U.S. patent application number 14/429293 was filed with the patent office on 2015-09-03 for laminated glazing with coloured reflection and high solar transmittance suitable for solar energy systems.
This patent application is currently assigned to SWISSINSO SA. The applicant listed for this patent is SWISSINSO SA. Invention is credited to Virginie Hody Le Caer, Andreas Schuler.
Application Number | 20150249424 14/429293 |
Document ID | / |
Family ID | 49515432 |
Filed Date | 2015-09-03 |
United States Patent
Application |
20150249424 |
Kind Code |
A1 |
Hody Le Caer; Virginie ; et
al. |
September 3, 2015 |
LAMINATED GLAZING WITH COLOURED REFLECTION AND HIGH SOLAR
TRANSMITTANCE SUITABLE FOR SOLAR ENERGY SYSTEMS
Abstract
Laminated and etched glazing unit for architectural integration
of solar energy systems comprising a substrate delimited by two
main faces and a multi-layered interference filter also delimited
by two main faces, one main face of said substrate being adapted to
be in contact with an incident medium, the other main face being in
contact with a main face of said interference filter, the other
main face of said interference filter being adapted to be in
contact with an exit medium; said incident medium having a
refractive index n.sub.inc=1, said substrate having a refractive
index n.sub.substrate defined as follows:
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm, and said exit
medium being defined as follows 1.45.ltoreq.n.sub.exit.ltoreq.1.6
at 550 nm; and wherein said unit is designed in such a way that the
following requirements are met: 1a) The saturation of the colour,
given by C*.sub.ab= (a*).sup.2+(b*).sup.2, according to the CIE
colour coordinates L*, a* and b* under daylight illumination
CIE-D65 is higher than 8 at near-normal angle of reflection, except
for grey and brown. 1b) The visible reflectance at near-normal
angle of reflection R.sub.vis is higher than 4%. 1c) The variation
of the dominant wavelength .lamda..sub.MD of the dominant colour MD
of the reflection with varying angle of reflection .THETA..sub.r is
smaller than 15 nm for .THETA..sub.r<60.degree.. 1d) The total
hemispherical solar transmittance at near-normal incidence is above
80%.
Inventors: |
Hody Le Caer; Virginie;
(Bussigny-pres-Lausanne, CH) ; Schuler; Andreas;
(Lausanne, CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SWISSINSO SA |
Lausanne |
|
CH |
|
|
Assignee: |
SWISSINSO SA
Lausanne
CH
|
Family ID: |
49515432 |
Appl. No.: |
14/429293 |
Filed: |
August 29, 2013 |
PCT Filed: |
August 29, 2013 |
PCT NO: |
PCT/IB2013/058115 |
371 Date: |
March 18, 2015 |
Current U.S.
Class: |
136/251 ;
165/48.2; 428/141; 428/212 |
Current CPC
Class: |
B32B 2367/00 20130101;
B32B 17/064 20130101; B32B 17/10788 20130101; B32B 17/10 20130101;
B32B 17/10201 20130101; B32B 17/10743 20130101; H02S 20/26
20141201; Y10T 428/24355 20150115; B32B 2307/418 20130101; Y10T
428/24942 20150115; B32B 7/02 20130101; B32B 17/10146 20130101;
H02S 20/23 20141201; G02B 5/281 20130101; Y02E 10/40 20130101; Y02B
10/10 20130101; G02B 5/286 20130101; H01L 31/0488 20130101; B32B
17/10036 20130101; B32B 17/1011 20130101; Y02E 10/50 20130101; Y10T
428/2495 20150115; B32B 17/10761 20130101; B32B 2457/00 20130101;
Y10T 428/24967 20150115; F24S 80/52 20180501; B32B 17/10 20130101;
B32B 2367/00 20130101 |
International
Class: |
H02S 20/26 20060101
H02S020/26; H02S 20/23 20060101 H02S020/23; H01L 31/048 20060101
H01L031/048; B32B 7/02 20060101 B32B007/02; B32B 17/06 20060101
B32B017/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 20, 2012 |
IB |
PCTIB2012055000 |
Claims
1-24. (canceled)
25. A laminated glazing unit for architectural integration of solar
energy systems comprising a substrate delimited by two main faces
and a multi-layered interference filter also delimited by two main
faces and being adapted to be in contact on one main face with said
substrate and on the other main face with a laminating polymer;
said substrate being in contact with an incident medium having a
refractive index n.sub.inc=1 and having a refractive index
n.sub.inc substrate defined as follows:
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and; said
laminating polymer being considered as the exit medium whose
refractive index is defined as follows
1.45.ltoreq.n.sub.exit.ltoreq.1.6 at 550 nm; and wherein said unit
is designed in such a way that the following requirements are met:
1a) The saturation of the colour, given by C*.sub.ab=
(a*).sup.2+(b*).sup.2, according to the CIE colour coordinates L*,
a* and b* under daylight illumination CIE-D65 is higher than 8 at
near-normal angle of reflection, except for grey and brown. 1b) The
visible reflectance at near-normal angle of reflection R.sub.vis is
higher than 4%. 1c) The variation of the dominant wavelength
.lamda..sub.MD of the dominant colour M.sub.D of the reflection
with varying angle of reflection .theta.r is smaller than 15 nm for
.theta.r<60.degree.. 1d) The total hemispherical solar
transmittance at near-normal incidence is above 80%.
26. The glazing unit according to claim 25 comprising a
light-diffusing rough outer surface obtained by chemical treatment
such as for example acid etching.
27. The glazing unit according to claim 25 using acidic etching
treatment leading to anti-reflective properties of the outer
surface and thus enhancing the optical properties of the system:
the solar transmittance of a light beam at normal incidence is
approx. 3% higher for the etched surface than for an untreated
surface.
28. The glazing unit according to claim 25 with optional
anti-reflective coating applied on the back-side of the laminated
glazing in order to enhance the optical properties of the system
for solar thermal applications: the solar transmittance of a light
beam at normal incidence is approx. 3% higher for the surface on
which the anti-reflective coating is applied than for an untreated
surface.
29. The glazing unit according to claim 25 comprising solar roll
glass, an extra-white float glass (iron content <120 ppm) or
polymeric materials (PET, PEN, PFA, FEP, ETFE, PTFE . . . )
characterised by a solar transmittance higher than 90%.
30. The glazing unit according to claim 25 where solar roll glass
surfaces is either flat or textured.
31. The glazing unit according to claim 25 using elastomer
cross-linking polymers such as EVA, thermoplastic products such as
PVB, or ionoplastic polymers to join the glass or polymeric panes
together by lamination and where the solar transmittance of the
unit is higher than 92% for a polymer thickness of 0.4-0.5 mm.
32. The glazing unit according to claim 25, wherein said
interferential filter is a multilayer interferential stack of up to
9, up to 400 nm-thick dielectric layers with low absorption
expressed by the extinction coefficient k.ltoreq.0.2 for
wavelengths .lamda. with 450 nm.ltoreq..lamda..ltoreq.2500 nm.
33. The glazing unit according to claim 25, wherein said
interference filter has a green coloured reflection deposited on a
glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 3
sub-layers based on low refractive index material L with
1.4.ltoreq.nL.ltoreq.2.2 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H.ltoreq.2.5 at 550 nm; the
general design being: incident medium air//substrate//30.+-.12 nm
of H/25.+-.12 nm of L/320.+-.12 nm of H///exit medium polymer.
34. The glazing unit according to claim 25, wherein said
interference filter has a green coloured reflection deposited on a
glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 5
sub-layers based on low refractive index material L with
1.4.ltoreq.n.sub.L.ltoreq.2.2 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H.ltoreq.2.5 at 550 nm; the
general design being: incident medium air//substrate//185.+-.12 nm
of H/25.+-.12 nm of L/35.+-.12 nm of H/35.+-.12 nm of L/130.+-.12
nm of H//exit medium polymer.
35. The glazing unit according to claim 25, wherein said
interference filter has a green coloured reflection deposited on a
glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 7
sub-layers based on low refractive index material L with
1.4.ltoreq.n.sub.L.ltoreq.2.2 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H.ltoreq.2.5 at 550 nm; the
general design being: incident medium air//substrate//160.+-.12 nm
of H/130.+-.12 nm of L/65.+-.12 nm of H/25.+-.12 nm of L/70.+-.12
nm of H/160.+-.12 nm of L/100.+-.12 nm of H//exit medium
polymer.
36. The glazing unit according to claim 25, comprising an
interference filter with blue coloured reflection deposited on
glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 3
sub-layers based on low refractive index material L with
1.4.ltoreq.n.sub.L.ltoreq.1.8 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H.ltoreq.2.5 at 550 nm; the
multilayer design corresponding hereby to: incident medium
air//substrate/45.+-.12 nm of H/70.+-.12 nm of L/45.+-.12 nm of
H//exit medium polymer.
37. The glazing unit according to claim 25, comprising an
interference filter with yellow-green coloured reflection deposited
on glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 5
sub-layers based on low refractive index material L with
1.65.ltoreq.n.sub.L.ltoreq.2.1 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H.ltoreq.2.5 at 550 nm; the
multilayer design corresponding hereby to: incident medium
air//substrate/175.+-.12 nm of H/85.+-.12 nm of L/50.+-.12 nm of
H/25.+-.12 nm of L/300.+-.12 nm of H//exit medium polymer.
38. The glazing unit according to claim 25, comprising an
interference filter with yellowish-orange coloured reflection
deposited on glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 7
sub-layers based on low refractive index material L with
1.4.ltoreq.n.sub.L.ltoreq.1.8 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H<2.5 at 550 nm; the multilayer
design corresponding hereby to: incident medium
air//substrate/120.+-.12 nm of H/120.+-.12 nm of L/95.+-.12 nm of
H/90.+-.12 nm of L/90.+-.12 nm of H/95.+-.12 nm of L/100.+-.12 nm
of H//exit medium polymer.
39. The glazing unit according to claim 25, comprising an
interference filter with grey coloured reflection deposited on
glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 2
sub-layers based on low refractive index material L with
1.4.ltoreq.n.sub.L.ltoreq.1.8 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H.ltoreq.2.5 at 550 nm; the
multilayer design corresponding hereby to: incident medium
air//substrate//40.+-.15 nm of H/75.+-.30 nm of L//exit medium
polymer.
40. The glazing unit according to claim 25, comprising an
interference filter with brown coloured reflection deposited on
glass or polymer substrate with
1.45.ltoreq.n.sub.substrate.ltoreq.1.6 at 550 nm and composed by 4
sub-layers based on low refractive index material L with
1.65.ltoreq.n.sub.L.ltoreq.2.1 at 550 nm and high refractive index
material H with 1.8.ltoreq.n.sub.H.ltoreq.2.5 at 550 nm; the
multilayer design corresponding hereby to: incident medium
air//substrate//50.+-.12 nm of H/90.+-.12 nm of L/65.+-.12 nm of
H/55.+-.12 nm of L//exit medium polymer.
41. The glazing unit according to claim 25, comprising one or more
glass pane(s) being heat treated (heat-strengthened or fully
tempered) for security in facade applications.
42. A solar energy system comprising a laminated glazing according
to claim 25.
43. The solar energy system according to claim 42 comprising a
thermal collector and wherein the glazing is directly glued to the
solar thermal collector.
44. The solar energy system according to claim 43 wherein the solar
glazing is larger than the frame of the collector.
45. The solar energy system according to claim 42 comprising a PV
system with an active system (silicon cells, PV thin films,
contacts, back-reflector . . . ) fully integrated in the laminated
glazing.
46. The solar roof or building facade comprising a solar energy
system according to claim 42.
47. The solar roof or building facade according to claim 25 where
the solar energy system is suspended by fixations attached to the
glazing.
48. The solar roof or building facade according to claim 46 with an
overlapping of the laminated glazing.
Description
FIELD OF THE INVENTION
[0001] The invention deals with coloured laminated glazing suitable
for solar energy systems offering architectural integration of
solar energy systems, e.g. as solar active glass facades.
DEFINITIONS
[0002] Direct Transmittance
[0003] If parallel beams of radiation incident on a surface, an
interface, or a specimen result in transmitted parallel beams, the
transmittance is considered as direct. This is the case e.g., for
flat surfaces or interfaces.
[0004] Diffuse Transmittance
[0005] If parallel beams of radiation incident on a surface, an
interface, or a specimen result in a more or less wide angular
distribution of transmitted beams, the transmittance is considered
as diffuse. This is the case e.g., for rough surfaces or
interfaces, or for specimens of granular structure.
[0006] In general, the diffuse transmittance depends on the angle
of incidence and the wavelength X of the radiation. If the angle of
incidence is not explicitly mentioned, commonly normal incidence is
assumed.
[0007] Total Hemispherical Transmittance
[0008] The total hemispherical transmittance is obtained by the sum
of direct transmittance and diffuse transmittance.
T.sub.total=T.sub.direct+T.sub.diffuse
[0009] In general, the total hemispherical transmittance depends on
the angle of incidence and the wavelength .lamda. of the radiation.
If the angle of incidence is not explicitly mentioned, commonly
normal incidence is assumed.
[0010] Solar Transmittance T.sub.sol
[0011] Given a calculated or measured spectrum of the total
hemispherical transmittance of a sample T(.lamda.), the solar
transmittance T.sub.sol is obtained by integration with the solar
spectrum I.sub.sol(.lamda.):
T sol = .intg. T ( .lamda. ) I sol ( .lamda. ) .lamda. .intg. I sol
( .lamda. ) .lamda. ##EQU00001##
where usually the solar spectrum at air mass 1.5 (AM1.5) is
employed as intensity I.sub.sol(.lamda.).
[0012] Visible Reflectance R.sub.vis
[0013] The visible reflectance R.sub.vis is a measure for the
brightness of a surface as it appears to the human eye under
certain illumination conditions. A white surface or a perfect
mirror exhibits 100% visible reflectance, coloured or grey surfaces
less. The determination of the visible reflectance R.sub.VIS is
based on the photopic luminous efficiency function V(.lamda.) and
depends on the choice of the illuminant I.sub.ILL(.lamda.):
R vis = .intg. R ( .lamda. ) I ILL ( .lamda. ) V ( .lamda. )
.lamda. .intg. I ILL ( .lamda. ) V ( .lamda. ) .lamda.
##EQU00002##
where R(.lamda.) is the simulated or measured hemispherical
reflectance of the sample.
[0014] Angle of Reflection
[0015] The angle of reflection .theta..sub.r is the angle formed by
a ray of light reflected from a surface and a line perpendicular to
the surface at the point of reflection. Here .theta..sub.1 and
.theta..sub.t correspond respectively to the incidence and
transmission angles.
[0016] Refractive Index and Extinction Coefficient
[0017] When light passes through a medium, some part of it will
always be absorbed. This can be conveniently taken into account by
defining a complex index of refraction N:
N=n-ik [1]
where the real part n (refractive index) indicates the phase speed,
while the imaginary part k (extinction coefficient) indicates the
amount of absorption loss when the electromagnetic wave propagates
through the material.
[0018] Antireflection
[0019] A treated surface is considered as antireflective when the
solar transmittance of a light beam at near-normal incidence is
higher than for an untreated surface.
[0020] CIE 1931 XYZ Colour Space
[0021] The International Commission on Illumination (CIE,
Commission Internationale d'Eclairage) described how to quantify
colours [2]. All existing colours can be represented in a plane and
mapped by Cartesian coordinates, as shown in the CIE Chromaticity
Diagrams. The quantification is based on the 1931 CIE Colour
Matching Functions, x(.lamda.), y(.lamda.), and z(.lamda.), which
reflect the colour sensitivity of the human eye. These functions
depend to some extent on the width of the observation field (we
will use the functions for an opening angle of 2.degree.).
[0022] CIE 1976 (L*, a*, b*) Colour Space (or CIELAB)
[0023] CIE L*a*b* is the most complete colour model used
conventionally to describe all the colours visible to the human
eye. It was developed for this specific purpose by the
International Commission on Illumination (Commission Internationale
d'Eclairage). The three parameters in the model represent the
lightness of the colour (L*, L*=0 yields black and L*=100 indicates
white), its position between magenta and green (a*, negative values
indicate green while positive values indicate magenta) and its
position between yellow and blue (b*, negative values indicate blue
and positive values indicate yellow).
[0024] Dominant Colour
[0025] The dominant wavelength of a colour is defined as the
wavelength of the monochromatic stimulus that, when additively
mixed in suitable proportions with the specified achromatic
stimulus, matches the considered colour stimulus [3]. Thus any
colour can be related to a monochromatic dominant colour MD defined
by its wavelength X,D.
[0026] Colour Saturation
[0027] The colour saturation is a measurement of how different from
pure grey the colour is. Saturation is not really a matter of light
and dark, but rather how pale or strong the colour is. The
saturation of a colour is not constant, but it varies depending on
the surroundings and what light the colour is seen in and is given
by:
C*.sub.ab= (a*).sup.2+(b*).sup.2
where a* and b* are the CIE colour coordinates under daylight
illumination CIE-D65.
STATE OF THE ART
[0028] The acceptance of solar energy systems as integrated
elements of the building's envelope is mainly limited by their
unpleasant visual aspect. They are often considered as technical
components to be hidden and confined to roof-top applications,
where they are less visible and have less impact on the
architectural design [4]. The development of better-looking solar
systems could open up new perspectives for the architectural
integration of solar energy systems, e.g. as solar active glass
facades. One solution is to apply a coloured interferential thin
film to the inner side of the glazing of the solar system. The
coating reflects a colour, thus hiding the technical part of the
solar device, but transmits the complementary spectrum. Coloured
glass panes based on dielectric thin films multi-depositions have
been demonstrated to be of special interest for solar thermal
collectors [5-8] and has been the subject to a PCT application in
2004 [9]. The invention disclosed in this PCT application had,
however, some weaknesses dealing with: [0029] The security: the
invention considered the use of non-tempered, non-laminated glazing
that did not fulfil the security requirements for facade
installation. Therefore the coloured designs calculated for single
glazing (exit medium air n.sub.exit=1) are not suitable for
laminated glazing (exit medium polymer
1.45.ltoreq.n.sub.exit.ltoreq.1.6 at 550 nm). [0030] The colour
stability: in the context of the 2004 PCT application, the colour
was based on quarter wave interference stacks exhibiting narrow
reflection peaks. By limiting the number of individual layers and
choosing the refractive indices of the involved materials,
reasonable amplitudes of the reflection peak were obtained, thus
providing excellent solar transmittance to the coating. However, as
the narrow reflection peak shifts to smaller wavelength with
increasing angle of reflection, the former developed colours
(except blue) were dependant on the angle of
vision/observation/reflection. Example 1 presents a green design
which shifted to blue for increasing angles of observation (see
FIG. 1, FIG. 2 and Table 1). [0031] The industrial scale
production: relatively thick (>100 nm) SiO.sub.2 layers were
needed in the coating stacks, thus limiting the production speed of
coloured glasses on industrial scale.
[0032] The PCT application also referred to the possibility of
applying a surface treatment (hot patterning, acid etching, sand or
stone projections . . . ) on the outer side of the collector
glazing to in order to create a diffuse light transmittance. This
treatment has the effect of reinforcing the masking effect of the
solar device technical parts, preventing glare effects and
producing mat surfaces that are in high demand in today's
architecture. Amongst available diffusive surface treatments, acid
etching is undoubtedly the most suitable and most widely used
treatment at industrial level. Historically, acidic etching
treatments of glasses are performed by using
fluoridric-acid-based-solutions [10]. Fluoridric acid is a strong
chemical agent responsible of various problems in terms of safety,
health of workers and environmental pollution. For this reason, the
use of buffered solutions (in which a part of the fluoridric acid
is replaced by fluoride salts such as ammonium bifluoride) [11-13]
or solutions based on fluoride salts [14-15], less aggressive and
more environmentally friendly, are becoming more common.
GENERAL DESCRIPTION OF THE INVENTION
[0033] The problems mentioned in the previous chapter have been
solved with the present invention which relates to a solar glazing
unit as defined in the claims. The present innovation deals with
coloured laminated glazing (preferably, but not exclusively, made
of glass) with enhanced masking effect, angular colour stability,
energetic performances and mechanical stability. The coloured
laminated glazing system is schematised in FIG. 3 and can be
described as the combination of: [0034] An encapsulated coloured
interferential multi-layered coating, deposited on the back side of
the outer glass (FIGS. 3a and 4a), on the back or the front side of
a polymeric film which is encapsulated between two glass panes
(FIGS. 3b and 4b) or on the front side of the inner glass (FIGS. 3c
and 4c). [0035] A textured or non-textured diffusive outer surface
[0036] An optional anti-reflection coating applied on the back-side
of the inner glass for thermal or PVT applications.
[0037] Whereas solar thermal or PVT systems are mounted behind or
directly glued to the laminated glazing, PV systems are totally
integrated into the laminated glazing.
[0038] 1. Coloured Coating
[0039] The choice of the substrate on which the coloured coating is
deposited is of main importance. In order to ensure a maximal
efficiency of the solar energy system, the substrate has to present
a high solar transmittance, thus limiting the possibilities to
solar roll glass, extra-white float glass (very low iron-content)
or polymeric materials such as polyethylene terephthalate (PET),
polyethylene naphtalate (PEN), fluorocarbon polymer (PFA, FEP,
ETFE, PTFE . . . ) and so on. The surface flatness is also a
critical issue, especially for facade applications. As no colour
variation of the interferential coating should be visible,
extra-white float glass and polymer materials, giving more freedom
in the choice of the glass nature, are preferred to solar roll
glass for the deposition of the coloured coating.
[0040] The coloured coating consisting in multilayer interferential
stacks of transparent layers has to be of high solar transmittance
T.sub.sol. Thus, as absorption in the coating should be minimised,
dielectric oxides are preferably chosen. Among the various
possibilities, materials such as SiO.sub.2, Al.sub.2O.sub.3, MgO,
ZnO, SnO.sub.2, HfO.sub.2, Nb.sub.2O.sub.5, Ta.sub.2O.sub.5 and
TiO.sub.2 are for example perfectly suitable for the invention
described here.
[0041] The visible reflectance R.sub.vis is the percentage of light
striking the glazing that is reflected back and provides
information on the masking capability of the glazing. This value
has then to be high enough to permit a good masking effect of the
solar energy system technical parts but low enough to ensure a good
solar transmittance. Good compromises have then to be found between
masking effect and performances of the solar device. In the context
of the invention, R.sub.vis has to be higher that 4%.
[0042] The intensity of the colour is given by its saturation
expressed by:
C.sub.ab= (a*).sup.2+(b*).sup.2
where a* and b* are CIE colour coordinates under daylight
illumination CIE-D65. In order to provide well-visible colours, the
colour saturation has to be higher than 8 at near-normal angle of
reflection. Exception is made for grey and brown which correspond
respectively to strongly desaturated cold and warm colours.
[0043] Concerning the colour stability, improvements have been
brought here as compared to the 2004 PCT application by modifying
the quaterwave interference stacks in order to get asymmetric
designs. The consequence of such modifications is the obtaining of
reflectance curves characterised either by a large single
reflection peak or by several small reflection peaks. Then, the
multilayer coating reflects a colour which is defined, as a
function of the shape of the reflectance curve: [0044] Either by
the wavelength of the maximum intensity of a single reflectance
peak situated in the visible part of the solar spectrum. For
example, FIG. 5 represents a reflectance curve at normal incidence
(angle of vision of 0.degree.) with a maximal intensity at
.lamda..sub.max=570 nm which corresponds to a yellow-green dominant
colour for the coating. [0045] Or by the combination of the
wavelengths of 2 or more reflectance peaks situated in the visible
spectral region. For example, FIG. 6 shows a reflectance curve at
normal incidence with 3 peaks in the visible part of the spectrum
and respectively situated at 413 nm, 534 nm and 742 nm. The
resultant dominant colour of the considered coating is situated at
.lamda.=500 nm (green).
[0046] With increasing angle of vision most features of the spectra
shift to smaller wavelengths, inducing a modification of the
position of .lamda..sub.max and thus of the dominant colour of the
coating. As example, the reflectance curves obtained for both
yellow-green and green coatings at various angles of reflection
.theta..sub.r (from 0.degree. to 85.degree.) are given in FIG. 7(a)
and (b) respectively.
[0047] Providing coloured glazing with good angular colour
stability is of high importance for building integration. Strong
efforts have then been made in order to avoid or limit the colour
variations. The principle of the colour stability can be explained
as follows. Generally, the colour M of a layer can be regarded as a
mixture of several colours whatever the shape of its reflectance
curve. For more clarity, the explanations will be given for a
fictive coloured layer characterized by two reflection peaks, in
the visible part of the solar spectrum, whose wavelengths and
colours are respectively .lamda..sub.1, C.sub.1 and .lamda..sub.2,
C.sub.2 (see FIG. 8a). The colour M is defined by a dominant colour
M.sub.D whose wavelength .lamda..sub.MD comprised between
.lamda..sub.1 and .lamda..sub.2, its position depending on the
relative intensity of both reflection peaks (see FIG. 8b). With
increasing angles of vision the reflection peaks shift to shorter
wavelengths. The shift of C.sub.1 to C.sub.1' has to be compensated
by an equivalent shift of C.sub.2 to C.sub.2' as well as a
modification of the relative intensity of both peaks in order to
conserve the position of the point M. At least, the point M has to
be kept on the on the colour segment defined by the line MM.sub.D.
In that last case, the dominant colour of the coating remains the
same. This compensation can be achieved by choosing carefully the
nature and the thickness of the materials of the individual layers
constituting the interferential coloured coating stack. This
principle can be extrapolated to more complex designs characterised
by more than two peaks of reflection (see FIG. 9).
[0048] Green coloured designs based on this principle are given in
Examples 2, 3 and 4 (see FIGS. 10, 11, 12, 13, 14, 15 and tables 2,
3 and 4). The (x,y) colour coordinates under CIE-D65 illuminant,
the visible reflectance R.sub.vis, the solar transmittance
T.sub.sol, the dominant wavelength .lamda..sub.MD and colour
M.sub.D and colour saturation C.sub.ab* of those 3 coatings are
given for different angles of reflection. Corresponding graphical
presentations of colour variations are also shown for each design.
For each design, only small variations in colour and in reflectance
(especially for .theta..sub.r up to 60.degree.) are observed in
combination with high solar transmittances (above 80% up to
60.degree.). The variation of the wavelength of the dominant colour
observed for these coating designs (9 nm of variation between
0.degree. and 60.degree. for Example 2) is almost 4 times lower
than for the 2004 PCT application design (Example 1).
[0049] Another advantage here as compared to the 2004 PCT
application [6], is that the relatively thick SiO.sub.2 coatings
have been replaced by other oxides with higher deposition speed. As
a matter of facts, multilayer interferential stacks are deposited
on industrial scale by in-line magnetron sputtering. For low cost
production, the number of sub-layers and the thickness of the
individual layers have to be limited.
[0050] Other examples of coating designs with various colours in
reflection (blue, yellow-green, yellowish-orange, grey and brown)
are given in Examples 5 to 9 (see FIGS. 16 to 25 and tables 5 to
9).
[0051] 2. Diffusive Surface
[0052] A diffusive surface treatment is applied on the outer
surface of the coloured laminated glazing. The glass substrate can
either be extra-white float glass or solar roll glass. Extra-white
float glass presents the advantage of having a better flatness and
will be preferred for facade applications. Both types of glass are
also commercially available with a wide variety of textures and
patterns applied on the outer surface. This kind of glass can be
used in order to add some relief and get closer to tiles appearance
in case of roof applications.
[0053] The etching treatment is applied in order to create diffuse
light transmittance which reinforces the masking effect of the
coloured filter. It also presents the advantage to create mat
surfaces often desired by architects and to prevent glare
effects.
[0054] By choosing appropriate compositions of the etching
solution, favourable micro/nano-structures on the treated glass
surface can also give rise to anti-reflection properties. For
example, the treatment of glass surfaces by acid etching in
buffered solutions [13] leads to a particular structure combining
micrometric islands with nanometric openings, both uniformly
distributed. The resulting low reflectance glass surfaces thus
obtained are perfectly suitable for the solar applications
described here.
[0055] Based on literature [14-15], etching solutions composed of
several of the following components have been developed: ammonium
bifluoride (ABF), water (H.sub.2O), isopropanol (IPA), sugars
(sucrose, fructose, etc.). These solutions are particularly
effective over a wide range of compositions and for treatment times
lower than 20 minutes.
[0056] Examples of effective solutions with range of reasonable
concentrations are given below: [0057] Solution 1: ABF/IPA/water
mixture with the following proportions 10-30 wt. %/20-40 wt.
%/balance.
[0058] Solution 2: ABF/sucrose/water mixture with the following
proportions 15-25 wt. %/15-40 wt. %/balance.
[0059] Excellent transmittances are obtained for the treated glass
surfaces thanks to anti-reflective properties. The measured
hemispherical normal transmittance of the treated glass surfaces is
about 95% as regards to 92% for an untreated glass (see FIG.
26).
[0060] FIGS. 27 a) and b) present SEM pictures of glass surfaces
respectively structured by an ABF/IPA-based etching solution
(ABF/IPA/H.sub.2O=30/10/60) and by an ABF/sucrose-based etching
solution (ABF/sucrose/H.sub.2O=18/18/64). Both pictures have been
taken for the same etching time (15 min) and at same magnification.
In the first case (FIG. 27a), the surface is relatively smooth and
presents some micro-scale protrusions and furrows arising from the
junction of nano-holes which are present on the entire surface. In
the second case (FIG. 27b), the surface features a much rougher
structure and is densely covered with some kind of pyramids. These
pyramids have a height around 10 .mu.m, are defined by different
types of polygons as their base area whose dimensions are often
around 100 .mu.m to 120 .mu.m and have pronounced nano-structured
side walls. The measured gain in solar transmittance can then be
explained by anti-reflective properties resulting from micro-scale
patterning in combination with a nano-scale roughness
modification.
[0061] 3. Tempering and Lamination
[0062] After coating deposition and etching, the different glass
panes are tempered. There is no restriction to perform this thermal
treatment, as both coloured coatings (made of oxides) and diffusive
surfaces (mainly SiO.sub.2) present very good thermal
stabilities.
[0063] Then, glass panes and if necessary other elements (coated
polymeric film, crystalline silicon cells . . . ) are joined
together by lamination. Laminating polymers are preferably, but not
exclusively elastomer cross-linking products such as EVA
(Ethylene-Vinyl-Acetate) or thermoplastic products such as PVB
(Polyvinyl Butyral). These products are characterised by high solar
transmittances, low refractive indices, and good adhesion to glass
or polymer panes. Both treatments are made and combined in order to
fulfil the security requirements for facade applications, but also
to provide some advantages. First of all, the lamination can offer
the possibility to have different supply chains for coating and
etching, depending on the chosen configuration (see FIGS. 3 and 4)
thus offering a wide time savings. Moreover the coloured coating is
encapsulated, avoiding any colour change due to water condensation
on the inner side of the glazing when mounted on thermal
collectors.
[0064] Another advantage is the good mechanical strength of the
laminated glazing which offers: [0065] The possible use of glazing
larger than the solar thermal or PVT systems which can be directly
bonded to the back of the glazing and thus be completely hidden.
Since the coloured coating is encapsulated, such collectors can be
obtained without any colour change along the glued collector frame
(which is the case when the interferential coating is in direct
contact with lamination polymer or glue). Thermal, PV and PVT
systems have therefore exactly the same external appearance. [0066]
The possible use of the glass for the mechanical fixation of the
solar devices.
[0067] These capabilities allow the production of polyvalent
products which provide considerable flexibility for roof and facade
installation. As example, FIG. 28 presents possible variations for
the mounting of thermal solar systems glued behind a coloured
laminated glazing. In FIG. 28 a), solar thermal collectors are
glued on the back of laminated glazing larger than the frame of the
collectors. Here the solar collectors are mounted on a roof with
glazing overlap and the waterproofing is provided by the presence
of seals between two overlapping glazings. Different variations for
the mounting of solar thermal collectors in ventilated facade
either for residential facade or for large buildings with glass
facades are shown respectively in FIG. 28 (b) and (c). Here, the
hangers, the overlap wings, the seals and so on can be adaptable to
the wishes of the architect, the type and requirements of the
building, the local culture of the country, . . . Same mounting
configurations are of course possible for photovoltaic devices, but
also for hybrid (combination of thermal and PV devices) roof and
facades installations.
[0068] 4. Optional Anti-Reflection Coating
[0069] In order to increase the solar transmittance of solar
thermal devices an anti-reflection coating can be applied to the
back-side of the inner glass (see FIG. 3).
[0070] As a matter of facts, a maximum transmittance value of
approximately 92% can be achieved for the best quality glass as a
reflectance of 4% on both sides of the glass occurs. By applying an
anti-reflection coating characterised by a low refractive index
(lower than 1.52) the reflectance of the glass side can be reduced
of approximately 3% in the best case.
[0071] Ideally, the solar transmittance of the coloured laminated
glazing can then increase of approx. 3% and thus compensating the
transmittance losses due to the presence of the interferential
coloured coating.
REFERENCES
[0072] [1] H. A. McLeod, Thin Film Optical Filters,
American-Elsevier, New York, 1969. [0073] [2] International
Commission on Illumination CIE, 1986. Colorimetry. CIE Publication
15.2., 2nd ed., ISBN 3-900-734-00-3, Vienna [0074] [3] CIE
Technical Report (2004) Colorimetry, 3rd ed. Publication 15:2004
[0075] [4] M. Munari Probst and C. Roecker, "Towards an improved
architectural quality of building integrated solar thermal systems
(BIST)," Solar Energy, vol. 81, September 2007, pp. 1104-1116.
[0076] [5] A. Schiller, C. Roecker, J.-L. Scartezzini, J. Boudaden,
I. R. Videnovic, R. S.-C. Ho, P. Oelhafen, Sol. Energy Mater. Sol.
Cells 84 (2004) 241. [0077] [6] J. Boudaden, R. S. C. Ho, P.
Oelhafen, A. Schiller, C. Roecker, J.-L. Scartezzini, Solar Energy
Materials & Solar Cells 84, 225 (2004). [0078] [7] A. Schuler,
C. Roecker, J. Boudaden, P. Oelhafen, J.-L. Scartezzini, Solar
Energy 79, 122 (2005). [0079] [8] A. Schuler, J. Boudaden, P.
Oelhafen, E. De Chambrier, C. Roecker, J.-L. Scartezzini, Solar
Energy Materials & Solar Cells 89, 219 (2005). [0080] [9] A.
Schiller, PCT International Publication WO 3004/079278 A1 (2004).
[0081] [10] H. Niederprum, H. G. Klein, J.-N. Meussdoerffer, U.S.
Pat. No. 4,055,458 (1977). [0082] [11] N. Enjo, K. Tamura, U.S.
Pat. No. 4,582,624 (1986). [0083] [12] G. E. Blonder, B. H.
Johnson, M. Hill, U.S. Pat. No. 5,091,053 (1992). [0084] [13] D. C.
Zuel, J.-H. Lin, U.S. Pat. No. 5,120,605 (1992). [0085] [14] S. H.
Gimm, J. H. Kim, US Patent 5281350 (1994). [0086] [15] H. Miwa,
U.S. Pat. No. 7,276,181 B2 (2007).
LIST OF FIGURE CAPTIONS
[0087] FIG. 1:
[0088] Angular dependency of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
1.
[0089] FIG. 2:
[0090] Reflectance curves of the coating design given in Example 1
for various angles of reflection (from 0.degree. to
85.degree.).
[0091] FIG. 3:
[0092] Schematic drawings of possible configurations of coloured
laminated glazing for thermal and PVT applications. The coloured
coating can be deposited (a) on the back side of the outer glass,
(b) on one side of a polymeric film which is encapsulated between
two glass panes, (c) on the front side of the inner glass.
[0093] FIG. 4:
[0094] Schematic drawings of possible configurations of coloured
laminated glazing for PV applications. The coloured coating can be
deposited (a) on the back side of the outer glass, (b) on one side
of a polymeric film which is encapsulated between two glass panes,
(c) on the front side of the inner glass. Here the technical parts
of the PV device are fully integrated into the laminated
glazing.
[0095] FIG. 5:
[0096] 1988 C.I.E. normalised photopic luminous efficiency function
delimiting the part of the solar spectrum which is visible for the
human eye and reflectance curve at normal incidence (angle of
vision of 0.degree.) of a yellow-green coating (.lamda..sub.max=570
nm) presenting a single reflection peak.
[0097] FIG. 6:
[0098] 1988 C.I.E. normalised photopic luminous efficiency function
delimiting the part of the solar spectrum which is visible for the
human eye and reflectance curve at normal incidence (angle of
vision of 0.degree.) of a green coating (.lamda..sub.D=500 nm)
presenting three reflection peaks in the visible part of the solar
spectrum (bulk part of the curve).
[0099] FIG. 7:
[0100] (a) Reflectance curves of a yellow-green coating for various
angles of reflection (from 0.degree. to 85.degree.). The reflection
peak situated in the visible part of the spectrum shifts to smaller
wavelengths: .lamda..sub.max varies from .lamda..sub.max
0.degree.=570 nm to .lamda..sub.max 60.degree.=500 nm leading to a
colour change of the coating from yellow-green to green.
[0101] (b) Same representation for a green coating design
presenting three reflection peaks in the visible part of the solar
spectrum.
[0102] FIG. 8:
[0103] (a) Graphical representation of a fictive reflectance curve
composed by two reflection peaks in the visible part of the solar
spectrum. .lamda..sub.1, C.sub.1 and .lamda..sub.2, C.sub.2 are the
wavelengths and colours of the reflectance peaks at low viewing
angle. .lamda..sub.1', C.sub.1' and .lamda..sub.2', C.sub.2' are
the corresponding wavelengths and colours at higher angle of
observation. The dominant colour M.sub.D of the coating is situated
at .lamda..sub.D comprised between .lamda..sub.1 and .lamda..sub.2,
its position depending on the relative intensity of both reflection
peaks.
[0104] (b) Principle of colour stability represented on the 1931
C.I.E. chromaticity diagram. M is the resultant colour of a coating
characterised by 2 reflection peaks, in the visible part of the
solar spectrum, defined by C.sub.1 and C.sub.2 at low angle of
vision. C.sub.1' and C.sub.2' are the corresponding colours for
higher angle of vision. M.sub.D is the dominant colour of M.
[0105] FIG. 9:
[0106] (a) Graphical representation of a fictive reflectance curve
composed by three reflection peaks in the visible part of the solar
spectrum. .lamda..sub.1, C.sub.1, .lamda..sub.2, C.sub.2 and
.lamda..sub.3, C.sub.3 are the wavelengths and colours of the
reflectance peaks at low viewing angle. .lamda..sub.1', C.sub.1',
.lamda..sub.2', C.sub.2' and .lamda..sub.3', C.sub.3' are the
corresponding wavelengths and colours at higher angle of
observation. The dominant colour M.sub.D of the coating is situated
at .lamda..sub.D whose position depends on the relative intensity
of all reflection peaks.
[0107] (b) Principle of colour stability represented on the 1931
C.I.E. chromaticity diagram. M is the resultant colour of a coating
characterised by 3 reflection peaks, in the visible part of the
solar spectrum, defined by C.sub.1, C.sub.2 and C.sub.3 at low
angle of vision. C.sub.1', C.sub.2' and C.sub.3' are the
corresponding colours for higher angle of vision. M.sub.D is the
dominant colour of M.
[0108] FIG. 10:
[0109] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
2.
[0110] FIG. 11:
[0111] Reflectance curves of the coating design given in Example 2
for various angles of reflection (from 0.degree. to
85.degree.).
[0112] FIG. 12:
[0113] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
3.
[0114] FIG. 13:
[0115] Reflectance curves of the coating design given in Example 3
for various angles of reflection (from 0.degree. to
85.degree.).
[0116] FIG. 14:
[0117] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
4.
[0118] FIG. 15:
[0119] Reflectance curves of the coating design given in Example 4
for various angles of reflection (from 0.degree. to
85.degree.).
[0120] FIG. 16:
[0121] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
5.
[0122] FIG. 17:
[0123] Reflectance curves of the coating design given in Example 5
for various angles of reflection (from 0.degree. to
85.degree.).
[0124] FIG. 18:
[0125] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
6.
[0126] FIG. 19:
[0127] Reflectance curves of the coating design given in Example 6
for various angles of reflection (from 0.degree. to
85.degree.).
[0128] FIG. 20:
[0129] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
7.
[0130] FIG. 21:
[0131] Reflectance curves of the coating design given in Example 7
for various angles of reflection (from 0.degree. to
85.degree.).
[0132] FIG. 22:
[0133] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
8.
[0134] FIG. 23:
[0135] Reflectance curves of the coating design given in Example 8
for various angles of reflection (from 0.degree. to
85.degree.).
[0136] FIG. 24:
[0137] Angular stability of 1931 CIE (x, y) colour coordinates
under CIE-D65 illuminant of the coloured design given in Example
9.
[0138] FIG. 25:
[0139] Reflectance curves of the coating design given in Example 9
for various angles of reflection (from 0.degree. to
85.degree.).
[0140] FIG. 26:
[0141] Normal hemispherical transmittance measurements of a glass
etched by solution 1 (ABF/IPA/H.sub.2O=30/10/60-15 min etch time),
a glass etched by solution 2 (ABF/sucrose/H.sub.2O=18/18/64-15 min
etch time) and an untreated glass. The normal hemispherical
transmittance is around 95% for both etched glasses and around 92%
for the untreated glass.
[0142] FIG. 27:
[0143] SEM pictures of glass surfaces structured by ABF-based
etching solutions:
[0144] (a) ABF/IPA/H.sub.2O=30/10/60-15 min etch time
[0145] (b) ABF/sucrose/H.sub.2O=18/18/64-15 min etch time.
[0146] FIG. 28:
[0147] Possible variations for the mounting of thermal or PVT solar
systems glued behind a coloured laminated glazing: (a) example of
roof installation with glazing overlap, (b) example of installation
for residential ventilated facade, (c) example of adaptation to
large buildings with glass facades.
EXAMPLES OF COATING DESIGNS
Example 1
[0148] air//136 nm of L/222 nm of H//glass//222 nm of H/136 nm of
L//air with n.sub.H=1.54 and n.sub.L=1.8
Example 2
[0149] air//glass//30 nm of H/25 nm of L/320 nm of H//polymer with
n.sub.H=2.4 and n.sub.L=1.65
Example 3
[0150] air//glass//185.+-.12 nm of H/25.+-.12 nm of L/35.+-.12 nm
of H/35.+-.12 nm of L/130.+-.12 nm of H//polymer with n.sub.H =2.4
and n.sub.i, =2.0
Example 4
[0151] air//glass//160.+-.12 nm of H/130.+-.12 nm of L/65.+-.12 nm
of H/25.+-.12 nm of L/70.+-.12 nm of H/160.+-.12 nm of L/100.+-.12
nm of H//polymer with n.sub.H=2.2 and n.sub.L=2.0
Example 5
[0152] air//glass//45.+-.12 nm of H/70.+-.12 nm of L/45.+-.12 nm of
H//polymer with n.sub.H=2.0 and n.sub.L=1.65
Example 6
[0153] air//glass//175.+-.12 nm of H/85.+-.12 nm of L/50.+-.12 nm
of H/25.+-.12 nm of L/300.+-.12 nm of H//polymer
[0154] with n.sub.H=2.4 and n.sub.L=2.0
Example 7
[0155] air//glass//120.+-.12 nm of H/120.+-.12 nm of L/95.+-.12 nm
of H/90.+-.12 nm of L/90.+-.12 nm of H/95.+-.12 nm of L/100.+-.12
nm of H//polymer with n.sub.H=2.0 and n.sub.L=1.65
Example 8
[0156] air//glass//40.+-.12 nm of H/75.+-.12 nm of L//polymer with
n.sub.H=2.4 and n.sub.L=1.65
Example 9
[0157] air//glass//50.+-.12 nm of H/90.+-.12 nm of L/65.+-.12 nm of
H/55.+-.12 nm of L//polymer with n.sub.H=2.4 and n.sub.L=2.0
* * * * *