Tintable Window Predictive Control for Occupant Comfort
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Solution Overview
Problem
Electrochromic windows, despite advances in technology, have not realized their full 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 achievement of optimal tint levels
Solution Approach 1:
The system performs preliminary actions by calculating and preparing optimal tint levels in advance based on predicted future irradiance conditions. The control logic determines what the optimal tint level will be at a future time point, allowing the system to proactively adjust rather than reactively respond to changing light conditions, thereby reducing the effective transition delay.
Solution Approach 2:
The system implements dynamic control by continuously monitoring current irradiance, calculating future irradiance based on environmental factors, and adjusting tint levels in real-time. This dynamic approach allows the window to adapt to changing conditions while compensating for transition time delays through predictive adjustments.
2Productivity
If predictive control logic is implemented to account for transition time, then optimal tint levels are achieved faster, but device complexity increases
Solution Approach 1:
The control logic is segmented into distinct functional modules: current irradiance measurement, future irradiance calculation, optimal tint level determination, and transition time compensation. This modular segmentation makes the complex predictive control system more manageable and implementable by breaking it into discrete computational steps.
Solution Approach 2:
The system introduces an intermediary computational layer that calculates future irradiance based on environmental factors (sun position, weather predictions, building orientation) before determining the final tint level. This intermediary step acts as a buffer that simplifies the overall control logic by separating the prediction function from the execution function.
3Ease of operation
If tint levels are adjusted frequently to maintain occupant comfort, then comfort is improved, but energy consumption increases
Solution Approach 1:
The system applies partial action by adjusting tint levels only to the extent necessary to maintain occupant comfort, rather than making maximum adjustments. The predictive control logic calculates the minimal required tint change to achieve comfort goals, avoiding excessive tinting that would waste energy. This selective adjustment reduces overall energy consumption while maintaining comfort.
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 savings by dynamically adjusting tint levels in electrochromic windows, ensuring they perform as well as or better than reference windows in terms of energy efficiency, 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. The optical property is typically one or more of color, transmittance, absorbance, and reflectance.
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 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.