Comcast Corp. is making smart-home features free for 15 million customers with its Xfinity Internet service, the Philadelphia company said  Wednesday.

The decision promises to make it cheaper for millions of Comcast customers to automate their homes with internet-connected garage door openers, locks, lightbulbs, and temperature-controlling thermostats.

It raises the prospect that customers could use their X1 voice remote to murmur, "Good night," and automatically bolt doors, extinguish lights, lower thermostats, and arm the home security system, the company said.

Comcast typically charges additional fees for such advanced telecom services. And until now, Comcast has made home-automation functions available only to customers who subscribed to Xfinity Home, a home-alarm and security service with 1.3 million subscribers. It costs at least $25 a month (on current promotion) in addition to an Xfinity Internet.

But Comcast has decided to free the smart-home features from its home security service to make Xfinity Internet service more appealing to consumers. Still, there is at least one catch.

Seeking to save money, many Comcast customers are considering purchasing routers at stores or online to avoid paying the monthly lease fees, which amount to about $11. But those store-bought routers now will lack the same free home-automation features as Comcast's leased routers, Comcast said Wednesday.

"The take-away is that we are giving away automation to 15 million Comcast customers," Daniel Herscovici, senior vice president and general manager of Xfinity Home, said Wednesday.

Herscovici said that Comcast would expand the number of Xfinity Internet customers with access to the free smart-home features as it upgrades its network and as new subscribers join Xfinity. Customers probably can get the service if they have an X1 set-top box and a relatively new router. Comcast has a total of about 25 million Xfinity Internet customers.

The automated features will become available over the next several months as Comcast announces partners that will interact with its network to handle duties in the home, such as closing the garage door.

Comcast said it could broaden its smart-home features through its acquisition of Stringify in September.The company provides a cloud-based platform for automating at least 500 internet-connected devices from companies ranging from General Electric to Kwikset.

"Xfinity will be the home operating system that integrates every [internet of things] device and transforms a connected home to an intelligent home," Chris Satchell, the company's chief product officer, said in a statement. He said the company would enable Xfinity customers to control their home features through the voice-control TV remotes and the X1 set-top box on the television.

Americans are expected to have an average of 50 WiFi-connected devices in their homes by 2020, the company said, and managing them could be tricky.

Comcast announced the changes at the CES, formerly the Consumer Electronics Show in Las Vegas, which despite all the new gadgetry on display, suffered the most basic of system failures: a power outage.

Lights dimmed starting around 11 a.m. local time in one of the main convention halls that hosts demonstrations from the likes of LG Electronics Inc. and Samsung Electronics Co. Though backup power kept some booths running at least partially, some
sections of the Convention Center were cleared of attendees while the problem was addressed. Power was fully restored around 1:20 p.m., according to CES's official Twitter account.

The region has been afflicted by heavy rainfall, and on Tuesday, a booth run by Google had to be closed because of flooding. A joint statement from city and convention officials said a preliminary check showed condensation affected one of the facility's transformers.

This article contains information from Bloomberg News.