Bathroom Exhaust Fan and Arrival Triggers Solutions?

For your light request. If you dont need anything fancy and you want the light to come in every time someone comes home?
I use smart lighting for this. It has worked great ever since I set it up. Turns on back deck light and an inside light. I then use other automation to turn them off automatically.


Thanks for your response. That sounds awesome. No user action needed with your setup. Just walk in and walk out. I would definitely be interested in hearing more about your setup when you have time.

To keep it simple to start with, I’m just looking for the exhaust fan to turn on when needed and off when not. Your setup with the 5% humidity trigger sounds like a great start. When the humidity falls back down 5%, then the fan can turn off.

I was thinking more along the lines of the fan turns on so the humidity levels never change, at least not higher anyway, because the fan is on. Once someone is done with a shower, the fan would turn off. I would much rather your way where the user doesn’t have to turn anything on or off. 100% automated.

Thanks again

I’ll try and pull the screen shots and post later this evening, if not tomorrow when my wife is working. I fell asleep last night so should probably spend some quality time with her tonight. The pistons aren’t complicated I just have them tied into my whole house humidity and I also have a timer so that if someone manually turns on the fan, like because of smelly bathroom cleaners, it will time out.


Thank you for your response as well. Your setup seems simple enough. I see presence is your trigger and I see your three “sensors” used. Don, Sandee and Aubree. I assume those are key fobs or smart phones or the like?

My question is what happens when Sandee and Aubree are already home and their sensor device is already “online”, what happens to the lights you have set to trigger with those sensors? What happens when you arrive home? Is the app and hub smart enough, with or without some tinkering, to know that there will be times when some people will be home and some won’t?

thanks again for your help.


Quality time is definitely more important!!!

take your time responding. i’m in no rush.

thanks again!!


I’d be interested in seeing your CoRE pistons for this. I’m currently using this app Bathroom Light Control, but I would like to migrate the logic to CoRE so I have greater control and flexibility.

This is what I’m trying to accomplish with a motion and humidity sensor.

  1. Turn on light and fan when motion is detected
  2. Turn off light after x minutes of no motion detection
  3. Turn off fan after x minutes of no motion detection
  4. Extend light off timer to 25 minutes if humidity sensor is above the average for the room and trending upward (shower in use)
  5. Extend fan off timer until the humidity level is back down to within 5 percent of the 24 hour average


Reader digest answer is yes, whenever any one of the 3 presence goes to arrived the lights turn on. That is because I selected to turn on when someone arrives. It’s not shown but I have also restricted it to between sunset and sunrise.

Long answer. There are probably lots of ways to do this. Here is what I am doing just for your reading.

The 3 presence you see above are actually virtual presence devices. They are controlled by a smart app called Reliable Presence. It takes multiple real presence devices phone, FOB, Life360, WiFi detection (whatever). It combines these into 1 presence. This is to increase reliability. In that if one real presence device (say FOB ) sticks in on or off state. When any other of the real presence devices change. The virtual one is changed to match the one that left or arrived. Vice being stuck in a state because say the FOB battery died, or phone presence is acting up.
We use phone presence and the FOB in my system.

Hope that makes sense. See this thread for more info.

Please ask more questions if you think of something else.


Thanks for that info. I’m going to read over the smartapp link you sent me.

So fobs that are sold and smartphone apps that trigger arrivals and departures are smart enough to know that Fob A has “Arrived” an hour ago and therefor won’t keep turning on the hallway light.

You mentioned using the FOB and phone presence. So each of the three listed “sensors” in your config are your virtual sensors consisting each of one FOB and one smartphone, combined using the app you linked to? So each person has a fob AND phone to trigger there arrival or departure?

Thanks, sorry, just making sure i understand this correctly.



thanks for your idea. your list sounds great. seems to have most bases covered. just one thing though, make sure the motion sensor for the light is within site of anyone who may be “reading the paper” in the bathroom. Would hate to have the lights go out… :slight_smile:


Yes. We each carry a smarthings FOB, girls in their purses, me in my backpack I take to work. Then when we each made our smarthings account we set up our phones to act as a presence sensor.

I set up the reliable presence app because my daughter likes to leave her purse in her car as she comes and goes for the day. Where she parks puts her FOB on the edge of detection. Also my wife would turn off her WiFi on her phone so her phone presence would sometimes fail.

The FOB and phone will signal the hub every time they think they came or left. (That’s a real basic way to put it) The smarthings system in the cloud is doing the thinking and tracking based on your rules you make using apps like smart lighting, core, ect…

For example in my Goodbye routine the logic I picked says when “Everyone Leaves” (so all 3 persons presence is away) then turn all this stuff off, make sure door is locked, and so on…

Smarthings is very versatile in setting up what you want it to do and when you want it to do it.

Thanks for all that information. Sounds exactly like what i’m looking for.

I hope is to have a setup similar to yours where when our parents come over to visit their granddaughter, their FOB’s and phones trigger the outside light by the side door to come on. When I come home or my wife comes home, our FOB’s trigger the garage light to come on. Of course, in both scenarios, the opposite should happen when those sensors leave the premise. Side door light off, garage light off etc…

I’m curious, Don, did you play around with different FOBs or did you just go with the ST fob without looking at others?? I purchased one ST fob and one of the Aeon Labs key fobs so i can see which one works best for me. From what i can gather the Aeon Fob doesn’t act like an arrival/departure sensor unless a button is pressed. Would be cool to have it act like the ST fob AND have 4 buttons for other random triggers. Oh well.




Here are my pistons and a simple smart lighting rule to control bathroom humidity. The pistons are from the original CoRE program.

Lighting for me is simple. Sense motion, turn on light. If door is closed, light won’t turn off. By using the door sensor, I removed the problem of the light turning off while showering (not seeing any motion or using multiple motion sensors) or if your sitting quietly in the bathroom for awhile. I also used it for updating the global humidity variable. I’m sure I could have written logic to work without the door sensor but, I had the sensor and it made sense to use it.

First, I’m using an Aeon gen 5 multsensor to monitor motion and humidity. I’m ignoring lux and temp. I have the humidity set to update every 4 minutes and motion to 1 minute. Because of these settings, I only get 2-3 months out of a set of batteries. I would think any Multisensor would work as long as you can adjust the update schedule. I.e. If it’s only reporting humidity every 16 minutes it’s not going to do you much good. I know from experience. I played with different humidity update times and 4 minutes seems to work the best for me.

For the bathroom door, I’m using a simple go control window/door sensor. Nothing fancy.

Above is my simple smart lighting rule that shuts the bath fan off after 60 minutes regardless of conditions. You can set this to whatever time you want. My wife will take approximately 60 minute baths and without the fan running, the room will get too warm. Yes, the humidity rises just about as fast during a bath as a shower. I was surprised by this, though this is a small room in our home.

Above is my piston that captures the humidity level of the bathroom each time it changes as long as the bathroom door is open. I use this value as a reference and I don’t want it to update when the door is closed (possibly showering).

In this piston we are storing the humidity in a global variable called @BathroomHumidity. The “@” sign makes the variable global so it can be used in other pistons. As long as the door is open and our virtual switch called “Humidity Bathroom Exhaust Latch Switch” is off, we update the global variable. I use the virtual switch to keep track if the fan is on because of rising humidity.

The above piston sets a virtual latch switch (manual bath exhaust latch switch) if the fan is turned on manually. My bride will use cleaners and will often turn the fan on to vent the bathroom. We don’t want the fan shutting off during this manual turn on state. This piston also resets both virtual latch switches when the fan finally turns off for any reason. Either by manually turning it off, dropping humidity level or timing out from our simple smart lighting rule that sets a 60 minute max run time.

The piston above is the piston that controls the fan based on humidity. The first IF/THEN checks that the door is closed, the humidity has risen 5% above our stored value and also makes sure we are not in a manual latched turn on state. If all of this is true, we turn on the humidity latch virtual switch and then turn on the fan. I believe I found I needed the short delay befire turning on the fan to get the virtual switches to set correctly. It’s been awhile but I know I needed the delay.

The ELSE/IF looks for two conditions. The first checks and makes sure that the fan is on because of humidity. If it is, it looks at an outlet that controls my house humidifier (humidifer outlet) to see if it’s on. If the outlet is on, the house needs the humidity so the fan will shut off as soon as the door opens to let the needed humidity escape into the house. If the house doesn’t need the humidity, the fan continues to run.

The second part just checks to see if the humidity is now low enough to turn the fan off. I used a value of within 1%. Here is why I had to use virtual switches. If the fan is on because of humidity and the door is open, we don’t want our global variable updating.

I live in Northern Michigan and indoor humidity level here in the winter has a lot to do with the outdoor temps. The lower the temp outside, the lower the ideal humidity inside or your windows and walls will sweat. This is why I tied the bath humidity to the house humidity. I can also use a much smaller humidifier by using the bathroom to help humidify the house. I found a smart app that looks at outside temp and inside humidity to decide if the humidifier should be turned on or not and control my humidifier outlet with that app. Since setting this up, I rarely get sweaty windows and my wife’s sensitivity to the winter dryness has gone away.

I know there is a lot here. Any questions ask. I try to get on daily but sometimes it’s every couple days especially during the weekend.

Best of Luck
Steve J

No ,I just bought the smarthings FOB.

As far as the light turning off when they leave. That is an option if the light is already on. For our back door light. I installed a door contact sensor. So now when the door opens, and it’s between sunset and sunrise the light turns off.
I then turn that light off automatically be 0 minutes later.

Great point! I hadn’t thought about the presence sensor triggering the outside lights during daylight hours. I know the first time i have this setup i would have noticed and said “duh”. Interesting that you chose a contact sensor. I would think that the outdoor light could have two rules, one related to the presence sensor and one related to sunrise/sunset settings. Of course that depends on if you have other devices being triggered from the same sensors.



Thanks for all of that information. Definitely a great starting place. I’m going to get my presence sensors working first. my wife and I just moved into our new house two months ago. We have a whole house humidifier. I’ve always been hesitant to use it because of moisture in the duct work. Not sure I’ll go that far as to incorporating it into my setup. I found the Core community page and definitely have a lot of light reading to do… :slight_smile:

I appreciate your help as well and will definitely return in a couple day when i have time to absorb the information and get my devices setup.

Thanks again,


You are welcome. My humidifier is not connected to my furnace either. It’s a small portable that we use only in the winter months. During the summer we have the opposite problem and have the AC removing the humidity.

I figured I’d be done by now, been at it for a couple years, but I’m still finding devices to add or just additonal control to existing devices and rules. I don’t think people like us will ever be done.

The sunset to sunrise is a restriction the keep the lights from turning on when someone arrives outside of those time limits. It’s part of making your smart lighting rule.

The door contact sensor can serve as a trigger for multiple things. I currently use it to turn on the light when we open the door and it’s dark outside Also so my Schlage lock knows if the door is opened or closed.

I see. Thank you so much for all the information.

This is definitely going to keep me busy on my next day off.

One other question i cant seem to find an answer for. When installing smartapps using a GitHub repo, how do I know which files need published and which don’t? If there isn’t a simple answer, i’ll keep doing some searching and reading.

Thanks again.

This monday is my day to play. :slight_smile: I’ll report back and let you know how everything goes.


Well, I really don’t know the answer to that. Typically I read the install directions for what I’m setting up and follow that.
After its i installed you can see what has been published since it tells you that in the IDE list of apps and device types.

There has been very few things I’ve set up that didn’t need published. I am still new at this so not a definitive answer.

Thank you very much!