In its largest funding round to date, Ecobee today announced the closure of a $61 million funding round to expand its vision of whole-home voice control for its products and incorporate more forms of artificial intelligence.

The round was led by Energy Impact Partners with participation from Amazon’s Alexa Fund. To date, Ecobee has raised $146 million.

Future homes will be defined by three seminal technologies, CEO Stuart Lombard told VentureBeat in an email: low-cost sensors, machine learning, and far-field voice to do things like interact with Alexa.

“The result will be a home that listens, learns, anticipates, and responds to your needs so you can focus on the things that really matter. We are all in on delivering a suite of products and services to deliver this vision — and this funding round will help accelerate it,” he said.

Alexa Fund also took part in a $35 million funding round that closed in 2016, shortly after becoming one of the first smart home thermostats to adopt Alexa voice control.

Since its creation in 2015, with up to $200 million at its disposal, Alexa Fund has backed a range of startups interested in voice control, from robotics companies to the makers of smart home hardware and games. The fund also been used to pay for things like Amazon’s Alexa Accelerator, now in its second year.

Ecobee will launch an Alexa-enabled smart light switch, the Ecobee Switch+, later this month.

The smart home competition among tech giants with AI assistants appears to be heating up.

Ecobee’s backing comes a week after Amazon acquired smart home startup Ring for a reported $1 billion.

Last week we also got more details about Amazon’s refusal to sell Google’s Nest home products on its marketplace. Google first accused Amazon of barring Nest products from its marketplace late last year.

Other investors in the series C round include North Leaf Capital Partners, Export Development Canada, Ontario Capital Growth Corporation, Tech Capital, and GXP Investments.

Ecobee is based in Toronto and has 310 employees, a company spokesperson told VentureBeat in an email.

Sign up for Funding Daily: Get the latest news in your inbox every weekday.