Indoor plants' effect on occupants' performance, perceived comfort, and affect in an open-plan space in composite climatic regions, India

Biophilic designs with indoor plants are being increasingly recognized for their potential to enhance indoor environmental quality (IEQ) and occupant satisfaction. This can contribute to sustainable and green buildings. However, evidence on the specific benefits of indoor plants remains ambiguous. Particularly, for the buildings in India, there is dearth of evidence of the impact of plants on occupants. We conducted a between-subjects study, with (WP) and without plants (WoP), to investigate effect of indoor plants on Indian building occupants in the composite climatic region of India. Subjective questionnaires queried participants' indoor climate perception, sick building syndrome (SBS) symptoms, emotional state, self-assessed performance, and overall satisfaction with the space. Participants undertook a cognitive task targeting working memory (Operations Span). Air quality perception, SBS symptoms, and subjectively and objectively assessed performance did not differ significantly between WP and WoP groups. The WP group perceived the space to be better decorated (|r|, effect size = 0.42, p < 0.0001), cleaner (|r| = 0.16, p = 0.04), visually more comfortable (|r| = 0.22, p = 0.01), and cooler (r = 0.18, p = 0.02). The WP group also had enhanced positive emotions (|r| = 0.21 to 0.45, p < 0.0001 to 0.02) and reduced negative emotions (r = 0.18, p = 0.02). Our findings indicated that potted plants improved occupant perception of indoor environment and can potentially lower cooling energy use by over 8 %.