A study on the impact of greenery in building interiors on the psychological well-being of occupants: an experimental study with special reference to Personalized Residential Spaces of University Students in Sri Lanka

This study aimed to investigate the impact of indoor greenery on occupants' well-being and design preferences. Previous research on outdoor greenery has left a gap in understanding the relationship between interior greenery and well-being. Using a sample of 36 final year Architecture students, the study tested four interior conditions in varying green coverage ratios and varying observing distances through a 3D simulated setup and virtual methods. The results showed that a high ratio of indoor greenery, regardless of observing distance, was consistently more beneficial than low greenery conditions. Specifically, a high amount of greenery at a far distance delivered the highest levels of psychological well-being, with 61.11% of participants reporting high wellbeing. In contrast, low greenery at a far distance was the least beneficial combination, resulting in lower well-being (38.89% - low, 2.78% - very low), personal satisfaction, negative feelings, and weaker connection to the indoor space. Most participants preferred indoor courtyards with 50% exposure to natural light due to the sense of naturalness and vibrant shadows they provided. The study recommends that Architects, Interior Designers, and Landscape Architects consider incorporating high indoor greenery at a distance and partial exposure to natural light to promote psychological well-being in future indoor green spaces.