Optimal design of low-emissivity coatings

We report a comprehensive numerical study demonstrating surprisingly good photoenergetic performance of low-emissivity (low-E) coatings comprised of just 5 layers. Simulations are performed within the transfer-matrix framework in conjunction with multiobjective optimization using a genetic algorithm. We show that upon utilization of conventional dielectric materials with only one silver layer, all that arranged in a multilayered stack with optimal thickness, large light-to-solar gain (LSG) ratio and visible transmittance (VT) up to 2.4 and 0.72, respectively, with neutral color ($a^{\ast }=-3\pm 1$ and $b^{\ast }=-5\pm 1$ in CIELAB color space) can be achieved. Such an outstanding behavior of single-metal glazing is explained by the emergence of open Fabry-Pérot cavity (so-called pseudo-cavity), the unusual concept for the low-E industry centered around conventional metal-dielectric-metal Fabry-Pérot cavities. Our work highlights the importance of large-scale computational optimization for the design of efficient low-E coatings and provides a useful guide for future developments in this field.