Bio-inspired Adaptive Building Skins - Biotechnologies and Biomimetics for Civil Engineering - page 114

envelope, as inspired by principles found in nature. Modern construction tech-
niques, developments in material sciences, and availability of controllable kinetic
façade components now offer ample opportunities for innovative building enve-
lope solutions that respond better to the environmental context, thereby allowing
the façade to ''behave'' as a living organism (Loonen et al. 2013 ; Loonen 2014 ).
Natural envelope-like structures such as shells, skins and coverings have evolved
over time to limit energy expenditure while maintaining conditions to thrive and
reproduce. In many instances, adaptability, either on the short- or longer-
term (Kasinalis et al. 2014 ), forms an essential mechanism for resilience and
survival. Mimicking these strategies, by finding functional analogies, and bringing
them to the domain of architecture, can form a key ingredient for environmentally
conscious sustainable development in the building sector. On a wider scale, bio-
inspired adaptable building skin design can play an important role in creating a
better mutual relationship between buildings and their surrounding local micro-
climate, through careful integration of principles from urban physics (Moonen
et al. 2012 ), for enhancing, e.g. natural ventilation potential (Ramponi et al. 2014 ),
pollutant transport in street canyons (Xie et al. 2007 ), acoustic properties (Van
Renterghem et al. 2013 ) and wind comfort (Montazeri et al. 2013 ). In the longer
term, such design considerations will help in the transition from biological prin-
ciples on the building scale towards the more holistic notion of ''biophilic cities''
(Beatley 2011 ).
This chapter presents an overview of building envelope surfaces, materials,
structures, functions, constructions, mechanisms, principles and processes, all
inspired by nature. We approach the building envelope design question from the
viewpoint of visual, acoustic and thermal aspects, and do this with a specific focus
on adaptability, the ability of a system to change in response to varying envi-
ronmental conditions. The next section continues with a discussion of systems-
based terminology to be able to better analyse the many ways of how adaptability
can be embedded in the building envelope. This is followed by a state-of-the-art
structured overview with examples of bio-inspired adaptive building skins
described in literature. Finally, this chapter concludes with discussing strengths
and challenges of design methods that can support a more systematic design
methodology for bio-inspired adaptive building skins.
5.2 Adopting Bio-inspired Adaptation Principles
in Building Envelope Design
The existence and manifestation of adaptation is an important condition for sus-
taining life in natural (eco-)systems. In nature, adaptation can be found at multiple
physical scales and time resolutions. It is not always straightforward to convey the
complexity and subtlety of these biological concepts in a form that is directly
applicable to the domain of architecture and building envelope design. The systems