Over the past few years, maths teacher Usha found her classroom sweltering during her usual 12.50–1.50 pm period, on the second floor of Perunthalaivar Kamarajar Government Girls Higher Secondary School. “It was so difficult to take class during the peak hours,” she says. But this year, she mentions that it feels slightly bearable, and attributes this to the shade of the trees, the wind blowing through the building, and the latest addition — solar-reflective paint on the roof. Data from a state government and UNEP Cooling pilot project at the Ambattur school shows that reflective coating brought the classroom’s internal…