Civil Engineering Reference
In-Depth Information
Electrochromic
layer (nickel oxide)
Electrochromic
layer (tungsten oxide)
Transparent
electrical
conductor
Electrolyte
Transparent
electrical
conductor
+
-
+
-
+
-
+
-
+
-
+
-
+/-
11.2
Construction principle for an electrochromic foil device. The
entire foil can be used as a laminate between two glass panes.
cycling can be continued for tens of thousands of cycles without severe loss
of performance.
The desired transmittance interval depends on the intended use of the
electrochromic device. For architectural glazings one may emphasize a high
bleached-state transmittance, and then low-cost antirefl ection coatings may
be of interest (Jonsson and Roos, 2010; Jonsson
et al.
, 2010). However, other
applications may require that a very dark state can be reached for the sake
of glare control. A simple way to obtain a very small transmittance in the
dark state is to put two or more electrochromic foils on top of each other
(Granqvist, 2008). As a fi rst approximation, the transmittance of a double-
foil device is the square of the transmittance of a single-foil device. Figure
11.4 indicates that the transmittance at a mid-luminous wavelength can
approach 1% in a double electrochromic foil, while the bleached-state
transmittance is still appreciable.
It was emphasized above that low-cost manufacturing is the key to large-
scale implementation of electrochromic glazings in buildings. Figure 11.5
shows some initial results on the transmittance modulation in an electro-
chromic foil-type device prepared by roll-to-roll deposition onto a
∼
1-km-
long and 0.6-m-wide PET foil.
Search WWH ::
Custom Search