This was originally a joke between a couple of us when I first started looking into home automation, but with iOS 10.2 adding notifications in many classes of devices, I've finally been able to make the dream come true.
The goal was to make it so I know before walking into the shitter if someone left it smelling like shit. Elgato Eve makes the Room sensor which is an air quality sensor that detects volatile organic compounds, AKA shit particles in the air. Threw one of these badboys in the bathroom, and now it can track precisely when it smells like shit, every 10 mins.
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It classifies air quality based on the amount of VOCs in the air, and after a couple of baseline shits, I was able to confirm that taking a dump with the fan off would spike it to the Inferior level. Once it lowered back to fair, I walked in, took a huge wiff, and confirmed it didn't smell like shit anymore.
I added a Philips Hue Bloom outside the bathroom door, and 2 triggers in Homekit. One to turn it on red when air quality changes to Inferior, and one to turn it off when it goes back to fair. So now, anyone taking a shit in the bathroom will light up the outside red, warning other users not to go in there until the red light turns off.
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This is officially the dumbest yet greatest in using home automation. As a bonus, we can now see who has the worst smelling shit.