Low Emissivity Coating UV Transmission for Reactive Glass
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Solution Overview
Problem
Conventional low emissivity coatings in architectural windows reflect too much UV light, preventing the activation or darkening of UV reactive glass, which requires increased UV transmission to respond to solar and UV light intensity.
Innovation Solution
A low emissivity coating comprising at least one dielectric layer and one metal layer, designed to be transmissive for long UV wavelengths, allowing for increased UV transmission while maintaining high reflectivity for IR and NIR wavelengths, thereby enabling the activation of UV reactive glass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional low emissivity coatings reflect UV wavelengths from the solar spectrum, then thermal energy transfer is reduced, but UV reactive glass cannot be activated or darkened
Solution Approach 1:
The low emissivity coating is divided into multiple layers with different optical properties. The first low-e coating layer (closest to the UV reactive glass) has modified optical characteristics that allow UV transmission, while outer layers maintain thermal reflection. This segmentation enables selective wavelength transmission: UV wavelengths pass through to activate the glass, while IR and NIR wavelengths are reflected to reduce heat transfer.
Solution Approach 2:
Different regions of the coating system are assigned different functional properties. The first low-e coating layer positioned adjacent to the UV reactive glass has local quality optimized for UV transmission, while outer low-e coating layers maintain traditional thermal reflection properties. This local differentiation resolves the contradiction by allowing UV activation at the glass interface while preserving thermal performance at the exterior surface.
2Loss of energy
If low emissivity coatings are designed to reflect IR and NIR wavelengths, then energy efficiency is improved, but UV transmission is reduced
Solution Approach 1:
The coating system is segmented into multiple low-e layers with differentiated optical functions. Outer layers are optimized for IR/NIR reflection to minimize thermal energy transfer, while the inner layer adjacent to the UV reactive glass is optimized for UV transmission. This segmentation allows simultaneous achievement of energy efficiency through thermal reflection and sufficient UV transmission for glass activation.
Solution Approach 2:
The coating system exhibits local quality variations where outer layers have optical properties tailored for thermal reflection, while the layer closest to the UV reactive glass has properties tailored for UV transmission. This local differentiation enables the system to reflect IR and NIR wavelengths for energy efficiency while allowing UV wavelengths to pass through for glass activation.
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
The coating achieves improved UV transmission, allowing UV reactive glass to activate in response to solar radiation, while minimizing heat transfer through the window by selectively reflecting and absorbing IR and NIR wavelengths, thus optimizing energy efficiency and glass functionality.
Implementation Method 1
low emissivity coatings (or 'low e' coatings) to reflect IR and NIR wavelengths from the solar spectrum and thereby reduce radiant thermal energy transfer through the window
Implementation Method 2
the low emissivity coating is transmissive for long UV wavelengths or actinic wavelengths from the solar spectrum
Data Source
AI summary
A coated article including a substrate and a low emissivity coating. The coated article includes increased TUV and/or actinic transmissivity for use in windows and similar applications.