Cooling the Cities

The temperature of cities continues to increase because of the undeniable climatic change and the heat island phenomenon. The observed high ambient temperatures intensify the energy problem of cities, deteriorate comfort conditions, put in danger the vulnerable population ­and amplify pollution problems. Higher urban temperatures increase the energy consumption for cooling and raise the peak electricity demand, intensify the pollution patterns in cities and increase the ozone concentration, deteriorate the outdoor thermal comfort conditions, increase ­the ecological footprint of the cities, intensify the health problems and increase the indoor heat stress on low income population.

To counterbalance this phenomenon, important mitigation technologies have been developed and proposed. Mitigation techniques aim to balance the thermal budget of cities by increasing thermal losses and reducing the corresponding gains. Among the more important of the proposed techniques are those aiming to increase the albedo of the urban environment, expand the green spaces in cities and use the natural heat sinks in order to dissipate excess heat. Recent real scale applications involving the use of the above mitigation techniques have resulted in very important climatic benefits and a significant reduction of the heat island strength.

During the lecture the scientific information available on the mitigation and adaptation potential of the existing major technological developments were reviewed in a critical light.