Heat islands, or dense urban areas that can aggravate high temperatures during heatwaves, will become a major problem in cities by 2050, according to a study by EPFL master’s students Clara Gualtieri and YueWanZhao Yuan from the School of Architecture, Civil and Environmental Engineering (ENAC). Gualtieri and Yuan analyzed surface temperatures in two Geneva “heat island” neighbourhoods – Les Vernets and Pointe-Nord, explains a statement from the university. They collected a huge amount of information on local topography and the surface of all built structures, including rooftops, building façades and roads, as well as the structures’ thermal properties.
Using these data sets the researchers simulated 3D computer models for the two neighbourhoods. These models described the current temperature profile with and without any changes being made, so best- and worst-case scenarios. Based on the different scenarios, their models predicted that this temperature could rise by an average of 10 degrees Celsius, and in some cases by 15 degrees Celsius in July and August.
However, the simulations also showed that mitigation strategies such as planting trees and other vegetation to create more green spaces can lower the ground-surface temperature by around five degrees Celsius in both neighbourhoods. Gualtieri and Yuan also note two further measures: the albedo effect – which is the capacity for lighter colours to reflect heat – and resurfacing rivers or other bodies of water to significantly cool the ambient air.
“Gualtieri and Yuan’s research shows that heat islands will become a major problem by 2050 if we don’t start cutting back on fossil-fuel emissions,” commented Kavan Javanroodi, a postdoc at EPFL’s Solar Energy and Building Physics Laboratory, who supervised the master project.
