Daily and seasonal climatic conditions of green urban open spaces in the Mediterranean climate and their impact on human comfort

This study examines the daily and seasonal climatic behavior of various urban parks with different vegetation cover and its impact on human thermal sensation in the summer and winter in Tel Aviv, Israel. The study draws a comparison between the climatic conditions developed in various types of urban green open spaces, exposed open urban squares and street canyons near such sites. The results showed that an urban park with a dense canopy of trees has maximum cooling effect during summer and winter in daytime. In summer it reduces temperatures by up to 3.8 degrees C and thermal comfort values by up to 18 degrees C PET (Physiological Equivalent Temperature), while in winter it reduces temperatures by up to 2 degrees C and thermal comfort by up to 10 degrees C PET. The climatic variable that mostly affects human thermal comfort conditions is the Mean Radiant Temperature (T-mrt) which is more dominant at exposed urban sites as compared to shady urban parks. These results emphasize the importance of treed open spaces as an effective tool for heat mitigation. The benefit of the cooling effect achieved by treed urban spaces is much stronger than the comparative disadvantage they create in winter. (C) 2011 Elsevier Ltd. All rights reserved.