To reduce the Urban Heat Island (UHI) effect Green Infrastructure (GI) is seen as a key measure. Though, often the need for water to evaporate is neglected. This study focuses on showing the effects of irrigation and increased soil moisture contents on GI within urban areas to reduce the UHI-effect. ENVI-met, a micro-climate model, is used to model various scenarios for a tropical day and a heatwave in the Netherlands. For two Dutch urban areas, with different building typology and subsoil, the current situation, a greener scenario and various soil moisture profiles have been modelled to show the effects of increased soil moisture content on thermal comfort and the UHI-effect.