Green Roofs: Nature-Based Solution or Forced Substitute for Biologically Active Areas? A Case Study of Lublin City, Poland

Abstract

Green roofs have become an increasingly popular feature in building design, driven by their bio-physical properties and aesthetic and recreational values. They serve as a key element in promoting the integration of Nature-Based Solutions (NBSs) in urban fabrics, aiming to enhance urban environments, mitigate climate impact, and create more sustainable urban spaces. Polish regulations mandate that investors maintain a designated proportion of biologically active areas, ensuring natural vegetation and rainwater retention. Green roofs fulfill this requirement and can serve as compensation for the loss of biologically active areas due to construction. Unfortunately, the regulations lack specificity regarding their construction. This study aimed to examine whether green roofs consistently represent NBSs, as frequently presented in the scientific literature, or rather serve as a legal substitute for biologically active areas. The research was conducted in Lublin, the ninth largest city in Poland. Field studies, analysis of planning documentation, and review of administrative decisions have revealed that the majority of green roofs in Lublin have a greenwashing character, meaning they were installed to meet urbanistic indicators rather than for climate, environmental, or aesthetic reasons. Such studies have not been conducted before in relation to local spatial development plans and administrative decisions in Poland, and they show that this approach does not contribute to increasing biodiversity on investment plots. Notably, the investor would be denied construction permits without the incorporation of green roofs. Consequently, this leads to the conclusion that not all green roofs fulfill the criteria of NBS, as not all ensure an increase in biodiversity. Therefore, legal provisions regarding their establishment should be revised and specified.