The EU LIFE VISIONS project ( https://lifevisions.gr/ ) aims primarily at demonstrating the applicability of photocatalytic paints as a viable means for reducing urban population exposure to concentration levels in indoor spaces that may give rise to adverse impacts on health. A secondary project aim is to identify options for energy consumption reductions. Towards this end two field trials were organized, under controlled and real-life conditions, respectively. The main objective was to utilize both in-situ measurements and numerical modelling to assess the depollution efficiency of these photocatalytic paints. In the present study a RANS CFD model is applied for the case of the demonstration houses in Heraklion, Greece, to assess the depollution potential of the photocatalytic paints in indoor environments under semi-realistic conditions and to validate the numerical methodology used on the basis on field trial measurements. First results from the in-situ measurements are very encouraging, indicating NOx concentration level reductions up to 67%, with comparable reductions obtained through the numerical simulations. This allows to conclude that the proposed modelling methodology is applicable for assessing the efficiency of photocatalytic paints in real-life conditions.