The integration of vegetation in urban areas is a constantly evolving research field. However, green envelopes (especially the most innovative vertical greening systems) are not yet fully accepted as an environmental quality restoration and energy-saving method for the built environment, due to the lack of data needed to quantify their effects and to evaluate the real sustainability (environmental and economic) of these. The many systems available on the market allow combining nature and built space to improve the environmental quality in urban areas; green façades, living wall systems offer more surfaces with vegetation and, at the same time, contribute to the improvement of the thermal performance of buildings. From a functional point of view, vertical greening systems often demand a complex design, which must consider a major number of variables. In the case of vertical greened surfaces, there are numbers of systems to green façades with or without windows, starting from a simple disposition of climbing plants at the base of the façade. Vertical greening systems’ characteristics and materials involved can either positively or negatively influence theirs performances, with respect to the improvement of the building envelope efficiency and microclimate conditions (cooling potential and the insulation properties), and the environmental burden produced during their life span (installation, maintenance, disposal, etc.). This paper analyses characteristics, advantages and critical aspects of four common vertical greening systems, with special attention to micro-scale benefits (the benefits most related to the systems peculiarities) and to environmental sustainability.
green façade, living wall system, building envelope, thermal behaviour, energy saving, environmental sustainability
 Bohemen van, H., Ecological Engineering, Bridging between Ecology and Civil Engineering, Aeneas Technical Publishers: The Netherlands, 2005.
 Köhler, M., Green façades – a view back and some visions. Urban Ecosystems, 11, pp. 423–436, 2008. doi: http://dx.doi.org/10.1007/s11252-008-0063-x
 Dunnett, N. & Kingsbury, N., Planting Green Roofs and Living Walls, Timber Press: Portland, OR, 2008.
 Novi, F., La riqualifi cazione sostenibile, Alinea Editrice: Firenze, 1999.
 Nuzzo, E. & Tomasinsig, E., Recuperoecoeffi ciente del costruito, Edicom Edizioni: Monfalcone, Gorizia, 2008.
 Thormark, C., A low energy building in a life cycle. Its embodied energy, energy need for operation and recycling potential. Building and Environment, 37(4), pp. 429–435, 2002. doi: http://dx.doi.org/10.1016/S0360-1323(01)00033-6
 Ardente, F., Beccali, M., Cellura, M. & Mistretta, M., Building energy performance: a LCA case study of kenaf-fi bres insulation board. Energy and Buildings, 40(2002), pp. 1–10, 2008.
 Prasad, D. & Hill, M., The construction challenge: sustainability in developing countries, London Royal Institution of Chartered Surveyors (RICS) Series, Leading Edge Series, 2004.
 Perini, K., Vegetation, architecture and sustainability. Article accepted in EAAE/ARCC International Conference, Milan, 2012. doi: http://dx.doi.org/10.1007/s11252-012-0262-3
 Hendriks, C.F., Bijen, J.M.J.M., Felix, F., Fraaij, A.L.A., Janse, H., de Munck, E.D., Reintjes, R.C., Schutte-Postma, E.T., Stroeven, P., Vogtlander, J.G. & van der Wegen, G.J.L., Durable and Sustainable Construction Materials, Aeneas Technical Publishers: The Netherlands, 2000.
 Perini, K., L’integrazione di vegetazione in architettura. Metodi e strumentiinnovativi. The integration of vegetation in architecture. Innovative methods and tools. Dissertation, University of Genoa, 2012.
 Perini, K., Ottelé, M., Haas, E.M. & Raiteri, R., Vertical greening systems, a process tree for green façades and living walls. Urban Ecosystems, 16(2), pp. 265–277, 2013.
 Bellomo, A., Paretiverdi, Sistemieditoriali: Napoli, Italy, 2003.
 Ottelé, M., Perini, K., Fraaij, A.L.A., Haas, E.M. & Raiteri, R., Comparative life cycle for green facades and living walls. Energy and Buildings, 43(12), pp. 3419–3429, 2011. doi: http:// dx.doi.org/10.1016/j.enbuild.2011.09.010
 Perini, K., Ottelé, M., Haas, E.M. & Raiteri, R., Greening the building envelope, façade greening and living wall systems. Open Journal of Ecology, 1(1), pp. 1–8, 2011. doi: http:// dx.doi.org/10.4236/oje.2011.11001
 Ottelé, M., The Green Building Envelope. Dissertation, Delft University of Technology, 2011.  Wong, N.H., et al., Thermal evaluation of vertical greenery systems for building walls. Building and Environment, 45(3), pp. 663–672, 2009. doi: http://dx.doi.org/10.1016/j. buildenv.2009.08.005
 Perini, K. & Ottelé, M., Vertical greening systems: contribution on thermal behaviour on the building envelope and environmental sustainability. Eco-Architecture IV. Harmonisation between Architecture and Nature, WIT Transactions on Ecology and the Environment, Vol. 165, ed. C.A. Brebbia, Wessex Institute of Technology, WIT Press: UK, 2012.
 Krusche, P., Krusche, M., Althaus, D. & Gabriel, I., Ökologischesbauen. Herausgegebenvomumweltbundesamt: Bauverlag, 1982.
 Peck, S.W., Greenbacks from green roofs: forging a new industry in Canada, Status report on benefi ts, barriers and opportunities for green roof and vertical garden technology diffusion, environmental adaptation research group, Canada, 1999.
 Minke, G. & Witter, G., Häuser mit grünen pelz. Ein handbuch zur hausbegrünung, 1982.
 Perez, G., Rincon, L., Vila, A., Gonzalez, J.M. & Cabeza, L.F., Behaviour of green facades in Mediterranean Continental climate. Energ Convers Manag, 52(4), pp. 1861–1867, 2011. doi: http://dx.doi.org/10.1016/j.enconman.2010.11.008
 Minke, G. & Witter, G., Häuser mit grünen pelz. 3. ed Frankfurt/Main, 1983.
 Bartfelder, F. & Köhler, M., Experimentelle Untersuchungenzur Funktionvon Fassadenbegrunungen. Förderungsprogramm der Freien, Universitat Berlin fur junge Wissenschaftler 3, Ausschreibung, 1987.
 Holm, D., Thermal improvement by means of leaf cover on external walls – a simulation model. Energy and Buildings, 14, pp. 19–30, 1989. doi: http://dx.doi.org/10.1016/03787788(89)90025-X
 Eumorfopoulou, E.A. & Kontoleon, K.J., Experimental approach to the contribution of plant covered walls to the thermal behaviour of building envelopes. Building and Environment, 44, pp. 1024–1038, 2009. doi: http://dx.doi.org/10.1016/j.buildenv.2008.07.004
 Perini, K., Ottelé, M., Fraaij, A.L.A., Haas, E.M. & Raiteri, R., Vertical green systems and their effect on air fl ow and temperature near the façade. Building and Environment, 45, pp. 2287–2294, 2011. doi: http://dx.doi.org/10.1016/j.buildenv.2011.05.009
 Mazzali, U., Peron, F. & Scarpa, M., Thermo-physical performances of living walls via fi eld measurements and numerical analysis. Eco-Architecture IV. Harmonisation between Architecture and Nature. WIT Transactions on Ecology and the Environment, 165, pp. 239–250, 2012.
 Corrado M., Il verdeverticale, Sistemi Editoriali: Napoli, Italy, 2010.
 Alexandri, E. & Jones, P., Temperature decrease in a urban canyon due to green walls and green roofs in diverse climates. Building and Environment, 43, pp. 480–493, 681, 2008.
 Henry, A. & Frascaria-Lacoste, N., Comparing green structures using life cycle assessment: a potential risk for urban biodiversity homogenization? International Journal of Life Cycle Assessmen t, 17, pp. 949–950, 2012. doi: http://dx.doi.org/10.1007/s11367-012-0462-3