Indoor climate and user satisfaction in classrooms after energetic retrofitting

Retrofitted classrooms are supposed to provide a better indoor environment and hence to have more satisfied occupants. The aim of this study was to survey the indoor climate in retrofitted, mechanically ventilated classrooms, to gain knowledge of the occupants’ perception of the indoor climate and their perception of the newly implemented ventilation systems. Subjective and objective data from 32 mechanically ventilated classrooms in 17 Bavarian schools in Germany was collected. In each classroom outdoor and indoor air temperature, relative humidity and CO2 concentration were measured for at least one week between May and July 2014. In addition teachers, pupils and caretakers were asked to fill in a questionnaire concerning user perception, behaviour and satisfaction. During lessons, classrooms showed median CO2 concentrations between 750 and 2110 ppm, with 90% of all values below 1500 ppm. During lessons, 72% of all measured indoor air temperatures were between 23°C and 26°C. The evaluation of the questionnaires shows dissatisfaction with indoor air temperatures in summer, available controls and a need for improved information. Taking into account the high expectations of especially the teachers, the majority of the other users proved to be satisfied.