Land development in an urban megalopolis: A holistic environmental assessment of housing on Chongming Eco-island, China

Over the last decade, the Chinese government has promoted Chongming Eco-Island as an example of sustainable urbanization and a means to mitigate the growth of residential districts within the Shanghai megalopolis. With the immense urbanization pressure of a growing city, we ask "what is an appropriate type and scale of housing for land development on Chongming?" This study uses the method of emergy (with an "m") synthesis to prepare a holistic assessment of the housing on Chongming, accounting for all renewable, non-renewable and imported resources used as well as greenhouse gas (GHG) emissions during building's life cycle stages. To overcome the lack of unit emergy values (UEVs) of building materials used on Chongming, this study first developed a method to derive accurate UEVs of local materials from a regional life cycle inventory (LCI) database. With Chongming Eco-Island as a case study, four typical residential housing types (farmhouse, single-family house, slab housing, high-rise apartment) were classified according to site density, the structure and floor area ratio (FAR) of buildings. Results indicate that slab housing with FAR as 3.1 contributes most to the total emergy and GHG emissions per building area, while it proves to have the highest environmental performance when taking into account the residential density. In this respect, high-rise apartments are not the optimum options for the overall sustainability of Chongming Eco-Island.