Hundreds of roofs in Ahmedabad, India, painted in reflective, white coating to keep occupants cooler. The effort is part of a global scientific trial to study how indoor heat impacts people’s health and economic outcomes in developing countries. Ahmedabad has suffered temperatures in excess of 46 C (115 F) in recent years. Other study sites are in Burkina Faso, Mexico and the island of Niue in the South Pacific, spanning a variety of building materials and climates. \”My refrigerator doesn’t heat up any more and the house feels cooler. I sleep so much better and my electricity bill is down,\” said Nehal Vijaybhai Bhil, whose roof was painted in January, after his roof was covered in the coating for the last two months. The trial will run for one year, and scientists will collect health and indoor environment data from residents living under a cool roof – and from those who do not. \”There’s nothing to stop the heat transfer coming down – there’s no insulation barrier from the roof,\” said Aditi Bunker, who is leading the project, supported by the UK-based Wellcome Trust.