Google has announced plans to buy thermostat maker Nest Labs for $3.2bn, continuing a string of recent acquisitions. Google said the cash deal was expected to be completed in the next few months, according to BBC News.

California-based Nest Labs was founded by two former Apple executives. It produces a thermostat capable of learning user behavior and working out whether a building is occupied or not, using temperature, humidity, activity and light sensors.

The firm will continue to be run by chief executive Tony Fadell and maintain its own distinct identity, Google said in a statement.

"Nest's founders, Tony Fadell and Matt Rogers, have built a tremendous team that we are excited to welcome into the Google family," said Google chief executive Larry Page.

Fadell was head of Apple's music division until he left the firm in 2008. He is known as the "father of the iPod" for his work on the first 18 generations of Apple's music player and was also involved in the hardware design of the original iPhone.

Fadell told the BBC that he first came into contact with Google in 2011 through a "chance meeting" with the firm's co-founder, Sergey Brin. He said he showed Brin an early version of the Nest thermostat. He liked it and many Google staff members later installed it in their homes.

"They've always been keen on what we were doing, because they thought we had a crazy idea and they love crazy ideas," Fadell said.

Google's purchase of Nest Labs follows its acquisition of military robot-maker Boston Dynamics last month and of human-gesture recognition start-up Flutter in October.

The search giant did not release any details of those deals.

The biggest deal in Google's history to date was its acquisition of mobile phone firm Motorola Mobility for $12.5bn in August 2011.