A Green Building Envelope: A Crucial Contribution to Biophilic Cities - Biotechnologies and Biomimetics for Civil Engineering - page 154

We have suggested that, far from being a radical or fashionable solution, this is
simply the reinterpretation of an approach with a long and distinguished history.
Before the full benefits of green buildings could be scientifically proven, the
principle was already accepted and practiced in cities all over the world. Green
building is most effective as part of an integrated green approach to cities. Such an
approach demands a much closer cooperation between architects, ecologists,
developers, and green planners than has so far taken place. The integration of
vegetation in the built space can be an opportunity to improve the environmental
conditions of dense urban areas and to reduce the energy demand of buildings,
especially in Mediterranean area due to its cooling capacity. This is an important
field to investigate considering the growing interest on these systems, which is not
only connected to a more sustainable approach to construction, but also to esthetic
intentions (Perini 2012 ).
To guarantee sustainable practices, benefits, and performances obtainable
thanks to greening systems, have to be considered along with the environmental
burden produced during the life span of greening systems, and with the possible
problems connected to maintenance demand. Also costs have to be considered for
a wider diffusion of these systems. Measurements carried out in the field by many
researchers show not only the potential of vertical green on the thermal perfor-
mance, but also under laboratory conditions (Ottelé 2011 ). The positive effect on
the thermal resistance (i.e., summer and winter) is mainly caused by the materials
used, extra cavity, water availability, and metabolism of the plant tissue. Through
(significant) less heat accumulation by the masonry in combination with evapo-
transpiration caused by the plant material, a positive effect to lower/mitigate the
urban heat island effect can be taken into account.
As discussed throughout the article, many aspects have to be considered to
avoid that green only plays an esthetic role with respect to sustainability. Char-
acteristics, components, and materials of vertical and horizontal greening systems
can have an influence on the environmental burden and environmental benefits,
etc. Some systems, as the living wall ones described, offer much more creative and
aesthetical potential, but due to the material used and durability in some cases
cannot be considered as sustainable. Material choice and durability aspects are
important (environmental impact) when the energy demand of a building can be
reduced or when the multifunctionality of the construction due to the integration of
vegetation can be increased. These aspects have been considered also through a
life cycle analysis (Ottelé et al. 2011a , b ). As suggested by Henry and Frascaria-
Lacoste ( 2012 ) the adoption of LCA analysis for the labeling of green products
could increase their use since it has the potential to boost the confidence of
consumers. Therefore, this could lead to particular focus being placed on specific
green elements, which could potentially further homogenize natural features
within cities, with possible negative impact on other benefits of green, such as
biodiversity (Henry and Frascaria-Lacoste 2012 ). However, a LCA could lead to
deeper consideration by manufacturers of the environmental burden produced by
their systems to improve the balance between benefits and burden for a more
sustainable built environment.