Greening Actions and the Related Potential Impacts on Outdoor Comfort in a Dense Built Environment

The increasing attention paid to the effects of climate change on the dense urban fabric of contemporary cities had led Public Authorities to develop local adaptation plans in order to suggest some effective measures to mitigate and reduce the impacts of urban heat island [UHI] and heat waves as well as to improve water management capacity. Among the suggested actions, the greening of in-between spaces of the built environment and the introduction of new green surfaces (roof and/or facades) in the framework of wider regeneration plans offers interesting perspectives and impacts. The paper reports the outcomes of a research activity run by the Department of Architecture and the Municipality of Bologna to investigate how to define/optimize the most effective arrangement of greening solutions with the aim to improve outdoor comfort conditions. The study takes into account several aspects including paved/green surfaces extension, the use of material, the geometry of the site, etc. and simulate the potential effects of changes using simulation software ENVIMET. Once the main features of each site are modelled the different deriving scenarios can be compared evaluating the different architectural, economical and practical constraints. The results are then compared with other factors, related to the social aspects, the use of the spaces, the perception of the sites, etc. A district of the city of Bologna is used as test bed in order to test the proposed methodology and the related potential impacts.