A Green Building Envelope: A Crucial Contribution to Biophilic Cities - Biotechnologies and Biomimetics for Civil Engineering - page 134

6.2 Green Building Envelope Strategy
The resilience of cityscapes against climate change is predominantly determined
by the properties of their surfaces and the spatial arrangement of the buildings.
These factors induce the occurrence of urban heat islands or flooding (Scharf et al.
2013 ). When global radiation reaches a surface it may be reflected (Albedo) or
transformed to sensible or latent heat flux. While plants are able to transform the
sun energy into biomass, oxygen, and air humidity, regular building surfaces (e.g.,
plaster) emit sensible heat flux. Plants regulate the urban microclimate, while
conventional surfaces lead to microclimatic extremes and reduce the thermal
comfort within cities (Scharf et al. 2013 ).
To deal with problems in dense urban areas often one-sided solutions are
chosen. With the increased focus on ecological impacts of human activities on our
environment the attention is shifted more and more to integrated solutions. Eco-
logical engineering principles and biophilic design, can contribute to integrated
solutions as it is applied and multidisciplinary science; it is integrating human
activities with the natural environment, so that both can have advantage of
designing and refurbishing of constructions. Conservation and the development of
biodiversity by utilization of biological processes are central in the designing
process. Dense and paved cities need an appropriate development, which incor-
porates an ecological approach to building and landscape design with respect to
link functions such as water management, air pollution reduction, energy con-
servation, the recycling of waste (water), and nature conservation (biodiversity).
One promising option for dense urban cities is the greening of buildings
(Johnston and Newton 2004 ; Ottelé 2011 ; Perini 2012 ). By strategically adding a
''green skin'', it is possible to create a new network of vegetation as roofs, walls,
courtyards, streets, and open spaces. These networks, also called stepping stones,
are particularly important in the city centers where vegetation may cover only
about one third of the land surface, compared with 75-95 % in the outer suburbs
(Johnston and Newton 2004 ). In these areas, there is less biodiversity and a lack of
breeding and nesting possibilities for animals, besides paved surfaces collect a lot
of heat, which negatively contributes to urban heat.
Application of plants rooted in the soil at the base of façades or on roofs by many
architects and landscape architects is indicative of the value placed upon their
presence in the urban landscape (Laurie 1977 ). Structures covered with green are a
symbol of building in harmony with architecture and nature (Lambertini 2007). The
garden-city movement at the end of the nineteenth century may be seen as one of
the first ecological reactions to industrialization in urban areas (Kaltenbach 2008 ).
The many systems available on the market allow combining nature and built
space to improve the environmental quality in urban areas (Fig. 6.1 ), and to retrofit
the wide building heritage (which is often unsuitable and cause of relevant energy
waste and discomfort conditions) with respect to architectural, functional, and
performance aspects (Novi 1999 ; Nuzzo and Tomasinsig 2008 ; Dunnett and
Kingsbury 2004 ). It is an important field to investigate since data show that