The New Japanese Housing Policy And Research And Development To Promote The Longer Life Of Housing
Introduction:
The average life time of newly-built detached wooden houses in Japan was almost fifty years. There are various reasons for the short life span of Japanese housing. Fires following the Great Kanto Earthquake that struck the Tokyo area in 1912 caused a huge loss of building stock, so only a small amount of old houses remain in the Tokyo Metropolitan area. The rapid economic growth that followed the Second World War enabled the Japanese to afford to live in larger houses with modern facilities. Many people rebuilt their smaller temporary houses built just after the end of the war.
Present-day Japan faces three problems:
1) people cannot enjoy the feeling of wealth they should as members of a mature society.
2) the falling birth rate and aging of society are increasing the welfare burden.
3) global environmental problems and waste problems are becoming increasingly severe.
To overcome these problems we must transform society from its existing state, a consumption society which builds and demolishes, into a stock society which builds good objects and takes scrupulous care of them to preserve them for long periods of time. The goal of extending the life span of housing is to overcome these problems.
Durability of the material; Deterioration measures:
House structures should be able to be used for several generations. They should be designed so that the period their structure can be used continually under maintenance conditions considered normal is at least 100 years. It should be counted on to be usable for between 150 and 200 years under appropriate maintenance.
Structural design; Earthquake resistance:
Make it easier to repair damage caused by an extremely uncommon earthquake to ensure the continuous use of the house by reducing the level of damage caused by earthquakes.
Either build it as a base-isolated building or take measures to reduce deformation caused by large earthquake force at or below a specified level.
Example: The ratio of the safety limit deformation of each above-ground story to its height should be 1/100 or less (in the case of wooden construction, 1/40 or less) during a large-scale earthquake.
Adaptability:
Measures should be taken which permit the modification of room layouts according to changes in the lifestyle of the occupants. Ceiling height of the building frame must be adequate for piping and wiring according to modification of the original room layouts.
Example: A specified building frame ceiling height or higher (2,650mm or higher) must be ensured.
Universal design for the elderly and handicapped:
Necessary space in common halls and corridors must be maintained so that it is possible to perform renewal work to make a home barrier free in the future. Example: The width etc. of common halls and corridors must be designed to ensure necessary space.
Incentive for longer life housing:
The client can apply for tax reductions and can receive subsidies by designing and building a house which complies with the new law and technical guidelines. Specific incentive measures have been implemented.
1) When a person has purchased or constructed and occupied long-life-span superior housing from 2009 to 2011, the person is exempt from income tax up to a maximum value of 6 million yen over a ten year period according to the balance of the person’s housing loan at the end of each year.
2) When a person has purchased or constructed and occupied long-life-span superior housing, the person receives an income tax exemption equal to 10% of the construction cost which exceeds that of ordinary housing (limited to 10 million yen).
3) The fixed asset tax on long-life-span superior housing is reduced by 1/2 for two years longer than in the case of ordinary housing.
CONCLUSIONS:
The approach toward lengthening housing life in Japan longer has only just begun. Real results of design methods and technological developments already started have not yet been seen. Although not enough research on the relationship between city planning and building life span has been conducted, it seems that there is a strong relationship in regard to the development of post-war Japanese cities.
Also Read: Affordable Housing Master Plan