Development of “Water Pressure Resistant Type” Flood-Resistant Housing Through Industry-Academia Collaboration; “Housings to Avoid Evacuation Shelters”

Mitsuya G-Home Co., Ltd.

Publication date	June 30, 2022 (Posted on May 10, 2023)
Sector	Natural Disasters / Coastal Areas, Life of Citizenry and Urban Life

Company Overview

Climate Change Impacts

Natural disasters are predicted to become more severe due to climate change. The flooding of the Chikuma River caused by Typhoon No. 19 in October 2019 resulted in significant damage including inundation above and below floor level and 3,922 residences were half destroyed or worse. The total amount of disaster waste (Note 1) in Nagano Prefecture reached 211,804 tons, and there are growing concerns about the negative impact of such disposal on the global environment.
Living in evacuation centers during a disaster causes the evacuees to live under poor conditions for an extended period of time, which can lead to disaster-related deaths or other serious consequences. From the perspective of securing funds to rebuild damaged houses, it is important to promote comprehensive disaster-resistant houses with disaster countermeasures, and prove how houses can be rebuilt with a minimum amount of money.

Adaptation Initiatives

Our company is located in Nagano Prefecture, and has long been developing and providing “comfortable homes with basements” with watertight/heat-insulating structural frames. After the large-scale flooding disaster caused by Typhoon No. 19, we started our joint research with Shinshu University in March 2020 to develop “flood-resistant housings to avoid evacuation shelters” which withstands the flood level of 3 meters based on our unique basement construction method technology (Fig. 1).
In a public experiment conducted in October 2020 on the campus of the Faculty of Engineering at Shinshu University, water was filled up to 3 meters inside an RC structure (1.8×2.7×3.5㎥) that simulated a flood-resistant house, and the deformation of walls, windows and doors from water pressure was observed to confirm that no water leakage or destruction occurred.
Based on the results of this research, we completed our “water pressure resistant type” flood-resistant housing that withstands a flood level of 3 meters in October 2021 (Fig. 2), after two years from its conception.

This flood resistant housing has three functions:

1. Unbreakable (adopting “reinforced concrete wall construction” that will not be destroyed by water pressure)
2. Flood proof (use of “window/entrance doors” and backflow prevention devices on drain pipes that withstand water pressure and prevent water intrusion)
3. No floating (maintains sufficient weight to withstand buoyancy and prevent house from drifting away)

This flood-resistant house has an intermediate water storage tank that can be used for domestic use, along with solar power and storage batteries to ensure emergency power supply, so that even if the infrastructure becomes unusable, the residents can “avoid evacuation shelters”. The floor plans are also designed so that all household facilities and equipment are located on the second floor or above to secure daily functions in case the first floor becomes flooded (Fig. 3).

Effects / Expected Benefits

After the verification test, it was meaningful that our first flood-resistant house was constructed in the area affected by a disaster. Another significant achievement was the creation of a comprehensive disaster-resistant housing with the highest housing performance in terms of energy conservation, earthquake resistance, wind resistance, fire prevention, and theft prevention. By spreading these flood-resistant houses, we hope to not only reducing casualties and property losses, but to avoid evacuation shelters and protecting lives, reducing the cost of shelter operations for local communities, facilitating the restoration of damaged areas, and reducing the negative impact of disaster waste on the environment.