What is the urban heat island effect (UHI)?
It describes how temperatures in urban areas are higher than in surrounding rural areas. This difference is particularly significant at night and can result in temperatures that are 2–5°C higher in urban areas.
What causes urban heat islands?
The UHI phenomenon is primarily the result of human activities and the characteristics of the built environment. Dark, heat-retaining surfaces, such as asphalt and concrete, absorb solar radiation during the day and radiate the accumulated heat at night, which keeps temperatures consistently high.
The reduction of green spaces also exacerbates the problem because natural evaporation has a significant cooling effect.
Traffic, air conditioning, and industrial activities generate continuous heat, further heating the environment.
Furthermore, dense urban structures—tall buildings and narrow streets—hinder the natural flow of air.
What problems does this cause?
This phenomenon is unpleasant and causes serious problems. Higher temperatures increase heat stress, especially among the elderly and people with chronic illnesses. They also increase the number of heat wave-related deaths.
Warming significantly increases energy consumption, mainly due to cooling needs. This, in turn, increases the environmental burden.