What kind of place is Minato Mirai 21?
Minato Mirai 21 is one of Yokohama’s best-known areas. It started to be built in 1983, and now has all sorts of buildings, such as office buildings, shopping malls, hotels, and condominiums. Many of them, like Yokohama Landmark Tower and Yokohama Museum of Art, attract numerous tourists every year.
Minato Mirai 21 is very careful about how it looks, including the height, exterior designs, and colors of the buildings, so the whole district looks beautiful.
There are also lots of public parks and other green spaces that provide good places for people to relax.
What is district heating and cooling?
Minato Mirai 21 Central District uses a system called district heating and cooling, or DHC for short.
Don’t worry if you’ve never heard of it—plenty of grown-ups haven’t, either!
In DHC, the energy for heating and cooling indoor spaces in buildings all over the district is produced in a huge factory called a “plant.” Heating and cooling are sent to buildings all over the district through a network of underground tunnels.
The plant produces cold water for cooling and steam for heating, and sends them to each building. After the cold water and steam are used in the buildings, they are sent back to the plant as water through the same underground tunnels.
Chillers: The machines used for cooling
Many of the buildings in Minato Mirai 21 are very large, so heating and cooling them requires machines that can produce lots of energy.
Let’s take a look at some of the machines used to heat and cool this area. We’ll start with chillers, which create the cold water used for cooling. One type of these chillers is one of the world’s largest inverter centrifugal chillers. It has the same cooling power as 5,400 room air conditioners!
There are also ice storage tanks that stand 28 meters tall. These make ice at night, and then melt the ice to make cold water.
Boilers: The machines that make heat
Next, let’s look at the machines that make heat. Boilers do this job by creating steam at about 170°C. That’s hotter than the steam from a kettle. With this one machine, we can produce as much heat as about 10,000 room heaters.
Why DHC is Good for the Environment
There are lots of good reasons for using DHC.
First, by producing all of the energy in one plant, we’re less likely to produce too much energy.
Second, DHC releases less carbon dioxide (CO2). That means DHC helps prevent global warming. By using DHC in Minato Mirai 21, we can reduce CO2 by as much as can be stored in a forest as big as 570 Yokohama Stadiums.
So, DHC is a system that’s really good for the environment.
Questions and Answers
Q.How many people work at MM21 DHC?
A.About 100 people work at MM21 DHC.
There are also people from other companies who help us at our plants.
Q. Do the plants run all day and night?
A.Yes! Our plants are busy 24 hours a day, 365 days a year, sending cold water and steam to buildings in Minato Mirai 21.
Q.How many chillers and boilers are there inside the plants?
A.The total for both plants is 25 chillers and 10 boilers (as of April 2025).
Q.Cold water and steam travel from the plant to each building by underground tunnels. But how do they get up to the rooms in the buildings above ground?
A.A fast-spinning machine called a pump pushes the cold water and steam up to the floors above ground.
Q.How does the cold water work to cool the rooms?
A.Air is blown across the cold water, making a cool breeze that cools the rooms.
It’s the same thing as putting something cold in front of an electric fan at your home—the air from the fan turns into a cool breeze.
Q.How does the steam heat the rooms?
A.Steam is heated to 180°C and sent to the basement of each building. Next, it is passed through a machine called a heat exchanger to change it to the temperature used for heating rooms. The steam is also used to heat water for the hot-water supply.