Multi-pane Window with Low Emissivity and Photochromic Glass
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Solution Overview
Problem
Conventional multi-pane windows fail to effectively limit solar heat gain and independently adjust visible light transmittance over time, as they either rely on low emissivity coatings that reflect a constant fraction of visible light or photochromic glass that is temperature-dependent, leading to inefficiencies in heat control and light filtration.
Innovation Solution
A multi-pane window configuration featuring an external glass pane with a low emissivity layer and an internal photochromic glass pane, where the low emissivity layer reflects and absorbs infrared and near-infrared wavelengths, while selectively transmitting visible light wavelengths to activate the photochromic glass, reducing visible light transmittance by 40% or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional low emissivity coatings are used to reflect solar radiation, then solar heat gain is reduced, but visible light transmittance remains constant and cannot be adjusted over time
Solution Approach 1:
The patent applies dynamics by replacing static low emissivity coatings with a dynamic photochromic glass system. The glass transitions from a transparent state to a darker state in response to UV light exposure, dynamically adjusting visible light transmittance while maintaining thermal insulation properties. This allows the window to adapt to changing solar conditions over time.
Solution Approach 2:
The patent utilizes parameter changes by employing photochromic glass that changes its optical properties (transmittance, color) in response to UV radiation. The glass composition and structural parameters are designed to enable reversible transitions between different optical states, allowing adjustment of visible light transmittance while maintaining low emissivity characteristics.
2Adaptability or versatility
If photochromic glass is used to adjust visible light transmittance, then adaptive light control is achieved, but temperature dependence reduces effectiveness in heat control
Solution Approach 1:
The patent applies segmentation by separating the functions of visible light adjustment and thermal insulation into distinct components. The photochromic glass handles visible light transmittance adjustment, while the low emissivity coating layer handles thermal radiation reflection. This functional separation allows each component to optimize its specific function without interference from temperature-dependent effects.
Solution Approach 2:
The patent uses an intermediary approach by positioning the photochromic glass at a specific distance from the external environment, allowing it to respond to UV light without direct temperature influence. The spacing and configuration act as intermediaries that decouple the photochromic response from temperature variations, maintaining effective heat control.
3Device complexity
If a single-pane window is used, then device complexity is minimized, but both solar heat gain limitation and adaptive light control are insufficient
Solution Approach 1:
The patent applies merging by combining multiple functional layers (transparent glass, low emissivity coating, photochromic glass) into a single integrated window assembly. This merged structure achieves both solar heat gain limitation and adaptive light control simultaneously, eliminating the need for separate windows or additional control mechanisms while maintaining reasonable device complexity.
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 configuration effectively reduces solar heat gain and provides adaptive control over visible light transmittance, minimizing heat transfer and maintaining thermal isolation of the photochromic glass from external temperatures, thus enhancing energy efficiency and comfort.
Implementation Method 1
The outside glass pane reflects light comprising a wavelength from 701 nm to 2000 nm
Implementation Method 2
the low emissivity layer reflects and absorbs infrared and near-infrared wavelengths
Implementation Method 3
The inside glass pane comprises a photochromic glass... Light having a wavelength from about 350 nm to about 700 nm transmitted by the outside glass pane contacts the inside glass pane and darkens the photochromic glass
Data Source
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AI summary
A multi-pane window having a low emissivity layer and a photochromic glass. The window includes at least two panes of glass. An outside pane for interaction with the outdoors and an inside pane spaced apart from the outside pane. The outside pane includes a low emissivity coating. The inside pane includes a photochromic glass. The outside pane transmits solar light wavelengths. The photochromic glass is darkened upon exposure to light transmitted by the outside pane.