Today, many applications in building automation and energy management, security and access control embed thermal sensors to detect the heat emitted by people or objects in the longwave infrared (LWIR) wavelength.
Traditionally, this type of sensor has used pyroelectric or thermopile technologies. These sensor technologies notably carry a very limited number of pixels (average 64 pixels). They have limited sensitivity and compactness. As they can essentially only give a Yes or No response to the presence of a signal, they have been effectively used to detect motion: the movement of a person, animal or object.
These types of sensors have several shortcomings, particularly when a target is immobile. In the absence of movement, this detection system cannot identify whether or not a person is still physically present. Another drawback of this detection solution is the frequency of false alarms it triggers. As pyroelectric technology is highly sensitive to the surrounding environment, such like vibrations, wind or dust, it is prone to make mistakes; for example, it lacks the capacity to distinguish between a human and a pet. Moreover, due to the low number of pixels housed in these sensors, the surface area they can monitor is also limited.
For existing detection systems to be able to deliver more accurate and detailed presence detection data, they will need to be designed with performance thermal sensors. Thermal sensors enable advanced functions that make buildings really smart: real presence detection; precise people counting; localization and activity classification.
Moreover, in order to render buildings more intelligent, detection systems (such as occupancy sensing) will have to provide more enriched data.
Activity sensing is an example of this type of intelligent information:
Is there anybody present in a room? How many people are there? Are people sitting, standing or are about to topple over?
By computing high added-value information, smart detection systems will be able to manage activity such as lights or HVAC apparatus. To achieve this, it is fundamental to use a thermal image activity sensor with the correct level of pixel resolution and performance.
That way, you achieve true presence detection and the ability to monitor larger areas at lower cost.