Occupancy Sensor with Dynamic Timeout Adjustment for HVAC Control
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Solution Overview
Problem
HVAC systems lack efficient control mechanisms that accurately adjust to occupancy status, leading to inefficient energy usage and comfort variations within buildings.
Innovation Solution
A wireless occupancy sensor assembly that uses a motion sensor to detect occupancy and adjust a dynamic time period, transmitting occupancy or un-occupancy signals to control the HVAC system, and allows user input for sensitivity and timeout adjustments via a remote interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed timeout period is used to determine un-occupancy, then the control logic is simple, but it cannot adapt to varying occupancy patterns leading to inaccurate HVAC control
Solution Approach 1:
The patent applies dynamics by making the timeout period variable rather than fixed. The controller dynamically adjusts the timeout period based on the frequency of motion detections: when motion is detected frequently, the timeout period is extended; when motion is detected infrequently, the timeout period is shortened. This dynamic adjustment allows the system to adapt to varying occupancy patterns while maintaining accurate HVAC control.
2Measurement precision
If motion detection sensitivity is high, then occupancy detection is accurate, but false detections increase leading to premature HVAC shutdown
Solution Approach 1:
The patent applies feedback by continuously monitoring the frequency of motion detections and using this information to adjust the timeout period. When motion is detected, the system checks whether additional motion occurs within the current timeout period. This feedback mechanism allows the system to distinguish between genuine occupancy (multiple motions within timeout) and temporary disturbances (single isolated motion), thereby reducing false detections while maintaining high sensitivity for accurate occupancy detection.
3Speed
If the timeout period is short, then the system responds quickly to un-occupancy, but it may prematurely declare un-occupancy during transient motion periods
Solution Approach 1:
The patent applies dynamics by making the timeout period variable rather than fixed. The timeout period is dynamically adjusted based on the frequency of motion detections. When motion is detected frequently, the timeout period is automatically extended to prevent premature un-occupancy declarations. When motion is detected infrequently, the timeout period is shortened to enable faster response to genuine un-occupancy events. This dynamic adjustment resolves the contradiction between quick response and avoiding premature declarations.
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
Enhances energy efficiency by dynamically adjusting HVAC operations based on occupancy, improving comfort and reducing energy consumption by accurately responding to occupancy changes.
Implementation Method 1
a motion sensor disposed relative to the housing
Data Source
AI summary
The occupancy status of a building space may be determined by sensing an indication of motion in the building space, in response to sensing the indication of motion in the building space, starting an occupied time period having a length during which the building space is indicated as being occupied, determining a measure related to a number of subsequent sensed indications of motion in the building space during the occupied time period, and selectively adjusting the length of the occupied time period based on the measure related to the number of subsequent sensed indications of motion in the building space during the occupied time period.