Local climate change and urban heat island refer to the development of higher urban temperatures of an urban area compared to the temperatures of surrounding suburban and rural areas. The phenomenon is related to positive thermal balance developed in the urban environment because of the increased heat gains like the high absorption of solar radiation and the anthropogenic heat, and the decreased thermal losses.
Incontestably, heat island is the most documented phenomenon of climate change and is very well documented in various geographic areas and mainly in Asia. In many cities the intensity of heat island may exceed several degrees while an important regional and temporal variability is observed. The phenomenon is observed in specific areas of the cities, presenting high density, and low environmental quality and results in a serious reduction of ambient thermal comfort levels and poor indoor thermal conditions.
Heat island has an important impact on the energy consumption of buildings and increases their energy demand for cooling purposes. In parallel, because of the higher urban temperatures, the emission and generation of urban pollutants and in particular of tropospheric ozone increases considerably, while the ecological footprint of the cities suffering from heat island is growing seriously.
Counterbalancing the effects of urban heat island is a major priority for the scientific community. Several techniques have been proposed, developed and applied with quite high success. Proposed mitigation techniques and technologies involve the use of the so called cool materials presenting a high reflectivity in the solar spectrum together with a high thermal emissivity value, able to amortize and dissipate solar and thermal energy, the development of smart materials presenting high optical and thermal performances, the use of green spaces in the urban environment involving appropriate landscaping and design of urban green modules, the use of appropriate heat sinks presenting low temperature to dissipate the excess ambient heat involving the use of the ground, ambient air and water, appropriate shading and solar control of urban surfaces, and the use of cool and green roofs in urban buildings.
The present lecture aims to analyse the actual developments in the field of urban heat island and local climatic change in Asiatic cities and also present the development and the characteristic of new advanced urban mitigation techniques designed to counterbalance the phenomenon.