Microclimate conditions in conservation spaces such as museums, galleries, storages, archives, and libraries significantly impact the preservation of cultural materials, potentially leading to permanent damage. This study focuses on quarantine rooms, essential for isolating and inspecting incoming collections for infestations or contamination. Despite their importance, systematic microclimate investigations in such spaces have not been conducted until now. In this research, temperature and relative humidity monitoring has been conducted over the past 3 years (i.e., 2021-2022-2023) within the quarantine room of the Norwegian University of Science and Technology (NTNU) University Library (located within the DORA I concrete bunker, Trondheim, Norway). Data analysis revealed stable indoor conditions due to the buffering capacity of the massive building envelope together with climate control system. Specific metrics for the estimation of climate-induced chemical and biological risks on vulnerable artifacts were applied to compute the percentage of time for which thermohygrometric conditions could favour cellulose hydrolysis and biodeteriogens proliferation on a yearly basis. In this way, the study provided a decision-making tool useful to evaluate the best time (in terms of safest temperature and relative humidity conditions) when to introduce incoming collections into the quarantine room, depending on the material they are made of and on the timeframe selected for their isolation.