A group of Illinois gas and electric utilities and the Environmental Law and Policy Center said that they would help pay for new smart thermostats for as many as 1 million customers in northern Illinois, including metro Chicago, over the next five years.

The program, announced on October 8, is the largest initiative of its kind in the country, the Policy Center said in a press release. Customers of Commonwealth Edison (ComEd) and three gas utilities will get $120 toward the purchase of a $249 thermostat, providing they have wi-fi, a furnace, and central air conditioning.

The program will cover Nest and Ecobee3 devices initially, but other manufacturers will be added, according to a statement from the American Council for an Energy-Efficient Economy (ACEEE).

Both the Nest and Ecobee3 are wi-fi enabled devices that let homeowners control heating and cooling remotely through their smartphones and tablets. They also are designed to adapt to the occupancy patterns of residents and adjust heating and cooling accordingly to save energy.

In a recent report, the ACEEE reviewed a half-dozen energy-savings studies and found that smart thermostats can reduce energy use for home heating and cooling by an average of 8% to 15%. The thermostats can save a kWh of electricity for between 2 and 3 cents, the report said, and collectively are capable of reducing U.S. electrical use across all sectors by 1/2%.

Under the program, ComEd will offer $100 rebates for the devices, with another $20 coming from participating gas utilities.

Similar programs in effect elsewhere

As ACEEE points out, the ComEd isn’t the only utility eyeing smart thermostats as a way of reducing consumption and easing strain on the grid at times of very high demand.

In Nevada, NVEnergy offers free thermostats to customers and includes installation as part of the deal in its mPowered Home Energy Management program.

In addition to allowing heating and cooling to be controlled remotely, these thermostats allow customers to track energy savings and compare the run times of HVAC equipment with other homes through an online portal. A key benefit to the utility is the ability to increase the temperature setting on a consumer’s thermostat during peak demands in the summer.

“During the peak summer months, on days when the demand for electricity is at its highest, NV Energy will occasionally initiate Energy Events,” the utility’s website says. “A signal is sent to your thermostat to increase the setpoint temperature up to 4 degrees. These events are optional and help reduce power consumption and electricity load to ensure a stable energy supply.”

Although customers can override this feature during peak events, ACEEE said, few apparently do.

Elsewhere, two utilities in Texas — Reliant Energy and Austin Energy — also offer rebate programs for smart thermostats. Reliant offers a no-cost Nest thermostat for customers who sign up for its Learn & Conserve program. Austin offers a $85 rebate for Web-connected thermostats, ACEEE said.