Occupancy Vs. Motion

[broconne]

The Wiring your new Home 101 guide doesn't seem to discuss too much about occupancy sensors. There is some discussion about motion sensors. I was going to put occupancy sensors in all bathrooms (turn the fan on if occupied for a while - ahem).

Do people run occupancy sensors elsewhere? What do they use them for? Any reason to run a motion over an occupancy?

 

[tmbrown97]

Others will probably have an opinion - but I believe Occupancy is typically for direct load control, whereas motions hook into something like an Omni or an Elk system and can be used for rule-based automation. For purposes of controlling a load, they are basically the same thing - if you sit totally still - say, in the bathroom, it may not detect you anymore - but if you're fidgeting a lot, they'll keep picking you up. Motions tend to have fewer false alarms and you can decide if you want pet immune or dual-technology (PIR and Microwave) for excellent immunity against false alarms... and when controlled by an elk or omni, you can basically set a timer - each time you detect motion, you reset the timer - until it sees nothing for 10 minutes or however long you choose. It really depends on if you're looking for simple load control or some type of automation/computerized solution and how much you want to spend.

I can also tell you that I absolutely hate those in-wall motion sensors... I've never gotten them to detect well or work with CFL's... Last house they'd come on randomly all night long... and in the laundry room you'd have already stubbed your toe before it'd come on...

 

[Madcodger]

For automation, occupancy can also be thought of as the state or status of an area. In other words, if motion is detected WITHIN a specified time period, the area is said to be occupied. If not, it is vacant. This means that you don't have to have constant motion, or body heat, or any other constant input to determine that an area is occupied. You just have to have this occur at least once (or twice, or whatever you determine) within a given time period. This starts to become important if you're using motion sensors to determine whether or not an area IS occupied, and can allow you to use less expensive and / or less sensitive sensors to determine occupancy. This may sound like an unimportant or abstract idea, but many people don't seem to wrap their heads around it and end up struggling with their HA systems because of that.

 

[ano]

Occupancy sensors are designed for maximum sensitivity so they catch the smallest movements. Motion detectors trigger an alarm, so they are designed to be REALLY sure there is movement, and usually they are designed to minimize false alarms. I use sensors that can be both by toggling a terminal high or low. For occupancy, either the microwave OR the passive IR will trip them, for motion detector, both types must trip within a certain time period. I use may HAI panel to toggle them from occupancy/motion when I set the alarm in AWAY.

 

[Lagerhead]

This may not advance the discussion, because AFAIK this is only a direct load carrying unit, but I have to say I have been very impressed with the occupancy sensors in my new office space.

They are Sensor Switch WSD-PDT wall switches. What is good about them is that they really, truly know when people are in the room, whether a small office or a larger conference room. The brochure describes "dual technology . . . that allow this sensor to see and hear its occupants," apparently having both PIR and Microphonics(tm).

They come on instantly when you enter and do not go out, I suppose even if you sleep (haven't had that luxury in the office).

 

[intozwave]

As stated before Occupancy sensors control a load in a certain space - there are several different technologies that occupancy sensors use:

Passive Infrared Occupancy (PIR) Sensors

PIR sensors use a semiconductor detector to sense the movement of infrared heat emitted from the human body. They require an unobstructed line-of-sight for accurate detection. Any furniture or decorationsthat block the sensor’s view will prevent an occupant’s movement from being “seen” by the sensor. The sensor will respond when a person moves across the sensing zones monitored by a multi-faceted Fresnel lens. Generally, PIR sensors respond to larger movements than ultrasonic sensors and work best in small, enclosed areas where there are high levels of occupant motion.

Ultrasonic Occupancy Sensors

Ultrasonic occupancy sensors act as transmitter/receivers, continuously sending out ultrasonic sound waves and responding whenever they “hear” a change in the transmitted wave’s frequency caused by a shift in position of a person relative to the sensor (doppler shift). They do not rely on line-of-sight sensing and are, therefore,
more effective in sensing motion around corners and in cubicles. They are also more sensitive to smaller motion than passive infrared sensors and are particularly appropriate for locations where only small amounts of motion are taking place.

Multi-Technology Occupancy Sensors

Multi-technology occupancy sensors combine both passive infrared and ultrasonic technologies to provide the most reliable detection means possible. They are triggered ON by passive infrared sensing and, once triggered, are kept ON by either a passive infrared or an ultrasonic detection signal. They combine the best of both technologies
with long-range detection from infrared technology and high sensitivity from ultrasonic technology.

Motion Sensors at this point work on the same premise as the PIR Occupancy Sensor except they are not tied to a load - so when the Motion Sensor detects motion you can trigger any action you want basically.

You see Occupancy Sensors commercially much more than residential - I am looking at putting a couple in my house to take care of certain rooms that I cannot put a Z-Wave Switches in (Fluorescent Lights - 50 year old house with no-neutral in the box) - what would be really slick if someone came out the an Occupancy Sensor with Z-wave built-in

 

[Lagerhead]

I am looking at putting a couple in my house to take care of certain rooms that I cannot put a Z-Wave Switches in (Fluorescent Lights - 50 year old house with no-neutral in the box) - what would be really slick if someone came out the an Occupancy Sensor with Z-wave built-in

Though it's a kludge, having current sensing on the load is one way to get the result.

 

[robolo]

Here is a really nice link from the state of Maine Public Utilites Commission explaining the different technologies for occupancy sensors.

Occupancy Sensor Technologies

Passive Infrared (PIR) Occupancy Sensors
Passive infrared sensors monitor the patterns of back-ground heat energy in the space. When the sensor detects a significant change in the background heat energy it responds by automatically turning the lights on, or by allowing the lights to be turned on manually. When the background heat energy returns to a stable condition, the sensor turns the lights off. Passive infrared sensors must have a direct “line of sight” to occupants in order to detect human presence. In order to minimize false sensing, the sensors are designed to respond to the heat energy wavelengths that are emitted by humans.

Active Ultrasonic Occupancy Sensors
These sensors broadcast sound waves at frequencies much higher than the human ear can detect. The sound waves bounce off of walls, objects, and people. When the frequency of the sound waves returning to the sensor changes (the Doppler effect), motion is detected and the sensor goes into the occupied mode. When the sound wave frequencies stabilize, the sensor turns the lights off. Unlike passive infrared sensors, ultrasonic sensors can “see” around objects and surfaces as long as there are hard surfaces in the space.

Dual-Technology Passive Infrared and Active Ultrasonic Occupancy Sensors
Utilizing both passive infrared and active ultrasonic technologies, these sensors are designed for use in large areas, in spaces that are difficult to cover, and for areas where maximum reliability is important for safety or productivity reasons.

Dual-Technology Passive Infrared and Microphonic Occupancy Sensors
These differ from the sensors described above in that no sound waves are transmitted by the sensor. The passive infrared technology senses initial movement and continues to monitor the infrared activity. In addition, a microphone monitors sound waves and keeps the lighting on until sound activity stabilize

Occupancy Sensors With Daylight Override
Many manufacturers now offer occupancy sensors with built-in daylight sensors. The daylight sensing can be adjusted to keep lights off when there is sufficient day-light, even when the space is fully occupied. These sensors are a great choice for private offices that receive significant amounts of natural light.

 

[felixrosbergen]

Occupancy sensors are designed for maximum sensitivity so they catch the smallest movements. Motion detectors trigger an alarm, so they are designed to be REALLY sure there is movement, and usually they are designed to minimize false alarms. I use sensors that can be both by toggling a terminal high or low. For occupancy, either the microwave OR the passive IR will trip them, for motion detector, both types must trip within a certain time period. I use may HAI panel to toggle them from occupancy/motion when I set the alarm in AWAY.

Ano: Can you provide a part/number or link?

Anybody know if occupancy sensors that would go in a wall swich location and have decora face and are not direct load control?

Basically I have my switch location expanded for an extra gang. This could be either a scene switch (for ALC) or if it fits some sort of occupancy sensing. I already have PIR for security purposes in some of the rooms, but not all.

 

[felixrosbergen]

http://www.smarthome.com/2520W/Leviton-Com...DS10-IDW/p.aspx

Any ideas on how to make these work for LV?

I guess one possible way is to not have direct loads and instead run the HV wire to a relay to trip an Elk input which is then picked up by CQC and in turn turns on the lALC based lights....seems a bit convoluded approach to me.

The devices themselves look promising..just need to figure out how to work with them...

What i don't like about these things as a direct load control is that there is no rampup/down to preserve the bulb life, i guess since they're mostly commerical use it doesnt matter? In my applicable the delays woudl probably be set around only a few minutes and i don't want that many cycles on my lights...

Here is one from GE that is LV only, but doesnt appear to have local overrides...this one still needs some work to become an input to the house contol system..


http://www.geindustrial.com/publibrary/che...mrsen-wlv%7CPDF

 

[tmbrown97]

Just a comment on the Leviton one mentioned above - that looks exactly like the ones that were put throughout our office here 6 years ago as required by code during remodel. Since then about half have gone out. I can't guarantee it was the same model, but please do some research before buying it for longevity ratings. As far as detection goes, they worked great though - eventually they just stopped controlling the load.

 

[felixrosbergen]

Just a comment on the Leviton one mentioned above - that looks exactly like the ones that were put throughout our office here 6 years ago as required by code during remodel. Since then about half have gone out. I can't guarantee it was the same model, but please do some research before buying it for longevity ratings. As far as detection goes, they worked great though - eventually they just stopped controlling the load.

Thanks for the word of caution...but i woudnt want them directly controlling the load anyway...

I am trying to find a dual technology wallmount decora size occupancy detector that will give me an input to an ELK / CQC / ALC or whatever...so i can decide to turn on the lights based on rules in combination with the occupancy information...

Havent found suhc a device yet...anybody have better luck? Or is there an alternate method to achive what i'm looking for?

Would it be possible to put a very high resistor on the load side of this thing, then have it drive a relay which gives a input to ELK....would be a bit of a cumbersome expensive solution but it should work right?

 

[KenM]

You see Occupancy Sensors commercially much more than residential - I am looking at putting a couple in my house to take care of certain rooms that I cannot put a Z-Wave Switches in (Fluorescent Lights - 50 year old house with no-neutral in the box) - what would be really slick if someone came out the an Occupancy Sensor with Z-wave built-in

I have been using HomeSeer's Z-Wave HSM100, that is able to reliably report motion/light level/temperature with the HomeSeer2 software, for some time now. I am currently using the first generation Vizia-RF Z-Wave stuff that does not require a neutral and will not support fluorescent lighting. My (1958) house is wired without neutrals in the switch box. I wired in some neutral wires when I tried out 'brand-x', but thought that was messed up (and against local code), so I dumped that.

A slight compromise that I discovered, is to use the 'plug in' wall modules for switching the fluorescent lights.

Just a thought.

Ken

PS:
By the way, the HSM100 has a user selectable (with HS2) motion detection level from something like 1 to 255. Set on 255, it makes a darned good occupancy detector.

k

 

[BraveSirRobbin]

My (1958) house is wired without neutrals in the switch box. I wired in some neutral wires when I tried out 'brand-x', but thought that was messed up (and against local code), so I dumped that.

Hi Ken;

Slightly off topic, but I'm curious why something like that would be against local code? Did you get an explanation from your local authorities on this?

 

[drozwood90]

I agree with BSR on this one.

The only thing they don't want you to do is cross phases. The same Neutral should be Neutral to either phase...which is how some houses are wires anyhow.

They take 12-3, pull 220V (on two 120 breakers) to where it needs to go...then split one phase to one set of plugs, and the other phase to the other. GND and Neutral are then tied to BOTH circuits.

This is because...when one 120V line is positive, the other should be negative...so, the neutral SHOULD NOT EVER have more current on it then ONE line can supply. When you are pulling perfect FULL current from both lines the current cancels itself out, and you should not have any current over the neutral.

--Dan