At the 2007 Annual Conference of China Association for Science and Technology (CAST), green architecture and urban energy saving also became one of the key issues that were discussed. Mr. Zhao Dingguo from the Research Institute of Ecological Environment Protection of the Shanghai Academy of Agricultural Sciences displayed a group of photos: cities filled with clusters of concrete buildings standing next to each other dull and solid, very much like a desolate and boundless desert. Especially the photos featuring bird's eye views of cities, only rooftops in grayish black can be seen, giving people a lifeless and lackluster feeling.
The desertification of urban rooftops is being given increasing attention by the people. When entering the inner areas of cities, the scenes are equally astonishing. Mr. Huang Zhenli, Chairman of the Board of Directors of the Beijing-based Zhenli High Tech Co. Ltd., observed that many buildings had adopted unreasonable technologies, resulting in a great many high energy consumption "junk architectures", hence the waste of energy and environmental pollution as well as other problems.
Prof. Tang Mingfang with the Urban Construction Planning College of Chongqing Universty attached special importance to the ecological adjustment effect of rooftop greenery on the temperature of the roofs of buildings. Given the humid and hot climatic characteristics of South China, as well as the ever increasing energy demand of architectural air-conditioning, she proposed to apply the technology of light type of rooftop greenery in cities and towns in South China.
As pointed out by Prof. Tang, traditional rooftop greenery has the disadvantages of being heavy in load and involving tremendous manpower management and enormous use of water in its maintenance, making it difficult to be widely used like building materials. The technology of light type of rooftop greenery, however, has broken through the many constraints of traditional rooftop greenery, and it has such climate utilization functions as absorbing rains and eliminating or reducing solar radiation heat in sunny days, which building materials do not have. Viewing from the entire year of climate utilization, the weather in spring moistens the plants to grow and flourish, whereas in the summer season these plants can protect the rooftop of a building against sunlight, making it factually a kind of systematic engineering of rooftop energy saving. The abundant precipitation per annum in the humid and hot regions of South China provides favorable conditions for rooftop greenery of buildings to make use of climate resources for energy saving purpose.