When we first learned the results of CNET's joint survey with Coldwell Banker asking Americans about their experience with the smart home, I was surprised. For starters, we discovered that more than a quarter of Americans (28 percent) already own some kind of smart-home product -- more than I would have guessed for a tech category that's still relatively new.

81 percent of current smart-home device owners say they would be more willing to buy a home with connected tech in place

Two years ago, when I started writing about the world of connected thermostats and door locks, I began to wonder whether smart-home technology is transferable -- whether it makes selling a house easier, and whether home buyers can effectively use smart products left behind. After all, installing a smart lock like an August Smart Lock means breaking out the tools and making the device a semipermanent fixture on your front door. It's easy enough to replace, but it's not quite the same as unplugging your TV.

According to the data, those already-installed smart devices could make a huge difference in how much and how quickly a buyer might spend on a home purchase.

Among the interesting findings in our survey (a stunning 91 percent of those who own a smart-home device would recommend it to others, for example), two stats surprised me the most, and they have implications for the future of home buying and selling. Eighty-one percent of current smart-home device owners say they would be more willing to buy a home with connected tech in place, while 66 percent say they would leave their smart-home products behind if they thought their house would sell faster as a result. The survey is groundbreaking in that it shows just how important smart-home products are becoming in making homes more saleable and valuable.

Danny Hertzberg, a Coldwell Banker agent in Miami, Florida, explained to CNET in an interview that interest in smart home products causes him to always recommend installing smart home systems if a seller is already planning to make upgrades to a home to sell it. He says that his "a-ha" moment on the topic came when he sold his own apartment two years ago after installing a system that orchestrates a delicate dance to make waking up easier. The Control 4 system raises blackout curtains five minutes before the morning alarm goes off, then slowly brings up the house lights and turns on CNBC in the bathroom.

Enlarge Image CNET/Coldwell Banker

"Buyers had a great reaction" to the system, Hertzberg said, noting that in his Miami market, the majority of homes selling in the top 25 percent of per-foot sales prices have smart home systems installed before the sale.

What exactly makes a home smart?

The entire concept of a "smart home" is evolving, and the industry is searching for the right way to define this category, which includes all the conveniences that connected devices -- programmable thermostats like the Nest Learning Thermostat or Internet-connected do-it-yourself programmable lighting kits -- provide for homeowners and renters.

Enlarge Image CNET/Coldwell Banker

For the purpose of this survey, we defined smart home devices as "products or tools that aid in controlling a home's functions such as lighting, temperature, security, safety and entertainment, either remotely by a phone, tablet, computer or with a separate automatic system within the home itself." Translation: connected appliances and devices that make your life easier.

(Including "entertainment" makes it a relatively broad definition, but that's on purpose, given that the likes of Time Warner and Comcast have added smart-home packages with controls built into your cable box. Expect more of that blurriness between entertainment services and home automation, including smart-home controls and connection hubs built into TVs.)

Many questions remain

47 percent of millennials own smart home products

We expect buyers and sellers of connected homes to sort through a number of remaining questions and challenges over the coming years.

Before you walk away from your connected house leaving your devices installed, remember that each product remains tied to your identity. Somewhere on a server in the cloud or a local SD card, all of those connected devices have stored data associated with activity going on in your household. In most cases you can set them all back to their factory default state and wipe your account information. But would you possibly forget to clean up your digital trail? As a buyer, would you feel anxious that the seller is still somehow able to log in to the house?

What if device makers were required to install a "moving out" button than wipes everything, for instance? Will buyers feel aggrieved if their Android phone can't control the lights and locks that only work with Apple's HomeKit platform? Will it be the spring/summer moving season, when people are rounding out the devices in their new homes, that dictates smart-home product cycles?

You can add those questions to the list of unknowns to the smart-home market in general. (Can it go mainstream? What about security? Which platform will win?) A higher adoption rate will help provide those answers, and at least one result from our survey suggests that might happen in the next five years or so.

Both millennials (47 percent of whom own smart home products) and parents with kids under 18 still living at home (42 percent) buy smart home devices at much higher rates than the average American, and that demographic spread suggest that ubiquitous smart home adoption may arrive at a breakneck pace.