Eligible Ontario households will be able to get smart thermostats for free on a first-come, first-serve basis under a new government program.

Environment Minister Chris Ballard announced Wednesday that $377 million in proceeds from Ontario's cap-and-trade auctions this year will be used to establish a Green Ontario Fund. That not-for-profit provincial agency will oversee programs and rebates for homes and businesses to reduce energy costs.

Part of that will be the GreenON Installations program, under which eligible households can register to have a technician visit and install a smart thermostat at no cost. There will be 100,000 smart thermostats available under the program to people who register through the Green Ontario Fund website.

Ballard estimated the smart thermostats and installations will use about $40 million from the green fund, and said the government will be announcing more programs funded by it in the future.

Smart thermostats are connected to the internet, adjust themselves automatically and can be programmed and adjusted through smartphones.

Ballard said he has had one for years and it comes in handy -- especially for parents.

"My kids would come home on a hot, sweaty spring day -- and you'll note there are more and more hot, sweaty spring days -- and I'd be at work and they'd immediately crank up the air conditioning and I would get a notification on my smartphone about some activity going on, and I would quietly dial back down the air conditioning," he said.

Owners and renters of detached and semi-detached homes, townhouses and row houses can qualify for the free smart thermostats, though renters must have their landlords' permission. Registration opened Wednesday, with installations starting in the fall.

Representatives from a number of smart thermostat companies were on hand for Wednesday's announcement. Parminder Sandhu, the chair of the Green Ontario Fund board of directors, said the procurement process is still ongoing, but the intention is to allow consumers to choose which smart thermostat they would like to have installed.

Environmental Defence applauded the announcement, calling the smart thermostat offer a "goodie" to entice Ontarians into a deeper conversation about energy use.

"They can have a big impact," the organization said in a statement. "Just changing out an old thermostat for a smart one can reduce energy use -- and energy bills, and carbon emissions -- by over 10 per cent."

Ecobee, a Canadian company, says its U.S. customers saved an average of 23 per cent on their heating and cooling costs.

Nest said its smart thermostat has saved customers an average of 10 to 12 per cent on heating and 15 per cent on cooling costs.

Adjusting a home's temperature a couple of degrees at night or when no one is home can save up to 15 per cent on bills, the Ontario government said.

Ontario has so far raised nearly $1 billion from its first two cap-and-trade auctions. The Liberal government hopes to raise $1.8 billion this year and $1.4 billion a year starting next year.

The next auction in the system aimed at lowering greenhouse gas emissions is set for Sept. 6.

The government has also recently announced that $200 million from cap-and-trade proceeds will be used to establish a fund for schools to improve energy efficiency, such as installing new windows, lights and furnaces, as well, up to $657 million over five years will be used for social housing repairs and retrofits.