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The Nest Thermostat: Saving Energy Can Be Fun

Posted by   |  Date May 18, 2012  |  Comments 2

In this guest post, CEE's IT Manager Tom Spielman tests out a Nest thermostat in his own home

If you haven't heard about the Nest, it’s a new thermostat that was created by some ex-Apple employees (among others). Since its release in October, 2011, it has generated enough buzz to sell out of its initial production run and to be sued by Honeywell.

I’m the geek in the family. When I first heard about the Nest thermostat it sounded really cool, but I couldn’t justify spending $250 for one. They had to be kidding, I thought, who would pay $250 for a thermostat? Nest claims the device will easily pay for itself in energy savings over time, but lots of less expensive programmable thermostats that can also save you money. As a matter of fact, we already owned a programmable thermostat and had already gone through the effort to program it… a few years ago.  And we overrode the settings frequently and sometimes even put it on hold for days. I can’t say for sure if even the time was set right. More than once I wondered if we’d actually save more energy with a regular old thermostat we could turn down manually before you leaving the house and before going to bed.

Unfortunately my family’s use (or disuse) of the programmable thermostat is not unique. Nest Labs created a product they claimed would address the shortcomings of both these thermostats and their owners but I felt their savings claims were overly optimistic. side.  Even though part of me really wanted a Nest, I managed to avoid the temptation... until my wife said that she thought getting one was a good idea.

What’s so special about a Nest?

The Nest attempts to solve two basic problems with programmable thermostats:

  1. The typical schedule settings don’t allow for the variable routine of many households

  2. No one likes to program them, and over time the programmed schedule often isn’t maintained and so gets out of date. People then just override the settings rather than changing them because it’s easier.

How does the Nest get around these problems? By not having you program it at all. You just use it like an old style thermostat for a week or two while it figures out your schedule. You turn it up when you get up in the morning and when you come home from work. You turn it down when you leave and when you go to bed. Tuesday’s schedule can be completely different from Wednesday’s: it doesn’t care.  It also uses proximity sensors to determine if no one is home, or everyone’s in bed, so you’re covered even if you forget to turn it down.

So what does a schedule look like when all is said and done?

The graphic above is our schedule as seen on our account at the Nest website, but we can see the same thing on our smart phones or tablet. The day is on the left. The time is across the bottom.

My wife gets up pretty early during the week, as shown by the column of dots that read 69 between 4 and 5 am from Monday through Friday. Now, we had an unusually mild winter, and  didn’t get our Nest until its tail end, so I don’t think it reflects heating in a typical Minnesota January.  It’s also a mix of what the Nest programmed for itself, and our own programming, - which is still an option. I am a geek after all. The online schedule shows which of the settings are yours and which the Nest created on its own. It also lets you adjust as you see fit by dragging the dots where you like, adding new ones, or removing them.

Oh, I forgot to mention: the Nest connects to the Internet through your home’s wifi. This means you can program it with your computer, smart phone, or tablet from wherever you happen to be. This is a lot easier than programming the thermostat itself, though setting the schedule on the Nest is quite a bit easier than on a typical thermostat. You can also turn it up or down in real time from your computer or smartphone if you forgot to turn it down before leaving home.

Is there more to it than automatic programming ?

Why yes, there is. There are several other nice features. For example, it will show you how much you’ve used your heating system or air conditioning on a given day and compare it to past use. It even guesses what caused the change!

This is what the energy usage screen looks like on my phone.

The little white icons on the right reflect the Nest’s reasoning as to why your usage could be above or below normal. For example, the sun/cloud symbol means that the low usage was weather related. It can be fooled. The blue line on the 3rd shows we ran the A/C for 3 hours. The Nest says that it was weather related but in reality we were just testing our new Energy Star A/C system.

It’s cute too.

Maybe we really shouldn’t care, but the Nest folks went to a lot of effort to make their thermostat look good. And they didn’t want any installer or homeowner to screw that up by mounting it crooked, so they even built a level right into the base.

Old thermostats needed to be level to work right. I don’t think that’s the true of the Nest but regardless, it’s a nice touch.

So, does it actually save energy?

The Nest is smart enough to turn the heat down if you end up not coming home until a few hours after work. And you can turn the heat down remotely. It also notes changes in your routine and makes adjustments to its schedule. Still, as far as heating goes, it’s tough to beat a non-programmable thermostat if you’re very diligent about turning it down when you leave and at night before you go to bed. The Nest is not really performing any heating magic, it just turns the furnace on and off.

For A/C, there IS a little magic. Nest recently updated its firmware. How many thermostats do you know that offer new features after purchase? Anyway, one of the new features is called “Airwave”. Airwave will turn the compressor on your A/C off BEFORE your house gets down to the set temp, but leaves the fan running. As long as the humidity in your house is relatively low, the A/C can continue to cool your home down for another 10 or 15 minutes after the compressor turns off. Since the Nest can also determine the humidity level, it knows whether it can use this trick. We don’t use the A/C much in our household and when we do, the humidity is more than likely pretty high, so we aren’t sure if this will work very often in our case.

It’s too soon to tell how much energy it’s saved in our household, but based on the way it works, I’d bet it will perform much better than a typical programmable thermostat.

Related posts:

in other words: $250 for a Thermostat?!

in other words: Understanding How to Interpret Your Energy Use

From the Field: CEE Programs and Mobile Devices



The problem with the Nest and most other programmable thermostats is they are already becoming obsolete. Few thermostats are capable of reading a customers smartmeter which will soon become a requirement to REALLY save energy. In efforts to reduce peak demand utilities are implementing variable peak pricing and demand charges during peak hours. The very latest thermostats are able to talk to the meter and detect when the PRICE of power is going up then scale back the A/C use. The ecobee and a few others are capable of reading power meters, but most aren't.
Bob, you make a good point, especially for cooling dominated climates that have time of use pricing. In MN, a heating dominated climate, most of our energy costs are from natural gas use for space heating. Setback thermostats still provide an important source of energy savings and the practice is not as widely adopted as it could be. Smart thermostats like the Nest and the ecobee still have a role, especially if the "cool" factor increases adoption and use.

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