Heat Recovery Ventilation in School Classrooms Within Mediterranean Europe: A Climate-Sensitive Analysis of the Energy Impact Based on the Italian Building Stock

In most European school classrooms, ventilation rates fall far short of standard requirements due to an inefficient use of manual airing, creating an unhealthy environment and increasing the risk of airborne viral transmission among occupants. To promote proper Indoor Air Quality (IAQ) levels, the required ventilation could be achieved by considering NV-oriented measures or Mechanical Ventilation systems with Heat Recovery (MVHR) implementation. This study defines a method to evaluate the potential primary energy implications of implementing MVHR in classrooms in the Mediterranean climate in comparison with NV control, selecting the Italian public-school building stock as a case study. Dynamic energy simulations were conducted across reference building construction types, considering locations representative of the national climate variability. Results show that MVHR can reduce primary energy up to 42.31 kWh/m². At the national level, it can achieve an attainable annual primary energy saving of 227 GWh, approximately 30% of current classroom consumption, with more than 70% of this potential located in northern provinces. A regression model was also used to relate energy impact to the Heating Degree Days, offering a scalable and transferable tool to support retrofit policies within similar southern European contexts.