The next generation of occupancy sensors is completely different.  They can be added or removed as needed, bridged between rooms, remotely tripped, and automatically interface with AV systems.  Conventional sensors may be able to do a few of these but certainly not all and then only with a lot of programming and general hassle. Packing all this capacity into a single sensor required a new way of thinking.  This is the story of how that new thinking came to be.

In the Beginning

The development of Starfield’s LS230 natural logic occupancy sensor begins 150 years ago with the invention of electric fire alarms.  Back then, electricity was new and the idea of combining a fire detector and switch was pretty high tech.  When fire was detected, the switch closed and an alarm activated.  When larger areas required more sensors, the additional sensors were wired in parallel so that closure of any one switch activated the alarm. Simple and effective.

Going Digital

30 years ago occupancy sensors started out in much the same way as fire alarms.  When motion is detected, a switch closes and lights turn on.  When motion stops, the sensor times out and then turns off the lights.  Also, like fire alarms, larger rooms are covered by multiple sensors wired in parallel.  Simple, effective, and pretty high tech for its time as well.

When digital sensors came along, the obvious path was create a synthetic version of existing analog sensors and circuits. This was relatively easy because it can be done with standard Boolean logic which is well understood and easily implemented.  Operationally it is relatively simple as well.  Such systems are called Master-Slave because they include a central “Master” that determines overall occupancy by collecting information from “Slave” sensors.  It works but at the cost of being inherently labor intensive, rigid, and prone to failure.

Organic Systems

Development of digital occupancy sensors at Starfield started out in a similar way. However, as the limitations of the Boolean approach became apparent, we started looking for something better. It took awhile but we found that something better hiding all around us.

Beehives, markets, traffic, and just about everything in the natural world don’t use Boolean logic. Instead, natural systems use an unstructured approach that allows them to interact and adapt.  The scientific term for this approach is Complex Adaptive Systems (CAS).  Such systems have the admirable properties of being self-organizing and inherently robust, resilient, and flexible.  There is no bee hive program and certainly no central controller to run such a program if it did exist.  Rather, bee hives, markets, and all other natural phenomena are emergent properties of the interaction of independent agents.

So that is what we created – a swarm of smart, independent sensors acting together to create an emergent occupancy control system.

We patented this new approach and named it a Master-Scout or just a Scout system to distinguish it from conventional Master-Slave systems.  In Boolean systems, the Master must know of and keep track of the state of each Slave sensor. In contrast, Scout sensors are anonymous and instead of tracing states they report events. Scout systems have a Master but it neither knows of nor tracks individual sensors.  Like its beehive cousin, a Scout system has no member list and individual Scouts may come and go while the occupancy system just keeps right on humming along.


Amazing, right!! But there’s more.  In addition to allowing any number of Scouts and  being resilient and configuration free, Scout reports can come from anywhere.

OK, maybe not so earth shaking at first glace but, imagine commissioning a large building. It’s after hours and the building is unoccupied. What better time to test the system. So, you hire a small army of testers, create a battle plan, do some training, arrange for security and access, and then deploy.  It’s a big job so you start early and work late because each room (if you can get in) must be manually visited, tripped, observed, and documented.

Now consider the Scout alternative. Same conditions but this time you’re back in your office across town or on the other side of the world. You log-in, turn on the lights, broadcast a Scout trip command, and then lean back and have a beer. Well, maybe just a cup of coffee, but after a short wait, you finish the test by scanning the whole building for any lights that failed to turn off.  Done, data collected, no errors, and comprehensive. Time for another beer.

Master-Scout logic breaks through the limitations of conventional occupancy sensors to deliver a new level of performance, reliability, and economy.  Lighting control will never be the same.