Office owners take notice: The use of sensors and data is allowing big companies to reduce their office space by as much as a third.

Speaking at the MIPIM Proptech Europe event earlier this month, Microsoft real estate portfolio director Xavier Perrin said he uses a “building utilization dashboard” which allows him to monitor how different teams in the company use space in different buildings, including peak usage times.

“I’ve found I have seats I don’t need,” he said, according to Property Week. “This has allowed us to have constructive discussions about how much space we really need,” and in some cases led to reductions in space of as much as 30%. This has meant significant financial savings, and it could mean Microsoft can make further consolidations that save it tens of millions of dollars, Property Week said.

“It’s all about data for real estate for us,” Perrin said. “If you don’t have the data, you can’t make the right decision.”

In 2017, an analysis by Green Street Advisors said the rise of flexible working could lead to a global reduction in demand for office space of 2% to 3%. If Microsoft is anything to go by, the rise of smart buildings and data analysis could have an even more radical effect.