Impact of Indoor Temperature and CO2 Levels on Occupant Thermal Perception and Cognitive Performance of Adult Female Students in Saudi Arabia

Abstract

Due to hot arid climate in Jeddah, Saudi Arabia, occupants rely on air conditioning (AC) to provide both ventilation requirements and thermal comfort. It is believed that this total reliance on AC have also a significant effect on thermal sensation as well as cognitive performance of building occupants. Using a multi-variable multilevel statistical analysis, the effects of classroom temperature and CO2 levels on cognitive performance were estimated. Eight neurobehavioral cognitive tests were used to evaluate cognitive performance of 499 female students (16-20 years old). In addition, thermal sensation votes were collected. All participants were exposed to nine different environmental conditions, a combination of three temperature levels 20°C, 23°C and 25°C, and three CO2 levels: 600 ppm, 1000 ppm and 1800 ppm. The baseline condition levels were set at 20°C and 600 ppm. In this paper the interrelationships between the thermal sensation votes and effects of classroom temperature and CO2 levels on vigilance (Simple Reaction Test, SRT) and memory tasks (Reversal Learning, RL) are presented. The results suggested that the 'cold' thermal sensations have been linked to significant increase in 'percentage of errors' for both memory and vigilance tasks. Also, the exposure to higher CO2 levels of 1800 ppm and 1000 ppm have led to a significant increase in the 'percentage of errors' for both cognitive performance tasks compared to the baseline conditions. The study has also confirmed that the significant influence of acclimatization should not be overlooked when setting up the environmental design criteria for buildings in hot arid climates.

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

“…The reported CO 2 concentration in the identified studies should be considered as an indicator of ventilation adequacy, which can be related to human bio‐effluents, but also to material emissions, chemicals used indoors, as well as other indoor sources of pollutants. The negative effect of elevated concentrations of bio‐effluents, but not pure CO 2 , and other constituents on cognitive performance is also confirmed by Zhang et al 52 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 53 .…”

“…However, this concentration of CO 2 still meets prevailing guidelines 53 . High CO 2 concentrations of 1800 ppm might affect cognitive performance with 24% ( P < 0.001) 22,23 . The influence of high CO 2 concentrations, as proxy for the IAQ, was higher on complex and memory‐oriented than for vigilance tasks.…”

“…Figure 3 shows that in the last decade the IEQ conditions have been examined more holistically and have been conducted in both controlled and free‐running conditions. Only three studies addressed all four indoor environmental parameters 22,23,41,43 . However, none of these studies analyzed the combined influence of these parameters on the quality of teaching, learning, or academic achievement.…”

“…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.…”

“…The influence of high CO 2 concentrations, as proxy for the IAQ, was higher on complex and memory‐oriented than for vigilance tasks. However, the study of Ahmed et al 22,23 is the only study that quantified the effect of IAQ on cognitive performance and examined only female students. Because of these limitations, these results need to be validated with additional field research to confirm the impact and should explore possible gender differences.…”