Thermal comfort in urban spaces: impact of vegetation growth: Case study: Piazza della Scienza, Milan, Italy

This paper reports on a study on the evolutionary impact of vegetation in a newly built square in Milan designed by V. Gregotti. The aim of the work is to evaluate the impact of vegetation growth on users’ comfort. The methodology adopted involves: sets of field measures (air and radiant temperature, wind velocity and relative humidity); a simplified thermal comfort evaluation with the energy budget method COMFA; and a scenario for the vegetation growth. When trees become adult we can observe different phenomena. The shading effect under an aged tree canopy clearly shows a reduction of the absorbed radiation by users, generating an energy budget very close to comfort (under 50 W/m2) even with a high air temperature. In the case of points exposed to direct sunlight all day long, tree growth reveals two phenomena of the global radiation absorbed by a user: (1) reduction, by the tree screening effect, of absorption of the diffuse solar global radiation, and (2) increase, by the elevation of the objects viewed in the sky hemisphere, in absorption of the terrestrial radiation.