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Hitachi’s Central Research Laboratory (CRL) is situated within the suburban area of Kokubunji City, Tokyo. This vast 22-hectare business site stretches roughly 600 meters east to west and 550 meters north to south. The grounds are on the former site of Musashi Kokubunji, one of the provincial temples that were erected by Emperor Shōmu throughout Japan during the Nara period (710-784). The ruins of the original temple can still be found about a kilometer southwest of the research laboratory. The grounds also contain a portion of the Kokubunji cliff line known as the "hake." The freshwater springs that rise here feed the headwaters of the No River, a tributary of the Tama River. In 2019, Hitachi, Ltd. completed the construction of our open innovation center, the Kyōsō-tō, within this nature-rich campus.
A great number of magnificent trees more than 20 meters tall remain on-site. Huge Himalayan cedars and Japanese zelkova over a century old are also interspersed around the facility. This makes for an environment of abundant greenery. A grassy field spreads out on the south side of the project area and runs up against Ohike Pond, which brims with water emerging from the cliff base.
In keeping with the commitment of our founder, to "build to avoid cutting down good trees," we have protected the trees within our grounds as much as possible. This commitment lives on today, and the environment around CRL preserves and maintains the natural landscape of the Musashino region. In constructing Kyōsō-tō, it was a top priority to maintain the Musashino area old-growth forest of about 30,000 trees and shrubs, the freshwater springs that are a source of the No River, and the archaeological remains of villages from the Jomon period (14,000–10th century BC).
After surveying and plotting all of the trees in the project area, we utilized a layout design which avoided cutting down as few existing trees as possible. We also employed building volume segmentation to reduce the impact on the forest (see figure below). We reused the wood from the two Japanese zelkova that we were forced to cut down to create table tops and other items used in our outdoor terrace, offering an environment that allows people to work comfortably while enjoying the rich natural surroundings.
We designed the landscape from an ecological perspective that minimized the burden on the existing forest, as our goal was harmonious coexistence.
The terrain of the area which includes the grounds of CRL is dominated by the Kokubunji cliff line formation. This is composed of a Kanto loam layer and a gravel layer that makes up the river terrace created by the Tama River. Kokubunji City views the Kokubunji cliff line as an important regional resource and has created an original standard to preserve its green space, create scenery, and protect springs via urban development ordinances. In this way, the city is working to protect and regenerate the verdant cliff line.
Ohike Pond, the large pond on our grounds, was created in 1958 using the numerous springs on the premises. It is one of the valuable water sources for the upper reaches of the No River.
The foundations of the previous building were reused as support foundations for the new building to avoid unnecessary digging during the foundation work for new structures in the project area, as this might disturb underground water sources and archaeological remains. This work was carried out in consultation with the Kokubunji Spring Water Conservation Association (see figure below).
We also constructed an observation well during this foundation work, and used it to survey water quality and water levels before, during, and after construction (for two years).
Hitachi believes it is important to cultivate a deeper understanding among employees who use the Kyōsō-tō with respect to the building's construction and operation. To this end, the company has hosted forums for general discussion several times, dubbed the Kyōsō-no-Mori Conference. At these conferences, the company explains steel frame construction which does not harm existing trees, construction which takes into account the preservation of groundwater, transplanting work which maintains the shape of the transplanted trees, and reuse of the wood from the two zelkovia trees that we were forced to cut down. These forums have provided a good opportunity for employees to gain a better understanding of the importance of ecosystem conservation.