In the Search for Sustainable Vertical Green Systems: An Innovative Low-Cost Indirect Green Façade Structure Using Portuguese Native Ivies and Cork

Green façades in the urban environment represent points of biodiversity value, contributing to species conservation, acting as urban wildlife corridors connecting elements, and also aiming at sustainability, when the materials and structure are thoughtfully chosen. Ivies (Hedera spp.) are perennial climbing evergreen plants that are easy to cultivate and demand little input, and their use in vertical green systems is much appreciated but may lead to damage to the constructions in the long term. Among the 14 species of Hedera currently recognized, a few have been bred into cultivars and are available in the market for cultivation, often as exotic species. Four Hedera spp. are native to Portugal, but most cultivated species in this territory are exotic and the suitability of native species for their use in green façades has not been documented. Thus, in the present work, we describe the installation of a low-cost indirect green façade structure supported on cork panels using plants belonging to the native H. iberica and H. hibernica. The structure is installed at the Ajuda Botanical Garden, under Mediterranean conditions, on a brick and cement wall, and will enable researchers and landscape architects to follow the development of this structure as a long-term experiment, prompting the use of native species toward increased biological and technical sustainability. The preliminary results indicate that the cork structure is able to provide adequate support for the plants and that these were able to climb and develop in this structure, avoiding direct contact with the wall and the possible subsequent damage. Therefore, the structure provides a viable solution to implementing sustainable green façades with native species, on brick-cement walls, able to be replicated in other urban locations under similar environmental conditions.