Category: Environment (Green)

Review: The Nest learning thermostat

Earlier this year, a new company known simply as “Nest” announced their first product: the Nest Learning Thermostat. Now available in Canada, its distinctive round shape is a design throwback to the non-programmable thermostats of a few decades ago.

That simple, elegant exterior which immediately drew praise for the way it complemented nearly every decor masked a highly sophisticated internal design that is more smartphone than thermostat. The Nest’s central selling feature (other than a design which sets it apart from every other thermostat on the market) is simplicity. It is designed to be a thermostat that never needs to be programmed because it has the ability to “learn” your needs and then program itself accordingly thus saving you time and hopefully, money too.

How much money? Up to 20% savings on your energy bill according to the company’s claims.

Nest achieves this savings by doing something automatically that people, it seems, don’t do by themselves: actually program a programmable thermostat. The company quotes a study which claims that 90% of programmable thermostats are rarely or never programmed.

How does it work?

After installing the Nest in place of your existing thermostat (see video below) and walking through a simple set-up procedure, you simply rotate the Nest’s outer ring to the desired temperature and walk away. The Nest will keep your home at that temperature until you change it – which is something you should do as often as possible during the first week. This is the Nest’s break-in period in which it learns your needs but also your habits. Thanks to a collection of on-board sensors, the Nest can determine when you are at home, when you are sleeping and when you are away. It uses this information combined with the temperatures that you physically set to come up with its own set of program parameters.

At any time you can view this self-programmed schedule (for an entire week) and make adjustments if you feel the Nest hasn’t chosen optimal settings.

In theory, this whole process should be very straightforward and not at all time-consuming – after all, this is supposed to be far easier than programming a regular thermostat. In practice however, I found that it wasn’t so simple.

What is the temperature?

One of the big differences between a standard thermostat and the Nest, is the way temperature is determined. You might think that 20 degrees is a standard measurement of temperature but the Nest has a different opinion. Nest has a range of sensors that measure temperature, humidity, and ambient light levels so when the Nest tells you it’s 20 degrees indoors, it can often feel colder, when compared to what 20 degrees felt like when your older thermostat said it was that temperature. As an explanation for this discrepancy, the company says, “Not all thermostats are created equal.  Different manufacturers use different sensors and different methods of calculating the ambient temperature. The thermostats can sometimes arrive at different ambient temperature measurements as a result.”

Control freaks, beware

In addition to the Nest's Auto-learning feature, you can program your own settings and modify any the Nest has programmed itself.

The Nest’s fully-automated setting, known as Auto-Schedule learning, is the feature that will have the greatest effect on your energy costs if you’ve never bothered to program your thermostat. It does this by combining the temperature settings you provide via the outer ring, with what it can detect of your at-home vs. away behaviour. After a few days, if you take a look at the schedule screen, you can see the results of this process. It may surprise you. I found that the Nest had decided on several temperature settings throughout the 24-hour cycle that seemed counter-intuitive. On Mondays, for instance, it included several temperature points that we colder than any temperatures we had ever input manually.

Upon closer inspection I found many of these seemingly random settings thrown in throughout the week (the Nest lets you program as many temperature settings over the course of a 7-day cycle as you wish) and became frustrated by the system’s decisions.

Again, if you never program your thermostat, the Nest’s Auto-Schedule is bound to save you money. But for someone like myself, who has always been very picky about programming the hell out of my thermostat, it seemed to be kicking on the air conditioner more than I would like.

Why it needs Wi-Fi

The Nest is truly a thermostat for the internet era. Its on-board Wi-Fi connects to your home network (no wired option exists) so that you can leverage some of the Nest’s features from the road. Using a PC with a web browser or the free Nest app for iOS and Android, you can set the temperature directly or access and change the schedule. This is handy for those situations where you depart from your normally schedule comings and goings, and want to get the house warmed up or cooled down before you come back. I’d like to see Nest add another feature to this app: send you an alert if it is taking an unusually long time to reach your set temperature – something that could indicate a serious problem with your air conditioner or furnace. N.B.: The Nest takes its power from your furnace/AC’s existing wiring. There is enough voltage to keep the Nest operational. However, it may not be quite enough to keep the Wi-Fi portion of the Nest’s functionality going all of the time. In my installation, I’ve noticed that if I keep the Nest’s display lit for longer than about five minutes, the battery depletes to the point where it can’t maintain the Wi-Fi connection. Typically, it regains the charge necessary to re-connect within a few hours. The company does mention in the install manual that this can happen, and if it becomes a constant problem, you can have a professional installer do some extra work to provide the Nest with the voltage it needs to be fully charged all of the time. For me, it hasn’t been worth going this extra step.

Home or Away?

We mentioned before that the Nest can tell if you’re around or not. Those on-board sensors can detect movement up to 20 feet away. When it thinks you’re not home, it enters into an “Auto Away” mode, where it suspends all heating and cooling functions in order to save energy. But it does so within parameters that you set. These so-called “safe temperatures” are the minimum and maximum temperatures that you are comfortable with when away from home. I set mine at 65F minimum, 80F maximum (yeah, I know those are Fahrenheit, but for some reason I’m incapable of thinking in Celsius when it comes to indoor temperatures. Weird, right?) which seemed prudent given that we have cats. If the house was truly empty when we’re not there, I might have set these even farther apart.

See the savings

The Nest can tell you whether you saved energy on a given day and what condition(s) caused the energy savings.

The Nest has two ways of showing you how much energy you’ve saved, should you care to look. On the Nest itself, you can enter the Energy option to view your energy history, day by day and get a sense both visually and via text of your energy usage. There’s no dollar value attached to the number, simply an indication of how long your AC (or furnace) was actively cooling or heating your home.

But if you really want to do a deep dive on your energy consumption, the iOS or Android app is the way to go – especially on a tablet. The Nest app’s detailed breakdown of energy use by day not only shows you precisely when and for how long you heated or cooled your home, it also shows you why any particular day was above or below average. Sometimes weather is the cause. Other times your own intervention will be the reason. Or the Nest will have saved you energy via AutoAway – all of these explanations are displayed on the energy tab.

 

Does it actually save money?

It depends. If you never bother to program your thermostat, the Nest will save you money for sure. Even if you don’t bother to try teaching the Nest, its Auto Away feature will at least keep unnecessary heating/cooling while you’re away to a minimum. If you opt for manual programming and essentially use the Nest the same way you would a conventional programmable thermostat, it can still save you a bit of cash – mostly in the summer. The Nest has a feature called AirWave, which takes advantage of the fact that when your air conditioner’s compressor turns off, the cooling elements that reside inside your furnace tend to stay cold for several minutes. During that time, the Nest keeps the fan going. Because the compressor is the part of the AC system that uses most of the electricity, the Nest can keep cooling your home at a much reduced expense – at least for a few minutes. It’s a neat trick that few if any other thermostats can do.

But to really see the financial benefit of the Nest, you need to a) have never programmed a thermostat before and b) be diligent in training the Nest during that key 1-2 week break-in period. Even though I have had the Nest installed for a month, it’s still too early to tell just how much money it may have saved me. Only a detailed analysis of my utility bills from the same period a year ago will reveal any useful numbers, and even then, with the incredibly hot summer Ontario has had this year, a meaningful comparison may be impossible.

Conclusion

Can the average homeowner justify a $250 thermostat? If you’re genuinely too intimidated by your existing programmable thermostat to actually program it, or your thermostat is so old it can’t be programmed, then yes, the Nest – even at $250 will likely pay for itself within a year, maybe two at the outside. After that, you’ll be saving money. Though the initial set-up may seem a bit daunting, the Nest, in day to day use is as straightforward as you could ask.

For the folks like myself who have always paid close attention to their heating and cooling settings, the savings may be harder to achieve. But even if it takes several years for the Nest to help your bottom line, the product does have other features which may help you justify the steep price of admission.

Being able to remotely control your home’s heating and cooling from anywhere in the world is pretty awesome. Add to that a detailed overview of your energy usage and the ability to program a nearly unlimited number of temperature control points on a 7-day schedule, and you might just find $250 a small price to pay for that level of control and information.

Finally, if you’re really looking for a reason to buy a Nest, there’s always the cool factor (and I don’t mean AC) – the Nest will look better on your wall than any other thermostat I can think of, and I guarantee it will be a conversation piece for the foreseeable future!

Advertisements