Effects of indoor vegetation density on human well-being for a healthy built environment

Vegetation in the built environment is known to affect human well-being. Although previous studies have provided quantitative evidence of the benefits of indoor vegetation on human well-being, the effects of vegetation density in indoor environments remain to be explored. To bridge this gap, this study explored the effects of indoor vegetation density on well-being, particularly on perceived restorativeness, stress reduction, and selective visual attention. This study employed the perceived restorativeness scale (PRS-11) and psychophysiological restorativeness (EEG) and found a positive association between increased indoor vegetation density and restorativeness. Despite the restorative effect, there was an inflection point in the indoor environments at 13%–24% vegetation density. For perceived restorativeness and stress reduction, 13%–24% was the most efficient density within indoor environments. Thus, this study contributes a baseline guideline and reference for designers and decision makers to understand efficient vegetation density in indoor environments.