Abstract
Office buildings in the Alpine region are generally only equipped with space heating systems, being located in traditionally heating-dominated climates. However, climate change and more and more frequent heatwaves, combined with urban heat island effects in the major settlements, have altered the typical ambient conditions in the summer months, requiring the adoption of active air-conditioning systems in the design of new high performance office buildings. Many existing offices in the Alpine region, nevertheless, still rely on natural ventilation and on manually controlled shading systems to deal with the risk of overheating, with results not always successful or fully satisfactory to ensure optimal thermal comfort conditions for the occupants. Given these premises, in this research we performed an objective and subjective assessment of indoor thermal conditions in three public office buildings of the Municipality of Bozen–Bolzano, Italy, with the goal of characterizing thermal comfort for the employees in the hottest period of the year, as well as its impact on their work performance. The three considered buildings are, respectively, an historical building, a non-insulated one, and a more recent building, partially insulated, built during the 1990s; only the latter one is equipped with cooling and mechanical ventilation systems. Thermal sensation votes and indoor air temperature and humidity data were collected during the last two summer seasons, allowing for a detailed comparison of thermal comfort conditions in the three buildings, as well as of task performance losses due to suboptimal indoor conditions, assessed according to models available from the literature.