"Defying common wisdom
in housing construction" A pioneer in the industrialization of housing, Daiwa House Industry leads the way in designing homes for Japan, where earthquakes are a part of life. Learning the lessons of major earthquakes, we have begun to develop new ways of building homes – methods that depart from accepted wisdom.

Imagine how much courage and energy it takes to try to forget for a while one's past successes and start again with a blank slate. Those successes had achieved recognition by society – you had built a track record of which you were proud, and which gave you great confidence. This is what lies behind the creation of Daiwa House Industry's top-of-the-range single-family house model, the xevoΣ.

It all began in October 2010, in a room at our Central Research Laboratory in Nara, where an elite group of ten staff members involved in research, product development and other fields were gathered. They had been instructed to think about new methods of construction that would meet Japan's anticipated needs in the coming years. This was akin to flinging down a challenge in the face of all the successful experience accumulated by Daiwa House Industry over the years.

The conventional method that we have used for our prefabricated houses is to combine load-bearing vertical steel columns with "panel-frames" that compose the exterior walls. This is an efficient method, and no homes built using this method were wholly or partially destroyed* in the 1995 Great Hanshin-Awaji Earthquake. On the other hand, it has the drawback that, precisely because it is a prefabrication method, freedom of design options is strictly curtailed.

In the one-year period following the initial massive earthquake off the coast of Japan's Tohoku region on March 11, 2011, six earthquakes of a magnitude of 7 or higher were registered. Central Research Laboratory staff member Tamaki Maeda, a specialist in structural engineering, realized that it was not good enough simply to meet the safety standards that had been laid down. She felt strongly that it was her responsibility to create a method of construction that would enable houses to withstand repeated violent earthquakes – to build houses that would stand up to both massive quakes themselves and to the possibly numerous aftershocks. The example set by the destructive 2011 Tohoku earthquake had forced her to raise her seismic resistance targets still higher.

Aftershocks continued to be recorded in the region hit by the major earthquake and tsunami, and we needed to put an effective new construction method onto the market without delay. Researchers Maeda and Nishimura were given a mere six months to come up with a solution. Up to that point, the two of them had been involved only in improving or refining technologies passed on to them from previous research staff. This time, they were given free rein to pursue whatever line of research seemed promising: they were starting with a blank slate.

In September 2013 we conducted tests of the resistance of our xevoΣ home to a massive earthquake, using a full-scale house model, at the world's largest three-dimensional earthquake destruction testing facility (also known as a shake-table), which has been nicknamed E-Defense*1.

In the months leading up to this major test of the new structure's viability, Maeda and her team busied themselves in getting ready, and preparations were started in June. The xevoΣ model was then assembled within the testing room in July. In August, measuring instruments were put in place around the model, and then in September, the date scheduled for testing finally arrived. Despite having done everything that needed to be done, Tamaki Maeda vividly recalls how her heart was in her mouth. Meanwhile, Ken Nishimura was so run off his feet getting things ready that he couldn't spare the time to exchange a word or two with his colleagues.

The tests – which were scheduled to last for six days – commenced with well over a hundred staff in attendance, including the development team members. The xevoΣ model was subjected to vibrations at a level of 175 kine*2. This is equivalent to 7 on the Japan Meteorological Agency seismic intensity scale, which measures the degree of shaking experienced, and surpasses the169 kine recorded at Japan Railways' Takatori Station at the time of the Great Hanshin-Awaji Earthquake – the most powerful recorded in Japan up to that time.

Shaking of this intensity is 3.5 times the 50 kine specified under Japan's Building Standards Act as the threshold level for the "major earthquake" category. During the tests, we also assumed a scenario of one main tremor followed by a number of aftershocks, and this procedure was repeated four times. Tamaki Maeda and her team stayed at a nearby hotel during the six-day tests, awaiting the outcome with bated breath.

Following the completion of testing at the E-Defense facility, Tamaki Maeda and her team continued to work on improvements to the design. A short while earlier, one of Maeda's former teachers had paid a visit to the Central Research Laboratory, and Ken Nishimura still remembers the words he heard on that occasion: "If you don't mind high costs, it's easy to do anything you like, but it's an engineer's job to create things that are affordable to the average person."

The team had successfully produced a home whose performance came up to standard, and the task that remained was to strip away the non-essentials so as to enhance productivity on the factory production line, thus enabling the Company to provide affordable homes.

Moreover, as the space taken up by walls and columns in the xevoΣ had been reduced to a minimum thanks to the strengthening of its structural framework, the developers were able to include extra value in addition to earthquake resistance and cost-performance. That is, the ceiling height was 2.72 meters and the width of the widest openings was 7.10 meters*.

When the xevoΣ went on sale in January 2014, many potential buyers were captivated by the home's spacious rooms and the way in which the large windows let in plenty of natural light. The number of design options available to buyers was also a major selling point. This new single-family house product was so popular that our production lines were temporarily unable to cope with the demand.