Quantitative criteria on the regulation of outdoor space quality in high-intensity residential areas: a case study of the Yangtze River Delta region in China

The compact city development model offers greater sustainability compared to urban sprawl. However, it presents challenges to the residential environmental quality. Meanwhile, the lack of effective quantification and regulatory mechanisms for outdoor space quality within the existing index system exacerbates the situation. This study builds upon a novel indicator, the Relative Open Space per Household (ROSH), introduced by us in prior research, to develop methodological details. The ROSH was developed through the integration of open space classification, value dimensions, and population data. This study leverages a sample of 101 high-intensity residential areas within China’s Yangtze River Delta (YRD) region. By employing statistical analysis combined with an optimized clustering algorithm, the study clusters data on the relationship between ROSH-Satisfaction (R-S). This research revealed three distinct ROHS value interval standards: prohibited, flexible, and approved, thereby establishing the ROHS value standard and the interval regulation methods. Furthermore, an innovative secondary indicator has been introduced for residential areas within the flexible interval, enhancing the control of the ROSH indicator over the quality of outdoor spaces. This research offers a methodological example for establishing quantifiable and actionable criteria for outdoor spaces in residential areas across various countries and regions. It provides urban planning authorities with practical, implementable regulatory measures, thereby contributing to the ecologically sustainable development of urban residential environments.