Rooftop Gardens Cool Chennai Urban Heat

Summary of Rooftop Gardens Study in Chennai

Study Overview

• Conducted by: IIT-Madras and Okapi Research and Advisory.
• Objective: Investigate the impact of urban rooftop gardens on thermal comfort and indoor temperatures in Chennai.
• Locations: Studies at four sites - Adyar, Chromepet, Otteri, and Adambakkam.

Key Findings

• Cooling Effect: Rooftop gardens resulted in indoor temperatures being 1°C to 2°C cooler compared to rooms under exposed roofs.
• Surface Temperature Reduction: Roof surface temperatures decreased by 8°C to 12°C with the installation of rooftop gardens.
• Specific Temperature Readings:
  • In Adambakkam, the garden-covered room recorded 33.7°C at 5 p.m. compared to 37°C in the room without a garden (a reduction of 3.2°C).
  • In Adyar, a garden-covered room recorded 32.1°C at 6 p.m., down from 34.3°C (a reduction of 2.2°C).
• Ambient Temperature Difference: In Otteri, an ambient temperature difference of 8.1°C was noted; 35.7°C over the garden-covered roof vs. 43.8°C over an exposed roof.

Methodology

• Various sensors were employed to measure:
  • Incoming and outgoing radiation.
  • Temperature at roof surfaces, ceilings, and heights above the roof.

Implications

• Urban Cooling Strategy: The study underscores the effectiveness of rooftop gardens as a passive cooling strategy, especially beneficial for vulnerable communities.
• Policy Recommendation: Advocated for consideration of rooftop gardens in broader urban heat mitigation strategies as they are an affordable option.
• Future Research: Further exploration intended to assess the scaling up of benefits from building-level to city-level, including the transformation of 20%-30% of urban terraces into rooftop gardens to combat urban heat island effects.

Conclusion

The study concludes that integrating rooftop gardens can significantly reduce heat exposure in urban environments and should be prioritized in urban planning and environmental policies for climate resilience.