Occupancy vs Motion Detection.

When I first started working with HomeKit, I certainly used geo-occupancy. So things like "When I arrive home....". However, what I really wanted was a room to know I was in it, and so I started to implement Motion Sensors. I used Hue, as I don't want too many different platforms to manage. Now these are great when you have an area which has continuous movement and not too many entrances.

So, why are those two items important?

Continuous Movement

Continuous movement should be obvious. It's a motion detector. Therefore, you need continuous movement to know if someone is in the room. Which means if you stop moving, then the motion sensor thinks no-one is in the room. This is problematical in spaces where you do not move much, such as when watching TV. Potentially, even eating in the dining room, if the sensors are not sensitive enough, could be an issue.... depending on how animated you are. Or the bathroom, when you are having a shower.

HomeKit has an interesting way to get around most of the limitations in this area. Essentially, you can turn off your automation after so many minutes, but it resets that count every time the motion detector senses motion.

So, you walk into a room and the lights come on. You can say "Turn off after 10 minutes". If you don't move for 10 minutes, the lights turn off. However, if you do move then the countdown to 10 minutes starts again.

What you have to do is balance this countdown against how long you want the lights to stay on when you leave the room, and thus wasting energy.

Lots of entrances.

This becomes an issue because where do you place the motion sensor in the room? You need to cover the entrances when placing a motion detector, especially if it is because you want to turn lights on. My kitchen has 4 entrances on 3 seperate walls, which means that at least one entrance is not covered at all and thus delaying lights coming on.

Occupancy detection.

This is actually what you need. You want to know if the room is occupied. There are various solutions out there for this. I have seen them based on a phone location, and one is based on phones and/or watches. However, for me, that doesn't work. I don't always carry either of those and how do you program for a phone/watch of a visitor?

For the last 12 months I've been running a beta for Hiome. This is an occupancy detector. The way it works is that it has a sensor over the door and it counts people entering or leaving a room. It also understands the concept of "outside". The integration with HomeKit is done a raspberry Pi hub, again. And, right now, it is not a certified integration.

Above, you can see me walking through a section of my house. The video is in real time. I walk from the Dining Room to the Guest Bedroom, to the Hall, into the Family Kitchen, back out to the Hall, into the Kitchen, and then return to the Dining Room. You can see how quick it is.

Following is a comparison between motion detection and occupancy detection with regard to speed as I enter a room opposite the motion detector. The initial detection I snot too bad, but it takes a while for the motion detector to know I'm no longer in the room.. and remember, you may add extra time to deal with being inactive. Whereas with occupancy detection, it knows I'm no longer in the room as soon as I walk out.

When I walk into the room from a door on the same Side of the room as the motion detector, the lag between occupancy detection and motion detection is significantly different. There is a 4s delay, which means I'm virtually on the other side of the room before the motion detector spots me.

To make a room work, it means that you have to have a sensor above every door. This is not as bad as it sounds as the sensors are directional.... they actually know which way you are moving. So, my Dining Room has 3 entrances from 3 rooms, but that means that the sensors over those doors also act for those adjoining rooms.

As an example, below is a section of my home. The Black rectangles are where the sensors are over the doors. 

You will see there is one sensor between the Living Room and the Vestibule, which means the Living Room is covered. It also contributes to covering the Vestibule which also has the front door and another sensor that covers the double doors going into the Dining Room, etc. Initially, when I was running the beta that was all I covered. However, I was so impressed I decided to cover the entire house (Another 4 rooms not shown here).

With Hiome, the sensors also act as door sensors, so they know if the door is open or not. So, you are really getting 2 sensors in one.

Now, would I say they are the most beautiful sensor I've ever seen? No. However, there is only so much you can do when retrofitting. It's good to see that they have sensors that you can bury behind the door way so that you can't see it... but that's really only feasible when you are building from scratch or remodelling.

Do you really notice them? I can tell you that when you live with them, you ignore them.... and I've never had anyone point them out to me... so don't be distracted by the video.

As far as I'm concerned, they are the best occupancy sensor I've found to date with none of the limitations mentioned earlier.

Automation with occupancy sensors

Unlike Motion sensors where you will tend to switch on devices and then start a countdown to turn off the devices, with occupancy sensors you'll create separate automations. At least one for the room being occupied and not being occupied. However, I've increased that as I also have automations for certain times of the day so that if I'm wandering around at night, I don't blind myself.

Above is a simple automation for the Living Room, which is where the TV is. Remember, when you re watching the TV, you tend not to move... so a motion detector does not really fit the bill. You may also note, from the last post, that I had the Light Strip set for 50% when I turn the TV on... which means I dim the lights in the room to watch TV.

Here, the logic is:

IF 

    Occupancy is detected in the Living Room 

AND

    time is between 30 mins before sunset and 30 mins after sunrise (Basically over night)

THEN

        Close the Living Room Blind

        Turn on the Lightstrip to 100%

        Turn on the Side Lamp to 51%

        Turn on the Standing Lamp to 50%

END

The way that HomeKit works is if the blind is already closed, or the lights are on, then it ignores what has already been done.

If I am watching TV more than 30 minutes before sunset, which means the Lightstrip is already on and the Blind is already down and then 30 minutes before sunset happens, only the Side Lamp and the Standing Lamp come on.

Having said that....

I have kept the Hue Motion sensors I already had because they also detect temperature and light levels. This enables me to start to move away from times of the day to turn lights on, and actually do it because of the light level. This was really important a few weeks ago when the middle of the day was like dusk, due to the smoke in the air from the wild fires. The temperature sensors also enable me to turn on ceiling fans and close blinds but, yep, that's another post!