A Green Building Envelope: A Crucial Contribution to Biophilic Cities - Biotechnologies and Biomimetics for Civil Engineering - page 152

Fig. 6.15 Cross section of a living wall system based on felt layers. Due to the minimum rooting
thickness very vulnerable for dehydration. Irrigation and nutrient system necessary
Fig. 6.16 Cross section of a living wall system based on mineral wool. Thicker rooting medium
resulting in more redundancy against dehydration. Irrigation and nutrient system necessary
systems varies according to the type of system available. Living wall systems with
panels based on felt layers have an average life expectancy of 10 years, and living
wall systems based on planter boxes last more than 50 years. A thorough design
(details of window ledges, doors, etc.) is always necessary to avoid damages, as
corrosion or rot, caused by leakage of water and nutrients (Ottelé et al. 2011a , b ).
The green layer also results in a shading effect, which reduces the amount of UV
light that will fall on building materials; since UV light deteriorates the material
and mechanical properties of coatings, paints, plastics, etc., plants will also have
an effect on durability aspects (Wong et al. 2009 ). Greening the building envelope
with living wall systems is a suitable construction practice for new building and
retrofitting (Ottelé 2011 ; Perini 2012 ). In both situations, it is possible to have a
higher integration within the building envelope by combining functionalities. For
example, in the case of the conventional bare walls constructed by several layers it
is possible to avoid building the outer façade element since the protection against
the environmental parameters is ensured by a living wall system. For retrofitting
projects an external insulation material can be easily covered with LWS panels
(Ottelé et al. 2011a , b ).