Silica nanogel for energy-efficient windows - Nanotechnology in Eco-efficient Construction - page 205

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Silica nanogel for energy-effi cient windows

C. B U R AT T I and E. MORETTI, University of Perugia, Italy

DOI : 10.1533/9780857098832.2.207

Abstract : This chapter discusses the utilization of silica nanogel to
develop high energy-effi cient windows and skylights. Silica aerogels are
fi rstly discussed in terms of chemical structure, production process, and
physical, mechanical, and thermal properties. The chapter then reviews
their current applications in buildings as thermal and acoustic insulation
materials. Finally, the potential of the nanogel windows for energy saving
in buildings and the main future research trends are discussed.

Key words : silica aerogel, nanogel windows, highly energy-effi cient
windows.

10.1 Introduction

The global share of buildings in energy consumption has progressively
increased, reaching a value of about 40% in developed countries. Because
of the increasing demand for building services and comfort levels, the
upward trend in energy consumption is expected to continue in the future
(Pérez-Lombard et al. , 2008), above all in emerging economy nations
(Southeast Asia, Middle East, South America and Africa). Energy policies
at regional, national, and international level have therefore made energy
saving one of the main objectives in residential and non-residential build-
ings (offi ces, public buildings, etc.), as shown by the recent directives of the
European Parliament on building energy performance (European Parlia-
ment and the Council of the European Union, 2002). Moreover, according
to data contained in a Pike Research report (2011), the total market for
energy effi ciency in buildings is rapidly increasing: from an estimated value
of $67.9 billion in 2011, it is expected to pass $103.5 billion by 2017. In a
building, the main total energy losses (up to 60%) can depend on the
windows (Jelle et al. , 2012).
Windows have a double role in the building thermal envelope (Zanetti
Freire et al. , 2011):

￿ ￿ ￿ ￿ ￿ ￿

• thermal transmission properties have to be as low as possible in order

to reduce energy consumption for heating and air conditioning;

• light transmission characteristics have to be as high as possible for visual

comfort and electric energy saving in illuminating plants, thanks to
natural lighting.

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