Assessing the Benefits from Retrofitting Green Roofs in Mediterranean, Using Environmental Modelling, GIS and Very High Spatial Resolution Remote Sensing Data: The Example of Thessaloniki, Greece

In the Mediterranean area, rural abandonment and the rapid urbanisation after the 1950's led to complex environmental problems, such as the exploitation of natural resources, the environmental pollution, whilst the unstrained urban growth caused excessive pressure on the existing infrastructure, which affects buildings, public transportation, water quality and public health.Various studies demonstrate that the implementation of green roof technology can moderate environmental problems, through the reduction of heat flux and solar reflectivity, the minimisation of buildings' energy consumption, the air pollution removal, the storm water runoff reduction, the air cooling and the effective management of the urban heat island effect.In this framework, the aim of this study is to assess the green roof potential and the quantification of its benefits over Thessaloniki, Greece's second largest city. In order to do so, very high spatial resolution satellite image and natural colour orthoimagery were used along with a geographical object-based image analysis approach. Carbon sequestration potential, rainwater retention and energy conservation were estimated based on coefficients adopted after a comprehensive literature review and actual dynamic energy simulations.