Green roofs for smart cities: experimental determination of the “fractional vegetation coverage” of six vegetated species

Towards a de-carbonization of European countries, green roofs are becoming popular, due not only to aesthetic reasons but also to energy and environmental issues. Indeed, especially in summer periods, the building cooling demand might be sensibly cut thanks to such passive components often chosen for planning smart cities. To properly model the energy performances of buildings equipped with these components, a particular attention must be paid to radiative exchanges occurring among soil surface, leaves and outdoor surroundings. These thermal exchanges depend on parameters, like the “fractional vegetation coverage” whose literature data do not seem particularly suitable for the simulation needs. To further populate database for thermal simulations of buildings equipped with these components, the experimental evaluation of the coverage ratio of six vegetated species, that is Phila nordiflora, Gazania (nivea and uniflora), Aptenia lancifolia, Mesembryanthemum barbatus, and Sedum adopted for the green coverings installed in a university campus, is presented.