Sustainability concern of housing: emergy storage and flow assessment

A city is an organized open structure made of assembled materials and buildings that constantly interface with changeable contextual agents such as clime, weather, solar irradiation and human beings. Urban systems feed on energy inflows in order to achieve an organization (e.g. society, economy, architecture) that is maintained in time. The interaction of different inputs from the environment generates the building as a built storage in which energy and materials have been stocked. Energy and materials inflows are required to maintain and to use the building in time (for instance, electricity, water and gas are needed for building use). These interaction processes between buildings and the external environment are the focus of this study. Is it possible to measure these processes to evaluate sustainability of urban systems? How can the impact due to resource exploitation of housing on local sustainability be measured? Can we evaluate the environmental effects of urban strategies and structural plans? An environmental accounting method, namely emergy analysis (spelled with an 'm'), was applied to an urban area considering the main activities of an entire human settlement and a detailed analysis was focussed on housing: the general environmental performances of buildings in terms of resource exploitation were evaluated considering their construction, maintenance and use. As a case study, an emergy analysis of the municipality of Ravenna (north-eastern Italy) is presented with a special focus on housing and on the trend of growth of the building industry. Keywords