Modeling and Measurements in Natural Ventilation of Massive Buildings: A Case Study

Numerical simulations are widely used to evaluate the thermal comfort and energy savings in the retrofit of historic buildings. In most cases, however, no detailed data are available on the materials and stratigraphy of the building envelopes, and on-site measurements can be expensive and time consuming. The present work uses as a case study a university building characterized by a high thermal capacity in the city of Rome to verify whether the use of natural ventilation can be a practice of use in order to guarantee energy saving and natural comfort. To this end, in the summer of 2020, an experimental campaign was carried out aimed at acquiring thermofluximetric measurements through the vertical walls, the air temperature inside and outside the analyzed environment and the air velocity. Measurements were conducted under three different usage protocols, including night ventilation and 24-hour continuous ventilation. These measurements made it possible to identify the thermophysical characteristics of a wall considered "equivalent" to the real wall, allowing the realization of thermofluidodynamic computational models. In particular, in the study, 3 different stratigraphies were considered and compared, corresponding in the first case to the equivalent wall, in the second to that available from the Comsol software library, and, finally, in the third and last case, from literature data (Tabula project) for the building typology analyzed. From the analysis, it emerged that the 3 groups of parameters do not have a significant impact in terms of variation of internal comfort, confirming the reliability of the use of the literature values for these types of modeling.