Bio-inspired Adaptive Building Skins - Biotechnologies and Biomimetics for Civil Engineering - page 124

Fig. 5.6 Artificial vascular window system having a 10 9 10 cm 2 array of 1 mm wide channels,
dry (left) and filled with water (right)(Source Hatton et al. ( 2013 ), reprinted with permission)

5.3.2.3 Function: Façade

Of the different scales and levels of abstraction discussed in this chapter, functional
bio-inspiration for adaptation at the façade level is the most popular one. Probably
this is because of the direct analogy that can be made with the skins of living
organisms. Numerous biological principles have been investigated, with mixed
success, for application in buildings, such as: animal fur (Webb et al. 2011 , 2013 ),
reptile skin (Zare and Falahat 2013 ), tree bark (Yowell 2011 ), bird feathers
(Taghizade and Taraz 2013 ), plant species (Rezaei and Zare 2011 ), seeds (Fernandèz
et al. 2013 ) or the hollow structure of polar bear hair (Stegmaier et al. 2009 ).
An exemplary case in this category is based on the optics of animal eyes and
their responsiveness to light (Park and Dave 2013 ). The optical composition of
reflecting superposition eyes is converted into a dynamic façade structure with
square tube structures, embedded with optical systems. When integrated into the
roof of large buildings, the technology is able to capture, concentrate and distribute
natural

daylight, to reach optimal lighting conditions and reduced energy

consumption.
In terms of solar shading control for buildings, the Homeostatic façade,
developed by DeckerYeadon, forms an interesting alternative compared to regular
screens or blinds systems (Dahl 2013 ). The system regulates a building's indoor
climate on the façade level by automatically and autonomously responding to
environmental conditions. Through deformations of a shape-changing dielectric
elastomer, the shading system expands under sunny conditions, and contracts when
to allow for passive solar gains. The mechanism is modelled after the motion in
muscles, and has an advantage over other systems because of its low power
consumption and localized control (Minner 2011 ).