Smart City and energy efficiency

 Since the world warⅡ，growing number of urban population and increasing frequency of economic activities has led to a high energy consumption urban life, which finally results in a significant amount of environment problems, such climate change, urban ecological decline. As an answer to those problems, urban designers implement some technological methods to mitigate the effect caused by environmental problems and redevelop the cities in a sustainable way.

 Smart city usually achieve the goal of efficient energy consumption in two ways: green transportation and energy-efficient building. Smart city improves the road condition and creates more road for green transportation to invite citizens to travel by feet or bicycling. Electrical cars are suggested to solve the energy problems on road. In China, government established many financial movement to encourage people to drive electrical cars on road，for example, people who buy a new electrical car could get a about 50% discount supported by local government. More power banks will be built on streets in order to meet the charging needs of electrical cars.

As for the energy-efficient buildings, the main purpose of sustainable buildings are to reduce the energy consumption and try to collect and reuse the waste heat in the buildings. Taking central park in Sydney as an example, green walls prevent the broadcast of waste and provide shadows during sunny days in summer. On the other hand, hot water is kept warm by the heat produced by the operating of machines like lift.

With limited resources and growing population around world, it is necessary to popularise the sustainable smart city. Without enough attention on the energy efficient society, our environment could be no longer be suitable for the next generation in the future.