Thermostat Self-Qualification for Occupancy-Based Away-State Control
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Solution Overview
Problem
Existing HVAC control systems face challenges in accurately detecting occupancy to automatically adjust energy usage, leading to inefficiencies and user dissatisfaction due to complex programming requirements and difficulties in integrating energy-saving technologies into daily routines.
Innovation Solution
A control unit with versatile sensing and control units (VSCU) that uses a combination of sensors, including passive infrared motion sensors and proximity sensors, to detect occupancy and adjust settings automatically, featuring a self-qualification algorithm to establish sensor confidence before enabling an away-state feature for energy savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a programmable thermostat with default schedules is used, then energy management capability is improved, but programming complexity increases
Solution Approach 1:
The thermostat automatically performs occupancy detection and schedule adjustment without requiring user programming. The system qualifies occupancy sensors during a trial period and then autonomously implements away-state setback schedules based on detected occupancy patterns, eliminating the need for manual programming while maintaining energy management capabilities
Solution Approach 2:
The system implements a trial period during which occupancy sensors are qualified before being used for automatic control. This preliminary action ensures sensor reliability is established before the system begins autonomous energy-saving operations, resolving the contradiction by preparing the system in advance rather than requiring complex user programming
2Loss of energy
If manual setback operation is required, then energy saving opportunity is improved, but user convenience deteriorates
Solution Approach 1:
The thermostat system performs automatic occupancy-based setback operations without requiring manual user intervention. The system autonomously monitors occupancy sensors, determines away states, and adjusts HVAC setpoints accordingly, capturing energy savings while eliminating the need for user action
Solution Approach 2:
The system continuously monitors occupancy sensor signals and uses this feedback to automatically adjust thermostat setpoints. When sensors indicate an away state, the system implements energy-saving setback schedules; when occupancy is detected, normal schedules resume, creating a closed-loop automatic control system that captures energy savings without user involvement
3Extent of automation
If occupancy sensors are immediately activated, then automation capability is improved, but reliability of occupancy detection deteriorates
Solution Approach 1:
The system implements a trial period before activating automatic occupancy-based control. During this period, occupancy sensors are monitored and qualified to ensure they provide reliable signals. Only after successful qualification during the trial period does the system enable automatic away-state functionality, ensuring both automation and reliability
4Measurement precision
If a trial period for sensor qualification is implemented, then occupancy detection accuracy is improved, but time to activate energy-saving features increases
Solution Approach 1:
The system implements a trial period of sufficient duration to qualify sensors with adequate confidence, accepting the time delay as necessary to ensure reliable operation. The trial period is calibrated to provide the minimum necessary qualification time while enabling energy-saving features as quickly as possible once confidence is established
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
The solution provides a user-friendly and energy-efficient HVAC control system that automatically adjusts settings based on reliable occupancy detection, ensuring comfort and reducing energy consumption without requiring manual intervention.
Implementation Method 1
uses a combination of sensors, including passive infrared motion sensors and proximity sensors, to detect occupancy
Data Source
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Figure 3A
AI summary
A thermostat, includes a housing and an occupancy sensor that is disposed within the housing and configured to detect physical presences of users within a responsive area of the occupancy sensor. The thermostat may also include a processing system that is disposed within the housing and in operative communication with the occupancy sensor. The processing system may be configured to determine, after a trial period, whether to activate an away-state feature by storing indications of how often the occupancy sensor detected physical presences during the trial period, computing an occupancy level for the trial period, comparing the occupancy level to a threshold criterion, determining whether sufficiently true indications of occupancy conditions were sensed by the occupancy sensor during the trial period, and enabling the away-state feature of the thermostat if it is determined that the sufficiently true indications of occupancy conditions were sensed during the trial period.