Using a Smart Thermostat on Shabbos

Smart thermostats such as those made by Nest and Ecobee use an array of sensors and intelligent programming to provide homeowners with greater control, comfort and energy savings from their heating and cooling systems. While these devices have proven popular with consumers, some Jewish consumers have refrained from upgrading their thermostats because they are wary of the permissibility of using smart thermostats on Shabbos.

In this article I will review the problematic functions of these thermostats and explore the various ways these problems can be avoided on Shabbos.

Sensors in a Smart Thermostat

What sensors do these smart thermostats have that are potentially problematic on Shabbos? Both the Nest and the Ecobee thermostats have proximity and passive motion sensors which are triggered when a person gets close or passes by the thermostat.

Proximity Sensor

The proximity sensor senses when a person approaches the thermostat which causes the screen to light up and display the thermostat’s settings. Although it may be debatable if inadvertently causing the thermostat to do this is halachically problematic on Shabbos,[1] for the purposes of this article will assume that causing the thermostat to light up is forbidden.

The Nest thermostat has what the company calls a “near-field sensor” which is their name for a proximity sensor. The sensor is used both for turning on the display when somebody comes within 3 feet of it and for detecting the presence of people in the room. The Nest thermostat allows one to set it so that the display will not turn on when the proximity sensor is triggered.

The Ecobee thermostat on the other hand does not have any settings for turning off the proximity sensor lighting up the screen. However, it is possible to effectively disable the proximity sensor by using a piece of tape to cover the sensor.

Motion Sensor

Both the Nest and Ecobee have a Passive Infrared (PIR) motion sensor used to detect the presence, or lack thereof, of somebody in the room. The presence status is used to either turn on or off the heating and cooling system without the interaction of the homeowner. Triggering the sensor on Shabbos and causing the heating or cooling to go on is likely forbidden on Shabbos.[2] Is there a way to disable this feature?

The third generation Nest thermostat has what the company calls a “far-field sensor” which is their name for a PIR motion sensor. The sensor is used for detecting the presence of people in the room. Additionally, the Nest thermostat uses its infrared motion sensor for its “Farsight” feature which turns on the screen when a person up to 20 feet away is detected to be directly in front of it. The Nest allows the Farsight feature to be disabled.

The Nest uses both its proximity and PIR motion sensors to detect the presence of people and learn the schedule of the residents of the home. When presence is not detected the Nest thermostat will set itself into ECO mode to save energy. How long it takes before it goes into ECO mode varies between 15 minutes and 2 hours depending on the habits of the residents which the Nest learns and adapts to. Once presence is detected again the Nest will set itself to the more comfortable HOME mode and heat/cool the home to the desired temperature range. Nest calls this feature “Home/Away Assist”.

Triggering the sensors and causing the system to go on would seem to be forbidden on Shabbos. What are the workarounds for this problem?

One solution is to simply turn off the use of the presence sensors in the Home/Away Assist menu. If you do this, your presence in your home will not be changed when your presence is detected by the sensors. A better solution is to simply make sure that at least one of the phones that has the Nest app installed remains on for the duration of Shabbos and have your presence at home be detected through your phone. This way even if no motion is detected by the thermostat it will not change to ECO mode.[3]

For both of these solutions there is a caveat that a phone with the Nest location tracking be plugged in and left on over Shabbos. If the phone’s battery were to die or even go into power-saving mode, the presence location enabled through the phone would stop working. If the phone’s presence is not detected the system will either rely on the motion sensor to detect presence if enabled (which is problematic on Shabbos) or it will turn the system to ECO mode (which is uncomfortable if you are home). Furthermore, it is important to remember that these solutions will not work for a situation when the homeowners are not home and would like to allow guests to stay at their home.

A third solution would be to simply turn off all devices from using the Home/Away Assist feature. When this feature is entirely turned off the Nest thermostat will remain in the mode that you set it until it is manually changed. (Note, you can only set Home or Away from the app but not the thermostat.)

The Nest thermostat is a learning thermostat, and according to their website “it uses advanced sensors and algorithms to create a custom temperature schedule”. Nest calls this feature “Auto-Schedule”. This may imply that even if the Home/Away Assist were disabled the sensors are being used to create a custom schedule. If this is true this may be problematic on Shabbos since one would benefit from the triggering of sensors, although the exact Shabbos prohibition is unclear. However, this statement seems to be overstated, and according to Nest’s own documentation it seems that Auto-Schedule only creates changes in the thermostat schedule if the thermostat is manually changed. Motion sensors don’t seem to be involved in this.

The Ecobee thermostat uses a PIR motion sensor in a similar way to the Nest in a feature it calls “Smart Home/Away”. When motion is not detected for 2 hours the Ecobee will set itself to Away mode until presence is detected again at which point it will return to Home mode and heat or cool the home to the desired temperature. Additionally, the Ecobee remote temperature sensors also contain a PIR motion sensor which, besides being used to determine if you are home or away, are also used for a feature it calls “Follow Me”, which tracks which rooms are occupied and averages the temperature based just on the occupied rooms.

Triggering the motion sensors on Shabbos would seem to be problematic, both for the Smart Home/Away and Follow Me feature. Thankfully, the Ecobee allows both of these features to be easily turned off. There are however other solutions.

Ecobee allows for the temperature to be adjusted and held for a certain period or even indefinitely. To avoid Shabbos issues with the thermostat going into Away mode automatically one can simply set an indefinite hold on the temperature and Auto Home/Away will be ignored.

Similar to the Nest, Ecobee allows the presence to be detected using a geofence by which a phone on which the Ecobee app is installed has its location tracked. This tracking can be used to set the thermostat to Home mode with an indefinite hold. With the Ecobee geofencing you don’t need to be worried about your phone dying since the geofencing to Away mode only activates when the phone is detected to have left (and not simply when it is not found in the home area).

As far as the Follow Me feature is concerned, this is less halachically problematic since the motion detection of the remote sensors is delayed. [4] However, it is possible to avoid this problem by setting up a special Shabbos comfort setting which will only use one temperature sensor, thereby forcing the thermostat to essentially disregard the occupancy of the room. Alternatively, as mentioned above the Follow Me can be turned off.

Are Smart Thermostats Really Smart for Shabbos Observers?

The idea behind smart thermostats is to design them so that they have their own intelligence and the homeowner doesn’t have to fiddle with them all the time to change their settings. If Shabbos observers have to turn off the smart features before Shabbos, this in a way obviates the point of such a thermostat since the homeowner is constantly fiddling with the thermostat settings before and after Shabbos. Moreover, since such thermostats present potential serious problems for Shabbos observance, the homeowner will be tempted to turn off the smart features permanently rendering the smart thermostat dumb.

However, there is a way to have a smart thermostat and not be bothered to constantly change the settings before Shabbos. With home automation it is possible to automatically turn off the problematic smart settings before Shabbos and Yom Tov and have those settings turned back on after the conclusion of Shabbos or Yom Tov.

While there are arguably significant issues that may arise on Shabbos in relation to a smart thermostat, Automated Abode is committed to providing you with a completely Shabbos-friendly smart home. We will respect and address any concerns you may have, and work with you to make sure that you can receive the benefits of a smart home without compromising on your beliefs. If you have concerns that you feel have not yet been addressed please feel free to comment below or send us a message at [email protected]

With the Ecobee thermostat programming such automation is easy. Every setting is configurable through their comprehensive API. For the Ecobee4 with Alexa built-in, you can even mute the mic through automation, something you can’t even do with the Amazon Echo. For those of you who use WebCore you can use this programing to automate the process.

[1] The intended function of this feature is to make it easier for one that is adjusting the thermostat to see the screen and adjust the settings. Since Jews are not allowed to adjust the thermostat on Shabbos when the proximity sensor is triggered on Shabbos it is usually done inadvertently while passing by. This would be considered a psik reisha dlo nicha lei since the passerby has no benefit from the screen lighting up. The redrawing of the LCD is only rabbinically forbidden since the contents are volatile will disappear were the power to be removed. The brightening of the LEDs may not even be rabbinically forbidden (see Rabbi Dr. Dror Fixler הדלקת נורות לד בשבת, cf. שו״ת מנחת אשר ח״א ס׳ ל) especially since they are already lit and there is no fire, heat or circuit being created. If so, passing by would an unintended consequence (דבר שאינו מתכווין) of a rabbinic prohibition which according to some is permitted. When taken in consideration with the opinions that one cannot transgress Shabbos by just walking on one’s regular way there is not necessarily a problem with triggering the proximity sensor by walking past it.

It should be noted however, if one were to approach the thermostat intending to trigger the proximity sensor that one can view the settings then this would definitely be problematic.

[2] Triggering the heating system is likely implicated in a malacha d’oraysa. Turning on a gas furnace or even an electric coil is considered maavir – burning. Even baseboard radiators or underfloor heating which use steam or water to distribute heat have this problem with the additional problem of cooking the water. Triggering a heat pump or an air conditioner might not be malacha d’oraysa but it has come to be accepted to be at least rabbinically forbidden. Additionally, causing the fan to turn on is also rabbinically prohibited. Although the sensor is being triggered by just walking by, this is at least a psik reisha d’nich lei since one benefits from the heating or cooling.

[3] Nest’s own website seems to imply otherwise: “So even if you leave your phone at home, or the battery dies, Home/Away Assist can tell that you’re gone and do things like turn down the heating, or turn it back up when you come home.” However, this is inaccurate and only true if the only thing tracking the home presence are the motion and proximity sensors. If phone tracking is enabled the system will not switch ECO mode.

[4] The remote sensors do report motion sensing in real time and only transmit back to the Ecobee thermostat in intervals of 3 minutes. For halachic purposes this will probably qualify as gramma. And since the triggering of the sensor that turns on the air conditioner may only be rabbinically prohibited there may be room to be lenient in circumstances such as this where the sensor is only being triggered by walking about one’s way and even the action is delayed.

5 thoughts on “Using a Smart Thermostat on Shabbos”

  1. Benjamin Samuels

    Have any of the major Kashrus organizations involved in Shabbat-Mode Appliances contacted Nest or Ecobee to explore creating a “Shabbat Mode” setting? Thank you, Rabbi Benjamin Samuels

    1. I have not heard anything about this. Such a feature could easily be implemented. Better yet, even older thermostats could receive such an update via an over-the-air firmware update.

  2. This article is absolutely fantastic. Thank you for taking the time to do the complex and time consuming research on these two devices. I was referred to this article because I am currently writing on article on the same issue. I thank you for providing me with the technical information that I was unaware of. My only question is, whether turning off all sensors or using the smartphone program to override the sensor, will indeed disable the sensor. Wil the sensors still be active albeit not react to the information? In other words, would walking by the turned off sensor still be noted by the device, causing some type of electronic change, even though no apparent action will be taken by the device? THANK YOU! [email protected]

    1. I can confirm that the Ecobee does indeed continue to record presence data even if the reactions to the data input are disabled (as can be seen in the Ecobee Smart IQ graphs). I imagine that the same holds true for the Nest. Although I would imagine that it would be fairly easy to design the sensors with a semiconductor switch to turn them off completely, it is probably just easier to programmatically ignore the data. I have even seen battery powered devices that continue to run their sensors even when they are programmatically turned off. For example, the popular Arlo wireless security cameras will continue to detect motion when the cameras are turned off and set to “private mode” in the mobile app. I know this because I noticed the IR light still comes on when passing by them. I observed something similar with the Blink cameras.

      When motion is detected in a PIR sensor there is a measurable electrical change that can be observed. Sometimes the data is recored even when not actually used. Despite this, causing this to happen on Shabbos is not problematic. Causing electrical fluctuations on an already open circuit does not violate any melacha. The recording of useless data encoded in binary 1s and 0s also does not violate any melacha. Passing by such a sensor is the equivalent of walking through an area which is under security surveillance (when the live footage is not being actively displayed on a screen), or speaking in place where audio is recorded. In this day and age it is almost impossible not encounter numerous such issues on Shabbos. Even opening a faucet may cause data to be recorded.

      I look forward to reading your article.

      1. Thank you for your response. Can you let me know your email via my my email [email protected]? I had a feeling that it works as you describe that shutting off the sensor doesn’t really do that, although as you point out, its not an issur to pass by such a thing. I would like to discuss with you the nest and arlo security cam, but maybe it would be best in an email.

Leave a Reply

%d bloggers like this: