Designing green roofs for arid and semi-arid climates. the route towards the adaptive approach

P.A. Nektarios, N. Ntoulas
It is widely accepted that green roofs provide multiple benefits to the urban environment and the well-being of the cities' residents. Despite their acknowledged contribution to the contemporary cityscape and environment, their broad implication in arid and semi-arid regions is extremely limited compared to northern countries. Thus, it is of great interest and importance to identify the hurdles that delay the broad implication of green roofs in challenging climatic zones. These hurdles can be categorized either as governmental or technical or psychological even though they all intermingle and interact. More specifically, in the arid and semi-arid climatic zones, such as those of the Mediterranean basin, the governmental incentives are absent forcing the private sector and the homeowners to take the initiative. In those cases, investing in green roofing can only be justified if green roofs are usable and aesthetically pleasing since the preference of the public has been documented towards the intensive green roof types. However, taking into account that the majority of existing buildings are old and can bare minimal additional loading, it is obvious that green roof substrate depth must be minimal. All the above parameters are contradicting and have led us to the introduction of a new green roof category, namely the adaptive type. Adaptive green roofs have minimal substrate depth ranging from 5 to 15 cm but utilize a broad palette of plant species such as groundcovers, turfgrasses, medicinal and aromatic plants coppices and small shrubs. All the above are feasible due to minimal and prudent irrigation inputs. The current presentation provides a thorough review of the plant species evaluated in adaptive green roof systems concerning their response to different substrate types and depths, their tolerance to either deficit irrigation or drought and their irrigation requirements.
Nektarios, P.A. and Ntoulas, N. (2017). Designing green roofs for arid and semi-arid climates. the route towards the adaptive approach. Acta Hortic. 1189, 197-202
DOI: 10.17660/ActaHortic.2017.1189.39
adaptive green roof systems, Mediterranean zone, substrate depth, substrate type, native plant species, deficient irrigation, drought tolerance

Acta Horticulturae