This paper presents the integration of microclimatic monitoring and dynamic simulations as an effective approach to comprehending the airflow thermodynamics in historical attic spaces. Ventilation is one of the most effective ways to maintain appropriate climatic conditions in the attic space, which can ensure the durability of centuries-old timber trusses. Therefore, the study focused on the optimisation of ventilation in the attic space of a historical church in an eastern-continental climate specific to the Slovak Republic. Interim results of microclimatic monitoring were analysed, and data on air temperature and air relative humidity were used to theoretically determine the equilibrium moisture content. The wood moisture content thus determined showed a higher risk of biological degradation of timber elements during the analysed period at the turn of winter and spring seasons, especially in the northern parts of the roof truss, where the moisture content reached approximately 18%. The obtained microclimatic monitoring data were also used to calibrate the dynamic simulation model of the attic space of the examined church. The calibrated and validated simulation model of the monitored attic space allowed to analyse the impact of various ventilation scenarios on the indoor climate. The simulation results suggested that differences in the wood moisture content during critical periods of the year can reach 1% depending on the ventilation method. These findings, therefore, provide important guidelines for effective modifications of attic ventilation to reduce the risk of wood biodegradation.