The rising instances of heatwaves across India have made it vital to redesign and adapt the urban form of cities. As climate change continues to cause major cities to grapple with livability issues, smaller ones are witnessing rapid growth, necessitating a “heat-proof” development approach.
The urban form of a city refers to its unique configuration, including both natural and human-made infrastructure and the activities that take place as a result. The density of buildings, green spaces, water bodies, and the relationship between these elements play a substantial role in a city’s ability to withstand high temperatures.
Urban Form and Its Role in Creating Heat-Resilient Cities
Various parameters such as urban morphology, aspect ratio, sky view factor (SVF), blue/green infrastructure (B/GI), floor area ratio (FAR)/floor space index (FSI), and street orientation work collectively to determine a city’s urban form, ultimately influencing its susceptibility to heat.
A 2022 study conducted by the Centre for Science and Environment (CSE) examined how different urban forms react to heat across ten major Indian cities, revealing significant findings for drafting strategies to combat urban heatwaves in India.
Critical Findings by The CSE on Urban Form and Infrastructure
According to the study, urban areas featuring open highrise, open midrise, and compact midrise morphologies with moderate vegetation displayed lower land surface temperatures (LST). Conversely, neighborhoods with predominantly lowrise buildings had 2-4°C higher LST due to less vegetation. Industrial zones with lowrise structures, often made with heat-trapping roofing materials, were identified as particularly heat-vulnerable. Improving these environments could involve using better roofing materials, reflective paints, and green roofs.
Aspect Ratio and Heat Trapping: A Significant Connection
Another important finding was the relationship between a city’s aspect ratio – the ratio of building height and street width – and heat trapping. Higher aspect ratios resulted in lower LST, suggesting that narrower streets absorb less heat because the buildings shade each other and reduce direct exposure to the sun.
How Street Layouts Influence Temperature
Findings also highlighted how street orientation affects heat gain due to sunlight exposure and wind speed. Streets oriented north-south saw higher LST due to increased sunlight exposure, while those aligned along the east-west axis were cooler due to reduced direct sun exposure.
The Role of Green Infrastructure in Urban Heat Mitigation
Green spaces are critical for improving the microclimate of an urban area. These areas regulate temperature and humidity, absorb pollutants, and enhance air quality. The CSE study found that a 30% increase in effective vegetation cover (EVC) reduces LST by 2-4°C. EVC is particularly effective under trees with thick canopies, leading to up to 10°C cooler temperatures compared to those under palm trees within the same locality.
Implementing Urban Form-Based Codes for Heat-Resilient Cities
The adoption of urban form-based codes can provide context-specific cooling solutions tailored to the unique characteristics of each city or neighborhood. Recommendations include creating shaded walkways in markets, cool roofs in temple precincts, and business districts with high EVC.
Amending building by-laws and master plans to incorporate these findings could significantly improve the cities’ heat resilience. For instance, Pune’s focus on SVF, aspect ratio, EVC, and urban morphology could serve as an effective model for similar cities. A modest decrease of 1°C in temperature could result in a 2% reduction in a city’s power consumption, highlighting the potential impact of thoughtful urban planning.
Sample UPSC Civil Services Examination Questions Related to Urban Heat Resilience
Note: Here are a few sample questions related to mitigating global warming in India for the UPSC Civil Services Examination. Refer to these examples to get an idea about possible examination questions on this topic.
Urban heat resilience has emerged as an imperative aspect of city planning in India. As climate change continues to pose major challenges, it’s crucial that cities adopt an urban form that minimizes heat absorption and maximizes livability. By factoring in aspects such as building density, green spaces, and street orientation in their planning process, cities can effectively combat rising temperatures and create healthier, more comfortable environments for their inhabitants.