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Sustainable Makeover in a Densely Populated Residential Area in Japan

April 9, 2022

Mizuho Kakiuchi

There are many famous sceneries in Japan. For example, Mt. Fuji, the historic cityscape of Kyoto, and the skyscrapers of Tokyo. However, Japan’s cityscape is not only like that. One of the sceneries that you often see in Japan is that the many houses are densely adjacent to each other. This landscape is deeply related to the history of Japan and is often seen in urban areas of Japan, but various problems have been pointed out.

"Wooden densely built-up area" refers to a residential area where old wooden houses are densely adjacent. Those areas can be found all over Japan, especially in such prefectures as -Tokyo, Osaka, Kanagawa and Okinawa. The background to the construction of densely built-up wooden areas in various parts of Japan is wars, disasters and the concentration of population in urban areas. Especially in Tokyo, such areas have been reproduced every time a disaster occurs. The specific period is the five years after the Great Kanto Earthquake (1923 to 1928), and the post-WWII (after 1945) and the high economic growth period starting from mid-1950s. The reason for the increase in the number of densely built-up wooden areas is that the land readjustment was not carried out before the war and that the population flowed in urban areas intensively, which required more residential land before the urban infrastructure was fully developed.

Why the Densely Built-up Wooden Areas Are Problem?

Densely built-up wooden areas are regarded as a serious problem in Japan because there are many disasters. When disasters happen, it is predicted many houses would suffer great dangers, such as collapse damage, large-scale fires, and blockages due to the collapse of buildings in evacuation routes during an earthquake. In fact, the Great Kanto Earthquake in 1923 caused the largest amount of damage in modern Japan, killing more than 100,000 people, and about 90% of them were said to be victims of the fire.

In Japan, various disasters such as the earthquake directly beneath the capital and the Nankai Trough Earthquake are expected in the near future. For this reason, in March 2011, the Japanese government set a goal in the Basic Plan for Living Life to "generally eliminate densely-populated urban areas that are extremely dangerous during an earthquake by March 2021". However, the current situation is that many local governments are delayed in eliminating dangerous densely populated areas because urban reform is extremely difficult.

There are three main reasons. The first reason is that the rights of land and architecture are very complicated. Because the problem is that the owners and residents of the land or building do not match, because the buildings that are targeted for rebuilding are often old wooden apartments and build on the rented land.

The second reason is that the owners are aging and have no desire to rebuild. It has been a long time since the development of the densely built-up wooden areas, and no influx of young people into such area with poor living environment has led to an aging population. For example, the aging rate of Sumida-ku, Tokyo, is 22.3%, while the aging rate of Kyojima 2-chome, a densely built-up wooden area in Sumida-ku, is very high at 33.3%. On the other hand, the aging rate of Kyojima 1-chome, by pursuing urban redevelopment, now has a relatively low ratio of 21.5% with new younger residents.

The third reason is that there are many existing ineligibility violations of the Building Standards Act. Since the buildings are located very close to each other and the roads are very narrow, they do not meet the requirements for road contact and

building coverage to secure certain level of space. When rebuilding the old architecture, the new houses should obey this standard, which means the new ones are smaller than the previous ones, or worst cases, it is impossible to spare enough space for a new house. Therefore, it is difficult to rebuild.

Sustainable Makeover in a Densely Populated Residential Area

Urban Renaissance Agency, a quasi-governmental residence developer, started the Dense Urban Improvement Project aiming at solving such problems. This is a project to purchase land in a wooden densely build-up area and utilize the land as a "land for promoting non-combustibility" for community development.

Specifically, they are doing two things. The first is that UR buys old vacant houses and unused land. The second is to rebuild the house on the acquired land or to consolidate the adjacent land and rebuild it.

In this way, when it is difficult for owners to rebuild old wooden houses on their own due to complicated rights and road conditions, UR carries out the difficult coordination of conflicting interests for the disaster prevention district development. In the new area, UR builds fireproof buildings and evacuation roads and improves the maintenance of the building. In addition, by redeveloping the densely into an attractive city that is strong against disasters, people can live with peace of mind. It maybe sure to bring younger generations back to the area again and promote sustainable towns.






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