Thickness-dependent coupled thermo-optical model of translucent material: a case study of glazing unit filled with granular silica aerogel

With the growing emphasis on low-carbon and energy-efficient buildings, advanced façade systems incorporating translucent materials—such as granular silica aerogel，3D printed facade and phase change materials (PCM)—are being actively researched due to their ability to modulate incident solar radiation while enhancing thermal performance.

However, the complex thermal and optical properties of these materials pose significant challenges for evaluating their performance across material, component, and building scales within conventional Building Performance Simulation (BPS) tools. While experimental characterization provides insights for specific case studies, ensuring both flexibility and generalizability remains a key challenge.

This study integrates a multi-flux radiation model, developed based on spectral scattering and absorption coefficients of Granular Silica Aerogel (GSA) obtained through a new methodology based on general experimental optical data.

The proposed model provide a more advanced modeling of the thermo-optical performance of translucent materials exhibiting strong scattering phenomena, enabling the evaluation of advanced transluscent building envelope components with customizable thicknesses and configurations.

To demonstrate the applicability of this methodology, a case study is conducted comparing two different modeling approaches: (1) a simplified implementation within EnergyPlus and (2) an R-C (resistance-capacitance) component model for assessing the thermal performance of a double-glazing unit filled with a 30 mm GSA layer.The results illustrate the flexibility and accuracy of the thickness-dependent thermo-optical coupling model, supporting its integration into building-level energy simulations.