Proximity Sensors for Energy Efficient Buildings

Occupancy or Proximity sensors are automatic scheduling devices that detect motion and turn lights on and off accordingly. We all are aware that lighting constitutes about 15% of the total energy requirement of any typical commercial building. There are many energy efficient ways through which lighting can be controlled to get the desired energy savings. People want lights for different purposes.

Right from task oriented to general lighting. Requirement of lights and Lux levels are different for every kind of work.But even with that constraints there are enough ways to optimize and reduce the energy burden. For offices, conference halls, lobbies occupancy sensors can be used to turn the lights on and off depending upon the defined schedules and detecting of movements in the spaces.

Most devices can be calibrated for sensitivity and for the length-of-time delay between the last detected occupancy and extinguishing of the lights. The most energy-efficient occupancy sensors, known as “manual- on, automatic-off,” require that the user manually switch on the lights when entering a controlled zone (the “lights off ” function is still automatic).

Proximity Sensors systems typically consist of a motion detector, a control unit, and a relay. Usually, two or more of the components are integrated into one package. Most systems also require a power supply in the form of a transformer, which steps down the building voltage to 24V. The detector collects information, then sends it to the controller, where it is processed. Output from the controller activates the relay, which in turn switches the light circuit.
There are two major types of occupancy controls.

• Wallbox units are designed to fit into a standard wall switch box and operate on the building voltage (i.e., a separate power supply is not required). They are excellent, inexpensive replacements for standard wall switches. Their main limitation is their relatively short range. Consequently, they tend to be used in small offices and meeting rooms.

•  Wall and Ceiling units typically contain an integrated sensor/controller unit wired (Class 2) to a switch pack containing the relay and power supply. They are far more popular than wallbox units and have very few application limitations.

Occupancy sensors or Proximity Sensors have become an integral part of all commercial buildings and offices. Their contribution to energy savings has been truly great.