Indoor Conditions in Educational Buildings: the Case of Bolzano Schools

Indoor environmental quality in educational buildings is recognized as a crucial aspect for the achievement of the learning outcomes for students. Nevertheless, indoor school conditions are often found unsatisfactory in several European countries, including Italy, especially as regards indoor air quality IAQ. For instance, taking CO2 concentration as IAQ indicator, the threshold of 1000 ppm is often overcome, suggesting insufficient ventilation rates. As observed in the literature, this cannot be referred to a specific type of building system or vintage: indeed, excess of CO2 concentrations was recorded in both old and recent buildings, with either natural or mechanical ventilation systems. In the current research, we focused on the school building stock of the city of Bolzano, Northern Italy, with the aim of monitoring the indoor conditions and defining new strategies and practices to improve the IAQ. After some preliminary measurements, we selected 5 schools, including 3 recent buildings and 2 buildings from the 70s-80s, for long-term campaigns. All educational buildings in the set rely on natural ventilation to renovate the air in the classrooms. CO2 concentration, relative humidity and air temperature were recorded in representative classrooms during a year with a 10-minute timestep. Acquired data were analyzed according to EN 16798-1:2019, determining the share of occupied time in the different IAQ categories of the technical standard. Indoor conditions recordings were used also to assess thermal comfort according to the PMV-PPD model, and to assess the pupils' performance loss according to models available in the literature. A diffuse problem of inadequate IAQ was highlighted in different schools, in particular during the winter season, regardless of their vintage, windows technology or students’ age. Recorded temperatures were found higher than recommended, with potential implications on occupants’ thermal comfort, performance and energy efficiency.