چكيده به لاتين
The world's urban population has been quadrupled since 1950, with more than half of the world's population living in cities for the first time, and this urbanization trend is growing. This trend has had many positive and negative effects around the world. Cities and urban elements are always affected by climate factors in addition to their performance. This influence was almost one-sided before the emergence of megacities, but since then, cities have also affected the climatic conditions of their surroundings and created micro-climatic changes. In such a way that today a special climatic territory called micro-urban climate has emerged. Micro-warming of urban climates will cause climate changes and increase the regional and global average temperature. With the increase of micro heat in urban climates, changes in urban climates and as a result the phenomenon of urban heat island occurs, which is one of the significant concerns of the continuous increase in urban heat, which is like an umbrella from the air and is often over the city or built-up areas. and the temperature inside it, is hotter than the air around it. The urban heat island phenomenon has led to a change in the thermal pattern of urban areas compared to the open and natural areas around them, and serious problems in various aspects of urban life, such as the endangerment of human health, the increase of toxic suspended particles in urban environments, and changes in the amount of precipitation and pattern of the temperature of the cities. Therefore, in the current period, it is necessary to pay attention to eliminating or reducing the intensity of the effect of the urban heat island phenomenon. The all-round and rapid expansion of Tehran city in the past decades has led to changes in the urban landscape, buildings and roads and replacement of open space with vegetation. Surfaces that were once permeable and moist have gradually become impermeable and dry. The continuation of this process will make the urban areas and surrounding areas warmer and warmer. The intensity of the temperature of the heat islands in the city affects not only the environment, but also the quality of life and the mental and physical needs of the citizens in urban life, and it also has significant negative effects on the amount of cooling energy consumption, the emission of pollutants and greenhouse gases.
The dense urban fabric in many areas, traffic and the frequency of passing cars, irregular buildings and the high level of air pollution have made the metropolis of Tehran a residential heat island that has created its own microclimate. The destruction of plants and their replacement with materials (asphalt, concrete, dark construction materials) in a wide part of the city fabric causes the absorption of heat through the dark construction materials during the day, which remains until hours after sunset. The increase in energy consumption for cooling lowers the quality of urban air and causes discomfort to city dwellers, and by affecting people's health, it increases the possibility of asthma and other types of respiratory diseases. The current research tries to first understand the basic concepts in the field of the urban heat island phenomenon, the factors that create it and the consequences of the impact of the urban heat island on the city environment, and then to provide mitigation strategies related to urban design and planning. In this regard, after recognizing the physical and environmental factors that can be changed and controlled in urban design and planning, by choosing the neighborhood of Sar Asiyab Mehrabad in the 9th district of Tehran as a study sample, the reduction strategies and different design scenarios are investigated in the context of the subject.
In order to implement the design scenarios in the micro-scale of the urban climate, the three-dimensional ENVI-met model, which is a widely used in the field of architecture, landscape architecture, urban design and urban planning, has been used. At the end, after presenting a sample design of the studied area, general design solutions in micro and macro scale will be developed in order to reduce and control the phenomenon of urban heat island.
