Experimental and statistical survey on local thermal comfort impact on working productivity loss in university classrooms

Abstract

The paper presents an experimental analysis of the relationship between local thermal comfort and productivity loss in classrooms. The experimental investigation was performed in a real university classroom during the winter semester in city of Belgrade. Measurements were taken for four scenarios, with different indoor comfort conditions. Variations were made by setting the central heating system on/off, adding an additional heat source to provoke higher indoor temperatures, and measuring the radiant asymmetry impact. Innovative questionnaires were developed especially for the research, in order to investigate students' subjective feelings about local thermal comfort and indoor environmental quality. Local predicted mean vote and predicted percentage dissatisfied indices were calculated using data measured in situ. The results were compared to existing models recommended in literature and European and ASHRAE standards. Student productivity was evaluated using novel tests, designed to fit the purposes of the research. Surveys were conducted for 19 days under different thermal conditions, during lectures in a real classroom, using a sample of 240 productivity test results in total. Using the measured data, new correlations between the predicted mean vote, CO 2 , personal factor and productivity loss were developed. The research findings imply that local thermal comfort is an important factor that can impact productivity, but the impact of the personal factor is of tremendous importance, together with CO 2 concentration in the classroom.

Classrooms' indoor environmental conditions affecting the academic achievement of students and teachers in higher education: A systematic literature review

“…Bajc et al 35 measured the short‐term academic performance of 240 students and related this performance to their perceived thermal comfort. To determine possible performance loss, students had to perform a listening exercise.…”

“…Nine of the included IAQ‐studies 22,23,26,29‐31,35,39,41 used CO 2 concentration in ambient air as the performance indicator of the IAQ. One may assume, however, as humans (generally) are the single source of CO 2 , both CO 2 concentration and other bio‐effluents are correlated.…”

“…Thermal sensations “cool” and “slightly cool” can positively influence cognitive performance 28 ; thermal sensations “cold,” “slightly warm,” “warm,” and “hot” can affect cognitive performance negatively 27 . The thermal sensation “hot” affects cognitive performance of vigilance tasks and memory and learning tasks more than the thermal sensation “cold.” 22,23 Nevertheless, Bajc et al 35 concluded that students' short‐term academic performance is not just a function of PMV index; there is no simple relation in real conditions that can link this performance to the PMV index alone.…”

“…27 The thermal sensation "hot" affects cognitive performance of vigilance tasks and memory and learning tasks more than the thermal sensation "cold." 22,23 Nevertheless, Bajc et al 35 concluded that students' shortterm academic performance is not just a function of PMV index;…”

“…Nine of the included IAQ-studies 22,23,26,[29][30][31]35,39,41 The cognitive performance of students can decline by as much as 13% (P < 0.001) when the CO 2 concentration increases from 600 to 1000 ppm. 22,23 However, this concentration of CO 2 still meets prevailing guidelines.…”