Silica nanogel for energy-efficient windows - Nanotechnology in Eco-efficient Construction - page 230

properties (thermal and acoustic insulation, lightness), they allow novel
architectural daylighting solutions, but further effort and work are
required to improve the visible transmittance.
• Research should be fi nalized to solve some problems such as the phe-
nomenon of light scattering, which gives a reduced optical quality of
vision through the material; furthermore, the production process is very
complex and it does not allow the use of very large sheets of monolithic
aerogels, without altering performance.
• Nowadays, alternative high-performance glazing solutions, such as
vacuum insulation panels (VIP), have technical limits and at the same
time very high costs: in fact, a functional VIP with U-values of 0.1 W/
m 2 K is not available due to the problem of keeping the glazing gas-tight.
Thus, the development of translucent or transparent aerogels, as a highly
effi cient insulating material to fi ll the glazing systems, seems at the
moment the best possible thermal insulation system.

• Nanogel windows could become a decent alternative to conventional

window solutions, above all in very cold climates, but aerogel manufac-
turers should put emphasis on cost reduction. A reference market price
for silica aerogel (2008) is on the order of US$4000/m 3 , but a price of
US$1500/m 3 could be foreseen by 2020 with increasing commercializa-
tion. Concerning the applications in buildings, the price of commercial
daylighting solutions with granular aerogel in polycarbonate sheets is
on the order of 1100-200/m 2 (frame excluded), depending on the thick-
ness (10-25 mm).

10.6 References

AbuBakr Bahaj S, James PAB, Jentsch MF (2008), 'Potential of emerging glazing
technologies for highly glazed buildings in hot arid climates', Energy and Build-
ings , 5, 720-731.
Ackerman WC, Vlachos M, Rouanet S, Fruendt J (2001), 'Use of surface treated
aerogels derived from various silica precursors in translucent insulation panels',
Journal of Non-Crystalline Solids , 285, 264-271.
Aegerter MA, Leventis N, Koebel MM (2011), Aerogels Handbook, Springer, Berlin.
Akimov YK (2003), 'Fields of application of aerogels (review)', Instrument and
Experiment Techniques , 3, 287-299.
Anderson AM, Wattley CW, Carroll MK (2009), 'Silica aerogels prepared via rapid
supercritical extraction: effect of process variables on aerogel properties', Journal
of Non-Crystalline Solids , 2, 101-108.
Baetens R, Jelle BP, Gustavsen A (2011), 'Aerogel insulation for building applica-
tions: a state-of-the-art review', Energy and Buildings , 43, 761-769.
Buratti C (2003), 'Transparent insulating materials: experimental data and buildings
energy savings evaluation', in Proceedings of Energy & Environment 2003 , First
International Conference on Sustainable Energy, Planning & Technology in Rela-
tionship to the Environment, Halkidiki, Greece.

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