1. School of Energy Studies
Jadavpur University
IV
th
International Conference on Advances in Energy Research
Indian Institute of Technology Bombay, Mumbai
Advance Glazing System- Energy Efficiency
approach for Buildings a Review
Snehashis Ghoshal, Subhasis Neogi
School of Energy Studies
Jadavpur Unversity

2. School of Energy Studies
Jadavpur University
Objective
 In building applications Windows and Glazing units are
utilised for light transmission.
 This leads to the path for heat flow through the glazing system.
This path is normally poor in its thermal characteristics.
 The paper reviews various type of glazing units and compares
thermal characteristics of such systems.
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3. School of Energy Studies
Jadavpur University
Introduction
 Since last century, glazing systems have been modified from
single glazed to double glazed in different forms and recently
developed multilayer evacuated glazing.
 In single glazed unit, significant heat gain/loss occurs.
 Initially, double glazed units had air as a medium in between.
 With the gradual development noble gas filled double glazed
units were developed.
 In recent days new concept of evacuated glazing units are
slowly emerging.
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4. School of Energy Studies
Jadavpur University
Glazing Techniques
I.
The Evacuated Glazing Technique
II.
Glazing System with TIM
III.
Electrochromic Evacuated Glazing
IV.
Multilayer Evacuated Glazing
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5. School of Energy Studies
Jadavpur University
I. The Evacuated Glazing Technique
 History: The concept of evacuated glazing was proposed by
Zoller in 1913 with a patent granted in 1924.
 Design Parameters:
1. In evacuated glazing, the internal cavity pressure between two
glass panes is maintained at very low value (less than 0.1 Pa).
2. To protect the glazing unit from the stress caused due to
atmospheric pressure, tiny support pillars (ss) are used.
3. Edge sealing by transition metal or transition alloy metal
maintains the internal vacuum level.
4. Radiative heat loss in evacuated glazing units is reduced by
applying low emittance coating.
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6. School of Energy Studies
Jadavpur University
Schematic representation of double pane evacuated glazing (Fang et al., 2009)
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7. School of Energy Studies
Jadavpur University
II. Glazing systems with TIM
 TIM or transparent insulating material combines the
contrasting requirements of high thermal insulation and high
visible transmittance.
 Aerogel is a promising material among TIMs for use in
windows from energy efficiency point of view.
 Aerogel can be classified as monolithic and granular.
Monolithic aerogel is not popular for mass production.
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8. School of Energy Studies
Jadavpur University
III. Electrochromic Evacuated Glazing
 Electrochromic evacuated glazing is developed by attaching an
electrochromic layer with a vacuum glazing unit. It can be
switched between transparent and opaque state.
 Electrochromic films have many potential applications in
automotive industry or in buildings that provide shading and
privacy applications.
 Under all aspect, electrochromic layer should face the outdoor
environment .
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9. School of Energy Studies
Jadavpur University
Schematic representation of electrochromic evacuated glazing (Fang et al., 2010)
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10. School of Energy Studies
Jadavpur University
IV. Multilayer Evacuated Glazing
 Triple evacuated glazing consists of three glass panes with two
evacuated gaps in between.
 Main drawback of such systems is increased weight and cost.
 The second cavity of the triple evacuated glazing unit is
beneficial because the resulting surface-to-surface thermal
resistance is twice as that of double pane evacuated glazing.
 A tabular representation regarding thermal property of
different glazing systems is given in Table 1 .
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11. School of Energy Studies
Jadavpur University
Table 1 Comparison of thermal properties of different types of glazing systems.
Type of glazing system
Description
U-value (W
mˉ²¯K¹)
Single Glazing
One glass pane
5.79-6.3
Double Glazing
Two glass panes with air filled cavity
2.78-3.24
Double Glazing
Two glass panes with argon filled cavity
2.61-2.95
Double Glazing
Two glass panes with argon filled cavity and
having night insulation
1.5-1.99
Double Glazing
Two glass panes with evacuated space in
between
0.86
Double Glazing
Two glass panes with monolithic aerogel in
between
0.63
Double Glazing
Two glass panes with granular aerogel in
between
1.69
Electrochromic evacuated
glazing
Two glass panes forming evacuated glazing
with a third pane having electrochrmic layer
Slightly less
than 1
Triple Evacuated glazing
Three glass panes with two evacuated space
in between
0.26
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12. School of Energy Studies
Jadavpur University
Conclusion
Extensive research work over the last decade led to different
glazing fabrication techniques allowing a wider range of
performance of glazing systems. This paper reviews different
types of glazing systems and their performances. U-value of
different glazing units have been compared.
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13. School of Energy Studies
Jadavpur University
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Jadavpur University
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16. THANK YOU
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