Evaluating Airtightness in Modular Office Buildings: a Case Study on Prefabricated Envelope Performance

Air infiltration through the building envelope significantly affects energy consumption, thermal comfort, and indoor environmental quality. While Blower Door Testing is widely used in residential contexts to quantify air leakage, its application to non-residential, prefabricated structures remains limited in both practice and literature. This study investigates the airtightness performance of three modular academic spaces located at the University of Calabria, constructed with prefabricated concrete panels and lightweight internal partitions. Using the UNI EN ISO 9972:2015 methodology and pressurization-only testing, a detailed analysis was conducted to quantify airflow behavior and compare results against normative benchmarks. Among the tested environments, Lecture Hall M1 recorded the highest air change rate $(n_{50}=10.06 h^{-1})$, while the most airtight space, Office A, exceeded reference thresholds with an n50 of 47.38 h⁻¹. These results underscore the inadequacy of applying generic benchmarks to modular non-residential buildings and point to the need for adapted diagnostic approaches and performance criteria.