Toward Sustainable World Development: An International Effort to Increase Building Efficiency in China

An international research program is underway at MIT -- a collaboration with six other schools in China, Switzerland and Japan -- to identify new technologies, and applications of current technologies, that will increase the environmental efficiency of Chinese building.

The impetus for the research lies in the fact that buildings not only produce substantial amounts of pollutants, they also use enormous amounts of resources and energy. In the USA, for example, buildings now account for fully a third of the country's energy use and it is projected that by 2094, housing will also account for a third of total energy use in China -- meaning that for every nine units of energy consumed in the world, one will be used for Chinese housing. Increasing the efficiency of the Chinese built environment, then, is an important step toward achieving sustainable world development.

Begun in 1998, the MIT program focuses on the design and evaluation of sustainable residential buildings -- individual buildings, as well as building groupings -- in cities such as Beijing, Shanghai and Shenzhen. Among the most promising approaches are technologies that focus on natural ventilation as an alternative to mechanical cooling, and on selected other strategies for passive heating and cooling. Indeed, initial simulations suggest that natural ventilation, combined with nighttime cooling and thermal storage in the walls, would eliminate most of the need for air conditioning in Beijing on an average summer day. Buffer zones such as winter gardens -- glass-enclosed terraces -- are also effective at reducing heating loads in winter by collecting solar energy.

Among the projects being studied are four buildings near the site of the Asian Games in Beijing which are being designed to promote natural ventilation through apartments due to pressure differences between north and south elevations, and to include a skip-stop elevator which stops only every three floors -- not only conserving energy but also encouraging social interaction among the three-story groups.

Another project, in Shenzhen, includes several strategies for different areas of the site:
(1) Buildings at the northern edge are designed with reduced surface area and augmented wall
construction to minimize noise from a nearby railway; (2) Units to the east are oriented to allow winds from the east to penetrate the site; (3) Buildings along the west are oriented to produce pressure differences, thus inducing air travel through the units; and (4) Shading devices and overhangs are integrated into designs to minimize heat gain in summer.

In all these cases, computer simulations are being developed to maximize efficiencies. Computations of the velocity field around a building can provide detailed information about the interaction of the wind with the building geometry, taking into consideration roof slopes and edges, the shape of the building, the placement of windows, smoke stacks and vents, and the clustering or joining of residential units. Using these predictions, exhaust openings in the roof can be properly placed and shaped for passive Venturi suction, and consequences for open windows on hot south-facing walls can be clarified. A model is also being used to evaluate the effects of natural ventilation on the thermal storage capacity of buildings.

In addition to designing, building and evaluating a number of buildings, the program also features a series of seminars and workshops conducted by MIT to educate developers and architects in China on the technologies and design approaches utilized during this project.

Along with MIT, program participants include representatives from the ETH (Zurich) Department of Architecture (Air and Climate Group); from the ETH (Lausanne) Institute for Solar Energy Research and from the University of Tokyo Institute of Industrial Science. Also participating are the Tsinghua University Department of Thermal Engineering and School of Architecture, the Tsinghua Design Institute, and the Tongji University Construction Engineering Department and Architectural Design and Research Institute. The project is being funded by the Kann-Rasmussen Foundation and the Alliance for Global Sustainbility.