Tintable Window Predictive Control Using Irradiance and Space Type
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Solution Overview
Problem
Electrochromic windows, despite advances in technology, have not realized their full commercial potential due to various issues such as inefficient control methods for tint levels, which affect occupant comfort and energy conservation.
Innovation Solution
The implementation of predictive control logic in window controllers that adjusts tint levels based on occupant comfort, energy considerations, and actual irradiance conditions, using modules that determine optimal tint levels for different space types and environmental factors, and communicate instructions to tintable windows for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional control methods are used for electrochromic windows, then the system is simple to operate, but occupant comfort and energy conservation are not optimized
Solution Approach 1:
The control system performs preliminary actions by predicting future irradiance conditions and pre-adjusting tint levels before peak sunlight exposure occurs. This allows the window to be proactively optimized for energy conservation rather than reactively responding to current conditions, thereby improving energy efficiency without requiring complex real-time control interventions.
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring actual irradiance conditions and comparing them with predicted values. This feedback loop enables the control algorithm to learn from discrepancies and improve future predictions, optimizing both energy conservation and occupant comfort while maintaining operational simplicity through automated adjustments.
2Loss of energy
If tint levels are adjusted frequently to optimize energy savings, then energy conservation improves, but the transition time and system complexity increase
Solution Approach 1:
By predicting future irradiance conditions in advance, the system can plan optimal tint level transitions ahead of time. This allows the control algorithm to determine the most efficient transition schedule that minimizes the number of adjustments while still achieving energy conservation goals, thereby reducing system complexity and transition frequency without sacrificing energy savings.
Solution Approach 2:
The control system dynamically adapts its transition strategy based on predicted irradiance patterns and actual window response characteristics. By learning the specific transition time of each window and optimizing control timing, the system achieves energy savings with fewer, more strategically timed transitions rather than frequent adjustments, simplifying overall system operation.
3Loss of energy
If the window tints darker to block more sunlight, then energy savings increase, but natural lighting and occupant comfort decrease
Solution Approach 1:
The system predicts future irradiance conditions and schedules tint level adjustments in advance, allowing it to maintain lighter tint levels during periods of low solar exposure when natural lighting is beneficial. By proactively darkening only when and where energy savings are most critical, the system optimizes the balance between energy conservation and natural lighting without requiring constant dark tinting.
Solution Approach 2:
The control system can apply different tint levels to different regions or zones of the building facade based on local solar exposure patterns, occupancy requirements, and energy conservation priorities. This allows sunlight to penetrate deeper into spaces that benefit from natural lighting while maintaining darker tints in areas where energy savings are most critical, achieving both goals simultaneously through spatially differentiated control.
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 solution enhances occupant comfort by reducing direct glare and allowing sufficient natural lighting while achieving energy savings by optimizing tint levels according to predicted and actual solar irradiance, ensuring compliance with energy efficiency standards.
Implementation Method 1
Electrochromism is a phenomenon in which a material exhibits a reversible electrochemically-mediated change in an optical property when placed in a different electronic state, typically by being subjected to a voltage change. One well known electrochromic material is tungsten oxide (WO3). Tungsten oxide is a cathodic electrochromic material in which a coloration transition, transparent to blue, occurs by electrochemical reduction.
Data Source
AI summary
A method of controlling tint of a tintable window to account for occupant comfort in a room of a building. The tintable window is between the interior and exterior of the building. The method predicts a tint level for the tintable window at a future time based on lighting received through the tintable window into the room at the future time and space type in the room. The method also provides instructions over a network to transition tint of the tintable window to the tint level.