Thermal comfort models and perception of users in free-running school buildings of East-Mediterranean region.

• Indoor conditions were monitored and subjective data from 606 people was collected. • The in-situ measurements often indicate temperatures out of the acceptable limits. • The acceptable temperature range allows for heat energy saving in the winter period. • Students' behavior is significantly determined by outdoor temperature. • The results comprise retrofitting guidelines for school buildings in southern Europe. This paper explores the impact of natural ventilation on the indoor thermal environment through an extensive field survey of educational architecture in Cyprus performed both during the winter and summer periods. The study included seasonal indoor and outdoor monitoring of physical parameters, as well as a questionnaire-based survey. The study shows that the naturally ventilated spaces on the upper floor demonstrate operative temperature below the acceptable comfort zone during the winter period, while during the summer period, the findings show the vulnerability of the occupants to summertime temperatures. During the winter, a closed classroom shows the best results in terms of operative temperature; however, this conflicts with the air quality. During the summer, the case of cross-ventilation, both during the day and night, is the most efficient and operative way to passively cool educational premises. Moreover, the results of the subjective survey demonstrate that most students feel comfortable in both the winter and summer demonstrating high thermal tolerance. The results of the current study can be applied to inform strategies for the improvement of thermal comfort and reduction of energy use in educational buildings, as well as the design of new educational buildings. [ABSTRACT FROM AUTHOR]