Integrated task performance score for the building occupants based on the CO₂ concentration and indoor climate factors changes

The task performance can be analyzed though various indices related to cognitive tasks, but few studies have been conducted to analyze various indices of task performance considering both the indoor air pollutants and the climate factors. Therefore, this study aimed to develop an integrated task performance score for 22 building occupants based on the IEQ condition changes. The experiment was designed with three scenarios simulating the IEQ condition changes during an 8-hour work period. In each scenario, six cognitive tasks were performed before and after the occurrence of IEQ condition changes. The relationship between cognitive task and IEQ condition was analyzed using a paired t-test. In addition, an integrated task performance score of the building occupants was developed with the use of a weighted Euclidean distance to utilize the results of this study in building design and operation. As a result, when the operative temperature is changed from 18.70 °C (cold) to 25 °C (neutral), the best task performance score was calculated as 0.187. The noticeable fact is that although scenario 1-1 was worse than scenario 2-1 based on the predicted percentage of dissatisfaction, a better occupants’ task performance score was obtained from scenario 1-1 (0.271) than from scenario 2-1 (0.346). Through the results of this study, the building occupants’ task performance according to the IEQ condition considering both the CO₂ concentration and the indoor climate can be expressed as a single index. Thus, it is expected that using this single index, decision makers, including facility managers, building occupants, and mechanical system designers, will be able to manage the IEQ conditions of buildings based on the quantitative indicators of the building occupants’ task performance.