The reduction of energy losses and destroyed exergy requires the optimization of the double-glazing space. The poor thermophysical characteristics of the air are a limiting factor in the attenuation of heat loss through the double-glazing of the solar collector.The aim of this study is to examine the effect of trapped gases (argon, xenon, krypton, and SF6) within the double-glazing and between the inner glass and the absorber on the efficiency, useful energy, overall heat loss coefficient, and outlet temperature of the back-plate solar air heater. This research was conducted by applying constant solar radiation of 1000 W/m2. The new Eismann correlation is implemented to iteratively evaluate the heat transfer coefficients in gas-filled interspaces and to optimally define these distances. Furthermore, the impact of these gases on exergy efficiency, destruction exergy, and system exergy has been studied. Among these rare gases, xenon leads to the best thermal performance, followed by krypton and argon, compared to air. Respectively, the efficiencies obtained are 51.8%, 50.6%, 48.8%, and 45.8% for xenon, krypton, argon, and air. The optimal gas-filled spaces corresponding to these efficiencies are 4 mm, 5 mm, 9 mm, and 10 mm. Similarly, the exergy approach leads to the same optimal widths of the gas-filled spaces.