Developing a principal components model of indoor smellscape perception in office buildings

In recent years, research has increasingly explored the relationship between humans, smells, and the built environment. However, a standardized system that fully captures all crucial perceptual dimensions of indoor smellscapes is still missing. To address this gap, a sensory test was conducted in a living lab to identify the underlying perceptual dimensions of indoor smellscapes in office settings. A total of 42 participants assessed 22 olfactory scenarios commonly encountered in offices, delivered through an olfactometer. Participants evaluated these scenarios using 80 unidirectional scales designed to describe human responses to indoor smellscapes, with each descriptor rated on a visual analogue scale (0–100) indicating the degree of "descriptor–smellscape match". Through Principal Component Analysis, Pleasantness, Presence, and Naturalness were identified as the three main perceptual dimensions, explaining 64.78 %, 13.61 %, and 6.91 % of the total variance, respectively. The relationships between principal component scores and smell categories were analysed using linear mixed-effects models, revealing significant effects of olfactory categories on principal components scores. Based on these findings, a measurement system is proposed, structured around a 2D space defined by two orthogonal axes—Pleasantness and Presence—with two additional axes, Engagement and Power, rotated 45° within the same plane. This model identifies key perceptual constructs to be measured (e.g., in post-occupancy evaluations), and specifies attribute scales. Furthermore, the study provides insights into which smell categories influence these perceptual dimensions in office environments. By offering a systematic approach, this framework provides a valuable reference for both research, standardization and practical applications in the built environment.