Occupancy-Sensing Thermostat Away-State Qualification
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Solution Overview
Problem
Existing thermostats often fail to accurately reflect user behavior, leading to inefficiencies in energy consumption, as users struggle to program schedules correctly, and devices are not user-friendly, resulting in low adoption and misuse of energy-saving features.
Innovation Solution
A thermostat with an integrated processing system and occupancy sensors that automatically determine an 'away-state' mode by analyzing sensor readings during a trial period, enabling an automated setpoint temperature setback only when reliable occupancy data is established, ensuring energy savings without user intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a programmable thermostat with default schedules is provided, then energy-saving functionality is available, but user programming complexity increases and schedules may not accurately reflect actual occupancy behavior
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 user configuration while achieving energy-saving goals
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 thermostat 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 control is possible, but user convenience decreases and most users never perform these tasks
Solution Approach 1:
The thermostat system performs automatic occupancy-based setback operations without requiring manual user intervention. The occupancy sensors continuously monitor the space and the processing system automatically adjusts HVAC setpoints based on detected occupancy states, eliminating the need for users to manually program or adjust settings while maintaining energy-saving performance
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 automatically implements energy-saving setback schedules, and when occupancy is detected, it returns to normal operation, creating a closed-loop automatic control system that eliminates manual operation requirements
3Extent of automation
If occupancy sensors are immediately activated, then automatic away-state control begins, but reliability decreases without established sensor accuracy
Solution Approach 1:
The system implements a trial period before activating automatic away-state 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 begin autonomous energy-saving operations, ensuring both automation and reliability are achieved
4Reliability
If a trial period for sensor qualification is implemented, then reliability improves, 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, balancing reliability requirements with activation speed
Data Source
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.