Occupancy-Based Utility Control Using Wearable RFID Tags
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Solution Overview
Problem
Current building utility control systems, such as lighting and HVAC, fail to accurately and immediately adjust based on occupancy levels, leading to inefficiencies and increased energy consumption due to reliance on unreliable sensors and costly technologies.
Innovation Solution
Implementing a system that uses wearable identification tags emitting low energy radio frequencies to provide real-time occupancy data, which is processed by a microprocessor to adjust lighting and ventilation rates according to ASHRAE standards, ensuring precise control and minimizing energy waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If carbon dioxide monitors are used to estimate occupancy, then ventilation rates can be adjusted based on occupancy, but the reliability and accuracy of the system deteriorates due to sensor reliability issues
Solution Approach 1:
The patent replaces mechanical/chemical sensing systems (carbon dioxide monitors) with electronic identification systems (RFID tags and readers). Instead of measuring environmental parameters that correlate with occupancy, the system directly detects occupancy through electronic tags carried by occupants, eliminating sensor reliability issues while maintaining energy conservation benefits
Solution Approach 2:
The system uses electronic copies/representations of occupancy information through RFID tags rather than physical measurement of occupancy conditions. Each tag carries identification data that serves as a digital copy of occupancy status, providing reliable and accurate detection without the limitations of environmental sensing
2Measurement precision
If active RFID tags are used to monitor occupancy, then occupancy detection capability is improved, but the cost of installing and maintaining the system increases
Solution Approach 1:
The patent employs passive RFID tags which are significantly cheaper than active RFID tags. These passive tags require no internal power source, reducing both initial cost and maintenance requirements. The tags can be easily replaced or reissued without significant expense, making the system economically viable while maintaining precise occupancy detection through the reader-tag interaction
Solution Approach 2:
The RFID tag system serves multiple functions: occupancy detection, identification, and potential integration with access control or building management systems. This multi-functionality reduces overall system cost by consolidating multiple capabilities into a single infrastructure, thereby improving ease of manufacture and deployment
3Loss of energy
If motion sensors are used to control lighting, then energy savings are achieved, but the system fails to detect stationary occupants causing lights to turn off incorrectly
Solution Approach 1:
The patent replaces motion-based detection (which requires physical movement to trigger) with electronic identification-based detection. Passive RFID tags are detected through radio frequency interaction with readers, allowing stationary occupants to be continuously detected without requiring movement, thereby eliminating the fundamental flaw in motion sensor systems while maintaining energy savings
Solution Approach 2:
The RFID tag system operates autonomously without requiring occupant action. Tags continuously emit or reflect radio frequency signals that are detected by readers, providing automatic occupancy detection whether occupants are moving or stationary. This self-service capability ensures reliable detection and appropriate lighting control based on actual occupancy status
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables granular, real-time energy savings by immediately turning off lights upon vacancy and optimizing HVAC ventilation rates, reducing energy consumption and extending equipment lifespan while being cost-effective and simple to implement.
Implementation Method 1
wearable identification tags emitting low energy radio frequencies to provide real-time occupancy data
Data Source
AI summary
To control lighting and other utilities in buildings based upon occupancy, mountable sensors are used to detect low energy radio frequencies emitted from devices, or tags, worn or carried by occupants. In a demand control system, identification (ID) codes embedded in tags worn by occupants are detected in each room by a tag sensor and may wirelessly communicate to a zonal compiler that determines zonal occupancy. The zonal occupancy count is transmitted to an interface relay that immediately adjusts the intensity and rate of the specific utility. HVAC systems may also be tied into the system to have adjustments made to the intensity and rate of ventilation as done with the lighting in this system. This system has many advantages over current systems such as not being dependent upon movement of an occupant or following the heat signature of an occupant that both may lead to false readings and delay in adjusting the specific building utility to save energy and costs.