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What's the smartest way to stay warm (or cool) at home?

Connected thermostats are super-competitive right now. Here's how we sorted through the options for the CNET Smart Home.

Now Playing: Watch this: Turning up the heat in the CNET Smart Home
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The CNET Smart Home, a 5,800-square-foot house located near our appliance testing facility in Louisville, Kentucky, is our new spot for reviewing all things connected and automated.

We're also transforming the house itself into a smart home so we'll have a sort of "living lab" that's separate from the products we're testing. And we've already done a lot, beginning with a Wi-Fi makeover, thanks to the Asus RT-AC87U router and a couple of range extenders, as well as a second-gen SmartThings Hub for convenient access to multiple devices and integrated lighting. But now we're on the hunt for the right climate control setup. Here's how we tackled it.

Why go smart?

We could manage the CNET Smart Home's heating and cooling system with simple nonprogrammable thermostats (we have first- and second-floor thermostats in the house) that you have to adjust manually, or even slightly smarter seven-day schedule-enabled models that auto-update your heat and A/C based on fixed Home and Away settings.

Those options can work fine if you keep to a consistent routine -- or if you are very good about remembering to tweak your thermostat settings as needed. They're not exactly "smart," though, so for our purposes they won't work. And even if you're not trying to build a smart home from top to bottom, Wi-Fi-connected thermostats have a lot of conveniences to recommend them. Sometimes they're even worth the $150 to $250 asking price.

While the specifics can vary by model, all smart thermostats are equipped with some sort of advanced tech, like presence sensors, learning algorithms, geofencing capabilities, voice control and beyond. Pair that with the compatible Android and/or iOS apps that accompany every smart model and you have constant on-the-go access (whenever you're connected to a Wi-Fi or cellular network, that is) to changing the temperature, adjusting schedules and reconfiguring your alert settings.

When smart thermostats work well -- and not every model we've reviewed meets that standard -- you can expect custom control over your heating and cooling. Your thermostat will also take on a lot of the responsibility of managing your home climate control for you. But it goes far beyond convenience; smart thermostats help you use your heat and A/C only when you really need them, which can save you money on your monthly power bill.

The options

So far, we've reviewed the Nest Learning Thermostat (first-, second- and third-generation models), the Honeywell Lyric , the Honeywell Wi-Fi Smart , the Honeywell Wi-Fi Smart with Voice Control , and the Ecobee3 . The Ecobee unit also has a new version out that we have not yet tested but which talks directly with Apple's new smart home platform, called HomeKit. These models represent the main smart thermostat competition in the market today, although you can find some other app-enabled units online and in stores, too.

The Nest Learning Thermostat is the best-known of the group, and it's also a poster child-product for the smart home in general. The Nest thermostat (like other models) relies on a learning algorithm that keeps track of the temperature tweaks you make and develops its own auto-adjusting schedule based on your routine. Nest also boasts built-in sensors that know when you come and go, making it even easier for it to learn and adapt to your schedule.

A view of the Honeywell Wi-Fi Smart home screen. Colin West McDonald/CNET

As the name suggests, the Honeywell Wi-Fi Smart with Voice Control lets you use commands like, "Make it (1 to 10) degrees warmer/cooler" after the wake-up phrase, "Hello, thermostat." That's a neat feature, but unfortunately, both Honeywell models have the same dated design and occasionally stubborn touchscreen display panel that make them hard to recommend.

The newly HomeKit-equipped Ecobee3 thermostat relies on built-in and remote sensors that detect ambient temperatures on a room-by-room basis and can also tell whether or not you're home. It also harnesses the voice-control capabilities of Siri (when you're on the same Wi-Fi network as the thermostat). However, HomeKit has some work to do before we fully embrace it as a platform, similar to the HomeKit Insteon Hub Pro that we're keeping in mind as a future addition to our current SmartThings Hub.

And, while the Honeywell Lyric looks nice (it has a rounded design that's somewhat similar to Nest), its geofencing feature that relies on a specific radius to track your comings and goings was glitchy at best.

If you had to buy a smart thermostat today, the Nest is the easiest option due to its good looks, its ease of use, and a strong and growing network of other devices it can interact with -- aka Nest Labs' Works with Nest, a program that connects Nest products with devices from both established (Mercedes, Whirlpool) and lesser-known third parties -- as well as through IFTTT and with Nest Labs' own Nest Cam and Nest Protect within the Nest app.

The Google-owned company also announced a partnership with Yale recently on the "Linus Lock," due out in 2016 complete with Nest's Weave tech, a protocol designed to provide localized device automations similar to Apple's HomeKit standard. There's more to consider, though.

Why Nest?

Nest wasn't the first smart thermostat ever released to the retail scene, but it did do something revolutionary. The team took a classically utilitarian hunk of plastic and metal parts and made something nice to look at. Giving a thermostat a gorgeous design may seem easy enough, but that decision solidified the startup ( which Google acquired in February 2014) as a dominant smart-home brand.

And now, the appreciation that many tech enthusiasts have for innovative laptop, tablet and phone designs has extended across categories to products like thermostats and door locks, due in large part to Nest's earlier industry efforts. This in turn makes concepts like energy savings more accessible because it's easier to feel intimidated by tech that looks complex and/or outdated.

Nest did more than design a simple, modern DIY gadget, though. Its thermostats do an excellent job of "learning" your routine over time and automatically changing your heat and A/C as you come and go, according to your preferred settings.

A look inside the Nest app. Screenshots by CNET

Nest's limitations and what's on the horizon

But, Nest's earlier advantage has diminished somewhat as models like the Ecobee3 have joined the smart thermostat fray. One major criticism is that Nest has no built-in capability to detect your presence in the house if you're in a different room that the one where you installed the Nest. Spend enough time out of range in a home office, for example, and the thermostat might switch to Away mode and drop or raise the temperature when you don't want it to.

While you can link your Nest thermostat with the brand's presence-sensor-equipped Protect smoke and carbon monoxide detector , you won't get any standalone remote sensors with your purchase. The Ecobee3, on the other hand, comes with a remote sensor that offers room-specific temperature readings. That would be a big help in a house as large as the CNET Smart Home. Ecobee also works with both SmartThings' Hub and, as mentioned, HomeKit.

We were tempted by the Ecobee3 given its SmartThings integration. Nest's interaction with SmartThings isn't officially supported right now. SmartThings' active developer community has designed a work-around, but it isn't especially easy to figure out if you aren't familiar with programming. We're also not holding out for official Google-owned Nest integration with Apple-owned HomeKit, given the competition between those two parent companies.

Even so, Nest 3.0 is our choice for the CNET Smart Home today. It has its drawbacks, but it's the most well-rounded smart option available today. It looks great, it works well, and it offers a lot of integration with other Nest products as well as devices from other manufacturers, both via IFTTT and its own Works with Nest platform. We'll continue to keep our eyes open for other options, and as we work in the house and continue to add connected components to it, centralizing control of everything may become a higher priority. How many smart-home apps is too many? I have a feeling we'll find out.