, the same system can help establish whether the affected area is actually drying.

Historic England specifically recommends monitoring temperature and relative humidity during the drying of historic buildings because data can help determine whether moisture removal is progressing appropriately. It also warns against drying traditional materials too aggressively, because timber and other historic fabric can itself be damaged by inappropriate treatment. [6] In this sense, sensors do not replace conservation knowledge. They extend the period over which a specialist can observe the building.

The economics of finding problems earlier

It would be misleading to claim that monitoring will prevent every expensive repair.

Roofs eventually need replacing. Timber components age. Earthquakes happen. Owners inherit buildings with decades of existing defects. Some deterioration remains unavoidable.

But the timing of discovery can matter enormously.

A localised drainage problem is easier to address before prolonged wetting affects surrounding materials. A leaking service is preferable to find before it creates a large concealed damp area.

Persistent subfloor moisture is more useful to identify while the response can still focus on drainage, ventilation or the original water source.

Japan's Agency for Cultural Affairs has warned that moist environments can encourage timber decay and harmful insects in cultural heritage buildings and specifically advises attention to ventilation beneath floors and adequate site drainage. [7] That is preventative conservation in very practical terms.

Monitoring cannot repair poor drainage. It can, however, help reveal that something has changed before the consequences become obvious from inside the building.

A useful addition to Kyoto's existing preservation network

Kyoto does not lack people who understand heritage.

The city has government programmes, specialist craftspeople, community organisations, preservation groups, academic expertise and owners who have maintained buildings across generations. The work of organisations such as the World Monuments Fund and Kyoto's local preservation groups has already demonstrated the importance of restoration, education and adaptive reuse. [1] KyoSensa should sit alongside that work, not above it.

Its potential contribution is much more practical: helping owners and specialists understand what is happening inside a building during the long periods when nobody is inspecting it.

That approach also fits comfortably with Kyoto's broader view of its own culture.

Kyoto City describes the city's history as one in which new culture has repeatedly developed through the combination of tradition and innovation. Its cultural strategy explicitly acknowledges technological change, including information technology and artificial intelligence, while emphasising the need to hand cultural assets to future generations. [8] Applying modern monitoring to a centuries-old method of building does not diminish traditional knowledge. Used carefully, it can help protect the conditions in which that knowledge continues to matter.

Preservation before restoration

There will always be a need for restoration. When a machiya has reached the point where a roof, wall or structural member needs major work, skilled intervention is irreplaceable.

But conservation should not have to begin at that point. Kyoto's new emphasis on everyday maintenance points toward a broader idea of preservation: care that takes place continuously, long before a building reaches crisis.

KyoSensa offers one way to support that approach.

A small sensor cannot preserve a machiya. Neither can an algorithm. Preservation still depends on people choosing to maintain, repair, inhabit and value these buildings.

What monitoring can provide is time and information. When a city is still losing around two traditional townhouses every day, both are worth having.