b'MUDD 24 URBAN NETWORKS|URBAN GATEWAYSCooling the Cities Advances in Science and Design for the Mitigation of Urban HeatMessage from Academics and Scholars:Scientia Professor MattheosSantamourisCities are centres of significant size where thedirect way. Although cities occupy 0.5% of the population, living in an organised way, consumesearths surface, they consume about 75% of the and develops commercial and cultural activities.global resources. In most of cases, urban sprawl Cities are supposed to improve the quality of lifeand associated land use change result in serious of human beings. A city comes into being forclimatic and environmental degradation - air the sake of life, but exists for the sake of livingpollution, noise, poor water quality, temperature well, in the words of Aristotle. Expectations forincrease, thermal stress. Urban expansion and a better life created by urban economic growthsprawl lead to a reduction in green areas, the and industrialisation, local conflicts in ruralsealing of urban surfaces through intensive areas, mechanization of agriculture and lack ofpaving and building construction, and increase resources in rural areas are the main drivers ofof the anthropogenic heat released to the the massive migration of the rural populationatmosphere. into cities, and the unprecedented growth of the urban population. Although in the 1950s, onlyUrban climate is the result of urban, local and 30% of the worlds population lived in cities,regional geographical features. Changes in land in our day the proportion has passed the 50%cover at the regional and local scale affect the 7 mark and now stands at 54% with the numberurban heat balance, increased heat storage of city dwellers passing 3.9 billion. Futureby the urban structure, higher anthropogenic projections show that by 2050 the proportion willheat liberated, lowered evaporative cooling and Mattheos Santamouris be around 66%.increased sensible heat released by buildings and pavements. The effect is known as the Worldwide the population of cities increasesUrban Heat Island (UHI) and it is the most at a rate of almost 1.5 million people per weekdocumented phenomenon of climate change. due to migration from rural areas and childbirth.Its magnitude is a function of the urban layout, Increase in the urban population has resulted inits morphological, physical and structural serious territorial urban expansion, spatial growthcharacteristics, the synoptic weather conditions, or sprawl that affects consumption patterns in alocal meteorological factors and finally the MUDD 24 - Urban Gateways | Urban NetworksINTRO 8pt.indd 8 26/11/2019 4:11:23 PM'