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Building Science

Nest Thermostat Data Revealed for First Time

At the recent ACI conference, Michael Blasnik showed big data on home performance collected from hundreds of thousands of homes

When Michael Blasnik gave a presentation on Nest's big data, the room turned out to be too small to hold everyone who tried to crowd in.
Image Credit: Energy Vanguard

The Nest thermostat has been around since October 2011, quietly collecting data on how your home — and the homes of hundreds of thousands of your neighbors — operates. It gathers information about indoor temperature, relative humidity, air conditioner runtime, auxiliary heat operation for heat pumps, and much more. Unlike the Ecobee thermostat, however, Nest doesn’t let its owners see all those data (which is a problem only for energy geeks really). Enter Michael Blasnik.

Blasnik, a building science and data guru, consulted on the Nest while it was under development and after its release. He has since joined the Nest team and is now a Google employee, and he’s been having a lot of fun looking at the data and trying to understand what they’re saying.

At the ACI conference in New Orleans last week, he gave attendees a first look at some of those data, and my, what a treasure trove he’s got his hands on! The room was packed, as you can see in the photo above. I took that photo a few minutes before the session began. After it started, a lot of people were standing in the back as well, and I’m sure many decided to go to a different session because they couldn’t get in.

So let’s get into the data. Blasnik showed 60 graphs of data, and I didn’t take pictures of all of them. Below are the ones that seemed most interesting to me. (It’s really hard to try to take notes, take pictures, and think about what you’re seeing all at the same time.)

Heating setpoints and temperature float

The chart at left shows thermostat setpoints during heating season in a few select states. Vermont won for lowest setting at about 60°F. I…

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  1. Greg Labbe | | #1

    Is Nest data "Average"?
    It would be prudent to consider who owns a Nest thermostats - I could be wrong, but I don't think the demographic is an "average" home owner.

    I know only two people who have a Nest thermostat installed in their home and both can afford the best mechanical equipment, both live in homes that are above average on energy performance, both homes have at least one PhD, both are 'double income no kids' with freakishly clean homes and both are early technology adopters.

    That being said, the big data being collected should be put to good use and kudos to Nest for not hoarding.

  2. User avater
    Dana Dorsett | | #2

    The heating degree-day base
    A heating temp of around 58F is actually pretty typical of tight houses built to IRC 2006 or better, but it's also heavily skewed in that direction by all of the parasitic or excess electric plug loads in the house, which is verifiable by careful Manual-J load calculations. Folks who buy the Nest are more likely gadget-guys, who likely have more background heat coming from DVRs, computers and the extra cooler in the video game room, etc. than another demographic.

    For electricity sippers the heating/cooling balance point is usually north of 60F in heating climates where the thermostat is set to 70F even in newer tight code-min homes (at least at colder climate code-minimums.)

    It looks like Vermonters still know how to knit sweaters, eh? :-)

  3. User avater GBA Editor
    Martin Holladay | | #3

    Thermostat settings in Vermont
    GBA reported the news that Vermonters prefer low thermostat settings back in January 2012. Here's a link to the article: The Strange Geography of Thermostat Settings.

    Richard Defendorf, who was GBA's news editor back then, reported, "One commenter ... noted that many dwellings in both Vermont and Maine are owned by vacationers who have equipped their homes with remotely controlled thermostats that they set at 50 degrees in wintertime, when the buildings are usually unoccupied. GBA editor Martin Holladay offered another theory. Many Vermont homes have wood stoves in addition to central heating. Even when a thermostat is set at 60 degrees, he points out, a wood stove can still warm a house to 72 degrees."

  4. User avater
    Dana Dorsett | | #4

    True enough...
    The thermostat can be set to 60F, with the wood stove burning, but a Nest thermostat would be able to detect the auxiliary heating. It simple has to be in their data- the question is whether that was teased out anywhere in their analysis.

    Many folks in the UK regularly keep their homes in the mid-50s and just dress warmly, only raising the temps for guests. ( I suppose that keeps the drippin's pan on the stove from going rancid too quickly. :-) )

  5. User avater GBA Editor
    Allison A. Bailes III, PhD | | #5

    Response to Greg Labbe
    True, Nest owners are generally a self-selected group that don't really represent an average homeowner. He talked about that at the beginning, but he also mentioned that there's been at least one study where an organization gave Nests to occupants, so there is some more average stuff out there.

  6. User avater GBA Editor
    Allison A. Bailes III, PhD | | #6

    Nests and woodstoves
    Michael did mention woodstoves in Vermont, perhaps because someone (David Keefe? Mike Rogers?) raised the issue. He said they can tell when that's the case because the outdoor temperature will be something like -20° F, the thermostat set at 60° F, and the indoor temperature at 75° F.

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