It is very unlikely that this is accurate, or there are substantial externals that are not being accounted for (e.g. stopping using a desktop as much as a tablet gets heavy usage) -- the difference between 2012-01-01 and 2013-01-01 is just way beyond what even the biggest Nest hyper claims.
Outside of savings that grossly exceed even the best expectations, when questioned whether they used a programmable thermostat already (the absolute bog standard $20 variety automatically dropping the temperature in a manner that is close to optimal for about 95% of people), the author gave a very wishy-washy answer that didn't actually answer the question.
I've been a Nest user since nearly Day 1, and about 19 months now overall. At this point I've probably recouped about 80% of the price of the thermostat, with my electric bill reduced by about $10-11/month ($55-65/mo to $45-55/mo) for a 725 sqft luxury apartment.
I should probably write a blog post with all the details, but here's my take:
* I have a south-facing apartment with about 110-square feet of window glass. It heats up like a sonofa in the morning. I was able to counter this by setting a warmer limit for cooling in the summer. The blinds were always correctly set every evening to minimize summer cooling and winter heating.
* The leaf stuck out at me. I always wondered "why can't I get the leaf with my setting -- what do I have to adjust it to to get the leaf to appear?" This resulted in behavioral changes such as wearing different clothes, and taking better advantage of the windows to make getting the leaf to appear achievable.
* Once I hit the leaf, I then looked into other ways to maintain comfort, particularly in the summer. I've since invested in a fan to eliminate the envelope of heat that surrounds my body. Running the fan 20 hours a day is equivalent to running the A/C for 20-25 minutes, which is a big savings if I can eliminate 2.5 to 3 hours of A/C usage a day (at 18.5 cents/kWh).
With the addition of the fan, and finally finding some LED light bulbs with the right lens type and color temp (to replace some halogens in the track lighting), my electric bill was $42 for July, despite the ridiculous northeast heat wave. Despite constant 90+ degree temperatures and high humidity, I was able to get by with about 1 hour and 15 minutes of A/C a day, and didn't feel bad about it.
I'm not sure I agree. If the Nest helps to change your habits then I would consider it a net win. It doesn't really matter how you saved the money, just that the Nest is paying for itself. Sort of like paying Weight Watchers to help you stick to your diet. :)
This is what I was trying to get across. The Nest isn't magic. Instead it provided information I could use to adjust my habits, and provide the data to show that my changes were resulting in a net benefit.
Of course, you don't need a Nest to learn to change your habits. Just stop using the HVAC, and you'll come up with alternatives. In my case, a mixture of fan usage and blinds/window usage.
If the nest is what makes it fun and simple enough to change the habits, it's entirely reasonable to say the nest caused them. Maybe most of the value of the nest comes from behavior modification rather than more precise temperature control. But even so, that's still value.
Exactly. It's like how the LCD with the real-time and historical fuel economy info in the Prius has been teaching people to drive more efficiently via the instant feedback you might not get in most other vehicles.
It's easy to say you could achieve the same thing without it, but facts show most people don't.
Many, many vehicles have real-time fuel-usage meters. Most people completely ignore them. The people who care about fuel-usage -- the sort of person who buys a Prius -- of course pay attention to it because it justifies the reason to buy the car.
Yet I suspect that very few of the people who bought the Nest actually care about energy usage, or reducing it. It is a lifestyle product and is a talking point, and while there are some who really desire it for that, many more set it to a static temperature and forget it. I hugely doubt that the total set of Nest users have seen any measurable decline in usage.
Isn't there a huge difference between the meter that the Prius has and the typical "real time" fuel meter. In particular, it is difficult to see how instant readings contribute to long term averages.
Not as many vehicles had those when the Prius first came out, and even now few make MPG as front-and-center with graphs and such. Implementation matters.
I have a south-facing apartment with about 110-square feet of window glass. It heats up like a sonofa in the morning.
You should consider solar screens. They cost about the same as regular window screens and are remarkably effective at keeping the heat out because they are on the outside, so the heat never enters the living space. Take them down in the fall when you start to want the heat.
At this point, it'd be diminishing returns. If it cut another $3-4/mo off the electric bill, time to recoup would likely be in excess of a decade. Next, it would ruin the gorgeous view I have (I very deliberately chose having a wall of glass). Additionally, it's an apartment building so I can't do any exterior modifications such as that. Last, I'm on the 4th floor, where installing 7 foot x 3.5 foot screens might be a bit dangerous.
Compared to buying a fan and a Nest, way too much effort.
TL;DR: Too much effort and sacrifice for negligible return.
Just so no one else gets the wrong impression - solar screens don't ruin the view, unless your nose is right up against them, they look like window tinting. Also it isn't just about saving money but also increasing comfort for the same amount of money.
Heck, I didn't have a programmable thermostat for three years, in Atlanta, and would be surprised to see anywhere near these savings. I had a thermostat with a manual lever, which was mechanically coupled to a mercury-glass switch that controlled the A/C (this was a new apartment building built in 1999, strangely enough, not some ancient relic). I turned the thermostat way up (i.e. reduced the intensity of the A/C) when I would leave, and turned it back down when I got home. This by itself was enough to reduce almost to zero the operation of the A/C when I wasn't home, which was a pretty good approximation of the desired outcome.
"the difference between 2012-01-01 and 2013-01-01 is just way beyond what even the biggest Nest hyper claims"
Doesn't the temperature chart explain most of the savings? A colder winter and hotter summer for the first year (pre-Nest). The simple total of net degrees by month disguises the fact that the second year is much milder. What you want to look at is KWH from months (days if possible) with nearly identical avg temperatures, come up with composite "savings" for different month types and project that on a year.
Below are the charts for each period. My attention isn't here but if someone with some statistical know-how wants to give even a casual analysis it would be interesting.
I agree ... And the thing I noticed is that during the cold snap (which wasn't nearly as long but was just as cold), they hardly used any power compared to the previous year. Perhaps they wer on vacation? I think "occupied hours" would be pretty important for these measurements. And if you multiplied occupied hours times the inside-outside temperature differential, you'd (maybe) start to see some patterns.
It's a convention of building physics to convert all energy useage to kW (sometimes BTU in the US) regardless of whether its gas, electric, oil, biomass etc. For example, Passivhaus calcs are done this way.
Outside of savings that grossly exceed even the best expectations, when questioned whether they used a programmable thermostat already (the absolute bog standard $20 variety automatically dropping the temperature in a manner that is close to optimal for about 95% of people), the author gave a very wishy-washy answer that didn't actually answer the question.