Bio-inspired Adaptive Building Skins - Biotechnologies and Biomimetics for Civil Engineering - page 118

5.3.1 Form

5.3.1.1 Form: Material

Adaptability of form at the material scale implies that changes take place at the
scale of nanometres. A myriad of responsive or smart building materials are capable
of changing their configuration at this level of spatial resolution (Bastiaansen et al.
2013 ; Klooster et al. 2009 ; Leydecker et al. 2008 ). The change itself, however, can
normally not be observed with the naked eye, but is manifested in the form of
variations in aggregate optical (Baetens et al. 2010 ), thermophysical (Quesada et al.
2012 ), or surface properties (Chen et al. 2012 ). This then results in a change of
function, rather than form, and for this reason, this class of materials is discussed in
Sect. 5.3.2.1 : Function—Material.

5.3.1.2 Form: Component

The efficiency of building-integrated photovoltaic (BIPV) façade systems can take
advantage of natural design strategies. SMIT Solar Ivy is such an innovative BIPV
system, inspired by the way foliage leafs are arranged to capture sunlight in an
optimal way. Instead of cladding the envelope with flat surface-mounted panels,
the system consists of smaller loose-hanging elements, the so-called solar leaves
that freely move and partly overlap each other. This arrangement not only
increases the usable surface for photovoltaic energy generation, but also induces a
natural, wind-driven cooling effect, which further enhances the energy generation
efficiency of the thin-film solar cells (Klooster et al. 2009 ; Brownell 2010 ).
One of the most well-known and widely studied (e.g. Dawson et al. 1997 )
examples of movement found in nature is the opening and closing behaviour of
pine cones in response to hygroscopic conditions. Reichert et al. ( 2014 ) recently
adopted this phenomenon, and transformed it into an innovative façade compo-
nent. Their approach, named Meteorosensitive Architecture, harnesses the elastic
deformation of veneer composite materials to make a tunable, humidity-responsive
façade opening system. An interesting feature of this concept is that the material
acts as sensor and actuator at the same time (Menges and Reicher 2012 ). The
adaptive capacity is an inherent feature of the subsystems comprising the building
shell. An advantage of this type of control, compared to conventional, external
control hardware is that these types of systems can immediately change their
configuration without expending any fuel or electricity to facilitate the state
transition. In addition, the subtlety of the technology is a main asset: the number of
components is limited since no add-on systems like control units, processors or
wires are necessary (Loonen et al. 2013 ). The material can be ''programmed'' in
such a way that it responds in different ways to prevailing environmental