Rapid urbanization and aspirational change is causing unplanned land use and land cover changes. Unplanned and unforeseen development are resulting in micro-climate changes which are evident in urban areas. The relative change (mostly increase) in urban temperature profile compared to its rural counterpart is termed as urban heat island effect (UHI). Such changes give rise to challenges associated with service deficiency, un-engineered built environment, public health, and other issues. This report aims to aid urban managers, engineers, architects and designers who may consider using cool roofs and passive ventilation options within urban built environment. The report provides information on traditional methods, new technology, native practices and cost effective solutions for increasing the thermal comfort of high, middle and low income settlements. In India, according to the Indian Meteorological Department nine out of the last twelve years were amongst the twelve hottest years since 1901. Such temperature rise has led to an increase in need for space cooling. Further, increase in affordability and aspirations among urban residents has led to increased usage of air-conditioners especially among middle and high income households. This trend has led to increase in energy load during summers leading to power surge. On the other hand, urban poor live in congested areas and unenginneered buildings. The building elements of these houses comprise of tin sheets or asbestos cement sheets for roofs with limited ventilation or cooling facility. Such roofs increases the ambient room temperatures to uninhabitable conditions resulting in health impacts amongst its residents. This trend is likely to worsen over the coming years due to climate variability and climate change. The use of inefficient technologies by urban poor and middle class is currently contributing to consumption/wastage of large amounts of water and energy. In India, one of the common coping mechanisms widely noticed among urban middle and lower class households (living in one or two storied buildings) is their preference to sleep on at concrete roofs during summers in order to overcome the indoor heat build-up during evenings. Also, traditional and cost effective methods of roof cooling and passive ventilation include using white oor tiles on roof and painting roof with lime wash every year thereby increasing the solar reflectance and decrease the heat gain. Another common option is using desert coolers during low humidity periods. But with widespread use of electricity for cooling, these traditional methods have been neglected. Surat and Indore lie in the transitional zone between humid south and arid north, and face extremely high temperatures during summers. Surat being a coastal city is also subjected to periods of high humidity. Increase in temperature combined with humidity has an impact on work productivity during day and decreased comfort level during evenings. This report aims to highlight urban heat islands, their impacts and possible mitigation strategies by considering case of Surat and Indore.

Type of publication
Technology Compendium
CTCN Keyword Matches
Air quality management
Greening the built environment
Heating - Ventilation and Air Conditioning
Integration of green spaces in planning
Non-ferrous metals
Small-scale Combined Heat and Power
Solar thermal
Traditional building materials and design