The effects of higher temperature setpoints during summer on office workers' cognitive load and thermal comfort

Abstract

Typical commercial lease agreements in Australia stipulate 22.5 ± 1.5 °C in summer as the acceptable thermal condition that buildings have to meet, even though the overcooling incurs excessive and unnecessary energy use, gas emissions and financial expense. An argument that backs up this practice asserts that office workers' productivity and comfort will be jeopardised outside this temperature range. This paper investigated whether the office environments with a practical higher temperature setpoint can still be cognitively efficient and comfortable for office workers. In a controlled climate chamber, 26 office workers experienced the typical summer indoor temperature condition in Australia (22 °C) followed by the condition with a higher temperature setpoint (25 °C). In both conditions, subjects were required to fulfil Cambridge Brain Science (CBS) cognitive performance tests, NASA Task Load Index (NASA-TLX), and thermal comfort and air quality questionnaires. Meanwhile, participants' electroencephalogram (EEG) and heart rate (HR) were recorded under three different difficulty levels of Paced Auditory Serial Addition Tests (PASAT). Results showed that CBS test scores were not significantly affected by temperature; a higher temperature of 25 °C incurred a significantly reduced cognitive load for subjects, as has been observed by NASA-TLX, but probably due to the learning effect; the comparison between EEG and HR features during different temperatures did not show any significant difference. Participants' thermal comfort was not significantly jeopardized by the 3 °C temperature setback either. Results from this study favourably support a practical setback of temperature setpoints in Australian office buildings during summer.

Personal thermal comfort models with wearable sensors

“…A personal comfort model using only control behavior of a personal chair system can generate a prediction AUC of 69% compared to approximately 53% (almost random) for the PMV and adaptive model [26]. Along with the behavior-tracking, physiological signals, such as skin temperature [27][28][29][30][31], heart rate variability [32], electroencephalogram (EEG) [33], skin conductance [34], and accelerometry [35], show a strong relationship with human thermal sensation and comfort. Sim et al [36] developed personal thermal sensation models based on wrist skin temperature measured by wearable sensors.…”

Differences in Occupants’ Satisfaction and Perceived Productivity in High- and Low-Performance Offices

“…While some studies document direct linkages of temperature and self-reported performance at work [34][35][36], there is still disagreement about "ideal" set-points. Some authors suggest lower temperatures to address distraction and complaints [37] while others make the case in favor of warmer indoors, without losses on reported perceived productivity [38,39]. The other dimension that has been studied was "ventilation rate" (i.e., supply of outdoor air) due to its indirect influence on workers' performance, caused by the impact of ventilation on thermal comfort, air quality, and concentration of indoor generated pollutants [40,41].…”

Impact of sustainable building design on occupant experience: A human centred approach

“…Most previous indoor environmental research has focused on the effect of environmental factors upon human cognitive performance but this is not the only important issue that should be considered. The problem is that it is possible that some occupants maintain the same, or better, cognitive performance in more difficult environmental situations but with higher cognitive load which can lead to increase in mental stress (Zhang et al, 2017). VSimulators allows indicators of stress to be measured at the same time as work performance is considered in relation to the environmental quality.…”