Impact of indoor environmental quality (IEQ) factors on occupant evaluation of workspaces

Abstract

This study aims to better understand the relationship between perceived building performance on specific Indoor Environmental Quality (IEQ) factors and occupants’ overall evaluation of their workspace environment. A three-factor satisfaction model, developed originally in the context of marketing, has been adapted to and found suitable for the IEQ domain. Analyses were conducted on the Post-Occupancy Evaluation (POE) database from Center for Built Environment (CBE) at the University of California, Berkeley to estimate the relative significance of individual IEQ factors on occupants’ overall workspace evaluation, depending on whether or not the occupants were satisfied with the IEQ factor in question. The empirical analysis suggested that a certain amount of input (i.e. increments or decrements of occupant satisfaction with individual IEQ factor) doesn’t necessarily lead to a commensurate desirable output (i.e. overall workspace satisfaction). According to each IEQ factor’s functional relationship with overall satisfaction, fifteen IEQ factors addressed in the CBE questionnaire were classified into three groups: (1) Basic Factors – having predominantly negative effects, (2) Bonus Factors – having predominantly positive effects, and (3) Proportional Factors – having both positive and negative effects with similar magnitudes. In general the IEQ factors tended to show negative asymmetry, becoming more critical when the building was deemed to be underperforming on them. This study also explored the influence of gender, building ventilation system type, and office layout configuration, on occupant IEQ satisfaction. (1) Female gender was significantly associated with increased dissatisfaction with all of the IEQ factors analysed in this thesis, but particularly with temperature, indoor air quality and workspace cleanliness. (2) Occupants of buildings with different ventilation systems responded in different ways to various IEQ dimensions. In naturally-ventilated buildings, good thermal conditions were associated with significantly enhanced workspace satisfaction and barely discernible adverse impacts. In air-conditioned buildings, on the other hand, thermal conditions were more directly associated with overall dissatisfaction with workspace environment. Occupants provided with higher degrees of adaptive opportunities were more satisfied with the IEQ of their workplaces. (3) Enclosed private offices clearly outperformed open-plan layouts iii in most aspects of IEQ, but particularly in acoustics, privacy and proxemics issues. Noise distraction and lack of privacy were identified as the major sources of workplace dissatisfaction in open-plan offices. The predicted decrements in overall workspace satisfaction due to privacy and acoustic issues in open-plan layouts were bigger than the predicted increment due to ease of communication between colleagues. Further analyses performed on an Australian POE database collected through Building Occupant Survey System Australia (BOSSA) project highlighted the benefits of external view through a window, positively affecting occupant satisfaction with workplace IEQ.