August 12, 2009


Sprinkling Water to Cool Down Summer's Heat

Keywords: Newsletter 

the Mission Uchimizu Campaign as Social Design

JFS Newsletter No.83 (July 2009)

In pre-air conditioner Japan, people tried various things to forget or cool down the summer heat: hanging tinkling wind chimes at the window to help them feel cool; blocking the direct sunlight with traditional bamboo blinds or reed screens; sprinkling water in front of house entrances and in gardens; wearing soft, absorbent summer "yukata" cotton kimonos; eating summer foods that cool the body; and taking walks in the cool of the evening to enjoy fireflies or fireworks. These are all traditional Japanese summer customs that are still commonly practiced as a part of everyday life.

Among these clever ways to feel cool through the medium of our five senses, sprinkling water, called "uchimizu" in Japanese, has recently drawn attention as a possible measure to help mitigate the urban heat island effect and global warming.

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A campaign to promote water sprinkling called "Mission Uchimizu," started seven years ago, and is now an annual summer event throughout the nation. The number of participants has been increasing every year and has recently reached over seven million. Now, 70 percent of Japanese people aware of the campaign. In this issue of the JFS newsletter, we trace the growth of the campaign to revive the traditional wisdom of uchimizu.

Campaign to Reduce Midsummer Temps by Two Degrees Celsius

Liquids trap heat from the environment as they turn into gas. This trapped heat is called vaporization heat. This phenomenon is applied, for example, in refrigerators and air conditioners. Water characteristically traps a lot of heat from the environment when it evaporates, so sprinkling water in places where heat is stored can decrease the temperature.

"On the assumption that water would be sprinkled at the same time over an area of 280 square kilometers in Tokyo using one liter of water per square meter, it was estimated that the temperature would drop about two degrees Celsius."

Researchers of the Public Works Research Institute conducted an experiment to simulate the effects of sprinkling water as an approach to mitigating urban heat island effects. Further calculation revealed that the temperature at noon could be reduced by a maximum of 2 to 2.5 degrees Celsius by sprinkling water on about 265 square kilometers of suitable area in Tokyo's 23 wards.

The idea for the campaign emerged in June 2003: the three initiators of the project were interested in obtaining an estimate and gathered to conduct a social experiment. The experiment was carried out by a coalition group of four non-profit organizations (NPOs), such as the Earthday Money Association and the 3rd World Water Forum, the domestic representative of which is currently the Japan Water Forum, which was held in Japan in March 2003. The secretariat of the Forum took the leadership in this effort.

The campaign was named the "Sidewalk Sprinkling Campaign" and its logo combines a water motif with one of the family crests common in the Edo Period. The launch in 2003 celebrated the 400-year anniversary of the start of the Edo Period in 1603, and indicating participants' determination to learn from Edo era wisdom. This logo, available from the following website, can be used for any non-profit purpose or activity. (Japanese)

Regarding the water used, in the hopes that the campaign would also be an opportunity to reconsider water use in daily life, initiators set up a rule that fresh tap water not be used, and called on people to use gray water such as collected rainwater or leftover bath water.

With just two months of preparation time, various people, including students, NPO members, and reporters who had come to interview participants, began to voluntarily get involved in the campaign. When groups in charge of creativity, marketing and publicity were organized and started to work in earnest, the campaign concept took a big step forward and it became a confident movement run by a self-organized body.

Finally, the "Sidewalk Sprinkling Campaign in Tokyo" was carried out at noon on August 25, 2003; it was a hot day - forecasts were for a high of 34 degrees Celsius (93 degrees Fahrenheit).

At four event sites in Tokyo, researchers and elementary school pupils measured temperature changes before and after sprinkling water. The results showed an average decrease of one degree Celsius in temperature and thus the effectiveness of uchimizu was demonstrated by this experiment. An estimated 340,000 people participated in 2003, the first year of the campaign. A lot of media reported that participants wearing yukata casual cotton summer kimonos had sprinkled water on streets and sidewalks together using old-fashioned dippers. This was the start of an environmental movement that anyone could easily join.

Campaign Spreads Out from Tokyo

In its second year (2004), the area of the campaign expanded from Tokyo to many places across Japan and the campaign title was changed to simply "Sidewalk Sprinkling Campaign." In addition, the campaign period was extended to one week, from August 18 through 25. Thus, various entities, including private companies, carried out activities large and small in scale throughout the nation. The campaign secretariat estimated that more than 3.29 million people participated in the one-week campaign.

In Nagoya, Osaka and Fukuoka cities, local NPOs took the initiative to organize local campaigns, with local governments, shopping arcades, schools and other entities joining in. In Tokyo, girls in Edwardian style maid costumes appeared to demonstrate uchimizu in Akihabara, a well-known center for custom sub-culture cafes, particularly maid cafes where waitresses wear maid costumes. In Shibuya, Tokyo, people tried to symbolically and momentarily restore a small stream, long since converted to a culvert, by sprinkling water together. The theme of culverts that were formerly streams is a motif in the traditional Japanese children's song "Haru no Ogawa (Spring Stream)."

In 2005, the campaign period was further extended to cover the summer vacation period from July 20 through August 31. By this time, uchimizu had begun to draw more attention not only as a countermeasure against the urban heat island effect, but also as an eco-friendly action to curb global warming. An estimated 7.7 million people or more participated in the 2005 campaign. Some large-scale events were set up in Tokyo's Minato Ward and at the 2005 World Exposition in Aichi Prefecture. Even in France, on August 17 over 100 people enjoyed sprinkling water in front of Paris's city hall.

The campaign has been promoted nationwide since 2005 involving a wide variety of campaign items and performances related to uchimizu: for example, a special pail and ladle were developed using the byproducts of forest plantation thinnings; official animation characters were created in Akihabara and an animated promotion video produced; a theatrical group, the "Uchimizu Company" was also launched - it gave shows and released a traditional dance song entitled "Uchimizu Ondo."

After the campaign's fourth year in 2006, the secretariat permanently set the dates for the Mission Uchimizu campaign from July 23 to August 23, from Taisho Day to Shosho Day, which fall on two of the 24 points in traditional East Asian lunar/solar calendars. Taisho falls around July 23 every year, usually the hottest day of the year, and Shosho falls around August 23. It is believed that by this date the hottest season is winding down and cooler breezes in the morning and evening start to blow, letting people know that autumn is approaching.

Mission Uchimizu in the World

The uchimizu movement is spreading around the world. In Stockholm, Sweden, 50 people from around the world enjoyed uchimizu using the water from a fountain in a park in front of the international Folkets Hus conference hall, venue of the 14th Stockholm Water Symposium.

After Sweden, the "Mission Uchimizu a la Place du Chatelet" was held in Paris, France in 2005. On July 21, 2008 at the World Exposition held in Zaragoza, Spain, the Crown Prince of Japan demonstrated uchimizu for high officials of the Spanish government, and this had a strong impact on the people around the world. (in Japanese)

The English name of the campaign, Mission Uchimizu first appeared in 2006. The mission of the campaign is described as "combating global warming" and "making Japanese traditional culture of uchimizu from Edo Period (1603-1867) known to the world."

Social Design and Mission Uchimizu

As illustrated above, Mission Uchimizu is spreading in Japan and the world. This is largely owing to one of its particular features -- everyone can join in, and playing with water in summer is simply fun and makes everyone feel good.

One of the campaign initiators, Masaaki Ikeda wrote in the latest edition of "Social Design of Mission Uchimizu," "Mission Uchimizu opened my eyes to the fact that this campaign is intrinsically design." His implication with respect to design in this context is that the campaign involves ceaseless processes moving toward a single goal based on a universal concept together with a self-organized body working to create a new reality.

The universal concept of Mission Uchimizu takes in the physical properties of water, its spiritual aspects such as its sacred function in ritual purification, its role in hospitality to guests and its awe-inspiring power. Appreciation for these qualities of water has been passed down to us over the generations.

"Sprinkle water together, and let's cool down 2 degrees Celsius in summer"
Since this call has been heard, uchimizu, a good old-fashioned Japanese tradition, has been transformed into a movement with new, 21st century-style values.

Let's sprinkle water on a hot summer day.
This can make a small but positive difference to the world.

Written by Kazumi Yagi