Name two occupancy sensing technologies used in HVAC controls.

Name two occupancy sensing technologies used in HVAC controls.

• A. Magnetic field sensors and accelerometers
• B. Thermometers only
• C. Passive infrared (PIR) and Ultrasonic sensors; CO2/VOC sensors serve as occupancy proxies
• D. Humidity sensors only

Answer: (C)

Occupancy sensing in HVAC controls relies on detecting whether people are present to adjust ventilation and comfort accordingly. Two common technologies are passive infrared (PIR) sensors and ultrasonic sensors. PIR works by sensing the heat emitted by people, signaling presence when a warm body is detected in the space. Ultrasonic sensors transmit sound waves and watch for changes in reflections to detect movement, indicating occupancy. CO2 and VOC sensors can also hint at occupancy by tracking gas concentrations; higher levels generally correlate with more people, making them occupancy proxies, though they’re indirect and slower to respond than direct detection. Other sensors like magnetic field sensors, accelerometers, thermometers, or humidity sensors don’t directly indicate occupancy, so they’re not primary occupancy sensing methods for HVAC controls.

Occupancy sensing in HVAC controls relies on detecting whether people are present to adjust ventilation and comfort accordingly. Two common technologies are passive infrared (PIR) sensors and ultrasonic sensors. PIR works by sensing the heat emitted by people, signaling presence when a warm body is detected in the space. Ultrasonic sensors transmit sound waves and watch for changes in reflections to detect movement, indicating occupancy. CO2 and VOC sensors can also hint at occupancy by tracking gas concentrations; higher levels generally correlate with more people, making them occupancy proxies, though they’re indirect and slower to respond than direct detection. Other sensors like magnetic field sensors, accelerometers, thermometers, or humidity sensors don’t directly indicate occupancy, so they’re not primary occupancy sensing methods for HVAC controls.