An eco-friendly house is one that saves energy and water while offering high comfort and no pollution. It takes advantage of various natural energies, such as solar energy, wind power, geothermal and marsh gases, as well as new technologies and designs. For instance, awnings with solar batteries can transform solar energy to electricity, which can provide lighting for basements and rooms facing north. Natural air-conditioning technology can warm or cool the house by adjusting surface and underground temperatures. Rain-collection and wastewater disposal technology can provide water for fire protection, gardening and washing cars, thus saving much water. To assure a safe environment, a house should use environment friendly building materials and household electric appliances, and owners should divide and recycle garbage or burn it to create heat or energy.

The demonstration base will be jointly developed by the Beijing Order Center for Research and Development of Urban Eco-friendly Housing and the Beijing Institute of Science and Technology. According to Yan Peijin, president of the Order Group, the site covering 120 mu (20 acres) will be comprised of public service and housing demonstration areas. The public service area will include a 2,000-square-meter (2,390-square-yard) multi-purpose exhibition hall and a 400-square-meter (478-square-yard) eco-friendly classroom. The demonstration area will introduce 50 eco-friendly houses each covering 1,000 square meters (1,196 square yards) and featuring different countries, regions, climates and environmental protection technologies. The first 20 will be built through international cooperation and the remainder will use domestic bidders. The project will cost over 100 million yuan (US$12 million) and be finished within two years.

The base will become the first exhibition of eco-friendly residences; but the planning, technology and material used in the houses have no limits. Ecological buildings have sprung up over the past 20 years, and many countries have built various kinds of eco-friendly residences. The demonstration base hopes to collect the most distinctive ones for exhibition and research.

The Beijing Order Center for Research and Development of Urban Eco-friendly Housing has invited domestic experts on environmental protection to collect and research information on foreign eco-friendly residences, and they have brought forward main-technologies for the 50 houses to ensure that the houses save energy and water, are pollution-free and highly comfortable.

Professor Xia Qing with the China Academy of Environmental Science said an eco-friendly residence should be safe for the environment in its planning, its construction, its use and eventually its disposal of waste. Such houses involve much more than just having a nice lawn. And because they need the latest technologies and materials, with garbage and water disposing facilities -- ordinary real estate developers cannot afford them. Nevertheless, although eco-friendly residences may be ahead of their time, they may also serve as models for future home development.

Each eco-friendly residence is unique -- different from others -- and has a specialty.

American house

An American university built a four-bedroom eco-friendly house with rainwater recovery and water filtration systems that were also installed with a wind dynamotor, solar batteries and a sewage and night soil disposal pit, which provided fermented waste as fertilizer for an attached garden.

A building in Chicago was walled with plants instead of bricks and concrete. An American construction company built housing frames with recycled steel and the American State Resource Protection Commission built their headquarters with recycled materials including used newspaper, glass and wheat.

German house

The first eco-friendly office building in Berlin was installed with a 64-square meter solar battery in its facade. The building was also equipped with a water-storage facility on its roof to collect and store rainwater, which was used to irrigate grass on the roof. Water not used by the grass filtered down to a storage facility and was used to flush toilets. German architect Sader Terhols devised a house that tracks the sun, with a floor that revolves 3 cm (1.18 inches) per minute to follow the sun and absorb twice the solar energy as an ordinary floor. A new highway with small holes appeared in a resident zone in Hanoverian. The grass growing in the holes protect the highway from wear and absorb sunshine reflection, noise and the smell of gasoline.

Another house?s energy is fueled completely from the sun. The southern exposure of the house is set to absorb more solar energy, and its walls are built by heat insulation materials that hold more heat. The house is warmed by sun in the day and then the walls send out heat in the night.

Netherlands house

A number of houses in the Netherlands are covered with grass on the roof and equipped with solar batteries in the walls and detectors inside to monitor temperature, dust, chemicals and radiation. Toilets are flushed with rainwater.

Japanese house

The ?healthy residence? built in Japan in 1997 tried to use materials harmless to people. Its every room has a ventilation cave and the air is circulated by a heat exchanger and dehumidifier. The heat exchanger can reclaim heat effectively and its filter can collect dust in the air to prevent mildew and growth of other bacteria. In a new eco-friendly residence in Kyushu, electricity is provided by a windmill, water is heated by solar energy, garbage is transformed to plant fertilizer by a disposal machine installed in balcony and the walls have ventilation machinery to ensure fresh air in the house. The parking lot is built with concrete that is easy for rainwater to soak through. The rainwater is stored underground makes a recycling system for watering the trees there.

(Sun Haidong for 北京晚报[Beijing Evening News], translated by Feng Yikun for china.org.cn April 18, 2002)