Occupancy sensor vs motion detector: what's the difference?

Can anyone tell me what exactly is the difference between a dumb occupancy sensor and a smart motion detector?

I have a lutron occupancy sensor in my downstairs hall bath and that thing is incredibly fast, and the bonus, it has never failed to turn on the light. I never walk into the room in the dark, it is literally instant.

It’s a totally different story with my Zwave motion sensors. I have two Ecolink sensors and an enerwave ceiling mounted one. The Enerwave is pretty good, and it’s light years beyond the Ecolinks.
But even it has its flaws.

I’m tired of walking into a dark room and hitting the wall on the opposite side of the room, beneath the motion sensor, before the light comes on.

So, I’m thinking of getting a couple of dumb occupancy sensors and hard wiring them into an Ecolink door contact.

Do you think I’ll see the same problems? Is the lag because of the hub/cloud?

I have noticed that sometimes the Zwave sensors take forever to notice I’m in the room (based on the light flash at motion detection).


GE/Jasco announced dimmers with built in occupancy/motion at CES. The zwave alliance website has the press release.

I have no idea why it’s taken so long for this sort of combo unit to arrive. I’ll be getting a handful.

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strange I have ecolink motion sensors and they are instantaneous… and using smart lighting with local control the light also comes on instant every time unless hub is down etc.

I got them due to the pet immune feature… the dogs have also never set anything off.

The drawback I have is that they stay active for 3 minutes instead of turning off the instant motion stops, but I have learned to work with that? Have you checked the dashboard and logs to see if it is actually the motion sensor failing you or something else in one of your rules?

Their range also is not that far, maybe 30 feet… that could be your issue as well?

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There have been a couple of forum topics on this in the past. We’re really talking about several different things here.

One) first, the reason why in the past there haven’t been light switches that also had motion sensors in them is just because of the size of the Z wave radio. Since the new Z wave plus devices are smaller, we may start to see more. There is one Zigbee device which has been out for a while that could do this, but it’s kind of ugly.

  1. if you have a Lutron occupancy sensor (they may be the first people who use that term) it’s not a “dumb” device. It’s a very smart one. It’s just not zwave or Zigbee. Lutron is an engineering company which is dedicated themselves from the beginning to making the absolute fastest most reliable automated lighting, they hold a lot of patents. It’s hard to compare anything else to their devices. No one else puts that amount of energy into perfecting a light switch.

Three) in most cases, it’s actually better to have two separate devices, one that controls the switch, and one that is the motion sensor, because this allows you to put the motion sensor wherever it makes the most sense. Or even to use multiples for zone detection. Otherwise, and you see this in some office conference rooms, you get the situation where you have to stand up every 15 or 20 minutes just to keep the lights on. :wink:

Some past discussions:


@codytruscottcodytruscott, I can’t wait to see them. I’ve always used the occupancy sensors and their quality is so much higher than what I’ve seen with the Zwave motion.

@lgkahn, I honestly hate the Ecolink motion sensors. I guess my expectations were too high and they were my first experience with the Zwave detectors. I’ve just been nothing but disappointed.

Response to #1 - I look forward to the future of the technologies. I see great things as a result of the diy price point increasing interest in the concept.

Response to #2 - Lutron rocks!

Response to #3 - I’m going to try this in the garage. It’s a large room with obstructions that can test out my idea pretty well. I believe in multiple devices as that provides better coverage and creates less negative results.

I’m thinking of taking two lutron occupancy sensors. I’ll put one each in the corners at the back of my garage. I’m going to place these in after construction wall boxes. They will not be placed in the wall. I’ll use a hard wired extension cord to power the devices.
I’ll wire both off them together with an Ecolink contact sensor in the center. When either one, or both, detect motion they will trip the sensor. Once motion stops, the sensor will trip again.
This sensor will talk to the hub allowing for remote control, monitoring, and scene implementation.

I’ll post pictures here of the project and let everyone know how this works out.

FYI, this is in response to having to rebuild my entries system this week due to what I believe is the Enerwave motion sensor. Also, yesterday I started using one of the Ecolink sensors in my office and I am deeply dissatisfied.

Actually if you open the ecolink sensor there is a little black jumper and some pins you can play around with and set it to a test mode so it stops reporting motion within seconds instead of 3 minutes. That’s how I have all of mind set.

I did that… it still times out at 1 minute vice 3 minutes.

The problem is how long it takes to pick up motion.

I have this same problem with my closet and ended up moving the sensor for outdoor instead.
It’s a pir sensor so some strategic position is required.
The one minute timeout is only for light with ST. I can’t get the light to go off less than a minute with smart light smartapps and yet my motion sensor timeout in 5 seconds.

The biggest reason the Lutron sensors work so quickly is they talk directly to the light switches. That is, the light switches are programmed to be listening to RF commands, ones that you set up ahead of time and download to all of the devices in the house. This way literally any of them could be controlled by anything else capable of being part of a scene. The motion sensor programming is able to issue commands to devices both upon detecting presence and again based on vacancy. That and the commands sent need not be the same or toggles. I’ve got a sensor in a porch shed that turns on just one light but turns off several other that might have gotten turned on incidentally. But it does those based on a longer delay until it start turning them off, and then does so more slowly. As in, waits two minutes and then does a 10 second ramp-down of the other lights. This way someone doesn’t get stuck in the dark should there not have been enough motion to keep the sensor in occupied state. They’re quite nice.

Well in very basic terms Occupancy Sensors are what is considered a “next generation” technology. It is based not only on motion but also on sound. It also may include other forms to identify presence in a room. infrared (body temp compared to the surrounding)

Example: Every been working late at night and talking the phone only to have the office light go out after 20 or so minutes after everyone else left in your area. You then have to wave your arms to get the light back on. This is an example of a “Motion Sensor” as it could not identify that you were present by the sound of the conversation in the room.

Occupancy sensors are not limited to just motion but also sound and (in some cases infrared) body temperature compared to the surrounding environment. Often hotels this technology to identify if someone is in their room to activate / deactivate the A/C Units or Lighting.

The two technologies have different focus applications. For example: One one hypothetically “Is anyone out there?” and seeks any form of response by their sensor. The other says “Is anyone walking over there?” It doesn’t care if anyone is moving over here or is talking/sitting.

So I have a sensor at my desk it’s also in my bedroom. I have the motion sensor set to identify if I am at my desk. But have the circulation fan turn on if i’m in the room (occupancy). It also turns on the Portable AC Unit in the room when Occupied and temp is over 76) I also have the sound portion set to turn on the lights in the room when my alarm goes off. In my example since the room is larger and is dependent on sound it is slower to respond than when I am walking and sit down at my desk which is only a 5x5’ square (instantaneous)

The lag or lack thereof is most likely a function of the area being observed by the sensor the larger the area, the more data for the device to process to identify motion or occupancy. An area like a bathroom is a vary small area so much faster to identify.

Hope that put things in more of a perspective.