چكيده به لاتين
Heat islands are one of the most important issues in urban and architectural studies. This phenomenon has been intensified in recent years by climate change and increased heat waves. In adition, the extensive urbanization and, consequently, the increase in the size of cities, is another important reason for this effect. According to land use information, residential usage is the highest rate in Tehran, therefore the aim of this research is to mitigate the heat islands in residential areas of the city.
In order to accurately explain the scope of the research, as the first stage, the study of existing litrature has been addressed and according to the litrature effects, adaptive strategies and urban heat island mitiagation strategies are analyzed. In the next stage, considering the phenomenon of heat islands, the climatic, urban and architectural features of the study area has been investigated. Regarding the previous studies, simulation is one of the common methods for studying the urban heat island effect. In the present study, the simulation of current situation and proposed scenarios has been done by ENVI-met software. After the final design was presented, the success rate of the design has been evaluated through another simulation.
Based on the results, increasing the vegetation coverage on the street level is the best strategy to provide the outdoor thermal comfort during the day. While the green roof has small effect on the urban heat island phenomenon. Increasing the albedo levels of materials also has positive effects on the heat islands, although the increase in the pavement albedo has more obvious effect than the increase in roof albedo. The change in the orientation of buildings from southwest to southeast greatly reduces the air temperature. However, with increased mean radiant temperature and decreased wind speed, thermal comfort does not improve except in the afternoon hours. Generally in order to mitigate the heat islands in this region of Tehran, the increase in vegetation and the increase in the albedo level of pavements are the best and most reliable strategies that can be applied in similar residential areas. Other strategies require further investigation of relevant parameters. It is recommended that the air temperature, the amount of radiations and the air flow should be analyzed and examined integratively in order to obtain a profound knowledge of heat islands.
Keywords: Urban heat island; Urban vegetation; Albedo; Orientation of buildings; Outdoor thermal comfort.
