A Wooden Zero-Energy Cool Spot
— First installation of COOL TREE LITE in Iidabashi, Chiyoda-ku —

On March 2, 2020, Nikken Sekkei Co., Ltd. set up a test installation of COOL TREE LITE at i-Garden Air in Iidabashi, Chiyoda-ku, Tokyo. COOL TREE LITE is a new compact version of COOL TREE, an eco-friendly cool spot installation that uses solar power and thinned wood from Japan to provide cool comfort in outdoor public spaces in midsummer.

COOL TREE was developed by Nikken Sekkei Ltd., MEIKEN LAMWOOD CORPORATION, Ltd., Koei Co., Ltd., and Murata Manufacturing Co., Ltd. in 2018 with the purpose of creating cool spots in outdoor public spaces through a combination of environmental performance and design excellence and contributing to urban development that offers a comfortable outdoor living environment in midsummer. In 2019, these companies developed a 4m x 4m square-shaped LITE version in consideration of a size and shape that is more suited to a cityscape affected by the heat island phenomenon.

Through the development of a solar-powered, total zero-energy cooling system and COOL TREE which suppresses CO2 emissions with the use of thinned timber from Japan, Nikken Sekkei is creating comfortable and eco-friendly city spaces and promoting the spread of energy-efficient technology.
  • Photo taken on March 3

  • Photo taken on March 1 (during operation test)


Height: Approx. 2.9 m, Size: (Roof) 4.0m x 4.0m (Base) 4.8m x 4.8m, Total weight: Approx. 3,500kg

①Cool sensation from mist, sunshade and cool contact

・Mist cools the air through the heat of vaporization and creates a visually cooling sensation.

・The lattice hinoki cypress sunshade provides an open feel and blocks direct sunlight like a canopy of trees.

・Sitting on a “cool bench” that uses the Peltier effect cools people’s bodies down.

*1 Peltier effect: Effect of absorbing and releasing heat at a junction where different metals are joined, voltage is applied and a current flows.

②Self-sufficient zero-urban energy system using solar power and IoT control

Solar panels are installed above the latticed sunshade, so the power driving cooling devices, such as the cool bench and mist, is all derived from solar energy. Power generated from the solar panels is temporarily stored in a storage battery, which is then used to operate the devices.
With this energy-efficient ingenuity, a zero-energy system has been developed that is completely independent from urban energy infrastructure.

③Ecological system using the 3Rs (reduce, reuse, recycle)

COOL TREE LITE uses 75-mm2 thinned hinoki cypress wood that is generally available with 90-mm thick CLT (Cross Laminated Timber) panels layered and joined together to form the foundation.
The use of thinned wood can reduce the energy needed to produce building materials.

COOL TREE LITE can be repeatedly assembled and dissassembled by joining together each of the parts with bolts only.

Wood can be recycled as materials for biomass power generation, and iron can be recycled and reused as scrap for electric furnace materials.

Installation at I-Garden Air

・Period: March 2 to September, 2020 (planned)
Cooling devices, such as the mist and cool bench, are scheduled to be put into operation from May.
Until the cool devices start operation, COOL TREE LITE will be illuminated at night with solar power and outlets have been installed in two places that can be used to charge smartphones.

・Location: i-Garden Air Central Plaza, “Front Forum”
3-10 Iidabashi, Chiyoda-ku, Tokyo

Original COOL TREE installations

The original COOL TREE with a diameter of 7.7 meters was installed at Kashiwa-no-ha Smart City (Chiba Prefecture, July 2018 to September 2019) and Nagoya Port Wildflower Garden Blue Bonnet (Nagoya City, July 2019 to present).


This website uses cookies. By continuing to use this website, you agree to the use of cookies. Our cookie policy.