IAQ Sensor Occupancy-Based Sampling to Extend Battery Life
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Solution Overview
Problem
Existing IAQ sensors in HVACR systems face challenges in extending battery life due to high energy consumption, particularly with CO2 and VOC detectors, and the effectiveness of passive infrared (PIR) modules is location-dependent, increasing complexity and cost.
Innovation Solution
The method involves using IAQ levels to determine occupancy status and adjust sampling intervals based on occupancy, reducing power consumption by extending intervals during unoccupied times and using machine learning to optimize sampling schedules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the IAQ sensor continuously monitors air quality at short intervals to ensure accurate real-time detection, then measurement precision and reliability are improved, but battery power is consumed rapidly, reducing battery life
Solution Approach 1:
The system dynamically adjusts the monitoring interval based on occupancy detection. When occupancy is detected, the system switches to a first monitoring interval for accurate real-time IAQ detection. When no occupancy is detected, it switches to a second, longer monitoring interval to conserve battery power. This dynamic adjustment resolves the contradiction by adapting the monitoring frequency to actual needs rather than using a fixed interval.
Solution Approach 2:
The system implements periodic occupancy detection using motion sensors or other occupancy detection mechanisms. Based on these periodic checks, the monitoring interval is adjusted between two states: a shorter interval when occupancy is present and a longer interval when the space is unoccupied. This periodic action allows the system to balance measurement precision with battery conservation by alternating between different monitoring frequencies.
2Duration of action of moving object
If the IAQ sensor uses a longer monitoring interval to conserve battery power, then battery life is extended, but the ability to detect and respond to real-time air quality changes is reduced
Solution Approach 1:
The system dynamically switches between two monitoring intervals based on occupancy status. When occupancy is detected, it transitions to a shorter first monitoring interval to ensure reliable real-time detection of air quality changes. When no occupancy is detected, it uses a longer second monitoring interval to extend battery life. This dynamic switching ensures that reliability is maintained when needed while conserving energy when not needed.
Solution Approach 2:
The system applies different monitoring qualities (intervals) to different temporal contexts based on occupancy. During occupied periods, high-quality frequent monitoring is applied. During unoccupied periods, lower-quality less frequent monitoring is applied. This local quality approach ensures that the system provides high reliability when spaces are in use while accepting reduced monitoring during unoccupied times when air quality changes are less critical.
3Measurement precision
If the system frequently wakes up the microcontroller and IAQ detector to check air quality, then measurement precision is maintained, but energy consumption increases, reducing battery life
Solution Approach 1:
The system dynamically adjusts the wake-up frequency of the microcontroller and IAQ detector based on occupancy detection. When occupancy is present, the system wakes up frequently at the first monitoring interval to maintain precise IAQ measurements. When no occupancy is detected, it reduces wake-up frequency to the longer second monitoring interval, significantly reducing power consumption while still maintaining measurement capability when needed.
Solution Approach 2:
The system implements periodic occupancy-based control of the monitoring frequency. Motion sensors or occupancy detection mechanisms trigger periodic assessments that determine whether to use the frequent first monitoring interval or the energy-saving second monitoring interval. This periodic action allows the system to balance measurement precision with power consumption by aligning frequent measurements with periods when occupancy is detected.
4Measurement precision
If the system uses a fixed short monitoring interval to ensure accurate IAQ detection, then measurement precision is improved, but battery power is depleted faster, reducing operational duration
Solution Approach 1:
The system dynamically adjusts the monitoring interval between two fixed values based on occupancy status. When occupancy is detected, it uses the shorter first monitoring interval to maintain accurate IAQ detection. When no occupancy is detected, it switches to the longer second monitoring interval to extend operational duration. This dynamic adjustment allows the system to optimize between measurement precision and operational duration based on actual environmental conditions.
Solution Approach 2:
The system changes the monitoring interval parameter based on occupancy detection. The parameter switches between a first interval value when occupancy is present and a second, longer interval value when unoccupied. This parameter change allows the system to maintain measurement precision during occupied periods while extending operational duration during unoccupied periods, effectively resolving the contradiction between these two requirements.
Data Source
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AI summary
A method extends battery life of a battery powered indoor air quality (IAQ) sensor that includes a IAQ detector, a radio, the battery, and a microcontroller with a memory and a processor. The method includes detecting IAQ at predetermined intervals to provide IAQ levels, and storing the IAQ levels and corresponding timing data in the memory. The method further includes determining an occupancy schedule based on IAQ level patterns and subdividing the occupancy schedule into a plurality of periods. The method further includes determining an occupancy status of each of the periods based on the IAQ levels. The method further includes operating the IAQ detector to sample at an active interval when the occupancy status is the occupied and at an inactive interval when the occupancy status is the unoccupied. The inactive interval is longer than the active interval. The IAQ detector can be, for example, a CO2 detector or a VOC detector.