As Tamil Nadu faces the dual challenges of rising temperatures and the Urban Heat Island effect, government schools are being retrofitted as heat-resilient learning spaces. “Cool Classrooms for Green Future” outlines a strategic roadmap for the Tamil Nadu Green Schools Programme—an initiative by the Department of Environment and Climate Change and Tamil Nadu Green Climate Company (TNGCC), supported by United Nations Environment Programme (UNEP), the Swiss Agency for Development and Cooperation (SDC), and technical partner Auroville Consulting.
By transitioning from energy-intensive active cooling to nature-based passive cooling strategies, the program aims to mitigate heat stress and ensure that high temperatures do not impede academic potential.
The Correlation Between Heat and Cognitive Performance
Urban heat island (UHI) effects, dense built-up areas, and a lack of trees are making neighbourhoods in cities significantly hotter. Research highlights a critical link between thermal comfort and learning outcomes. While the optimal comfort threshold is between 24–29 °C, classroom temperatures in unshaded concrete buildings frequently exceed these levels.
Cognitive Impact: Student concentration begins to decline significantly once indoor temperatures surpass 30 °C.
Performance Gap: Data indicates that exam performance can drop by approximately 10% when temperatures reach 32 °C.
Climate Justice: For Tamil Nadu, where heat is recognised as a state-specific disaster, heat-resilient classrooms are a priority for equitable education and public health.
A Technical Toolkit for Passive Cooling
A multi-pronged approach to temperature reduction using passive cooling strategies has been developed under the BeCool Project situated within a larger scaling strategy led by UNEP’s India Cooling Programme and supported by SDC, which works with Tamil Nadu to mainstream passive and nature-based cooling in schools, housing and cities:
Cool Roofs: Application of high-SRI (Solar Reflectance Index) coatings or tiles that reflect solar radiation, potentially lowering indoor temperatures by 2–8 °C.
Strategic Shading: Use of external louvres, pergolas, and verandas to reduce surface temperatures by 11–25 °C compared to surfaces exposed to direct sunlight.
Enhanced Ventilation: Implementation of cross-ventilation, “jaali” (perforated screens), and roof vents to facilitate the removal of trapped hot air.
Nature-Based Solutions: Leveraging evapotranspiration and natural shade from trees and climbers to lower local air temperatures by approximately 2–3 °C.
Scaling and Implementation
For Tamil Nadu, which has officially recognised heat as a state-specific disaster, making classrooms heat-resilient is framed as both a public health and climate justice priority, and the call to action outlines what schools, teachers, students, and government can do to keep classrooms cool, comfortable and sustainable.
The initiative has moved from pilot projects in Chennai to a statewide scale-up. Through the BeCool Project, these passive design principles and the established technical methodologies are being mainstreamed and integrated into building codes and government infrastructure standards. The program also focuses on capacity building for “Green Fellows” and engineers to ensure the long-term sustainability of these technical interventions.
