Effects of temperature and outdoor air supply rate on the performance of call center operators in the tropics.

Abstract

A study was performed in a call center that provides billing inquiry services using a 2 x 2 balanced experimental plan for nine consecutive weeks. Two independent variables, temperature and outdoor air supply rate, were combined and introduced to the occupants in a blind intervention approach. The temperature set-points were fixed at 22.5 degrees C and 24.5 degrees C, and outdoor air supply rate at 5 l /s/p and 10 l/s/p. Temperature and outdoor air supply rate had significant interaction effects on worker's talk time (P < 0.001), which means that the effects of temperature on talk time performance were not independent of the effects of outdoor air supply rate or the opposite. Talk time was reduced significantly when the outdoor air supply rate was increased from 5 l /s/p to 10 l/s/p at 24.5 degrees C (P < 0.01); this may be associated with the significant reduction in a principal component factor which includes intensity of dryness, aching eyes and nose-related symptoms (P < 0.01). Decreasing the temperature from 24.5 degrees C to 22.5 degrees C at 10 l /s/p significantly increased talk time (P < 0.01). Analysis of the principal component factor based on the neurobehavioral symptoms also revealed that temperature reduction led to an increased mean factor score of these symptoms (P < 0.04). For moderately complex office work which involves manipulation dexterity such as a call center operation where call operators interact with computer-based information systems, tropically acclimatized workers' performance could be improved by increasing the outdoor air supply rate from 5 l/s/p to 10 l/s/p if the temperature is to be maintained at the higher band of the thermal comfort range, around 24.5 degrees C. At a low ventilation rate (5 l/s/p), decreasing the temperature from 24.5 degrees C to 22.5 degrees C (which is a commonly adopted set-point in tropical office buildings) also leads to improvement of talk time performance. The magnitude of talk time improvement was greater by more than four times when the strategy to increase the outdoor air supply rate was implemented at a lower range of outdoor air supply rate (5-10 l /s/p) as compared to the higher range (9.8-22.7 l/s/p).