Steven Holl's Linked Hybrid project in Beijing is quite a good example of a sustainable design. The project consists of several buildings linked together to create a city within a city. Some of its sustanability features include green roof gardens, geo thermal wells to heat and cool the building and a recycled grey water pond.
Below is a presentation in two parts showing the architecture of the design and its green features.
Further info visit architecture.mnp blogspot which shows a great deal of green architecture features of the project.