Assessment of the contributions of different flat roof types to achieving sustainable development

The sustainability of cities is being influenced by their roofs, which cover a high proportion of built-up areas and whose design is crucial to control their economic, environmental and social impacts in a context of urban sprawl and Climate Change. For this reason, this research developed a Multi-Criteria Decision Analysis (MCDA) methodology combining the Analytic Hierarchy Process (AHP) and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to support the selection of four representative flat roof types (self-protected, gravel finishing, floating flooring and green) according to their contribution to sustainability, based on their performance across a list of indicators aligned to the United Nations Sustainable Development Goals (SDGs). The analysis was carried out under three different climate scenarios (Mediterranean, Oceanic and Continental) and relied on the judgments provided by a panel of experts in the building sector to both refine and weight the proposed indicators. The results proved that green roofs were the most sustainable alternative for all the scenarios evaluated, by virtue of their insulation, recycling, cost, energy, water and ecosystem-related benefits. Consequently, this type of roof emerges as a multifunctional solution to be strongly considered in the design of planning strategies seeking urban regeneration.