Ideas for Staying Cool Outdoors in the Summer
"COOL TREE," a Cool Spot with Zero Urban Energy Consumption
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The urban heat island effect is becoming more severe every year, and the risk of heatstroke is increasing.
We’d like to introduce “COOL TREE,” a zero-energy-consumption cool spot designed to help people spend time safely and comfortably outdoors in the city during the summer.
In recent years, as intense heat has persisted nationwide during the summer, measures to combat outdoor heat have become an urgent issue. Nikken Sekkei conceived the idea of “Cool Spots” by combining environmental technology with design, and collaborated with experts from various fields—including Meiken Kogyo, Koei, and Murata Manufacturing—to pool their expertise and jointly develop the concept. The result is “COOL TREE”—an open structure modeled after a tree that allows people to enjoy a refreshing coolness, as if they were standing in the shade of a tree, even under the scorching sun.
Built from domestically sourced hinoki cypress thinned timber to minimize energy consumption, this structure incorporates cutting-edge technology designed to create a cool environment. Its power needs are met solely by solar panels, without relying on the city’s infrastructure. We also took great care to ensure that devices operate in an energy-efficient manner using IoT technology.
So, what kind of cooling mechanisms does COOL TREE feature?First, there’s the overhead awning that blocks direct sunlight. This awning, with its layered wood structure that creates delicate shade like a tree canopy, is highly effective at lowering the surface temperature of the surrounding area. When seeking relief from the heat outdoors, finding shade is the most important thing.
When you approach, a motion sensor activates, and a “welcome mist” cascades down from the eaves of the canopy. This mist, resembling white water vapor, creates a cooling sensation just by looking at it.
When you approach, a motion sensor activates, and a “welcome mist” cascades down from the eaves of the canopy. This mist, resembling white water vapor, creates a cooling sensation just by looking at it.
If you sit on the bench around the pillar, you’ll be surprised by how cool the aluminum seat feels. This is because an electronic component called a “Peltier element” is attached to the underside of the seat.These components are commonly used for cooling computer CPUs or maintaining the water temperature in tropical fish tanks. They utilize the Peltier effect, in which heat is absorbed or released at the junction when an electric current is passed through a junction of dissimilar metals.
When you sit on the bench, an ultra-fine mist is sprayed out through the holes in the transparent acrylic air cylinder installed inside the pillar, carried by a gentle breeze. Because the mist particles are so small, they feel cool when they touch your skin, but they evaporate in an instant, so you won’t get wet.
When you sit on the bench, an ultra-fine mist is sprayed out through the holes in the transparent acrylic air cylinder installed inside the pillar, carried by a gentle breeze. Because the mist particles are so small, they feel cool when they touch your skin, but they evaporate in an instant, so you won’t get wet.
Simulation results show that COOL TREE can lower the perceived temperature by 5°C through the combined effects of these mechanisms. The first COOL TREE was installed in July 2018 in the plaza of Kashiwanoha Smart City in Chiba Prefecture by Mitsui Fudosan.It is expected to enrich public spaces by serving as an urban oasis where people can relax comfortably even outdoors in the height of summer.
Since COOL TREE is simply constructed by stacking wooden beams and securing them with bolts, it can be assembled and disassembled in as little as one day and reused in different locations. Its fully self-sufficient energy system also enhances its installation flexibility.
The hexagonal shape was chosen because it allows multiple units to be freely combined to fit the contours of any site. For example, imagine a scene where several units are lined up along a straight walking path, with one side of each hexagon connected to the next.While creating a continuous stretch of shade, it avoids the monotony often seen when connecting square structures. The hexagonal design can be arranged not only in straight lines but also spread out over a larger area, making it adaptable to a variety of terrains.
Once COOL TREE units have been reused in various locations and have reached the end of their useful life, the materials—wood and steel bolts—can be 100% recycled. The wood is shredded into wood chips and used as fuel for biomass power generation, helping us aim for carbon neutrality. We have been thoroughly committed to ensuring eco-friendliness throughout the entire life cycle.
COOL TREE holds a wealth of potential. Eventually, it may even utilize solar power to function as a Wi-Fi and charging station. It would be fun to build a network connecting COOL TREEs across different regions, allowing people cooling off in different locations to interact via the network—asking each other, “What’s the temperature over there right now?”
Hoping to help people stay comfortable even in the sweltering city heat, Nikken Sekkei continues to propose “cool hospitality” through COOL TREE.
[Photo]
Third from the top: Photographed by Tsuyoshi Ono
Fourth from the top: Photographed by Kunihiko Ishijima
The hexagonal shape was chosen because it allows multiple units to be freely combined to fit the contours of any site. For example, imagine a scene where several units are lined up along a straight walking path, with one side of each hexagon connected to the next.While creating a continuous stretch of shade, it avoids the monotony often seen when connecting square structures. The hexagonal design can be arranged not only in straight lines but also spread out over a larger area, making it adaptable to a variety of terrains.
Once COOL TREE units have been reused in various locations and have reached the end of their useful life, the materials—wood and steel bolts—can be 100% recycled. The wood is shredded into wood chips and used as fuel for biomass power generation, helping us aim for carbon neutrality. We have been thoroughly committed to ensuring eco-friendliness throughout the entire life cycle.
COOL TREE holds a wealth of potential. Eventually, it may even utilize solar power to function as a Wi-Fi and charging station. It would be fun to build a network connecting COOL TREEs across different regions, allowing people cooling off in different locations to interact via the network—asking each other, “What’s the temperature over there right now?”
Hoping to help people stay comfortable even in the sweltering city heat, Nikken Sekkei continues to propose “cool hospitality” through COOL TREE.
[Photo]
Third from the top: Photographed by Tsuyoshi Ono
Fourth from the top: Photographed by Kunihiko Ishijima
