Architectural and construction firms
The need to reduce damage in regions that face greater risks from more intense tropical cyclones and storm surges, etc., due to climate change and the resulting damage from inundation.
By reinforcing structures in hazard zones, vulnerability to climate change will be reduced, and impacts on human safety, property, and economic activities will be reduced.
・ In order to reduce damage due to storm surges, tropical cyclones, and inundation, etc., buildings are reinforced and raised, and architectural forms are changed. Examples include the following construction methods.
√ Raising buildings (using pilotis, such as columns, pillars, stilts, or supports that raise a building)
√ Use of reinforced concrete
√ Using higher building foundations
・ In some methods, existing dwellings and other buildings can be lifted to a higher level with the home furnishings and equipment as it is, meanwhile the building foundation can be raised, or the entire building can be moved to a higher elevation.
・ Municipal and other governments can designate high-hazard zones, and then require or encourage changes in architectural form on buildings in those zones.
・ Costs depend on the construction costs and methods in the designated zones.
・ The standard prices for work under a subsidy program to raise buildings in Nakano Ward (Tokyo, Japan) are indicated below:
√ House raising: 78,000 yen/m2
√ Renovation or new construction of wood-framed structure: 55,000 yen/m2
√ Renovation or new construction of steel framed building: 42,000 yen/m2
√ Renovation or new construction of reinforced-concrete building: 29,000 yen/m2
・ Depending on the method of implementation of the measures, the building owner must cover the costs alone.
・ These options in some cases reduce convenience of day-to-day living.
・ Buildings with raised floors, reinforced concrete, raised foundations and so on, require certain civil engineering and construction technologies.
・ In the case of raising existing homes and buildings, it is important to use technologies that are suited to the types of buildings found at the sites concerned.
・ Even in areas where major infrastructure/physical measures cannot be immediately implemented due to cost or time constraints, etc., there may be ways to reduce damage.
・ In some cases, the convenience/comfort of housing can be improved by the changes.
Case 1: Nakano Ward, Tokyo (Japan)
・ After experiencing damage from inundation of many homes due to overflowing of rivers during heavy rains, Nakano Ward in order to prevent and minimize damage to homes, initiated a subsidy program to cover a portion of costs of raising homes (projects to raise existing homes, and build homes higher when renovating or building new).
・ The program is implemented in designated areas, and for house-raising work that meets certain criteria relating to floor height and below-floor space, etc., the ward will provide a subsidy of half of the standard construction cost per square meter of floor raised (maximum 2 million yen).
・ Panel on Infrastructure Development (2008): Report on adaptation to changes in climate associated to global warming, on water-related disasters (in Japanese).
・ Nakano Ward website (page regarding construction subsidy program to raise buildings)