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 inc =1, said substrate having a refractive index n substrate defined as follows: 1.45≦n substrate ≦1.6 at 550 nm, and said exit medium being defined as follows 1.45≦n exit ≦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* ab =√(a*) 2 +(b*) 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 vis is higher than 4%. 1c) The variation of the dominant wavelength λ MD of the dominant colour MD of the reflection with varying angle of reflection Θ r is smaller than 15 nm for Θ r <60°. 1d) The total hemispherical solar transmittance at near-normal incidence is above 80%.

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 inc =1 and having a refractive index n inc  substrate defined as follows: 1.45≦n substrate ≦1.6 at 550 nm and; said laminating polymer being considered as the exit medium whose refractive index is defined as follows 1.45≦n exit ≦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* ab =√(a*) 2 +(b*) 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 vis  is higher than 4%. 
 1c) The variation of the dominant wavelength λ MD  of the dominant colour M D  of the reflection with varying angle of reflection θr is smaller than 15 nm for θr<60°. 
 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≦0.2 for wavelengths λ with 450 nm≦λ≦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≦n substrate ≦1.6 at 550 nm and composed by 3 sub-layers based on low refractive index material L with 1.4≦nL≦2.2 at 550 nm and high refractive index material H with 1.8≦n H ≦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≦n substrate ≦1.6 at 550 nm and composed by 5 sub-layers based on low refractive index material L with 1.4≦n L ≦2.2 at 550 nm and high refractive index material H with 1.8≦n H ≦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≦n substrate ≦1.6 at 550 nm and composed by 7 sub-layers based on low refractive index material L with 1.4≦n L ≦2.2 at 550 nm and high refractive index material H with 1.8≦n H ≦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≦n substrate ≦1.6 at 550 nm and composed by 3 sub-layers based on low refractive index material L with 1.4≦n L ≦1.8 at 550 nm and high refractive index material H with 1.8≦n H ≦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≦n substrate ≦1.6 at 550 nm and composed by 5 sub-layers based on low refractive index material L with 1.65≦n L ≦2.1 at 550 nm and high refractive index material H with 1.8≦n H ≦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≦n substrate ≦1.6 at 550 nm and composed by 7 sub-layers based on low refractive index material L with 1.4≦n L ≦1.8 at 550 nm and high refractive index material H with 1.8≦n 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≦n substrate ≦1.6 at 550 nm and composed by 2 sub-layers based on low refractive index material L with 1.4≦n L ≦1.8 at 550 nm and high refractive index material H with 1.8≦n H ≦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≦n substrate ≦1.6 at 550 nm and composed by 4 sub-layers  based on low refractive index material L with 1.65≦n L ≦2.1 at 550 nm and high refractive index material H with 1.8≦n H ≦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 façade 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 façade comprising a solar energy system according to  claim 42 . 
     
     
         47 . The solar roof or building façade according to  claim 25  where the solar energy system is suspended by fixations attached to the glazing. 
     
     
         48 . The solar roof or building façade according to  claim 46  with an overlapping of the laminated glazing.