I am quadriparetic, wheelchair dependent with limited and function, so I pay a lot of attention to the various hands-free control options.
MOTION SENSORS HAVE A LOT OF FALSE ALERTS
That said, in my own house I never use inactivity from motion detectors to turn lights off. They always fail at the wrong time. It’s true there’s a lot of different scheduling tricks you can use to try to make them work well. But it’s just such an annoyance when the lights turn off when someone is in the room that I don’t even go there.
There’s also the issue if you have anybody who is potentially subject to falling, seizures, heart problems, that if you just use motion sensors the person might fall to the floor, pass out, and wake up in the dark.
ZONE DETECTION WORKS BETTER, BUT INCREASES COST AND COMPLEXITY
When people are talking about multiple motion detectors, they aren’t talking about one for on and one for off. Instead, they are talking about the “zone detection” where the lights turn on because there is motion on multiple sensors, or turn off because there is inactivity on multiple sensors. All designed to reduce problems from the inherent unreliability of motion sensor technology.
MOTION SENSORS AS INTENTIONAL SWITCHES
I personally do use motion detectors as touchless switches. But the detector is in a box that someone waves a hand over as they go past. An intentional gesture.
Back to these case you described. This is called “microlocation.” Everybody wants it, nobody has it now, at least not for less than many thousand dollars per room.
The Kinect is a really good device for knowing that there is more than one person present, but only in a range of 6 to 8 feet. There are actually hospitals using this for patient detection in some wards. But it’s a cost of several hundred dollars per device. And it’s only for this limited range. Great for knowing if an Alzheimer’s patient has gotten out of bed, but not really suited for the room light scenario.
Sometime in the next 10 years we’ll have exactly what you asked for at a lower cost, probably by a device that listens for heartbeats.
I beacons are another option, particularly for those with iOS devices, but as others have mentioned you have to have a device with you.
It’s possible to put a plug-in tablet in each room and use that as the beacon detector, and then give each person a beacon to carry around with them. Perhaps even worn with a belt loop or a bracelet band.
This has some interesting possibilities, and it keeps the Beacon detection from
Burning through The battery life on your phone, but it does mean each person has to remember to have the device with them. Including your guests. That can get tricky.
Also since Ibeacons use Bluetooth, they are not stopped by walls which means even if you have a pretty small region, say 6 feet, it might pick you up on both sides of the same wall.
This is actually the approach that I am currently experimenting with, but again I’m in a personal situation where it’s worth investing more in touchless solutions. Although to be honest it looks more and more like voice control will be the solution for my case. But that does require someone remembering at some point to say “lights off.” I am successfully using a Beacon on my wheelchair to trigger a tablet at home so that it picks me up just as I reach the base of the ramp to my front door and it knows the difference between me and my roommate coming home.
YOUR USE CASE
If you could tell us a little more about the use case details you’re considering, we might be able to make some practical suggestions.
For example, if your household includes someone with Alzheimer’s or on the autism spectrum and you really need things to happen even though the person doesn’t intentionally ask for them, that’s one situation.
If your entire house is set up with solar power and you need to take extreme energy saving measures, that would be a different situation.
Or if you have a light in a closet that people always forget to turn off.
Or, if you just think it would be cool and convenient to have the lights come on when someone walks in the livingroom, that’s different yet again.
There are technical solutions for the base case you described, but it’s a question of cost and priorities. When it comes to meeting the budget for a typical household case then there’s no one single approach right now, but there are some options that might fit depending on the details.