Until now, as a way of reducing greenhouse gas emissions from Japanese homes, the emphasis has been on reduction of energy consumption for air-conditioning and lighting. In recent years, there has been progress in CO 2 emission reduction through research into the water-saving performance of bathroom fixtures such as toilets and showers. Simulations have shown that CO 2 emissions associated with water consumption in Japanese homes can be reduced by 25% (1% of Japan's total CO 2 emissions) by 2020 through the adoption of the use of water-saving fixtures. In response to this finding, a program to promote the replacement of current fixtures with water-saving toilet bowls and thermally insulated bathtubs has been added to the Government of Japan's energy-saving policy. Furthermore, CO 2 emission reduction through widespread use of water-saving fixtures has been adopted by the domestic credit system promoted by the Government of Japan as a way of achieving CO 2 emission-reduction targets; application of this credit system has also begun. As part of a bilateral offset credit mechanism promoted by the Government of Japan, research to evaluate the CO 2 reduction potential of the adoption of water-saving fixtures has been done in the city of Dalian, in China. OPEN ACCESSWater 2012, 4 534
Abstract:In a previous study, we showed that widespread adoption of water-saving equipment had the potential to reduce CO2 emissions by 1% in Japan. The usage of already diffused equipment was used as an evaluation baseline. This was an evaluation model of developed countries. In order to evaluate the potential benefits of water-saving in developing countries, it is necessary to set the baseline, as cities in developing countries are expected to have the necessary infrastructure in place in the near future. In this paper, the potential for reducing CO2 emissions by water saving in Vietnam was evaluated. Based on the development of water infrastructure, and envisioning a society in which the latest high-efficiency flush toilet bowls and showers installed in Hanoi and Ho Chi Minh City are used in all Vietnamese houses as a near future baseline, we evaluated the potential reduction when a water-saving project is implemented. Under these conditions, an 8.8% reduction in CO2 emissions in Vietnam would be achieved by the widespread adoption of water-saving equipment. Following the recognition of the large environmental contribution potential of water saving, a water-saving project has been planned for implementation in Vietnam in the near future.
This study was conducted as part of the Joint Crediting Mechanism (JCM) of the Japanese Ministry of Economy, Trade and Industry, and the Ministry of the Environment project's preparation in Vietnam. Samples were taken from hot and cold water supplies from guest rooms' faucets in 12 hotels in Hanoi city, Vietnam, and 13 hotels in Japan for comparison. A simple water quality measurement and determination of Legionella was carried out. The results showed that residual effective chlorine-which guarantees bactericidal properties-was not detected in tap water supplied in hotel rooms in Vietnam, and nitrite (an indicator of water pollution) was detected in 40% of buildings. In the hotels in Japan, the prescribed residual chlorine concentration met the prescribed levels, and nitrite was not detected. Additionally, while there was no Legionella detected in the Japanese cases, it was detected in most of the Vietnamese hotels, which were found to manage the hot water storage tank at low temperatures of 40-50 • C. It was found that there were deficiencies in cold and hot water supply quality, and that there was no effective system in place for building operation maintenance and management.
From the viewpoint of combating global warming in Japan, measures to reduce emissions from the activities involved in daily life have been accelerated in concurrence with the efforts made in the industrial sector to save energy. As one such measure, the reduction of energy consumption in waterworks and sewer systems by reducing the volume of water used in the housing sector is gaining attention; measures for the conversion of water saving into CO 2 reduction credit in the domestic credit system are also being examined. To address the credit development for CO 2 reduction by water saving, it was necessary to determine the CO 2 emission factor for water. Hence, we calculated the CO 2 emission factor of water use in Japan and determined the value to be 0.376 kg CO 2 /m 3 which applied the generating end electricity value. In addition, since electricity contributes to 90% of the energy consumption of the waterworks and sewer systems of Japan and since the emission factor for electricity changes with the power source composition ratio, the CO 2 emission factor for water also needs to be updated to match the emission factor for electricity. We therefore developed a calculation equation for updating this emission factor.
Abstract:The purpose of this study was to construct a scheme that makes it possible to compare the relationship between water usage, satisfaction, and physical properties in three countries. The physical properties of the shower were measured using physical properties testing apparatus of water-saving standard or scheme for showerheads issued in several water-saving countries and data for users satisfaction evaluation was acquired through bathing experiments. In this paper, we analyzed the result from Taiwanese and Vietnamese individuals to compare them to of Japanese subjects analyzed in the previous study. We compared the physical properties of showers assessed low in satisfaction by Taiwanese, Vietnamese and Japanese subjects. It was assumed that spray pattern tends to decrease satisfaction when the water volume ratio within 100 mm and 150 mm of a measuring device is located a 450 mm distance from the showerhead is low, and that, because all three countries showed the same value, it was imagined that there were no differences in the water volume ratio of high-satisfaction showerheads among three countries. On the other hand, the values of Spray Force-per-Hole, Temperature Drop, and Spray Angle were different among three countries. We speculated that these differences are affected respectively by ethnic differences in pain tolerance, thermoregulatory response and bathing habit.
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