With the rapid growth of the Chinese economy, increased efficiency of energy use in China is an important element of a strategy to achieve sustainable world development. It is projected that future buildings in China will consume about one-third of the total energy. The aim of this project is to identify new technologies and applications of existing technologies that will significantly increase the efficiency of new and renovated Chinese buildings. In addition, the strategies for energy efficiency must be appealing to Chinese builders and consumers, and they must be made aware of the advantages in using the strategies. Our focus is on residential buildings in large Chinese cities beginning with Beijing, Shanghai and Shenzhen.

The development of the Chinese economy encourages the demand for higher living standard in China. At present air-conditioning is a key symbol of improvement of living standards. In 1997 about 3.5 million air-conditioning units were sold. The air-conditioning industry has increased 13 times since 1985. The infrastructure investment in air-conditioning exceeds 25 billion Yuan ($3 billion U.S.). Energy consumption by air conditioners in the summer has become a main cause of severe electrical power shortage. The electricity consumed by air conditioners in the basin of the Yangtze River is more than 1/3 of the total power supply during peak summer demand. If the trend continues and all 1.2 billion Chinese live in a style similar to Americans, the world's fossil energy will be more rapidly exhausted.

The trend of massive energy use in China has raised global concerns. Fossil energy consumed by power plants and by building heating plants results in an increase in CO₂ and SO₂ emissions. Green house gases such as CO₂ lead to global warming. The SO₂ emissions in China bring acid rains to the entire fast-east region. In addition, the Chlorofluorocarbons (CFC) from the air-conditioning systems can cause further damage to the ozone layer. Therefore, conservation of energy, protection of environment, and improvement of indoor air quality and thermal comfort are challenges we are facing.

Many old Chinese buildings can provide reasonable comfort and indoor air quality without using air-conditioning systems. A few years ago, in the countryside in China, the main objective of Chinese home buildings was to protect occupants from severe climatic conditions. The designs were simple and in harmony with nature. Natural ventilation and/or thermal mass provided passive cooling and additional heating could be made available when required. The buildings often were built by the owner and occupant of the building. This allowed a continuous improvement of these designs, based on a close feedback between the occupants and builders.

Due to the development in the Chinese economy, new building technologies allow builders to construct more comfortable buildings. For example, the artificial control of the indoor environment using air-conditioning makes it possible to build a building without paying attention to the outdoor climate conditions. As a result, most recent buildings are built without traditional technologies but with mechanical systems. Although modern life will not accept the comfort levels of the past, it is still possible to apply these excellent traditional technologies to modern designs. Shading devices, natural ventilation, passive and evaporative cooling, steep roofs, passive heating, thermal walls, etc. are useful to improve thermal comfort, reduce the energy demand and significantly protect the environment.

On the other hand, the use of air-conditioning systems may not improve the welfare of the occupants as assumed. More and more occupants are not satisfied with their living environment. The Chinese have realized the problem of sick building syndrome due to poor indoor air quality and thermal environment. The main problems in those new buildings associated with indoor air quality are:

• Many buildings do not have sufficient fresh air supply.
• New building materials used in China emit too many volatile organic compounds.
• Air conditioning systems generate various biological contaminants.

The thermal environment provided by air-conditioning systems is normally of a constant temperature. Under a constant temperature environment, the human body resistance to diseases has been weakened sharply. The overall healthy level of the occupants in air-conditioned environment is poorer. In addition, the occupants can easily get heat shock when they enter the outdoor environment in summer from an air-conditioned room. In 1996, so many people had heat shock in Nanjing that the hospitals could not handle all the patients. In the 1970s, the temperature recorded was much higher than that in 1996 but not as many people had heat shock. Overwhelming use of air-conditioning systems is an obvious factor to blame.

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