Nurefsan SonmezArzu Cilasun Kunduraci2025-10-0620230236-29451068-97612541-993510.33383/2023-053http://dx.doi.org/10.33383/2023-053https://gcris.yasar.edu.tr/handle/123456789/5976This simulation -based study investigates the po-tential of tubular daylight guidance systems (TDGS) to enhance daylight availability in historical build-ings. Historical buildings often face challenges in providing sufficient daylight to non-lit areas with-out altering the building's facade. TDGS offer a pas-sive building-integrated solution that redirects day light to target areas while preserving the building's originality. The study focuses on a historic passage building without ground floor openings and aims to improve visual comfort and daylight availabil-ity. Climate Studio software is used to assess the current daylighting conditions and to simulate vari-ous scenarios for TDGS implementation. The study considers four TDGS alternatives with different di-ameters evaluating their impact on useful daylight illuminance (UDI) and spatial daylight autonomy (sDA). The findings reveal significant increases in UDI and sDA ranging from 68.7 % to 403.7 % and from 79.9 % to 1813.6 % respectively depending on the tube diameter. These results underscore the importance of daylight tube diameter in increasing the availability and distribution of useful daylight. The study emphasizes the potential of TDGS to op-timize daylighting experiences in historical build-ings with limited daylight.Englishhistorical buildings, tubular daylight systems, case study, simulationArticle