COOLBIZ - Why 28°C?
Professor Shin-ichi Tanabe
Department of Architecture, Faculty of Science and Engineering, Waseda University
The hot summer has come again! It's almost like a tropical island here due to the urban heat island effect. As part of the government initiatives to fight global warming, the COOLBIZ campaign was launched in 2005. An old friend of mine, who has visited Japan often over many years, says attitudes of Japanese people towards clothing have changed significantly, as many people dress casually these days in summer. He has a lasting impression of a Japan full of very polite and well-dressed people, where even in hot summer men wear suits with ties wherever they go. In fact, as short sleeve shirts are very informal, even today those who are very careful about dress codes only wear dress shirts with long sleeves, in spite of the summer heat. Some regard dress shirts as underwear, so they never take off their jackets (more power to them!)
The COOLBIZ campaign has had a very positive effect on Japanese people, as psychological resistance and social barriers to informal dress have been removed, and as each individual has been encouraged to consider saving energy. The UN also launched the COOL UN campaign, allowing members and staff to dress more casually, and in turn setting the air conditioning to a higher room temperature to save energy.
People say that casual clothing is nice when it is hot, but 28°C seems a little too high for a room temperature setting in summer. The most comfortable temperature when sleeping naked is 29°C. People burn more calories in the workplace than at home where they are more relaxed, and however casually they may dress, they are still not naked in the workplace. The Building Hygiene Inspection Group of Tokyo Municipality conducted a survey on the room temperatures of more than 16,000 offices that were air conditioned over twenty years before the COOLBIZ campaign started. According to the survey, the average cooling temperature was approximately 25°C and the average heating temperature was rising year after year close to 25°C. Even in the interest of saving energy, the change from 25°C to 28°C is too drastic and sudden for everyone to accept.
What are the grounds for changing the temperature to 28°C? This temperature setting is based on the "Act on Maintenance of Sanitation in Buildings", which is intended to ensure hygiene in buildings and contribute to improving and promoting public health. This act applies to buildings with a floor area of 3,000 square meters or more, and requires the room temperature of an air conditioned building to be below 28°C.
Lower Settings in Other Countries
It is important to note that the ambient temperature is not always the same as the temperature that the air conditioner is set to, and people sometimes notice this difference. Even though the air conditioning is set to 28°C, the heat from office equipment such as computers and printers may raise the room temperature beyond 28°C in some areas of the room. Poor building envelope in terms of energy efficiency may further increase the perceived temperature beyond 28°C, as the high surface temperature of the ceilings, windows, walls and floors result in higher actual ambient room temperatures. In addition, the higher the room temperature is, the more stagnant the ambient air feels. Of course, humidity, air velocity, and activity may effect thermal comfort. It is also important to address the air-conditioned room temperature more flexibly and on a more scientific basis-rather than just setting a 28°C temperature across the board-in order to reduce the impact on the environment. Otherwise, the COOLBIZ campaign will not last long.
A large-scale survey on fully air-conditioned buildings in the U.S. and Australia showed that the optimal temperature during summer was 23.5°C. It also reported that the cooling temperature set in air-conditioned buildings in Singapore and other South East Asian countries were set at very low temperatures. A guidebook recently published by the Federation of European Heating, Ventilating and Air Conditioning Associations (REHVA) reports that 21.8°C is the optimal room temperature to foster intellectual productivity. Waseda University conducted a survey on the most comfortable room temperature, targeting 406 people of various nationalities working for foreign trading companies. While non-Japanese male employees felt that the most comfortable temperature was 22.9°C, Japanese female employees felt that 25.2°C was best. The Japanese female employees were not happy with the low temperature that was adjusted for the non-Japanese male employees. Even a cooling temperature of 25°C, which is regarded as comfortable in Japan, is significantly higher than that in other countries. I really hope foreign countries will follow Japan's lead.
Objective and Scientific Analysis
Since the COOLBIZ campaign is intended for business offices that are engaged in production activities, it requires objective and scientific insights into energy efficiency, rather than simply forcing workers to put up with less favorable working conditions. The labor costs of office workers are much higher than energy and building costs. We conducted a survey on productivity and the office environment at a call center where quantitative measurement on productivity could be made easily in order to ascertain the actual effects of temperature changes. We analyzed the data of 13,169 persons handled by about 100 operators on a cumulative basis. When the average room temperature of 25.0°C was increased by 3°C to 28.0°C, the average response ratio per hour of the operators went down by about 6%. On an average working day of 8 hours, it required 29 minutes more for operators to achieve the same results when the temperature went up.
Raising the cooling temperature of a standard building in Tokyo from 25°C to 28°C could increase energy efficiency by 15%, which is equivalent to saving ¥72 per square meter of office space during the COOLBIZ campaign. On the other hand, the resulting decrease in working efficiency could cause a loss of 13,000 yen per square meter of office space. Using mesh office chairs, breathable clothes and fans with temperature controls in the office may help to gain \3,000; however, such thorough measures may not be feasible in reality. Therefore, it is necessary to set a practical room temperature and implement feasible measures which are appropriate for the building performance and air conditioning equipment at each workplace, and which do not adversely affect intellectual productivity. Reducing the heat generated by computers and lighting equipment also makes a significant impact. Construction of an environmentally friendly building that is specifically designed to address the COOLBIZ measures could achieve superior energy efficiency while maintaining optimal comfort.
The Kyoto Protocol enacted in February 2005 aimed at reducing global warming gas emissions required that Japan reduce emissions by 6% from the 1990 level. However, in 2005, emissions from office buildings increased by 42% from the 1990 reference year level. Immediate action is critical to fight global warming. It is essential that we implement practical measures that will not hinder economic activities.
Professor Shin-ichi Tanabe:
Department of Architecture, Faculty of Science and Engineering, Waseda University
Professor Tanabe graduated from the School of Science and Engineering at Waseda University in 1982 and completed the Doctoral Program at the School of Science and Engineering at Waseda in 1987. He joined the faculty of Waseda University in 1999 as an Associate Professor, and since 2001 he has served as a Professor on the Faculty of Science and Engineering in the Department of Architecture at Waseda University. Before joining the faculty of Waseda University, he worked as an assistant at Waseda University; as an Associate Professor at Ochanomizu University; University of California, Berkeley; and as a Visiting Professor at Technical University of Denmark and Dalian University of Technology.
Awards: He won an award from the Society of Heating, Air-Conditioning and Sanitary Engineers of Japan in 1995, an award from the Architectural Institute of Japan and a fellow membership of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
Publications: Professor Tanabe's main publications and editorial supervisions include "Chemical Pollution Inside the Room" [Shitsunai Kagaku Osen] (Kodansha Ltd.), "Book on Home Building Technology in the Near Future" [Kinmirai Jutaku no Gijutu ga Wakaru Hon] (PHP), "Sensible Information Processing" [Kansei Joho Shori] (Ohmsha Ltd.), " Consideration on Officing Environments" [Ofishing Kankyo Ko] (Libroport) and "The Style of the 21st Century Residence" [21 Seiki Kata Jutaku no Sugata] (Toyo Keizai, Inc.).