Jim Butler's home, a rustic four-bedroom overlooking a marsh in Southampton, N.Y., is quiet. On a weekday afternoon in February, the snow, piled up over two feet, muted what little noise the water made.

Inside, however, the house buzzed with digital life.

Before leaving his primary home in New Jersey, Mr. Butler, president of Isobar U.S., a Dentsu Aegis digital agency, uses his iPhone to switch on the five Nest smart thermostats at his Southampton home. En route, he pulls out his phone again, navigates to the "smart home" folder containing six apps, and taps the screen for the August Smart Lock. He adds my phone number, and almost immediately, I receive a text prompting me to download August's app.

When we pull up to the house, I open my new app, hold my phone up to the door and watch it open with a tinny ping.

The veteran agency executive is an early and enthusiastic adopter of connected domesticity.

Chamberlain makes a smart gadget for the garage; Pentair for the pool. There are five sensors from Kumostat, which are connected to Wi-Fi and monitor the heaters. Wemo devices control the lights; the two Samsung TVs are smart, too. When Mr. Butler first heard about August, he immediately submitted a pre-order. He now has two of the smart locks.

But he's not done with his collection. He envisions additional sensors tucked inconspicuously into the hallway. If he sent a plumber to the house and the visitor crossed beyond the foyer, for example, his phone would light up. "It's great," Mr. Butler said. "You can put these little devices everywhere."

Soon enough, they might be. By year's end, Gartner estimates more than 2.8 billion consumer devices will be connected to the internet -- both the gizmos born smart and older appliances that learned new tricks. In five years, the number will exceed 13 billion. Gartner predicts the overall Internet of Things market -- consumer plus automotive and enterprise categories -- will nearly quadruple in value in five years to $263 billion.

That tidal wave will alter the digital industry. New devices will hit the market, with consumer marketing dollars trailing them. Nest, which Google owns, recently began mass-media marketing; August is planning broader advertising soon. Samsung, one of the largest media spenders in the country, has pledged that everything it manufacturers will be connected to the internet by 2020. In August, the electronics giant acquired a connected-device startup, SmartThings, to lead the charge. SmartThings CEO Alex Hawkinson founded his company after his dumb water pipes burst.

Once the devices land, waves of new data will follow. With smart devices learning more and more about our behavior, on our phones and inside our homes, the opportunities for advertisers are huge.
For Mr. Butler, like most in the digital ad world, those avenues are not yet clear. His affection for connected living comes largely from the "peace of mind" it brings. In the winter, he visits the Southampton house infrequently, maybe once a month, and he enjoys the ability to monitor it from afar.

He also takes some aesthetic pleasure in the devices. "The platform, the screen is fantastic," he said, showing off the Nest digital interface, which he described as "iPod-like" (a natural analogy: Tony Fadell, Nest's founder, built the iPod).

A few of the device apps drain his battery, and one, from Kumostat, was glitchy, refusing to shut off the heat. The August lock, a metallic gray orb that sits on the door, is not his favorite. "Aesthetically, it's beautifully designed," he said, "but it's big and bulky." He is confident it will get sleeker.

His greatest joy is that the devices converse. After I unlocked the door, the August app asked if I would like to go into "stay" mode. I clicked, and the Nest thermostats came to life. "They can all talk to each other," Mr. Butler explained.

How long they will is a matter of debate. For now, the Internet of Things market is infused with a rare convivial spirit. Samsung's SmartThings is open-source, working with products from Apple, Google and others. Apple and Google are doing the same. At some point, that could end, as the silos favored by tech companies develop.

Those at the forefront of the smart market insist they won't.

"There's not one smart-home platform that is going to win," Mr. Hawkinson said. "Human interests are so diverse; there will be a million different smart homes."

~ ~ ~
CORRECTION: An earlier version of this story referred to Mr. Butler's agency as Roundarch Isobar. The agency is now known as Isobar U.S.