Predictive Tint Control for Electrochromic Windows
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Solution Overview
Problem
Electrochromic windows, despite advances in technology, have not fully realized their commercial potential due to various issues, including inefficiencies in controlling tint levels for 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 to determine optimal tint levels and communicate instructions for transitioning tint levels in electrochromic windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If electrochromic windows are used to control light transmission, then energy savings and occupant comfort are improved, but transition time delays the window's ability to respond to changing light conditions
Solution Approach 1:
The system performs preliminary action by calculating and initiating tint transitions in advance of when they are actually needed. The predictive control logic determines future tint levels based on forecasted irradiance conditions and schedules transitions to occur before the conditions arise, compensating for the inherent transition time delay of the electrochromic material.
Solution Approach 2:
The system applies dynamics by adjusting the rate and timing of tint transitions based on predicted future conditions rather than reacting to current conditions. The control logic dynamically schedules transitions at optimal times, allowing the window to adapt proactively to changing environmental conditions while accounting for its own transition characteristics.
2Speed
If tint levels are adjusted based on current irradiance conditions, then response time is improved, but energy savings are reduced due to lack of predictive optimization
Solution Approach 1:
The system uses preliminary action by scheduling tint transitions in advance based on forecasted irradiance conditions. Rather than waiting for conditions to change and then reacting, the system proactively determines future tint levels and initiates transitions at optimal times, maximizing energy savings while maintaining adequate response to actual conditions.
Solution Approach 2:
The system implements feedback by continuously monitoring actual irradiance conditions and comparing them to forecasted conditions, then adjusting the predictive model and transition scheduling accordingly. This closed-loop approach ensures that the predictive control remains optimized for energy savings while adapting to real-world variations in environmental conditions.
3Reliability
If multiple control modules are used to balance occupant comfort and energy savings, then overall system performance is improved, but device complexity increases
Solution Approach 1:
The system applies merging by integrating multiple control functions into a unified predictive control logic that simultaneously optimizes for both occupant comfort and energy savings. Rather than operating separate control modules independently, the system combines irradiance forecasting, comfort assessment, and energy optimization into a single coordinated control framework.
Solution Approach 2:
The system implements universality by designing the predictive control logic to perform multiple functions: forecasting irradiance conditions, determining optimal tint levels, scheduling transitions, and evaluating both comfort and energy metrics. This multi-functional approach reduces the need for separate specialized modules while maintaining comprehensive system performance.
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 effectively balances occupant comfort and energy efficiency by dynamically adjusting tint levels in electrochromic windows, ensuring they perform as well as or better than reference windows in terms of energy savings, while also providing comfortable lighting conditions.
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.
Data Source
Figure 1A~1B
Figure 1C
Figure 2A
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 a penetration depth of direct sunlight 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.