Civil Engineering Reference
In-Depth Information
Buildings dated before 1970 usually do not have very large windows, but their
performance in terms of thermal insulation is generally very poor (Peréz-Lombard
et al.
2008
; Sadinemi et al.
2011
). Thermal and solar transmittance, light trans-
mission, and finally size and orientation of windows are very important in the
energy use in building (Oral et al.
2004
; Hassounehn et al.
2010
). In particular, in
the refurbishment of buildings, windows should be substituted with innovative
glazing systems (AbuBakr Bahaj et al.
2008
). Aerogel is one of the more prom-
ising materials for use in highly energy-efficient windows: innovative glazing
systems with silica aerogel in interspace were investigated as a solution for energy
saving (Jelle et al.
2012
; Koebel et al.
2012
; Ivanov et al.
2010
). Aerogel is a
highly porous nanostructured and light material, with a very low thermal con-
ductivity (down to 0.010 W/m K). Granular translucent and transparent monolithic
silica aerogels were developed as insulation materials for windows: advanced
glazing systems with monolithic aerogel in the interspace are not yet used in mass
production; nevertheless, many daylighting systems with translucent granular
aerogels in interspace, such as polycarbonate panels, structural panels for
continuous façades, and insulated glasses, are spreading on the market (Baetens
et al.
2011
; Rigacci et al.
2004
).
The chapter reviews the applications of aerogels in buildings as thermal and
acoustic insulation materials: the potential of nanogel windows for refurbishment
of buildings and the main future research trends are discussed.
2 Silica Aerogels: State of Art
2.1 General Overview
Aerogel is a special solid material with nanometre-scale pores and an extremely
low density when compared with other solids. The porosity is higher than 90 %,
and it can reach 99 % (Riffat and Qiu
2012
). Usually, it is described by the term
'frozen smoke' because of its appearance (Fig.
1
).
Fig. 1 'This is not (the
smoke of) a pipe: Silica-
aerogel-based sculpture
realized by the artist Iannis
MICHALOU (di) S
(photograph and copyright:
MICHALOUS, 1/2008)
