Metamaterial Window Glass

Abstract

A computational study of a metamaterial (MTM)-on-glass composite is presented for the purpose of increasing the energy efficiency of buildings in seasonal or cold climates. A full-spectrum analysis yields the ability to predict optical and thermal transmission properties from ultraviolet through far-infrared frequencies. An opportunity to increase efficiency beyond that of commercial low-emissivity glass is identified through a MTM implementation of Ag and dielectric thin-film structures. Three-dimensional finite difference time-domain (FDTD) simulations predict selective nonlinear absorption of near-infrared energy, providing the means to capture a substantial portion of solar energy during cold periods, while retaining high visible transmission and high reflectivity in far-infrared frequencies. The effect of various configuration parameters is quantified, with prediction of the net sustainability advantage. MTM window glass technology can be realized as a modification to commercial low-emissivity windows through the application of nanomanufactured films, creating the opportunity for both new and after-market sustainable construction.

A Scalable optical meta-surface glazing design for agricultural greenhouses

“…In this work, the standard ASTM G137 spectrum is used to evaluate solar cells and other meta-surface designs. This is known as the AM1.5 spectrum [19,20].…”

“…The thickness, surface finish and the grain structure are the most important factors affecting the performance of thin films. The thickness of the silver layer varies from 5nm to 20 nm [19]. The coated glass is often used in a double-pane design for maximum thermal insulation.…”

“…The silver thin film coating exhibits high reflectance in this spectrum thereby wasting a significant part of the incoming solar irradiation. There is a potential to improve the IR admittance of Ag thin film low-e glazing using metamaterial structures as demonstrated by [19].…”

“…It is intented to improve the absorption in the solar frequencies by creating strong resonance and field intensification at the silver metal surface using a silver thin film structure. It is worthy to mention that designs with strong absorption peak at 700nm with the extension into the infrared region has already been produced by the other researchers [19]. This enables greater admittance thereby capturing more of the available incident solar energy.…”

“…The silver NPs of 150 nm diameter is considered for a broad spectral response and activity in the infrared region based on Mie theory [26]. The centre distance to the thin film layer is selected to match the silver square design by [19]. All the parameters are varied to understand the general trend with respect to the performance of the glazing [19].…”