Nest Learning Thermostat: Shiny Toy or Serious Tool?

It looks a bit like a hockey puck, but it’s designed to keep your home warm in the winter, while cooling it in the summer. but while it is indeed slick, it’s a lot smarter than a hockey puck; so smart, in fact that it can learn. I’m talking, of course, of the Nest Learning Thermostat.

It seems that the folks at Nest Labs, a group that includes a number of Apple expatriates such as Tony Fadell, former head of the iPod Division and Matt Rogers, the iPhone’s lead engineer, decided that the lowly thermostat was a device that had been under-innovated and was too important to be left in the dark ages.

According to CEO and co-founder Faddell, “It was unacceptable to me that the device that controls 10 percent of all energy consumed in the U.S. hadn’t kept up with advancements in technology and design.”

This, then, is clearly the thermostat for the iPhone generation. What does it do?

It programs itself. This is a programmable thermostat, like the ones you remember from the 90’s, only you don’t need an engineering degree to program it. instead, you simply set it to whatever temperature you want, whenever, you want it, turning it down when you go to bed, or leave for work, then turning it back up when you wake or when you return home. After a few days, the thermostat learns your schedule and implements it.

But that’s only the beginning. the Nest tracks your settings, then encourages you to use more energy efficient ones, displaying a green leaf when you have saved and showing you your percent savings through your Energy History.

Occupancy sensors determine when the house is empty and turns down the heat when it is. This feature is called AutoAway.

Better yet, the Nest can connect to your wi-fi which means you can connect to it over the Internet or with your smart phone. That let’s you check your energy usage, or adjust your settings remotely. This could be handy if you are coming home unexpectedly and want the house warmed up by the time you get there, or if you are stuck at work, you can postpone the warm-up time till your expected arrival, thus saving energy.

The Nest is beautifully designed, with an elegant user-interface, as one would expect from this pedigreed design team and with backing from the likes of Google Ventures, Kleiner-Perkins and other big name VCs. At $249, it’s certainly not cheap, but it should be a hit with totally-connected gadget lovers.

The only remaining question is, does it actually save energy? when all the niceties are peeled away, what you have here is, in essence, a very well-implemented programmable thermostat and an energy monitoring system, the likes of which we can expect to see more of as smart meters make their way into homes.

Both of these are purported to save energy, though figuring how much they actually save is pretty difficult.

Let’s start with the programmable thermostat. Savings from setting back the temperature while you are away can be a somewhat tricky business. Because there are energy penalties associated with letting the house cool down and then heating it up again, there are limits to what can be saved. clearly if you are away for a whole day, then you will save energy by turning down the temperature, then turning it back up again when you return. but if you are away for just an hour, then it probably won’t. It‘s not exactly clear where the breakeven point is, because that will vary for each home as well as the weather conditions at the time.

According to energy efficiency specialist Ted Kidd, “Big savings are not achieved by temporary temperature reductions of the home.  In fact, reducing air temperature in the home means high mass items like couches and beds get cold and stay cold.  People bump thermostats to counteract the additional comfort challenge this introduces, so some setback strategies may really cost energy.  And all of this approach to ‘conservation’  implies sacrifice, living with less comfort.”

The fact is, programmable setback thermostats were removed from the EPA’s Energy Star program at the end of 2009, because people were having difficulty using them properly and because the energy savings that were being claimed could not be substantiated.

While it is true that the state of the art in electronic controls has advanced considerably since the mid 90’s, when programmables first came on the scene, there is a limiting factor that won’t go away for a while. That is the fact that the “standard interface” between furnaces and thermostat are essentially limited to a minimal amount of information, which is little more than, “turn on,” and “turn off.”

So, regardless of how much sophistication is provided at the front end, where the user is, the back end is more or less limited to the standard furnace interface, unless or until some new non-proprietary standard is developed that allows for a much richer data set to be exchanged between the two pieces of equipment regardless of manufacturer.

Does it matter? In a word, yes. if you look at what a manufacturer like Carrier has done with their Infinity series furnaces and air conditioners, they have a proprietary interface between their HVAC equipment and their top-of-the-line communicating thermostat, which, ironically, was designed by Ideo, the same design firm that created the original Apple mouse.

This system, which  admittedly costs between $10,000-15,000, not only allows electronic remote access at the front end through the Skytel radio network, (a wi-fi version is in the works), but on the back end, it can interact with multi-stage burners, variable speed fans, zone control dampers, duct static pressure sensors and heat recovery ventilators to provide highly accurate and efficient multi-zone temperature control, as well as fresh air ventilation, humidity control, embedded diagnostics and airflow control that compensates for ductwork variability. What that means in a nutshell, that with such a rich set of sensors and actuators, the performance can be much more highly tuned.

With this much information available at the furnace end, I am sure that Nest, which does collect information about humidity and light, in addition to temperature and activity at the user end, could provide comparable results. but since they are not making the furnaces, only the thermostats, they are limited to the information that can pass through the standard interface.

On the other hand, some of Nest’s interface features that provide feedback on energy consumption could actually turn out to deliver more savings than the setback feature. for example, the Nest thermostat has a feature called “time to temperature,” which displays the amount of time it will take to heat or cool the home. This information is intended to prevent people from oversetting the temperature with the idea that when they turn it up higher, it will heat the room up faster, which, by the way, it won’t. What happens instead is that the home becomes overheated and the owner ends up opening the windows to cool it back down, wasting a ton of energy in the process.

What’s more, Nest also provides a website that shows you how much energy, and money you are saving, a classic example of behavior modification. This kind of direct immediate feedback is also much of the impetus behind smart meters, where it is used to monitor and reduce household electrical usage.

Could this be a case of terrific industrial design and software wizardry whizzing right past the basic laws of physics and the principles of engineering? I wouldn’t go so far as to say that. In fact, I’m confident that the Nest Learning Thermostat will save energy, especially for users who take the time to inform themselves as to the best ways to utilize its capabilities. and I have little doubt that a robust user community will sprout up to propagate just this kind of information. and with the user feedback capability it provides, with its highly appealing interface, users will enjoy getting more involved in their home’s energy management, which is bound to be beneficial for most of the people, most of the time.

RP Siegel, PE is the President of Rain Mountain LLC. he is also the  co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water.

Follow RP Siegel on Twitter.

1 Comment