Ultraviolet and visible (UV-VIS) radiation is responsible for the photolysis of stable trace gases and production of highly reactive atoms and radicals in the lower boundary layer of the atmosphere. Photolysis frequencies of the key species in the atmosphere depend on the spectrally resolved actinic flux. However, to date direct measurements and modeling of the actinic flux and photolysis frequencies of species relevant for indoor atmospheres are scarce. In this study, we present systematic indoor measurements of actinic fluxes and photolysis frequencies of nitrous acid (HONO), nitrogen dioxide (NO2) and the nitrate radical (NO3) during summer and winter periods. The emerged experimental data of indoor actinic fluxes and the photolysis frequencies were compared to the ambient data obtained by the Tropospheric Ultraviolet and Visible (TUV) model. Finally, an architectural model was run by which integrated spectral irradiance (UV-VIS) values were compared to the measurements performed by the spectroradiometer. The comparison of the measurements with the architectural model yields an equation which can be used in the future to predict the integrated spectral actinic flux values in various indoor environments as a function of the architectural parameters such as orientation of the building, the size and the thickness of the glass windows. (C) 2016 Elsevier Ltd. All rights reserved.