Simulating micro-scale thermal interactions in different building environments for mitigating urban heat islands

Area of Science:

• Environmental Science
• Urban Planning
• Climate Change Adaptation

Background:

• Tropical cities are highly vulnerable to global warming due to their location and rapid growth.
• Existing urban heat island (UHI) mitigation strategies developed for temperate climates may not be effective in tropical regions.
• Understanding localized surface energy balance is crucial for effective UHI mitigation in the tropics.

Purpose of the Study:

• To evaluate the effectiveness of four UHI mitigation strategies in the Kolkata Metropolitan Area (KMA), India.
• To assess the performance of cool pavement, cool roof, urban vegetation, and a combined cool city approach.
• To provide insights for climate-resilient adaptation in tropical urban environments.

Main Methods:

• Utilized ENVI-met V 4.0 software to simulate urban environments.
• Selected study sites representing diverse urban morphologies: open low-rise, compact low-rise, and mid-rise residential areas.
• Simulated the impact of four distinct UHI mitigation strategies on temperature reduction.

Main Results:

• The 'green city' model (added urban vegetation) showed the best performance in reducing neighborhood air temperature (T_a).
• The 'cool city' model (combined strategies) was most effective in reducing physiologically equivalent temperature (PET).
• Urban vegetation played a more significant role than cool roofs or pavements in regulating surface energy balance.

Conclusions:

• Urban vegetation is the most critical factor for UHI mitigation in tropical cities like KMA.
• Tropical cities exhibit lower sensitivity to UHI mitigation strategies compared to temperate cities.
• The findings offer valuable data for developing effective, climate-resilient urban planning in tropical regions.