A review of the impact of the green landscape interventions on the urban microclimate of tropical areas

The population explosion continually witnessed in urban areas results in more impenetrable surfaces like built structures and roads. Rapid urbanization increases air temperature and creates an urban heat island (UHI) effect due to dwindling greenery. Thus, the UHI directly impacts the indoor and outdoor thermal comfort, air quality, and well-being of the city dwellers by affecting the microclimate. Further, the artificial cooling demand is increasing steeply in tropical cities, increasing carbon emissions. Therefore, researchers are currently focusing upon mitigation of the UHI effect and improving the urban microclimate. This review article deals with urban microclimate control using trees, grasses, shrubs, green walls, green roofs, and waterbodies. The contributory role of vegetation in regulating air temperature is reviewed comprehensively, and recommendations are made for ensuring the thermal comfort of urban residents. The effective use of vegetation in tropical cities can significantly improve the microclimate by reducing the air temperature up to 4 degrees C by green roofs, 9 degrees C by using trees, 12 degrees C by the vertical greening system. The rooftop greeneries with trees, shrubs, and turfs can reduce the building's overall cooling load by 20.01 %, 18.85 %, and 9.08 %, respectively. Implementing urban greeneries is essential to become sustainable cities and communities through a perfect blending of green landscape elements. Further, the present work will be helpful to urban planners and architects working on incorporating such green landscape interventions to provide better thermal comfort, mitigation of carbon emissions, and consequently improve the quality of life for tropical urban city dwellers.