Extreme heat is putting added strain on Colorado’s electric grid, prompting Xcel Energy to ask hundreds of thousands of customers to reduce their energy use.

For Kyri Baker, that request became more than a suggestion. Baker, an associate professor of engineering at CU Boulder, had enrolled in an Xcel program that allows the utility to adjust customers’ air conditioning during periods of high demand. But during a recent stretch of extreme heat, Baker said she tried to lower the temperature in her home and found she couldn’t.