Smells modulate thermal sensation: A multisensory study in office environments during winter

Recent advances in multisensory studies have highlighted the potential influence of sensory interactions on human perception. However, the relationship between environmental smells and thermal sensation remains underexplored. This study investigates how exposure to olfactory stimuli influences perceived thermal sensation over time, using two fragrances with “warm” (vanilla) and “cool” (fig) connotations. A controlled experiment was conducted in a living lab in Bolzano (Italy) during winter, involving 24 participants and three identical test rooms: one odourless (control), and two scented with vanilla and fig scents. Participants experienced each condition for 15 min and rated their thermal sensation using a 7-point Thermal Sensation Vote scale at 5-minute intervals. Data analysis using a Cumulative Link Mixed Model revealed that the vanilla scent consistently increased the likelihood of reporting warmer thermal sensations compared to the odourless condition, with the effect strengthening over time and peaking at 15 min. At that timepoint, the probability of perceiving warmth in the vanilla-scented room was approximately 95% higher than in the control setting (p < 0.001). Conversely, the fig scent produced a delayed cooling effect, becoming significant only after 15 min, with an 88% higher probability of reporting cooler sensations compared with the control setting (p < 0.001). These effects are attributable to perceptual and cognitive association mechanisms. The findings suggest that incorporating olfactory cues into building design could enhance perceived thermal comfort without changing the set-point temperature, thereby potentially enabling energy savings.