The paper presents the operation mode of a ventilation chimney placed in a historical building through the use of Design Builder, a modeling and dynamical simulation software. The aim is to verify the improvement of the comfort level and energy efficiency of the simulated environments through the usage of the duct as a passive ventilation system. The method adopted to intervene in a complex system, such as that represented by historic buildings, is to enhance the preexisting architectural values through their conversion into devices able to improve the performance of the building in terms of CO2 and energy consumption reduction. The case study is Palazzo Bruni-Riga, a valuable building located in the historic center of L'Aquila. The building has a double ventilation duct, probably also used as a light-pipe, in correspondence of two windowless rooms of similar dimensions. The dynamical simulations presented concern the analysis of the passive ventilation duct and its effects on the thermo-hygrometric well-being of the modeled rooms. The goal of this paper and this research in general, is that the wise use of such devices installed in times when there were no air conditioning systems, allows you to better use the ventilation chimneys, and have the maximum thermal indoor comfort, with the minimum effort and use of mechanical systems. Through the simulations it was possible to verify that through the use of the ventilation chimney, it is possible to have the indoor comfort conditions, by checking the Fanger indices for the data obtained from the simulations carried out. (C) 2018 The Authors. Published by Elsevier Ltd.