Tintable Window Predictive Control for Sunlight Penetration and Glare
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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 for electrochromic windows to balance comfort and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If electrochromic windows are used to control tint levels, then energy savings are achieved, but occupant comfort from direct sunlight and glare is not adequately addressed
Solution Approach 1:
The system performs preliminary calculations to determine the transition time required for electrochromic windows to reach desired tint levels. Based on these calculations, the system proactively adjusts tint levels in advance of when occupants will be affected by direct sunlight or glare, ensuring comfort is maintained while achieving energy savings.
Solution Approach 2:
The system continuously monitors solar position, irradiance levels, and window tint state to dynamically adjust tint levels. This feedback mechanism ensures that the windows respond to changing environmental conditions and occupancy patterns, balancing energy savings with occupant comfort from direct sunlight and glare.
2Object-affected harmful factors
If tint levels are adjusted to reduce direct sunlight and glare, then occupant comfort is improved, but energy savings are reduced
Solution Approach 1:
The system calculates transition times and proactively adjusts tint levels before direct sunlight or glare becomes an issue, rather than reacting after occupants are affected. This timing optimization allows the system to achieve both comfort and energy savings simultaneously.
Solution Approach 2:
The system dynamically adjusts tint levels based on real-time conditions including solar position, irradiance, occupancy, and transition time requirements. This dynamic control allows the system to optimize the balance between occupant comfort and energy savings continuously rather than using fixed tint levels.
3Adaptability or versatility
If electrochromic windows transition to different tint levels, then control flexibility is achieved, but transition time causes delay in reaching desired tint levels
Solution Approach 1:
The system performs preliminary calculations of transition times and initiates tint level changes in advance of when they are needed. This proactive timing ensures that the desired tint levels are reached exactly when required, eliminating delays while maintaining control flexibility.
Solution Approach 2:
The system dynamically adjusts transition timing based on occupancy patterns, solar position, and environmental conditions. By optimizing when transitions occur, the system minimizes the impact of transition time delays while maintaining the ability to achieve desired tint levels.
4Object-affected harmful factors
If predictive control logic is implemented, then occupant comfort and energy savings are optimized, but system complexity increases
Solution Approach 1:
The predictive control logic is segmented into separate functional modules: solar position calculation, irradiance determination, transition time calculation, and tint level optimization. This modular approach reduces system complexity by making each component independent and manageable while achieving the overall optimization of occupant comfort and energy savings.
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 enables electrochromic windows to effectively manage tint levels, enhancing occupant comfort by reducing glare and allowing natural lighting while ensuring energy savings that meet or exceed those of reference windows, thereby improving their commercial viability.
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.
Implementation Method 2
Tungsten oxide is a cathodic electrochromic material in which a coloration transition, transparent to blue, occurs by electrochemical reduction.
Implementation Method 3
calculates a future time based on a current time and a predicted transition time of a representative window of the zone. The processor also is configured to predict a solar position at the future time
Implementation Method 4
The method predicts an appropriate 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
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.