A data-driven approach to thermal transmittance (U-factor) calculation of double-glazed windows with or without inert gases between the panes

Abstract

Understanding the thermal performance of window units is of utmost importance for the advancement of energy-efficient building design. Thermal transmittance (U-factor) is one of the most important indicators of a window system's efficiency, especially in colder climates. Presently, the Window U-factor is typically calculated using one of two standard approaches: experimental methods and computational modeling both having significant limitations. This makes it crucial to develop methods that can calculate the thermal performance of windows in the field and more on already installed windows. This research introduces a data-driven approach to calculating the U-factor of double-glazed windows filled with and without inert gases. The study is confined to double-glazed windows containing either air or a defined percentage of inert gases (75 % Argon, 85 % Argon, and 95 % Argon). The study reveals that the center of glazing, due to its prominence in window construction, plays a significant role in determining the window's thermal attributes. It also establishes a correlation between glass emissivity and center of glass U-factor (thermal transmittance). Furthermore, our developed data-driven approach exhibits considerable reliability in calculating the thermal transmittance of double-glazed windows, as validated by comparison with industry-standard NFRC 100-certified U-factor values. The insights garnered from this research contribute significantly to the understanding of double-glazed window design and the development of more energy-efficient fenestration products. It provides a robust foundation for industry professionals aiming to reduce energy consumption and work towards a sustainable future.