occupancy sensors

What is Occupancy Sensor?

Occupancy sensors are the motion sensing devices.

It mainly works on infrared, ultrasonic and microwaves.

It activates the connected electrical devices (fan, light, etc) when it senses motion and deactivates them when it seizes to sense motion.

Occupancy sensors are sometime also called “presence sensors” or “vacancy sensors.

These sensors are typically used to save energy, provide automatic control, and comply with building codes.

It was initially developed for security systems and now used to control not only light or electrical devices but also HVAC systems for commercial spaces

A complete sensor consists of a motion sensor, an electronic control unit, and a controllable switch/relay. The detector senses motion and determines whether there are occupants in the space. It also has a timer which signals the electronic control unit after a set period of inactivity. The control unit uses this signal to activate the switch/relay to turn equipment on or off.

Occupancy sensors have a two-fold purpose. They are not only useful gadgets for home security, but are also very handy when it comes to bringing down energy consumption costs.

Occupancy Sensor Benefits

  • This sensor can be easily integrated with your home’s security network to provide you with an added element of security.
  • Occupancy sensors can cut workplace energy costs significantly, especially when used in meeting rooms, cafeterias and even in stairwells, where safety lighting can be dimmed when people aren’t present. For example, the typical office uses 30% of its electricity for lighting. Occupancy sensors can reduce this use by half.
  • They are also capable of controlling the heating and cooling systems.

Types Of Sensors

There are four main types of sensors:

  1. Passive Infrared (PIR)
  2. Ultra sonic Sensors
  3. Microwave Sensors
  4. Hybrid Sensors
  1. Passive Infrared (PIR)

PIR is an electronic sensor which measures the infrared radiation being emitted from an object in its view.

Motion is detected when an infrared source, such as a human, passes in front of another infrared source with a different temperature such as a wall.

PIR sensors react to the changes in heat patterns created by the moving person and turn lights on accordingly. The controller “eye” must have an unobstructed view of the building area being scanned.

The best applications for passive infrared occupancy sensors are small open spaces, such as private offices and conference rooms.

Advantages of Passive Infrared are

they are highly resistant to false triggering,

relatively inexpensive, and

do not radiate any energy (hence the name “ passive ” ) .

Disadvantages are

they are strictly for line of sight use, and cannot see around objects.

Doors, stairways and partitions have a tendency to block motion detection and reduce effectiveness.

Also, the farther away the object to be detected is, the larger the motion needs to be to trigger the device.

How PIR sensor works?

It detects changes In amount Of IR radiation which depends upon outside characteristics and temperature of the objects in front Of detector. It means if human or animal will come in range of detector, it will detect movement because live body eliminates warm energy in the form of IR radiation, so it will give you signal by light or alarm when any live object comes in front of PIR.

  1. Ultrasonic Sensors

Ultrasonic sensors emit an inaudible sound pattern and then “read” the reflection. This sound is above the range of human hearing. A break in the pattern caused by any motion in the area triggers the control.

Ultrasonic sensors can “see” around obstructions and are best for areas with cabinets and shelving, restrooms and open areas requiring 360-degree coverage.

Advantages of Ultrasonic devices are

they are sensitive to all types of motion and generally there are zero coverage gaps, since they can detect movements not within the line of sight.

        There are two types of Ultrasonic Detectors

 Active Ultrasonic Detectors

This detector emits sound waves of a frequency that is inaudible to the human ear. The sensor within this unit picks up on any movement in the room by using reflecting sound waves.

This detector can activate lighting, air conditioning, heating systems or sound an alarm to notify in case of an intrusion.

Passive Ultrasonic Detectors

These work with the same technology as active ultrasonic detectors, with the difference being that these are relatively less expensive but more prone to causing false alarms.

  1. Microwave Detector and Occupancy Sensors

These sensors are the perfect balance between reliability and cost.

Microwaves emitted from a sensor are able to cover a wide space to detect any form of movement and activate lighting or sound an alarm.

Microwave detectors are also compatible with batteries, so they work during power outages as well, making them ideal for use in homes.

  1. Hybrid Sensors

Some occupancy sensors use both passive infrared and ultrasonic technology.

They can control one lamp, one fixture or many fixtures.

They are usually foolproof, allowing for wide coverage and range of applications.

The disadvantages are

they are more expensive, and may require more adjustments. Because they use both technologies,

hybrid sensors can be used to control lighting in almost any space, however large open areas and areas with irregular occupancy patterns are generally the most cost effective.

Combined PIR and Ultrasonic Detectors

A PIR detector is combined with an ultrasonic wave emitting detector. As compared to a simple PIR detector, this provides a much more accurate reading of when people walk in and out of the designated areas.

Combined PIR and Microwave Occupancy Sensors

These sensors have an added advantage of working well in spaces with windows, which is something PIR detectors are not capable of doing because glass blocks infrared radiation.

The type of detector you choose will be dependent on your existing security system’s compatibility, the amount of money you are willing to spend, and what sort of features do you require your sensor to have. Once you have purchased your occupancy sensor

To know more about occupancy sensors and how it can help you in reducing your electricity bills, visit www.1leaptechnologies.com

Ensuring your sensors work properly

To make the most of this energy-saving technology

Choose the right type of sensor for the space and activity levels.

  • Design the sensor layout and controls to suit your purposes.
  • Customize settings like delay time and trigger sensitivity.

Correct Placement of Sensors

Sensors are mounted on the ceiling or on walls. Ceiling-mounted models tend to cost more, but they cover more area and so work well for larger spaces. Wall mounts are best in private offices and small rooms that don’t have obstructions.

Poor placement often results in false triggering — for example placing a sensor behind the swing of a door might mean it can’t detect the occupants within, or locating a private office room sensor where it will be triggered by movement in the hallway.

To mitigate false triggering in an open floor plan, you can install sensors in quadrants or on distinctive project-pool workstations. Sensors can also be embedded in luminaries (light fixtures), allowing all areas to be individually controlled.

The biggest energy savings tend to be in places that have long periods of vacancy, such as meeting rooms, cafeterias, school rooms etc.

Sensors can also communicate with each other wirelessly. This is particularly useful in underground parking lots, where sensors can be set up so when one is triggered, it triggers the next light, and so on, along a determined pathway.

They can also be connected through the Internet and accessed remotely.

Points to remember while installing Sensors!

Analyze the space you wish to put an occupancy sensor in and place the sensors accordingly.

  • Don’t mount sensors close to air vents since the vibration of the air flow might affect the effectiveness of the sensor
  • Be sure to account for all possible entrances into the premises
  • Make sure that tall furniture or any other equipment in the room won’t hinder the sensor’s view of the room.
  • Make sure the sensor’s view of the room isn’t blocked by the door when it opens.
  • One of the biggest problems with occupancy sensors is that people don’t customize them for the particular needs and activities of their workplace. Settings like the delay time — how long before lights turn off — and the sensitivity of the sensor make a huge difference in how well the sensor suits the individual situation.
  • Depending on the size and configuration of a space, you will need a different numbers of sensors and a different scheme of controls.
  • Keeping the above hints in mind will help you strategically place sensors all over your house. Be sure to get professional help with the placement. It’s better to place a few sensors intelligently rather than a large number of ill-placed ones.

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