Permeable and ventilated roofs: an emerging solution for building comfort and climate mitigation in urban centers. The Project LIFE SUPERHERO

During the last 15 years, the frequency and intensity of heatwaves have increased in all the EU. In response to warming cities, the growth in environmental impacts and global demand for building cooling are two of the most critical energy issues of our time. Many EU cities are already working on climate mitigation strategies, while urban adaptation is still a novel challenge and requires the urgent development of specific measures to change urban design and structures. Indeed, renovation of existing buildings and design of new ones has a great urban adaptation potential against the “heat” challenge. An effective sustainable and low-cost answer to cities and building overheating is using building “passive cooling” technologies, which allow reducing the temperatures of the building envelope and consequently of the surrounding air, rather than increasing energy demands from artificial cooling. LIFE SUPERHERO seeks to exploit a specific building passive cooling solution: the Ventilated and Permeable Roofs (VPRs) based on roof tile designed during the previous project LIFE HEROTILE. As the roof is the most exposed element to solar radiation, a “vented roof”, obtained through an air space between the installed roof covering and the roof sheathing, could limit the summer heat fluxing into the building, thus reducing roof and wall temperatures. This space reduces heat transfer and allows the roof to “breathe” and disperse the accumulated solar heat. If this ventilation is coupled to a “high permeability” of the roof tiles, it is possible to obtain a considerable increase in the cooling performance. However, current EU national regulations, standards, green rating systems and procurements in the building sector do not recognize the cooling potential of VPRs, mainly focusing on winter heating saving. In particular, there are two main barriers to overcome: the lack of specific policies/legislative frameworks and the lack of people's awareness of their potential. The goals of the project will be achieved: - by implementing a specific EU standard (ETA) and improving building environmental protocols and national building codes considering HBR (Herotile- Based Roof) benefits; - through two building demonstrators where the impact of HBR on occupants’ behavior will be monitored and consequently public and stakeholders’ awareness promoted; - by entailing the development of free LCA/LCC software, to facilitate the implementation of climate change adaptation strategies and action plans at a local level. LIFE SUPERHERO thus promotes a synergy between climate adaptation and mitigation actions. The VPR-HBR allows increasing building and city thermal comfort (adaptation) due to the limitation of external building roof temperature in hot seasons, thus reducing the Urban Heat Island phenomenon. The limitation on internal building roof temperature in hot seasons improves occupants’ comfort, entailing a reduction of cooling energy demand and GHG (Green House Gases) and accelerating the phasedown of HFC (Hydro Fluor Carbon) included in refrigerants (mitigation).