Perceived and measured indoor environment in educational buildings

Abstract

In educational buildings there is strong variation of the user-caused loads on indoor air during the working days. The challenge is to energy efficiently maintain comfortable indoor environment allowing good working and learning conditions for the building users. The objective was to define the main factors having effect on the user experience of indoor environment and to evaluate what range of measured factors are found comfortable in different building user groups. Three educational buildings representing different grades and one day care center were studied at least for a one-year period to find the main factors affecting the perceived indoor environment comfort in these spaces. Altogether 30 selected spaces were monitored, and perceived comfort of the users was collected through a novel real-time feedback system. The users could give their feedback concerning the perceived thermal comfort, humidity, air freshness and cleanliness, odours, lighting, noise and capability to work and learn. The feedback was based on the targets presented in the classification of the indoor environment [1] using Likert-scales [2) in questions. Each feedback of the experienced indoor environment condition had the space and time identification for the comparison with the corresponding monitored values. All the four sites had modern building technology systems. Only a weak correlation could be found between measured temperatures and the primary goal, i.e. good learning and working conditions. However, stronger correlation was found with the lighting, noise/acoustics, air freshness and humidity. With the humidity levels, both too low and too high levels affected the comfort. The effect of the total VOC-level on the comfort depended on the case - only in the day care center it had a strong negative effect. One relevant finding was that there was no difference between the user comfort in a case with full time ventilation compared to a case where the ventilation that was shut down during unoccupied hours to save energy. This paper presents the analysed findings for the measured and feedback data for these cases.