Occupancy-Sensing Thermostat Away-State Qualification for Easy Energy Saving
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Solution Overview
Problem
Existing energy-saving technologies for HVAC systems face challenges in user adoption due to complexity and difficulty in integrating them into daily routines, often resulting in users disabling advanced features or returning to simpler devices, as the initial experience with these systems is not user-friendly.
Innovation Solution
A thermostat with an integrated processing system and occupancy sensors that automatically determines an away-state mode based on sensor readings during a trial period, enabling an automated setpoint temperature setback only if sufficient occupancy indications are detected, thus simplifying user interaction and enhancing energy-saving capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a programmable thermostat with default schedules is used, then energy management capability is improved, but ease of operation deteriorates due to programming difficulty
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 achieving energy savings.
2Loss of energy
If manual setback operation is required, then energy-saving opportunity is improved, but ease of operation deteriorates due to user burden
Solution Approach 1:
The thermostat system autonomously monitors occupancy sensor signals, determines away states, and adjusts HVAC setpoint temperatures without requiring manual user intervention. The system qualifies sensors during installation and then automatically executes energy-saving setback schedules, capturing energy savings that would otherwise require diligent manual operation.
Solution Approach 2:
The system continuously monitors occupancy sensor outputs and uses this feedback to dynamically adjust thermostat setpoints. When sensors indicate an away state, the system automatically implements energy-saving temperature adjustments, creating a closed-loop control system that responds to real-time occupancy conditions.
3Loss of energy
If occupancy sensors are activated immediately, then energy-saving functionality is improved, but reliability deteriorates due to false occupancy detection
Solution Approach 1:
The system performs sensor qualification during a trial period before activating energy-saving away-state functionality. During this preliminary phase, the thermostat monitors sensor outputs to determine if they reliably indicate true occupancy conditions, and only after successful qualification does it enable automated setback operations, preventing false activations.
4Reliability
If a trial period for sensor qualification is implemented, then reliability is improved, but loss of time is worsened due to delayed activation
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 qualification confidence needed to prevent false away-state activations while enabling energy-saving functionality as quickly as possible.
Data Source
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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.