Researchers at the Massachusetts Institute of Technology have found that the pattern of streets in a city can have a big effect on the strength of the local heat island effect which causes cities to be hotter than their surroundings.
Some cities, such as New York and Chicago, are laid out on a precise grid, like the atoms in a crystal, while others such as Boston or London are arranged more chaotically, like the disordered atoms in a liquid or glass. The researchers found that the “crystalline” cities had a far greater buildup of heat compared to their surroundings than did the “glass-like” ones.
The team adapted mathematical models developed for analyzing atomic structures to analyse satellite images of 47 cities. For each city, they collected temperature data from one station within the city and another outside it but nearby, and then determined the difference.
The analysis revealed significant differences in the heating effect depending of the layout of the city. The differences seem to result from the way buildings re-radiate heat that can then be reabsorbed by other buildings that face them directly.
For places such as China where new cities are rapidly being built, and other regions where existing cities are expanding rapidly, the finding could be used to improve urban design. In hot locations, cities could be designed to minimize the extra heating, but in colder places cities could be designed to maximise it.
Doing this could produce significant savings. For example, in the state of Florida urban heat island effects cause an estimated $400 million in excess costs for air conditioning.