Cities are 5 to 9 degrees Celsius (9 to 16 degrees Fahrenheit) warmer than rural areas because of several reasons. Not only do built environments emit heati and urban surfaces absorb more sunlight and heat than natural landscapes, but urban areas also lack vegetation to cool through evaporation. This phenomenon, termed “urban heat island effect,” triggers an increase in building energy use and air pollution, reduces the quality of urban life, and increases urban health issues and mortality rates, especially when paired with heat waves and uncommon periods of heat.
Surface cooling can deliver significant benefits to cities in addressing both urban heat island effect and heat waves. Surface cooling solutions are often simple, cost-effective, and available throughout the world. Roofs and pavements cover about 60% of urban surfaces (with roofing typically accounting for between 20–25% of urban surface, and paving about 40%), and absorb more than 80% of the sunlight that contacts them and is then converted to heat.
Apart from introducing surface cooling for roofs and pavements, depending on the city, a substantial portion of the remaining surface area can also be utilized, as it presents an opportunity for parkland or other green landscaping. The C40 Cool Cities Network, launched in 2012 in partnership with the Global Cool Cities Allianceiii , was established to increase C40 cities’ understanding of the urban heat island effect and to support the launch and implementation of successful cool surface programs. The purpose of this Good Practice Guide is to summarise the key elements of cool cities good practices for global dissemination, highlighting the success of C40 cities in planning and delivering cool surface solutions.