Civil Engineering Reference
In-Depth Information
Switchable Glazing Technology:
Electrochromic Fenestration
for Energy-Efficient Buildings
Claes G. Granqvist
Abstract Switchable electrochromic glazings employ multilayer devices with a
basic resemblance to thin-film electrical batteries and color/bleach upon electrical
charging/discharging. The transmittance of visible light and solar energy can be
varied reversibly and persistently between widely separated extrema, which makes
it possible to regulate solar energy inflow for energy savings as well as visible light
level for comfort reasons. This chapter outlines the basics of electrochromic
glazing technology and its implementation in buildings. Device designs and
component materials are discussed in some detail. Several practical electrochromic
glazing designs are introduced with focus on a foil-type construction applicable as
a lamination material between glass panes. Electrochromic glazing has been dis-
cussed for many years and has many unfulfilled promises; it is argued here that
today's developments are likely to change this situation so that electrochromic
glazing will be able to take its proper place as an important energy savings and
comfort enhancing technology for near-zero-energy building refurbishment as well
as for new buildings.
1 Introduction
Switchable glazings based on electrochromics allow the transmittance of visible
light and solar energy to be changed reversibly and persistently by the use of
an electrical signal (Granqvist
1995
), thereby creating energy efficiency as well
as human comfort in buildings wherein this glazing is employed. Electro-
chromic glazings have been discussed for many years and have largely been
viewed as interesting for niche markets rather than as commodity products
