This study investigates the impacts of varying spectral calculation methods on the thermal and optical performance of smart glazing windows in building environments. Emphasizing localized solar spectra, the research assesses how these variations influence key parameters such as heat transfer and daylight utilization. Comparative analyses demonstrate the significance of using context-specific spectra for optimizing energy efficiency. The findings guide the selection of appropriate calculation techniques for dynamic building designs, with a particular focus on adapting international standards to regional atmospheric conditions.