Green and cool roofs’ urban heat island mitigation potential in European climates for office buildings under free floating conditionsGreen and cool roofs’ urban heat island mitigation potential in European climates for office buildings under free floating conditions Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2015-11-052013enHeat island which is the most documented phenomenon of climatic change is related to the increase of urban temperatures compared to the suburban. Among the various urban heat island mitigation techniques, green and cool roofs are the most promising since they simultaneously contribute to buildings’ energy efficiency. The aim of the present paper is to study the mitigation potential of green and cool roofs by performing a comparative analysis under diverse boundary conditions defining their climatic, optical, thermal and hydrological conditions. The impact of cool roof’s thermal mass, insulation level and solar reflectance as well as the effect of green roofs’ irrigation rate and vegetation are examined. The parametric study is based on detailed simulation techniques coupled with a comparative presentation of the released integrated sensible heat for both technologies versus a conventional roof under various climatic conditions.Δημοσίευση σε επιστημονικό περιοδικόhttp://creativecommons.org/licenses/by/4.0/Solar Energy95118–130 Kolokotsa Dionysia Κολοκοτσα Διονυσια Santamouris Mat Zerefos Stelios C. Elsevier Green roofs Cool roofs Urban heat island