Bio-inspired Adaptive Building Skins - Biotechnologies and Biomimetics for Civil Engineering - page 115

engineering literature provides a well-described taxonomy that can help make
this connection (Chalupnik et al. 2013 ). The same terminology can be used to
highlight the need for adaptation in the built environment (Loonen et al. 2013 ).
With respect to building envelopes, the underlying principles of adaptation can
offer advantages on the following three levels: adaptability, multi-ability and
evolvability.
5.2.1 Adaptability
Adaptability is defined by Ferguson et al. ( 2007 ) as the ability of a system to
deliver intended functionality considering multiple criteria under variable condi-
tions through the design variables changing their physical values over time.
Building skins having this attribute can seize the opportunity to deliberately act in
response to changes in ambient conditions, such solar radiation, wind speed and
direction, temperature, rainfall, etc. Doing this offers a potential for energy savings
compared to conventional, static buildings because the valuable energy resources
in our environment can be actively exploited, but only at times when these effects
are deemed favourable (Loonen et al. 2011 ). Adaptable facades can thus act as
climate mediator, negotiating between comfort needs and what is available in the
ambient environment (Wigginton and Harris 2002 ). With embedded adaptability,
façades no longer have to be a compromise solution for the whole year, performing
acceptable under a wide range of conditions, but never optimal regarding a specific
situation (Ochoa et al. 2012 ). Moreover, it gives opportunities to adjust to the
individual user (Bakker et al. 2014 ), rather than a best average for all, as usually
prescribed in comfort standards. In addition to the immediate effect, adaptability of
building envelopes also helps in achieving gains through smart utilization of
building constructions' thermal storage capacity. The dual effects of shifting peak
demands can help in mitigating comfort problems, and also limit redundancy in
installed heating and cooling capacity (Hoes et al. 2011 ).
5.2.2 Multi-ability
The concept of multi-ability originates from the existence of non-simultaneous
performance requirements, or the need to fulfil new roles over time. The 'balcony
that can be folded' (Hofman and Dujardin 2008 ) is an illustrative example of a
responsive building envelope that features multi-ability: depending on ambient
conditions and users' preference, it changes function from window to a balcony-on-
demand (Weaver et al. 2008 ). Multi-ability differs from adaptability in the sense that
multiple requirements are fulfilled successively, not at the same time (Ferguson et al.
2007 ). Unlike conventional systems, designed to satisfy a single set of conditions, it
allows for addressing change via a plurality of individually-optimized states. In this