Daylight Harvesting Sensor Correlation for Incorrect Lighting Adjustment
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Solution Overview
Problem
Daylight-harvesting systems face reliability issues due to factors other than daylight variations, leading to incorrect lighting adjustments and occupant frustration, as single sensors can be affected by changes in occupancy, reflectance, and external daylight variations that do not impact the controlled area.
Innovation Solution
A system using multiple sensors, including both closed-loop and open-loop photosensors with different fields-of-view, to correlate light level changes and prevent incorrect lighting adjustments, ensuring that only synchronized changes across sensors trigger adjustments to the lighting system, thereby maintaining target light levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sensor is used to control lighting output, then the system is simple and cost-effective, but the system becomes unreliable and causes incorrect lighting adjustments due to factors other than daylight variations
Solution Approach 1:
The patent divides the sensing function into multiple separate sensors, each monitoring different aspects of light levels. The first sensor monitors overall light levels in the space, while the second sensor specifically monitors daylight levels through windows. This segmentation allows the system to distinguish between different types of light changes and make more reliable lighting adjustments.
Solution Approach 2:
The patent introduces an intermediary processing mechanism that compares the outputs of multiple sensors before triggering lighting adjustments. The controller acts as an intermediary that validates sensor readings against each other, ensuring that lighting changes are only made when multiple sensors confirm a genuine daylight variation, thereby preventing incorrect adjustments.
2Adaptability or versatility
If the lighting system responds to every light level change detected by a single sensor, then the system is responsive and adaptive, but it causes over-dimming and light-level fluctuations due to occupancy and reflectance changes
Solution Approach 1:
The patent segments the light level monitoring into distinct functions: one sensor monitors overall space illumination while another monitors specific daylight input. This segmentation enables the system to filter out spurious changes caused by occupancy or reflectance variations by requiring corroboration between sensors before responding to light level changes.
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously compares sensor readings and adjusts lighting based on validated changes. The system uses feedback from multiple sensors to confirm genuine daylight variations before triggering lighting adjustments, preventing over-dimming while maintaining adaptability to real changes.
3Measurement precision
If the system uses multiple sensors with different fields-of-view, then the system can distinguish between different light sources and improve accuracy, but the device complexity and cost increase
Solution Approach 1:
The patent assigns different fields-of-view to different sensors: one sensor is positioned to monitor overall space light levels while another specifically monitors daylight through windows. This segmentation of monitoring functions enables precise differentiation between indoor and outdoor light sources, improving measurement precision to distinguish genuine daylight changes from other light variations.
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
This approach enhances the reliability and functionality of daylight-harvesting systems by reducing incorrect dimming and ensuring consistent lighting levels, thereby minimizing occupant annoyance and energy waste.
Implementation Method 1
measures a first light level in an area using a first sensor
Implementation Method 2
measures a second light level for a different field-of-view using a second sensor
Data Source
AI summary
One embodiment of the present invention provides a system for preventing incorrect lighting changes in a daylight-harvesting system, which controls the output of a lighting system based on the presence of daylight and/or other light sources to reduce energy usage. During operation, the system measures a first light level using a first sensor. Next, the system measures a second light level for a different field-of-view using a second sensor. When the system detects through the first sensor a change in the first light level, the system determines from the second sensor whether the second light level has also changed. If the first sensor and the second sensor both detect a change (in the same direction) in the measured light levels, the system adjusts the light output of the lighting system to maintain target light levels for the area.