On the identification of most appropriate green roof types for urbanized cities using multi-tier decision analysis: A case study of Istanbul, Turkey

Green roofs (GRs) have gained considerable attention in recent years as a sustainable solution for densely urbanized cities to mitigate the negative impacts of urbanization on the environment. Hence, this research proposed a hybrid multi-criteria decision-making scheme aiming to determine the best-matched GR formation for metropolitan city of Istanbul. Therefore, fuzzy AHP and TOPSIS were adopted for weighting a total of 16 criteria and performing binary prioritization of intensive GRs (IGRs) and extensive GRs (EGRs) for the focalized region, respectively. Two GR types were examined based on four major dimensions, i.e., financial, technical, knowledge, and environmental aspects. The results highlighted the vitality of financial (35.01%) and environmental (34.91%) facets, followed by the technical (21.83%) dimension, whereas knowledge (8.24%) was the least significant aspect. Also, initial and operational costs (global weight: 17.37%) and stormwater retention capacity (global weight: 16.98%) outperformed their counterparts. Combining the criteria weight computed and the average scores of each factor with regard to the city further illustrated that EGR (CC_i: 0.7442) was found as the optimal GR configuration for Istanbul. The key findings of this research aimed to contribute to the growing GR literature by exploring the paradigms regarding the sustainability and resilience of urbanized cities.