An urban integration approach of green roofs and rooftop photovoltaics towards carbon neutrality and biodiversity enhancement

• Α Natura 2000 protected area city fabric is analysed for RPV, GR, and biosolar deployment potential. • A five-step, Earth Observation based framework is developed for rooftop suitability assessment. • RPV and GR coupling support city’s climatic adaptation and biodiversity enhancement. • 197 GWh/year of RPV potential is estimated under shading-aware simulations. As cities take action toward carbon neutrality and biodiversity integration in contemporary city planning, the development of rooftop photovoltaics (RPV) and green roofs (GR) presents a multifaceted approach to achieving resilience and sustainability. For the first time, this article quantifies the combined effects of coupling these technologies on urban environments, focusing on their potential to reduce energy consumption, mitigate climate change, and enhance urban ecosystem services, biodiversity, and overall livability. We propose a five-step Earth Observation-based framework including (1) satellite data collection, (2) roof/vegetation classification, (3) structural and shading assessment, (4) irradiance and geometry modeling, and (5) suitability and scenario analysis. This approach is applied to a continental city in Greece, included in the EU Natura 2000 protected area network, where the spatial distribution of suitable roofs is determined for different solar systems or nature-based solutions with the associated benefits of reducing carbon footprint and enhancing biodiversity. With city coverage by RPV in half of the available area of pitched roofs and GR development on all the flat terraces, internal carbon emissions are reduced by 38,000 tons/y, and biodiversity is enhanced; however, it is dependent on the complexity of vegetation communities, connectivity, and structures that the GR matrix will develop. These quantified findings underscore the importance of adopting a holistic approach combining renewable energy production with nature-based solutions to transform urban pathways of resilient and sustainable cities that support biodiversity.