Unobtrusive occupancy and vital signs sensing for human building interactive systems

Area of Science:

• Smart Buildings
• Human-Building Interaction
• Sensor Technology

Background:

• Cognitive buildings aim to optimize occupant comfort and building efficiency by adjusting environmental parameters based on occupant responses.
• Current sensor technologies for unobtrusive and ubiquitous occupant monitoring are limited, especially in challenging scenarios.
• Accurate sensing of occupancy and physiological data is crucial for developing responsive and intelligent built environments.

Purpose of the Study:

• To evaluate the effectiveness of Doppler-radar based sensors for occupancy detection and vital sign estimation in realistic building environments.
• To demonstrate the sensor's capability to function in challenging conditions where other sensor types fail.
• To explore the potential applications of this sensor technology in smart building control and human-building interaction.

Main Methods:

• Utilized Doppler-radar based sensors capable of detecting subtle physiological motions.
• Conducted experiments in a 3.4 m x 8.5 m conference room with both wall and ceiling-mounted sensor configurations.
• Assessed sensor performance for occupancy detection, including scenarios with visibly blocked occupants.
• Measured heart and respiratory rates from all seating positions within the room.

Main Results:

• Achieved over 93% accuracy in differentiating occupied from empty rooms.
• Successfully detected occupancy even when the occupant was hidden (e.g., under a table), outperforming traditional sensors.
• Accurately estimated heart and respiratory rates from all locations in the room using a single ceiling-mounted sensor.
• Demonstrated the potential for real-time control of HVAC and lighting systems with a minimal delay.

Conclusions:

• Doppler-radar sensors offer a robust and accurate solution for occupancy detection and vital sign monitoring in smart buildings.
• This technology overcomes limitations of existing sensors, enabling reliable performance in complex environments.
• The sensor data can enhance building automation for energy efficiency and occupant comfort, and provide valuable insights for space utilization and wellness monitoring.