Glazing panel

Abstract

A glazing panel 300 for a vehicle comprising an outer glazing layer 302 which is adhered to an inner glazing layer 304; a low emissivity coating 308 located on the glazing panel; and a heating assembl

Description

TECHNICAL FIELD The present disclosure relates to a glazing panel. Aspects of the invention relate to a glazing panel, to a glazing panel heating system, and to a vehicle. BACKGROUND It is known to provide glass roofs on vehicles. Condensation can form on the inside of such glass roofs. In cold conditions, the condensation may freeze. The frozen condensation may, when thawed, drip on the occupants of the vehicle. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a glazing panel, a glazing panel heating system, and a vehicle as claimed in the appended claims. According to an aspect of the present invention there is provided a glazing panel for a vehicle, the glazing panel comprising a heating element, wherein the heating element is configured to increase the temperature of the glazing panel. The glazing panel may be a roof glazing panel. The heating element may be a resistive heating element. The heating element, for example the resistive heating element, may be used to increase the temperature of the glazing panel, for example the roof glazing panel. This advantageously enables condensation, mist and other moisture to be removed from the glazing panel. According to another aspect of the present invention there is provided a glazing panel for a vehicle. The glazing panel may include one or more glazing layers. The glazing panel may, for example, include two glazing layers. The two glazing layers may include an outer glazing layer and an innerglazing layer. The outer glazing layer may be adhered to an innerglazing layer. The glazing panel may include a low emissivity coating. The low emissivity coating may be located on the glazing panel. The low emissivity coating may, for example, be included on one or more of the glazing layers. The low emissivity coating may be included on each of the glazing layers. In some embodiments, the low emissivity coating is located on the outer glazing layer. In some embodiments, the low emissivity coating is located on the inner glazing layer. In some embodiments, the low emissivity coating is located on the outer glazing layer and the inner glazing layer. Advantageously, the low emissivity coating may be included at various different positions in the overall layered glazing panel and provide heat reflecting properties. The glazing panel may include a heating assembly. The heating assembly may be located between the two glazing layers. The heating assembly may be, for example, located between the outer glazing layer and the inner glazing layer. The heating assembly may be configured to increase the temperature of the glazing panel. According to a further aspect of the present invention there is provided a glazing panel fora vehicle, the glazing panel including an outer glazing layer adhered to an inner glazing layer, a low emissivity coating located on the glazing panel, and a heating assembly located between the outer glazing layer and the inner glazing layer, wherein the heating assembly is configured to increase the temperature of the glazing panel. Advantageously, the heating assembly reduces condensation and freezing on the inside of the glazing panel. The low emissivity coating reflects heat back into the interior of the vehicle, which means that the glazing panel is cold (when it’s cold outside the vehicle). Any moisture in warm air within the vehicle e.g. from a passenger, will condense, and might freeze, on the cold glazing panel. The heating assembly can be used to increase the temperature of the glazing panel, thereby removing any condensation, mist or ice that forms on the cold glazing panel. The outer glazing layer may have a thickness, for example an outer glazing layer thickness. The innerglazing layer may have a thickness, for example an inner glazing layer thickness. The outer glazing layer thickness may be the same as the inner glazing layer thickness. The outer glazing layer thickness and / or the inner glazing layer thickness may be, for example, approximately 2 mm. Advantageously the glazing panel may be manufactured with an overall thickness which is not unduly thick or heavy. The low emissivity coating may, for example, be included on one or more of the glazing layers of the glazing panel. The low emissivity coating may be included on one, some or all of the glazing layers. In some embodiments, the low emissivity coating is located on the outer glazing layer. In some embodiments, the low emissivity coating is located on the inner glazing layer. In some embodiments, the low emissivity coating is located on the outer glazing layer and the inner glazing layer. Advantageously, the low emissivity coating may be included at various different positions in the overall layered glazing panel and provide heat reflecting properties. The outer glazing layer may have an inner surface that faces the inner glazing layer and outer surface on an opposing side of the outer glazing layer. In other words, the outer surface of the outer glazing layer may be outside of the vehicle. Advantageously the glazing layer provides an outer protective layer to the overall glazing panel. The low emissivity coating may be included on the inner surface of the outer glazing layer. The inner glazing layer may have an outer surface that faces the outer glazing layer and an inner surface on an opposing side of the innerglazing layer. In other words, the inner surface of the innerglazing layer may be inside of the vehicle. The low emissivity coating may be included on the outer surface of the innerglazing layer and / or on the inner surface of the innerglazing layer. The low emissivity coating may be configured to improve the thermal and / or optical performance of the glazing panel. The low emissivity coating may, for example, be configured to improve the thermal radiation properties of the glazing panel. The low emissivity coating may be configured to control radiation of heat from the sun, for example, thermal radiation in a wavelength range of 300 nm to 2500 nm. Additionally, or alternatively, the 2 low emissivity coating may be configured to control radiation of heat between the glazing panel and indoor (i.e. inside a vehicle) and outdoor (i.e. outside a vehicle) environments, for example thermal radiation in a wavelength range of 5 pm to 50 pm (e.g. far infra-red radiation). Advantageously, heat control within the vehicle is improved. The low emissivity coating may be configured to minimise the thermal radiation radiated to the indoor and / or outdoor environments. The low emissivity coating may be configured to minimise the thermal radiation absorbed by the glazing panel from the indoor and / or outdoor environments. The low emissivity coating may be configured to minimise the thermal radiation exchanged between the glazing panel and the indoor and / or outdoor environments. The low emissivity coating may be a hard low emissivity coating, for example a low emissivity coating applied to a surface using a pyrolytic coating process. The low emissivity coating may be a soft low emissivity coating, for example a low emissivity coating applied using a sputtering process, for example a magnetron sputter vacuum deposition (MSVD) process. The low emissivity coating may include a metallic film, for example a silver film. The low emissivity coating may, for example, include one, two, three, four or more films of silver. The low emissivity coating may include a dieelectric film, for example a ceramic dielectric film. The low emissivity coating may include two or more films of a ceramic dielectric material. The films of silver may be sandwiched between films of the ceramic dielectric material. The low emissivity coating may include a metallic film, for example a metal oxide film. The low emissivity coating may, for example, include one, two, three, four or more films of metal oxide. The low emissivity coating may include a dieelectric film, for example a ceramic dielectric film. The low emissivity coating may include two or more films of a ceramic dielectric material. The films of metal oxide may be sandwiched between films of the ceramic dielectric material. The low emissivity coating may be a triple silver low emissivity coating. The low emissivity coating may have a thickness of approximately 100 to 200 nm. The low emissivity coating may have a thickness of approximately 150 nm. The glazing panel may have an emissivity that is less than 0.4. The emissivity of the glazing panel may be less than 0.3. The emissivity of the glazing panel may be less than 0.1. The emissivity of the glazing panel may be at least 0.01. The emissivity of the glazing panel may be at least 0.02.The emissivity of the glazing panel may be between 0.01 and 0.4. The emissivity of the glazing panel may be between 0.02 and 0.3. The glazing panel may have a transmission of total solar energy (TTS) of less than 25%. The TTS of the glazing panel may be less than 20%. The TTS of the glazing panel may be less than 15%. The thermal and / or optical performance of the glazing panel may, therefore, be improved to enhance the comfort for passengers in the vehicle by tuning the properties of the low emissivity coating provided on the glazing panel. The heating assembly may contact the innerglazing layer. A portion of the heating assembly may, for example, contact the inner glazing layer. Advantageously, the heating assembly may be used to increase the temperature of the inner surface of the glazing panel, thereby allowing condensation or mist from arising from moisture in warm air within the vehicle, e.g. from a passenger, to be removed from the inner glazing layer of the glazing panel. The heating assembly may include a resistive heating element. The resistive heating element advantageously allows the heating assembly to increase the temperature of the glazing panel to a temperature that results in de-misting at relatively low power and without the need for complicated components. The heating assembly may include a heating wire. The inclusion of a heating wire in the glazing panel can be achieved without unduly complicating or lengthening manufacturing processes. The heating assembly may include a plurality of heating wires. The or each heating wire may be arranged in a serpentine configuration. The or each heating wire may comprise a metallic material, for example tungsten. The number and / or density and / or the diameter of heating wires in the glazing panel may be tuned according to the de-misting requirements of the glazing panel. The heating assembly may include a reflective coating. The reflective coating may be the or an additional low emissivity coating. The reflective coating may be an infrared reflective coating. The use of the low emissivity coating as the reflective coating of the heating assembly benefically allows two objectives to be achieved from one component of the glazing panel, therefore enabling efficient and more straightforward manufacture of the glazing panel. The glazing panel may also include includes a switchable layer located between the outer glazing layer and the inner glazing layer, where the switchable layer is switchable between a first condition, in which the switchable layer is opaque or translucent, and a second condition, in which the switchable layer is transparent. The switchable layer may be configured to switch from the second condition to the first condition when an electric current is applied to the switchable layer. The switchable layer may, for example, include a film of polymer dispersed liquid crystals (PDLC). The switchable layer may, in the first condition, transmit less than 25% of visible light. The switchable layer may, in the first condition, transmit less than 10% of visible light. The switchable layer may, in the first condition, transmit less than 1% of visible light. The switchable layer may, in the second condition, transmit more than 50% of visible light. The switchable layer may, in the second condition, transmit more than 60% of visible light. The switchable layer may, in the second condition, transmit more than 70% of visible light. In other words, the opacity of the glazing panel may be adjusted using a switchable layer. The inclusion of a switchable layer advantageously provides control over the amount of light passing through the glazing panel into the vehicle. The provision of a switchable layer in the form of a film, enables the manufacture of the glazing panel using existing manufacturing processes. The glazing panel may include an adhesive layer. The adhesive layer may be located between the outer glazing layer and the innerglazing layer of the glazing panel. The adhesive layer may include an adhesive tape or an adhesive film. The adhesive layer may include ethylene-vinyl acetate (EVA) or polyvinyl butyral (PVB). The adhesive layer may include a colour or tint. The adhesive layer may be any colour, for example the adhesive layer may be any shade of pink, blue, green, grey, yellow, red, white, orange or black. The adhesive layer may have a visible light transmittance of between 0% and 85%. The adhesive layer may have a visible light reflectance of between 5% and 55%. The adhesive layer may have a solar transmittance of between 0% and 70%. The adhesive layer may have a solar energy absorbance of between 22% and 95%. The adhesive layer may have a solar heat gain coefficient of between 0.20 and 0.77. As well as adhering the innerglazing layer to the outer glazing layer, the adhesive layer can be used to adhere one or more components of the heating assembly to the glazing panel The provision of an adhesive layer in the form of a tape or film, advantageously enables the manufacture of the glazing panel using existing manufacturing processes. A hydrophobic layer may be provided on the inner surface of the inner glazing layer. The hydrophobic layer repels water, so minimises condensation formation on the inner surface of the inner glazing layer. The low emissivity coating may cover more than 25 percent of the inner glazing layer. The low emissivity coating may cover more than 50 percent of the innerglazing layer. The low emissivity coating may cover more than 75 percent of the innerglazing layer. The glazing panel may be a roof glazing panel. The glazing panel may be a rear side glazing panel. The glazing panel may be a rear windscreen glazing panel. According to another aspect of the invention there is provided a glazing panel heating system. The glazing panel heating system may include a glazing panel according to any of the preceding aspects of the invention. The glazing panel heating system may include a power control system. The power control system may be configured to limit the power supplied to the heating system. According to another aspect of the invention there is provided a glazing panel heating system including a glazing panel according to any of the preceding aspects of the invention and a power control system, wherein the power control system is configured to limit the power supplied to the heating system. According to a further aspect of the invention, there is provided a vehicle. The vehicle may include the glazing panel of any of the preceding aspects of the invention. The vehicle may include the glazing panel heating system of the preceding aspect of the invention. The heating assembly may be configured to connect to a power supply on-board the vehicle. Additionally, or alternatively, the heating assembly may be configured to connect to a temperature control system on-board the vehicle. Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: FIG. 1 shows a schematic plan view of a vehicle; FIG. 2 shows a glazing panel having two glazing layers; FIG. 3A shows a schematic representation of a glazing panel according to an embodiment of the invention; FIG. 3B shows a schematic representation of a glazing panel according to an embodiment of the invention; FIG. 3C shows a schematic representation of a glazing panel according to an embodiment of the invention; FIG. 3D shows a schematic representation of a glazing panel according to an embodiment of the invention; FIG. 3E shows an alternative schematic representation of the glazing panel of FIG. 3D; FIG. 4 shows a schematic representation of a glazing panel according to an embodiment of the invention; FIG. 5 shows a schematic representation of a glazing panel according to an embodiment of the invention; and FIG. 6 shows a schematic representation of a glazing panel according to an embodiment of the invention. DETAILED DESCRIPTION Glazing panels in accordance with embodiments of the present invention are described herein with reference to the accompanying FIG. 3A to FIG. 6. The glazing panels may be installed on a vehicle, as shown in FIG. 1. With reference to FIG. 1, there is shown a vehicle 100. The vehicle 100 includes a front windscreen glazing panel 102, front side glazing panels 104, 106, rear side glazing panels 108, 110, a rear windscreen glazing panel 112 and a roof glazing panel 114. The vehicle 100 also includes A-pillars 116, 118, which support the front windscreen glazing panel 102. The vehicle 100 may also include a power control system 120, a power supply 122 and a temperature control system 124. Referring now to FIG. 2, there is shown a glazing panel 200 for a vehicle 100. The glazing panel 200 includes two glazing layers 202, 204. In use, one of the glazing layers 202 is located outermost relative to the vehicle 100 and is, therefore, an outer glazing layer. The other glazing layer 204 is located innermost relative to the vehicle 100 and is, therefore, an inner glazing layer. The glazing panel 200 may be, for example a laminated glass panel. Each of the glazing layers 202 may be a glass layer of the laminated glass panel. The outer glazing layer 202 has an inner surface 210 that faces the inner glazing layer 204 and an outer surface 208 on an opposing side of the outer glazing layer 202. In other words, the outer surface 208 of the outer glazing layer 202 is outside of the vehicle 100. The outer glazing layer 202 has an outer glazing layer thickness 216. Similarly, the inner glazing layer 204 has an outer surface 212 that faces the outer glazing layer 202 and an inner surface 214 on an opposing side of the inner glazing layer 204. In other words, the inner surface 214 of the inner glazing layer 204 is inside the vehicle 100. The inner glazing layer 204 has an inner glazing layer thickness 218. The inner glazing layer thickness 218 is the same as the outer glazing layer thickness 216. In the art, the outer surface 208 of the outer glazing layer 202 may be referred to as surface or layer 1; the inner surface 210 of the outer glazing layer 202 may be referred to as surface or layer 2; the outer surface 212 of the inner glazing layer 204 may be referred to as surface or layer 3; and the inner surface 214 of the inner glazing layer 204 may be referred to as surface or layer 4. An adhesive layer 206, for example a film of polyvinyl butyral (PVB), is provided between the outer glazing layer 202 and the inner glazing layer 204 to secure the two glazing layers 202, 204 together. A glazing panel 300 for a vehicle 100 according to an embodiment of the present invention will now be described with reference to FIG. 3A. The glazing panel 300 has an outer glazing layer 302, an inner glazing layer 304, an adhesive layer 306, a low emissivity coating 308 and a heating assembly 322. The outer glazing layer 302 is a transparent glass layer and has an outer surface 310, an inner surface 312 and an outer glazing layer thickness 318, for example, of approximately 2.1 mm. Similarly, the innerglazing layer 304 is a transparent glass layer and has an outer surface 314, an inner surface 316 and an innerglazing layer thickness 320, for example, of approximately 2.1 mm. The thickness of the outer glazing layer 302 is thus the same as the thickness of the inner glazing layer 304. The adhesive layer 306 is a film of tinted PVB and has a thickness, for example, of approximately 0,76 mm. The low emissivity coating 308 in this example includes thin layers of a silver or other metal oxide materials and multiple layers of a dielectric material in a stack having a thickness of approximately 3 nm. The heating assembly 322 includes a number of heating wires 324, e.g. tungsten heating wires 324. The low emissivity coating 308 is applied to the inner surface 316 of the inner glazing layer 304, for example using a magnetron sputter vacuum deposition (MSVD) process. The tungsten heating wires 324 are positioned adjacent to the outer surface 314 of the innerglazing layer 304 (also known as surface or layer 3) and may be connected to busbars on an outer edge of the glazing panel 300. The adhesive layer 306 in this example is positioned between the inner surface 312 of the outer glazing layer 302 and the outer surface 314 of the inner glazing layer 304 in order to secure outer glazing layer 302 to the innerglazing layer304. The heating wires 324 are thus sandwiched in between the outer glazing layer 302 and the inner glazing layer 304, which are secured together by the adhesive layer 306, and the low emissivity coating 308 is provided on the innermost surface of the glazing panel 300 (also known in the art as surface or layer 4).The glazing panel 300 may then be installed in a vehicle 100, for example as the roof glazing panel 114. The heating assembly 322 may be connected to a power supply 122 on-board the vehicle 100. When a current is applied to the heating wires 324, the temperature of the inner glazing layer 304 is increased, causing any condensation or mist on the inner surface 316 to evaporate. A glazing panel 300 for a vehicle 100 according to an embodiment of the present invention will now be described with reference to FIG. 3B. Features in common with the embodiment shown in FIG. 3A are identified with the same reference numeral and will not be described further. In this embodiment, the (e.g. tungsten) heating wires 324 are positioned adjacent to the inner surface 312 of the outer glazing layer 302 (also known as surface or layer 2) and may be connected to busbars on an outer edge of the glazing panel 300. The adhesive layer 306 is positioned between the inner surface 312 of the outer glazing layer 302 and the outer surface 314 of the innerglazing layer 304 in order to secure outer glazing layer 302 to the inner glazing layer 304. The heating wires 324 are thus sandwiched in between the outer glazing layer 302 and the inner glazing layer 304, which are secured together by the adhesive layer 306, and the low emissivity coating 308 is provided on the innermost surface of the glazing panel 300 (also known in the art as surface or layer 4). The glazing panel 300 may then be installed in a vehicle 100, for example as the roof glazing panel 114. The heating assembly 322 may be connected to a power supply 122 on-board the vehicle 100. When a current is applied to the heating wires 324, the temperature of the inner glazing layer 304 is increased, causing any condensation or mist on the inner surface 316 to evaporate. A glazing panel 300 for a vehicle 100 according to an embodiment of the present invention will now be described with reference to FIG. 3C. Features in common with the embodiment shown in FIG. 3A and FIG. 3B are identified with the same reference numeral and will not be described further. The heating assembly 322 includes a reflective coating 326, rather than heating wires (as described in relation to FIG. 3A and FIG. 3B). The reflective coating 326 is provided on the outer surface 314 of the innerglazing layer 304 (also known as surface or layer 3) and may be connected to busbars on an outer edge of the glazing panel 300. The adhesive layer 306 is positioned between the inner surface 312 of the outer glazing layer 302 and the reflective coating 326 on the outer surface 314 of the innerglazing layer 304 in order to secure outer glazing layer 302 to the inner glazing layer 304. The reflective coating 326 is thus sandwiched in between the outer glazing layer 302 and the inner glazing layer 304 and the low emissivity coating 308 is provided on the innermost surface of the glazing panel 300 (also known in the art as surface or layer 4). The glazing panel 300 may then be installed in a vehicle 100 as e.g. the roof glazing panel 114. The heating assembly 322 may be connected to a power supply 122 on-board the vehicle 100. When a current is applied to the reflective coating 326, the temperature of the inner glazing layer 304 is increased, causing any condensation or mist on the inner surface 316 to evaporate. A glazing panel 300 for a vehicle 100 according to an embodiment of the present invention will now be described with reference to FIG. 3D. Features in common with the embodiment shown in FIG. 3A, FIG. 3B and FIG. 3C are identified with the same reference numeral and will not be described further. The heating assembly 322 of the glazing panel 300 of this embodiment includes a reflective coating 326. In this embodiment, the reflective coating 326 is applied on the inner surface 312 of the outer glazing layer 302 (also known as surface or layer 2) and may be connected to busbars on an outer edge of the glazing panel 300. The adhesive layer 306 is positioned between the reflective coating 326 on the inner surface 312 of the outer glazing layer 302 and the outer surface 314 of the innerglazing layer 304 in order to secure outer glazing layer 302 to the inner glazing layer 304. The reflective coating 326 is thus sandwiched in between the outer glazing layer 302 and the inner glazing layer 304 and the low emissivity coating 308 is provided on the innermost surface of the glazing panel 300 (also known in the art as surface or layer 4). The glazing panel 300 may then be installed in a vehicle 100 as e.g. the roof glazing panel 114. The heating assembly 322 may be connected to a power supply 122 on-board the vehicle 100. When a current is applied to the reflective coating 326, the temperature of the inner glazing layer 304 is increased, causing any condensation or mist on the inner surface 316 to evaporate. With particular reference to FIG. 3E, schematically showing the example of FIG. 3D in operation, the low emissivity coating 308 on the inner surface 316 of the inner glazing layer 304 helps to ensure that warmth within the vehicle 100 does not radiate through the glazing panel 300 and is instead desirably retained within the vehicle 100. The transmission of total solar energy (TTS) of the glazing panel 300 may be, for example, approximately 20%. Referring now to FIG. 4, there is shown a glazing panel 400 for a vehicle 100 according to an embodiment of the present invention. The glazing panel 400 has an outer glazing layer 402, an innerglazing layer 404, a first adhesive layer 406, a second adhesive layer 406, a low emissivity coating 408, a heating assembly 422 and a switchable layer 426. The outer glazing layer 402 is a transparent glass layer and has an outer surface 410, an inner surface 412 and an outer glazing layer thickness 418, for example, of approximately 2.1 mm. The innerglazing layer 404 is a transparent glass layer and has an outer surface 414, an inner surface 416 and an inner glazing layer thickness 420, for example, of approximately 2.1 mm. The thickness of the outer glazing layer 402 is thus the same as the thickness of the inner glazing layer 404. The first and second adhesive layers 406 in this example each comprise a film of tinted PVB and each has a thickness, for example, of approximately 0.76 mm. The low emissivity coating 408 in this example includes thin layers of silver or other low emissivity materials and multiple layers of a dielectric material in a stack having a thickness of approximately 3 nm. The heating assembly 422 includes a number of heating wires 424, e.g. tungsten heating wires 424. The switchable layer 426 in this example comprises a polymer dispersed liquid crystals (PDLC) film having a thickness, for example, of approximately 0.38 mm. The low emissivity coating 408 is applied to the inner surface 416 of the inner glazing layer 404, for example using a MSVD process. The tungsten heating wires 424 are positioned adjacent to the outer surface 414 of the innerglazing layer 404 and may be connected to busbars on an outer edge of the glazing panel 400. The first adhesive layer 406 is positioned on the outer surface 414 of the innerglazing layer 404. The second adhesive layer 406 is positioned on the inner surface 412 of the outer glazing layer 402. The PDLC film is applied to either the first adhesive layer 406 on the outer surface 414 of the inner glazing layer 404 or the second adhesive layer 406 on the inner surface 412 of the outer glazing layer 402 and connected to a power supply 122 on-board the vehicle 100. The PDLC film is sandwiched between the first and second adhesive layers 406 when the outer glazing layer 402 is mounted on the innerglazing layer 404. The heating wires 424 are thus sandwiched in between the outer glazing layer 402 and the inner glazing layer 404, which are secured together by the first and second adhesive layers 406, and the low emissivity coating 408 is provided on the innermost surface of the glazing panel 400 (also known in the art as surface or layer 4). The glazing panel 400 may then be installed in a vehicle 100, for example as the roof glazing panel 114. The heating assembly 422 may be connected to the power supply 122 on-board the vehicle 100. When a current is applied to the heating wires 424, the temperature of the innerglazing layer 404 is increased, causing any condensation or mist on the inner surface 416 to evaporate. Similarly, when a current is applied to the switchable layer 426, microscopic crystals within the film are aligned along a parallel axis, thereby increasing the transparency of the film. In other words, the switchable layer 426 is switchable between a first condition, when no current is applied to the film (and in which the switchable layer is opaque), and a second condition, when current is applied to the film (and in which the switchable layer is transparent). The switchable layer advantageously scatters light to produce an opaque condition when no current is applied. It will be appreciated that, in other embodiments of the invention, the heating wires 424 may be positioned adjacent to the inner surface 412 of the outer glazing layer 402 (also known as surface or layer 2), as described in relation to the embodiment of the invention described with reference to FIG. 3B. In other embodiments of the invention, the heating assembly 422 may include a reflective coating. As described with reference to FIG. 3C, the reflective coating may be provided adjacent to the outer surface 414 of the innerglazing layer 404 (also known as surface or layer 3). Alternatively, and as described with reference to FIG. 3D, the reflective coating may be applied adjacent to the inner surface 412 of the outer glazing layer 402 (also known as surface or layer 2). Referring now to FIG. 5, there is shown a glazing panel 500 for a vehicle 100 according to an embodiment of the present invention. The glazing panel 500 has an outer glazing layer 502, an inner glazing layer 504, a first adhesive layer 506, a second adhesive layer 506, a low emissivity coating 508, a heating assembly 522, a switchable layer 526 and a reflective coating 528. The outer glazing layer 502 is a transparent glass layer and has an outer surface 510, an inner surface 512 and an outer glazing layer thickness 518, for example, of approximately 2.1 mm. The innerglazing layer 504 is a transparent glass layer and has an outer surface 514, an inner surface 516 and an inner glazing layer thickness 520, for example, of approximately 2.1 mm. The thickness of the outer glazing layer 502 is thus the same as the thickness of the innerglazing layer 504. The first and second adhesive layers 506 are a film of tinted PVB and each has a thickness, for example, of approximately 0.76 mm. The low emissivity coating 508 is thin layers of silver or other low emissivity materials and multiple layers of a dielectric material in a stack having a thickness of approximately 3 nm. The heating assembly 522 includes a number of heating wires 524, e.g. tungsten heating wires 524. The switchable layer 526 is a PDLC film having a thickness, for example, of approximately 0.38 mm. The reflective coating 528 is an infrared reflective coating, for example a coating including between 5 and 25 layers of a film including metal or metal compounds, having a thickness of approximately 50 to 300 nm. The low emissivity coating 508 is applied to the inner surface 516 of the inner glazing layer 404 using, for example, a MSVD process. The reflective coating 528 is applied to the inner surface 512 of the outer glazing layer 502 using, for example, a vacuum magnetic sputtering process. The tungsten heating wires 524 are positioned adjacent to the outer surface 514 of the innerglazing layer 504 and connected to busbars on an outer edge of the glazing panel 500. The first adhesive layer 506 is positioned on the outer surface 514 of the inner glazing layer 504. The second adhesive layer 506 is positioned on the coated inner surface 512 of the outer glazing layer 502. The PDLC film is applied to either the first adhesive layer 506 on the outer surface 514 of the inner glazing layer 504 or the second adhesive layer 506 on the inner surface 512 of the outer glazing layer 502 and connected to a power supply 122 on-board the vehicle 100. The PDLC film is sandwiched between the first and second adhesive layers 506 when the outer glazing layer 502 is mounted on the innerglazing layer 504. The heating wires 524 are thus sandwiched in between the outer glazing layer 502 and the inner glazing layer 504, which are secured together by the first and second adhesive layers 506. The low emissivity coating 508 is provided on the innermost surface of the glazing panel 500 (also known in the art as surface or layer 4). The glazing panel 500 may then be installed in a vehicle 100 as, for example, the roof glazing panel 114. The heating assembly 522 may be connected to the power supply 122 on-board the vehicle 100. When a current is applied to the heating wires 524, the temperature of the innerglazing layer 504 is increased, causing any condensation or mist on the inner surface 516 to evaporate. Similarly, when a current is applied to the switchable layer 526, crystals within the film are aligned along a parallel axis, thereby increasing the transparency of the film to be increased. In other words, the switchable layer 526 is switchable between a first condition, when no current is applied to the film (and in which the switchable layer is opaque), and a second condition, when current is applied to the film (and in which the switchable layer is transparent). The switchable layer 526 advantageously disperses light to provide an opaque condition when no current is applied. The reflective coating 528 beneficially reflects infra-red rays, allowing the temperature within the vehicle 100 to be better controlled and reducing the reliance on air conditioning systems for climate control (thereby improving fuel efficiency for the vehicle 100). It will be appreciated that, in other embodiments, the heating wires 524 may be positioned adjacent to the inner surface 512 of the outer glazing layer 502 (also known as surface or layer 2), as described in relation to the embodiment of the invention described with reference to FIG. 3B. In other embodiments, the heating assembly 522 may include a reflective coating. As described with reference to FIG. 3C, the reflective coating of the heating assembly 522 may be provided adjacent to the outer surface 514 of the inner glazing layer 504 (also known as surface or layer 3). Alternatively, and as described with reference to FIG. 3D, the reflective coating of the heating assembly 522 may be applied adjacent to the inner surface 512 of the outer glazing layer 502 (also known as surface or layer 2). Referring now to FIG. 6, there is shown a glazing panel 600 fora vehicle 100 according to a further embodiment of the present invention. The glazing panel 600 has an outer glazing layer 602, an innerglazing layer 604, a first adhesive layer 606, a second adhesive layer 606,a third adhesive layer 606, a low emissivity coating 608, a heating assembly 622, a switchable layer 626 and a reflective coating 628. The outer glazing layer 602 is a transparent glass layer and has an outer surface 610, an inner surface 612 and an outer innerglazing layer thickness 618, for example, of approximately 2.1 mm. The innerglazing layer 604 is a transparent glass layer and has an outer surface 614, an inner surface 616 and an innerglazing layer thickness 620, for example, of approximately 2.1 mm. The thickness of the outer glazing layer 602 is thus the same as the thickness of the inner glazing layer 604. The first, second and third adhesive layers 606 may each be a film of colourless PVB and each have a thickness, for example, of between 0.38 mm and 0.76 mm. The first adhesive layer 606, for example, may have a thickness of approximately 0.38 mm. Each of the second adhesive layer 606 and the third adhesive layer 606 may have a thickness, for example, of approximately 0.76 mm. The low emissivity coating 608 may include thin layers of silver or other low emissivity materials and multiple layers of a dielectric material in a stack, wherein each layer in the stack has a thickness of approximately 3 nm. The heating assembly 622 includes heating wires 624, e.g. a number of tungsten heating wires 624. The switchable layer 626 is, for example, a PDLC film having a thickness, for example, of approximately 0.38 mm. The reflective coating 628 may be an infrared reflective coating, for example a coating including between 5 and 25 layers of a film including metal or metal compounds, having a thickness of approximately 50 to 300 nm. The low emissivity coating 608 may be applied to the inner surface 612 of the inner glazing layer 604 using a MSVD process. The tungsten heating wires 624 are positioned adjacent to the outer surface 614 of the innerglazing layer 604 and connected to busbars on an outer edge of the glazing panel 600. The first adhesive layer 606 is positioned on the outer surface 614 of the inner glazing layer 604. The PDLC film is applied to the first adhesive layer 606 on the outer surface 614 of the inner glazing layer 604 and is connected to a power supply 122 on-board the vehicle 100. The second adhesive layer 606 is positioned on the PDLC film of the switchable layer 626. The reflective coating 628 is applied to the second adhesive layer 606, for example, using a vacuum magnetic sputtering process. The third adhesive layer 606 is applied to the inner surface 612 of the outer glazing layer 602. The heating wires 624, the switchable layer 626 and the reflective coating 628 are thus sandwiched in between the outer glazing layer 602 and the inner glazing layer 604, which are secured together by the first, second and third adhesive layers 606. The low emissivity coating 608 is provided on the innermost surface of the glazing panel 600 (also known in the art as surface or layer 4). The glazing panel 600 may then be installed in a vehicle 100 as the roof glazing panel 114. The heating assembly 622 may be connected to the power supply 122 on-board the vehicle 100. When a current is applied to the heating wires 624, the temperature of the innerglazing layer 604 is increased, causing any condensation or mist on the inner surface 616 to evaporate. Similarly, when a current is applied to the switchable layer 626, crystals within the film are aligned along parallel axis, thereby increasing the transparency of the film to be increased. In other words, the switchable layer 626 is switchable between a first condition, when no current is applied to the film (and in which the switchable layer is opaque), and a second condition, when current is applied to the film (and in which the switchable layer is transparent). The switchable layer 626 advantageously disperses light to an opaque condition when no current is applied. The reflective coating 628 beneficially reflects infra-red rays, allowing the temperature within the vehicle 100 to be controlled and reducing the reliance on air conditioning systems (thereby improving fuel efficiency for the vehicle 100). It will be appreciated that, in other embodiments of the invention, the heating wires 624 may be positioned adjacent to the inner surface 612 of the outer glazing layer 602 (also known as surface or layer 2), as described in relation to the embodiment of the invention described with reference to FIG. 3B. In other embodiments of the invention, the heating assembly 622 may include a reflective coating. As described with reference to FIG. 3C, the reflective coating of the heating assembly 622 may be provided adjacent to the outer surface 614 of the inner glazing layer 604 (also known as surface or layer 3). Alternatively, and as described with reference to FIG. 3D, the reflective coating of the heating assembly 622 may be applied adjacent to the inner surface 612 of the outer glazing layer 602 (also known as surface or layer 2). It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. In some embodiments of the invention, for example, a hydrophobic layer may be applied to the inner surface of the innerglazing layers in order to reduce the accumulation of moisture on the inner surface. In some embodiments of the invention, a power control system 120 of the vehicle 100 may be connected to the power supply 122 and the glazing panel. The power control system 120 may, for example be configured to limit the power supplied to the heating assembly. The power control system 120 and the glazing panel together may be considered to form a glazing panel heating system. In some embodiments of the invention, a temperature control system 124 of the vehicle 100 may be connected to the glazing panel. The temperature control system 124 may be configured to limit the temperature to which layers of the glazing panel are heated in order to reduce the risk of components of the glazing panel overheating. In the embodiments of the invention described with reference to FIG. 3A to FIG. 6, the low emissivity coating is provided on an inner surface of the innerglazing layer. It will be appreciated that, in other embodiments of the invention, the low emissivity coating may be applied to any of the surfaces within the glazing panel. The low emissivity coating may be applied to the inner surface of the innerglazing layer and / or the outer surface of the inner glazing layer and / or the inner surface of the outer glazing layer and / or the outer surface of the outer glazing layer. In some of the embodiments of the invention described above, the or each adhesive layer is a tinted PVB layer. In one of the embodiments of the invention described above, the adhesive layers are colourless PVB layers. It will be appreciated that in other embodiments of the invention, the adhesive layer may or may not include a tint or dye. The or each adhesive layer of glazing panels according to embodiments of the invention may be any colour or have no colour. Where more than one adhesive layer is provided, it will be understood that each adhesive layer in the glazing panel may be a different colour and / or have no colour. In the embodiments of the invention described above, the glazing panels are each installed as roof glazing panels on a vehicle. It will be appreciated that a glazing panel according to the present invention may be installed elsewhere on a vehicle. The glazing panel may, for example, be installed on any or all glazing panels that are rearward of the A pillars (relative to forward direction of the vehicle). The glazing panel may be, for example, a rear windscreen glazing panel and / or a rear side glazing panel and / or a roof glazing panel.

Claims

1. A glazing panel for a vehicle, the glazing panel comprising:an outer glazing layer adhered to an innerglazing layer;a low emissivity coating located on the glazing panel; anda heating assembly located between the outer glazing layer and the inner glazing layer, wherein the heating assembly is configured to increase the temperature of the glazing panel.

2. The glazing panel of claim 1, wherein the low emissivity coating is located on the inner glazing layer.

3. The glazing panel of claim 1 or 2, wherein the emissivity of the glazing panel is less than 0.4.

4. The glazing panel of any one of claims 1 to 3, wherein a portion of the heating assembly contacts the inner glazing layer.

5. The glazing panel of any one of claims 1 to 4, wherein the heating assembly comprises a resistive heating element.

6. The glazing panel of claim 5, wherein the resistive heating element comprises a heating wire .

7. The glazing panel of any one of claims 1 to 6, wherein the heating assembly comprises a reflective coating.

8. The glazing panel of any one of claims 1 to 7, comprising:a switchable layer located between the outer glazing layer and the inner glazing layer, wherein the switchable layer is switchable between a first condition, in which the switchable layer is opaque, and a second condition, in which the switchable layer is transparent.

9. The glazing panel of any one of claims 1 to 8, comprising:an adhesive layer located between the outer glazing layer and the innerglazing layer.

10. The glazing panel of any one of claims 1 to 9,wherein the innerglazing layer has an outer surface adjacent to the outer glazing layer and an inner surface on an opposing side of the innerglazing layer;wherein the glazing panel comprises a hydrophobic layer located on the inner surface of the inner glazing layer.

11. The glazing panel of any one of claims 1 to 10, wherein the low emissivity coating covers more than 50 percent of the inner glazing layer.

12. The glazing panel of any one of claims 1 to 11, wherein the glazing panel is a roof glazing panel.

13. A glazing panel heating system comprising:the glazing panel of any one of claims 1 to 12; anda power control system, wherein the power control system is configured to limit the power supplied to the heating assembly.

14. A vehicle comprising:the glazing panel of any one of claims 1 to 12 or the glazing panel heating system of claim 13.

15. The vehicle of claim 14, wherein the heating assembly is configured to connect to a power supply onboard the vehicle, and / or to a temperature control system on-board the vehicle.

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