Bio-inspired Adaptive Building Skins - Biotechnologies and Biomimetics for Civil Engineering - page 122

Fig. 5.4 Algae facade, BIQ
house at the International
Building Exhibition 2013 in
Hamburg (Source http://
www.flickr.com/photos/_
bundjugend/ under CC BY 2.
0 license)
5.3.2.2 Function: Component
Aero Dimm (Fig. 5.5 ) is a good example of a biological principle that is directly
transformed into a building component (Gruber 2011a ). The façade component is
inspired by coloration of cephalopod molluscs, and works via a pneumatic chamber
that changes its volume between two elastic membranes. By controlling air pressure
inside the cavities, a colour change and corresponding impact on radiant heat
exchange is achieved. Doing the adaptation in a smart way, it is possible to realise a
significant positive contribution in the building's energy balance.
An indirect example at the component level is the artificial green façade con-
ceived by Šuklje et al. ( 2013 ). The façade system consists of bionic leaves, which
are made of photovoltaic cells attached to evaporative matrices. These components
serve the dual purpose of increasing photovoltaic system efficiency and cooling of
the air in the microclimate that surrounds the building. The technical manifestation
of this envelope system is only distantly related to evapotranspiration of actual
vegetation in green facades. Results from the experiments nevertheless show that
the evaporative cooling effect of the bionic façade approaches its natural coun-
terpart, while introducing a 6.6 % increase in energy production compared to PV
leaves without evaporative cooling.
Bio Skin, the façade construction of the Sony Research and Development
Center in Tokyo, Japan, is inspired by transpiration to reject heat in summer, but
is, in contrast to the sweating polymers from Sect. 5.3.2.1. packaged in the form of
a more technological approach. The system uses a network of porous ceramic
tubes, mounted on the exterior surface of the building. The tubes are fed with
rainwater that is collected from the roof and nearby surroundings. By means of
evaporation, the system provides a cooling effect due to latent heat transfer. Bio
Skin's goal not only is to reduce cooling load of the building, but also to act as a
mitigation strategy for the urban heat island effect by cooling the surrounding air
(Yamanashi and Hatori 2011 ).