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Bridget's Suite

PIR: Remember These Three Letters

PIR sensors are the most common motion sensor type used for occupancy-based control technology in hospitality, and also in general. If we were to look at all the ways motion sensors are used today, PIR sensors make up over 70% of them.

PIR (passive infrared) sensors detect occupancy in three ways: by sensing the infrared radiated by the room’s occupants, by sensing the infrared radiated by the unoccupied room itself, and by measuring the differential between the two.

Why is sensing occupancy important? Sensing occupancy is the key to saving energy, particularly in the hospitality industry.

As an example, as part of an EMS platform, a PIR motion sensor transmits a signal to the thermostat indicating whether there is someone in the room, enabling the thermostat to automatically set back the PTAC temperature setting to a lower level when the room is empty. As a consequence of the automatic temperature setback, the PTAC can stay off for a longer period of time when the room is empty and therefore save energy, and prolong the life of the PTAC.

The quality of the PIR sensor matters. For example, some PIR sensors are more sensitive than others and can detect the presence of a sleeping guest, while others don’t have that sensitivity.

Without that extreme sensitivity, the occupancy will not detect sleeping guests. This is what leads to those 2:00 AM complaints that the air conditioning shut off.

To avoid false negatives and false positives the HVAC can also be equipped with light-level sensors that help detect daytime versus nighttime. In addition to using occupancy sensors that can be calibrated to extreme sensitivity, a property can supplement the PIR with integrated devices. Thermostats can be integrated with door contacts, external occupancy sensors in the case of multi-room dwellings, and light-level sensors.

In Contrast, There’s Active IR
Differently from PIR (passive infrared), IR (active infrared) sensors in addition to receiving infrared light also emit infrared beams. When the IR beams are cut by an object, the sensor notices that and emits a signal to the controls to trigger the consequence (for example to turn AC on). They are commonly used on garage doors in the residential sector to increase safety. Installation of active IR sensors is more complex.

The other downside of active IR is the limited field of vision when there are obstructions in the room. That would be a major disadvantage in a hotel setting.

It is important to reassure customers that a passive infrared occupancy sensor cannot “see” or “hear” an occupant. A resident or hotel guest can be confident that their privacy is completely secure without compromise.

Telkonet thermostats feature high-quality PIR sensors, calibrated to extreme sensitivity. They also feature light-level sensors that supplement accurate occupancy detection, allowing extra minutes to detect motion and heat in the middle of the night. Additional occupancy sensors are not typically necessary, with the exception of unusually large spaces or multi-room dwellings.
Contact our regional sales managers today to discuss the options that are right for your property.