It was just before dinnertime on Day 16 of the worst heat wave in Phoenix history, and the temperature outside Karen Shute’s suburban home was 117 degrees.

Inside, Shute mixed two cocktails and sat down with her friend at the kitchen table. To save on her electric bill, Shute kept her thermostat around 80 degrees during the summer, but she decided she’d treat her friend that evening. She got up and turned it down to 77.