As environmental issues such as global warming gained awareness around the world, Keio Plaza Hotel began implementing a variety of initiatives both inside and outside the hotel as an effort to preserve the global environment since 1991. One of them was the large-scale greening of the roof on the 7th floor of the main building in 2008.
“Rooftop greenery” attracted attention as an effective measure for the urban heat island effect. Cultivating plants in lightweight soil on a waterproof rooftop space, plant transpiration helps lower the temperature of the surrounding area.
On the 7th floor of Keio Plaza Hotel, covering about 3000㎡ is an outdoor pool which is popular every summer, and a rooftop garden that has a traditional Japanese rock garden where one can enjoy seasonal trees, as well as a new rooftop green area. In the green area, with both environmental consideration and beautiful landscaping in mind, we planted the evergreen mondo grass (ophiopogon japonicus), which can withstand the strong winds on high-rise buildings, in a modern striped design.
The amount of energy that our rooftop greenery reduces the urban heat island effect by is equivalent to an average of 145,000kcal an hour, which is 75 air-conditioner units running continuously in 15 ㎡ rooms for 3 months during July to September (summer). Keio Plaza Hotel’s rooftop garden contributes positively to the environment through beautiful and pleasant greenery. An oasis amongst the skyscrapers in Nishi-Shinjuku, and having been working on waste separation, recycling, energy conservation and wastewater treatment, this is also a symbol of Keio Plaza Hotel’s environmental movement.