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Sunday, March 24, 2002

Hotel turns over a new leaf

Staff writer

Big hotels are features of most big cities, and Tokyo is no exception. Rearing into the sky, often straddling whole blocks, they're the temporary homes and permanent workplaces for small armies of people -- which brings serious environmental consequences.

The new rooftop garden, seen from the hotel's 31st floor

As huge garbage producers and copious consumers of water and electricity, even a small eco-friendly step taken by a big hotel can go a long way toward achieving green goals. And as public awareness increases, such steps can also improve the hotel's image and be good for business.

However, the most obvious way a hotel can display its green credentials is by literally greening its own patch -- and in so doing contributing to the greening of the metropolis as a whole.

For new structures on sites of more than 1,000 sq. meters, Tokyo Metropolitan Government ordinances now require builders to devote 20 percent of the site's nonbuilding area to greenery, and to cover at least 20 percent of the roof area with vegetation in an attempt to beautify the city and reduce its heat-island effect.

Though these ordinances do not apply to older buildings, acting in the spirit of TMG's strategic thinking, the prestigious Imperial Hotel in Chiyoda Ward nonetheless decided to create a "rooftop green" on its 17-story main building. To be completed next week, the 530-sq.-meter area which has lush Hibiya Park as its backdrop is now covered with varieties of sedum perrenials set to offer refreshment for guests' eyes and minds.

For older high buildings not designed to carry such a weighty topping, creating a roof garden is no easy task. But after nearly a year of research and discussions among the project team led by Shozo Ikeguchi, deputy director of the hotel's facility department, the necessary structural modifications were undertaken. Then the plants, soil and water system were carefully prepared to create the garden, covering more than 75 percent of the 700 sq. meters of free space available.

In choosing which plant varieties to grow, a key consideration was their ability to survive the effects of hot sunshine, strong winds, rain and even typhoons at that exposed location 76 meters above street level. Hence the choice of sedum varieties, which are believed to be strong enough to endure the conditions, says Ikeguchi. To convince himself, he conducted tests by placing plants in the hotel's dry, warm boiler room, then in a refrigerator.

The other key consideration was soil, since just hauling up stuff dug from the ground would have bust the site's weight constraints. As a result, the special soil being used contains powdered minerals, such as vermiculite, that help both to aerate it and improve water retention for the plants' benefit. And the whole finished project weighs in at an acceptable 30 tons.

But if you imagine this E0-million rooftop garden as a place where you can enjoy strolling around, you may be disappointed. Instead, it was designed to be a green and natural site to be enjoyed by viewing through the windows of the hotel's adjoining 31-story tower.

"One aim in creating this area is to make the view from the tower more colorful," Ikeguchi says. To underscore that aim, at night the garden is lit -- with the power coming from an eco-friendly 6-kilowatt solar panel installation amid the greenery.

Now keenly awaiting the final completion date, Ikeguchi says that other than worrying about rainy days and cloud dimming the solar-powered lights, his main concern is whether the plants will survive and thrive. And as well there's the crows, who he hopes won't make his roof their home.

Other than that, though, Ikeguchi seems to be rather enjoying his role as chief gardener of some of Tokyo's highest greenery -- joking that "it will be exciting if one day we find unexpected plants blooming there prettily."

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