75% of American smart thermostat users say that it has reduced their electricity bills

"The Market for Smart Thermostats, new energy research from Parks Associates, finds smart thermostats are among the strongest categories of smart home devices, with more than 10% of U.S. broadband households planning to buy a smart thermostat over the next 12 months. Nearly 75% of current owners report that this device has reduced their electricity bill."

Source:  Parks Associates, 13th August 2015