This study explores the interconnection between environmental stress and the discordant psychological well-being of the population through a specific focus on permeability and enclosure. In Sidoarjo, where only 21.6% of open space is allocated—well below the required minimum of 30%—and characterized by poor quality, noticeable changes in behavioral patterns occur, resulting in a disruption of psychological well-being. The research argues that optimizing the design of enclosures within public spaces, considering the permeability factor, holds promise for alleviating environmental stress in Sidoarjo Regency. Utilizing a mixed-methods approach, incorporating both descriptive qualitative and quantitative methodologies, the study employs mean score analysis and continues with Multivariate Analysis of Variance (MANOVA). The findings reveal that spaces with a strong level of enclosure (D/H < 1) and high permeability significantly influence positive psychological well-being. Conversely, spaces with a moderate level of enclosure (1 < D/H < 2) exhibit an indeterminate effect, suggesting adaptability to specific spatial functions, while those with low levels of enclosure (D/H > 2) and lower permeability imply a diminished impact on psychological well-being. These insights, incorporating permeability and enclosure as key factors, contribute to the understanding of the interplay between design elements, environmental stress, and psychological well-being, potentially influencing urban planning and public space optimization in Sidoarjo Regency within the context of the Sustainable Development Goals (SDGs).