The present invention is concerned with thermal insulation of windows and doors.

Certain embodiments of the invention are addressed to problems associated with louvre shutters.

Window shutters and blinds having a louvre structure are popular and widely used. They can be aesthetically attractive and can take a variety of different forms in keeping with a room's decor. Often the angle of the louvres is adjustable so that they can serve to regulate Incoming sunlight in a manner which is adjustable by the user, and also to provide privacy when required.

However louvres do not provide a window with effective thermal insulation since by their nature they have multiple openings which allow air to pass, especially if the window's itself has a poor seal which allows drafts in from the outside, and permit convective circulation of air in the vicinity of the glazing unit itself, one of the mechanisms of heat loss.

So it is desirable to improve the thermal insulation properties of louvred shutters and blinds. But this needs to be achieved without unacceptably impairing the appearance presented to occupants of the room, or the ability of the blind to admit light to the room and to enable the user to see through the window.

Certain aspects of the present invention address the more general problem of how to improve thermal insulation of a window or door, whether or not it is provided with a shutter. It is desirable to achieve this in a manner which is economical and constructionally simple.

DE19855166A (Berthold Heyne) discloses a "picture window" comprising a roller shutter (which is not a louvre as such, being formed from multiple bars whose edges are hingedly coupled) which is mounted alongside a roller blind, the shutter and the blind being able to be raised and lowered together. The blind is partially transparent and images are displayed on the bars of the roller shutter, on the roller blind and on the window to make a visual display. Whether this picture window would have significantly improved thermal insulation is open to question.

According to a first aspect of the present invention there is a shutter or blind arrangement for mounting adjacent a window or door, the arrangement comprising multiple elongate parallel slats which are juxtaposed to form a planar window screen and which are inclined, or which are mounted for rotation and able to be inclined, to the plane of the window screen, providing openings between the slats for passage of light, and a sheet arranged alongside the window screen to cover the area of the window screen, so that when the arrangement is mounted for use the thermally insulating sheet is able to be interposed between the window screen and the window or door, the sheet being provided with a peripheral seal, and providing a barrier to passage of air through the shutter or blind arrangement.

The sheet may be transparent or translucent. The sheet may be retractable. The sheet may take the form of a roller blind.

The peripheral seal may comprise at least one channel which receives an edge of the sheet and embraces it to form a seal, the sheet being able to slide with respect to the channel to enable retraction of the sheet. The channel may contain a brush seal or an elastomeric seal. The sheet may have left and right edges received in respective channels, the arrangement further comprising a bottom channel in which a bottom edge of the sheet is releasably and sealingly receivable when the sheet is fully extended.

The slats may be mounted within a frame, the peripheral seal being formed formed between the sheet and the frame. The frame may be configured to be hingedly mounted at the window or door and provided with a frame seal on its outer periphery to seal against a surrounding structure.

The frame may comprise elongate hollow plastics frame members joined through right-angled corner couplings which are received in the frame members.

The sheet may be a flexible membrane. The sheet may comprise plastics. According to a second aspect of the present invention there is a blind arrangement for mounting adjacent a window or door, the blind arrangement comprising a transparent or translucent flexible sheet carried on a roller arrangement mountable at the top of the window or door; means for securing an edge of the flexible sheet which extends parallel to the roller arrangement at the top of the window or door, so that between the roller arrangement and said edge the flexible sheet is able to form a "U" formation; a bottom bar receivable in the "U" formation of the sheet in such a manner as to be rotatable as the blind is raised or lowered using the roller arrangement. Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a window shutter embodying the present invention, viewed from its interior side; Figure 2 is a simplified section through the shutter of Figure 1, and associated glazing, in a vertical plane;

Figure 3 shows a further window shutter embodying the present invention, viewed from its exterior side;

Figure 4 is a detail view of the shutter of Figure 3, again viewed from its exterior side; Figure 5 shows the components of the shutter of Figure 3 in exploded form;

Figure 6 is a simplified representation of a pair of shutters embodying the present invention provided with external seals;

Figure 7 is a simplified representation of part of one of the shutters of Figure 6; and

Figure 8 shows a frame and sheet used in a further embodiment of the present invention; Figure 9 is a simplified vertical section through a thermally insulating blind arrangement according to an aspect of the present invention;

Figure 10 is a simplified vertical section through a blind and shutter arrangement according to an aspect of the present invention; and

Figure 11 shows the blind arrangement of Figure 9 mounted in a window along with a pair of shutters.

The term "louvre" as used herein refers to an arrangement of elongate slats arranged with their lengths substantially parallel. A "louvre blind", as the term is used herein, is any form of window covering having louvres. A "shutter" is a window covering having a movable rigid frame. Shutter frames are typically hinged but may in principle be movable in some other way, e.g. by sliding. A "window screen" may be any form of screen to be placed in front of a window and includes louvre type shutters or blinds.

The shutter arrangement 10 represented in Figures 1 and 2 is of louvre type, having multiple slats 12 which are mutually parallel and which in this example extend horizontally. The slats 12 are mounted across openings in a rigid frame 14. Viewed in section (Figure 2) the slats 12 are seen to be inclined with respect to a plane defined by the frame, as seen in Figure 2, providing openings 13 through which light is able to pass through the louvre, especially if the direction of the light is downwardly inclined in the direction from outside to inside the building. The angle of inclination of the slats 12 may be fixed, or it may be variable so that by changing this angle the user is able to vary the amount of light entering the room and the degree of privacy provided. When the slats 12 are at right angles to the frame 14 it offers little obstruction to light or to viewing through the window. When the slats 12 are close to parallel to the frame 14, the long edges of neighbouring slats are juxtaposed and overlap, largely blocking out light and obstructing vision through the window. The shutter 10 is mounted in a window frame on the interior side of glazing unit 16. This type of shutter is in itself well known and widely used, and is often referred to as a "plantation shutter".

It will be apparent that the openings 13 the slats 12 permit flow of air through the shutter. So if the window itself admits drafts from the outside of the building then the shutter 10 offers little resistance to these, and there is scope for convective circulation of air in the vicinity of the window in a manner which promotes heat loss to the outside through the glazing unit 16. In accordance with the present invention the shutter arrangement 10 is provided with a thermal insulation insulating sheet 18 which serves to reduce heat loss to the outside. The insulating sheet is arranged between the louvre slats 12 and the glazing panel 16, extending across the entire area of the shutter arrangement 10. The insulating sheet 18 can serve several functions: it blocks passage of air from the building side of the shutter to the glazing unit 16; if the glazing itself is poorly fitted, leaving room for drafts from the outside, the insulating sheet 18 can block these; it completely or partly blocks the path for convective flow adjacent the glazing panel 16, and so reduces heat loss by that mechanism; it can provide a captive volume 20 of air which itself serves as an insulating layer. In all of these ways the insulating sheet 18 reduces heat loss through the window.

The insulating sheet 18 is transparent, or at least translucent, so that it does not block passage of light through the window, and need not impair viewing through the window. It can thus be visually inconspicuous, especially since its periphery can be disposed behind the shutter's frame 14, and the main area of the insulating sheet 18 is partly concealed by the slats 12. The insulating sheet 18 can be membranous in nature, taking the form e.g. of a transparent plastics film. A PVC film or sheet is suitable. Other transparent plastics membranes may be used. Alternatively the insulating sheet 18 may in some embodiments be of a more rigid nature. For example, transparent plastics sheet material may be used. Polycarbonate is one suitable plastics material having good insulating qualities. Other materials that may be used include polyethylene terephthalate (PET), polypropylene, polystyrene and acrylic. The insulating sheet 18 may, in accordance with aspects of the present invention, be fixed in place in normal use, or it may be movable in normal use. A movable insulating sheet 18 may be retractable when not required (it may for example be retracted in summer time, when thermal insulation may be of little importance). In particular, the insulating sheet 18 may be carried on a roller and able to roll onto it in the manner of a roller blind. Figures 3 and 4, show the exterior side (i.e. the side present to the glazing unit 16) of a shutter arrangement 10a comprising two shutters 22, 24 each provided with a respective insulating sheet 18a formed in the manner of a roller blind, being carried upon a roller rotatably mounted between a pair of roller brackets 26 so that rotation of the roller enables the insulating sheet 18a to be pulled down to cover the rear face of the shutter 22, and rotation of the roller in the opposite direction causes the insulating sheet 18a to be wound onto the roller and so retracted upwardly. Mechanisms for turning the roller are well known and will not be described in detail here, but may for example use a pull cord led over a pulley, or a crank handle driving a gear arrangement through an elongate rod.

The thermal performance of the insulating sheet 18a is further improved by providing it with a peripheral seal to prevent or at least reduce flow of air from one side of the insulating sheet 18a to the other, around its edges. In the shutter arrangement 10a of Figures 3 and 4 "U" shaped channels 28, 30 are provided which are positioned to receive left and right edges of the insulating sheet 18a, extending along left and right upright members 32, 34 of the shutter frame 14a. A seal arrangement is provided within each channel to form a seal against the insulating sheet 18a to resist drafts. This feature is omitted from the drawings but may for example take the form of an opposed pair of brush seals or elastomeric blades arranged to engage opposite faces of the insulating sheet 18a. A further channel may be provided to receive the bottom edge of the sheet 18a to resist drafts in that area. Figure 2 shows a suitable construction in which the sheet is provided with a bar 36 along its lower edge to releasably locate and seal in an upwardly open horizontal channel member 38 when the sheet 18a is fully deployed. Plantation shutters are traditionally made of wood and can be expensive items. The present invention can be implemented in shutters partially or wholly constructed from wood, but a potentially more economical alternative is to use plastics construction. Recycled plastics can be used. Figure 5 shows the components of shutter 22, 24, whose frame comprises left, right, top and bottom elongate frame members 40, 42, 44, 46 which may have a common cross sectional shape, and which are hollow and configured to receive right-angled corner couplings 48 to form a square frame. This construction makes it easy to fit the frame 14a to the window opening simply by cutting one end of each of the frame members to the required length and then joining them with the corner couplings 48. If the width of the frame 14a has been reduced in that process, it remains necessary to trim the individual slats 12a to fit. This drawing shows a rotary stub 50 received by roller bracket 26 to mount the roller itself. A sight bar 52 extends across the top of the frame's opening to conceal the roller, its ends being received in pre-formed cut-aways 54 at upper ends of the left and right frame members 40, 42. The left and right channels 28, 30 and the bottom channel 38 are in this example seen to be separately from the frame members 40, 42, 46 carrying them, although in other embodiments the channels may be integral with the frame members.

Referring now to Figures 6 and 7, in the case of hinged shutters 22b, 24b, outwardly directed seals may be provided on the shutter's frame 14b to seal against a surrounding structure and, where two shutters close against one another, between the shutters themselves. Figures 6 and 7 show hinged shutter frames 14b each carrying such a seal in the form of an elastomer blade 56. Other types of seal, such as brush seals, may be substituted.

Figure 8 shows an alternative embodiment in which insulating sheet 18c is not retractable but is instead fixed to frame 14c of the blind or shutter.

The slats 12 making up the louvre of the blind may be adjustable in inclination (various mechanisms for such adjustment are well known in the art) or may be fixed.

Figure 9 is a simplified representation of a thermally insulating blind arrangement 58 in accordance with an aspect of the present invention. This arrangement does not include a shutter. It has a transparent or translucent insulating sheet 18d carried on a roller arrangement 60 in the manner of a roller blind. In this example the roller arrangement 60 is mounted at the top of the window, on the underside of the window's reveal. An edge 62 of the insulating sheet 18d parallel to the roller arrangement 60 is also secured at the top of the window, on the underside of the window reveal. This may be done by providing a slim bar along the edge 62 for attachment to the window reveal. The insulating sheet 18d thus hangs downward from both the roller arrangement 60 and the edge 62, forming a narrow "U" or "V" shape. A bottom bar 64 lies inside and at the bottom of this "U" shaped formation, serving to keep the insulating sheet in the desired form and resisting its natural tendency to rise up or billow out when subject to drafts. The bottom bar 64 of the illustrated embodiment is in the form of a roller resting in the insulating sheet 18d but able to rotate. In the illustrated embodiment the weight of the bottom bar enables it to perform its function without it needing to be fixed in position. However in other embodiments the two ends of the bottom bar may extend outwardly of the insulating sheet 18d to engage some fixing means or other formation to keep the bottom bar in place at the bottom of the window reveal. Additionally or alternatively the ends of the bottom bar may carry some form of handle or handles by which the bottom bar can be drawn downwards by a user, to deploy the insulating sheet 18d.

In the present embodiment a bracket or panel 66 serves both to (a) carry and mount the roller arrangement 60 and (b) secure the edge 62 of the insulating sheet 18d to the underside of the window reveal.

The arrangement of Figure 9 provides the potential for improved thermal insulation because it serves to create an additional air gap 68 between the room and the glazing of the window. This air gap 68 is within the "U" formed by the insulating sheet 18d. An additional air gap is formed in the space between the insulating sheet 18d and the glazing itself, further improving thermal insulation.

The insulating sheet 18d can be retracted when not required by winding it onto the roller arrangement 60. The bottom bar 64 rises along with the insulating sheet 18d but because it is free to rotate and to move along the insulating sheet 18d it remains at the bottom of the "U" shaped part of the sheet and does not foul as the depth of this "U" shape diminishes. When the sheet is fully wound up, the bottom bar can lie against the roller arrangement 60 making a tidy and compact configuration.

To improve thermal performance still further, a seal arrangement may be provided to resist passage of air between the left and right hand edges of the insulating sheet 18d and the adjacent left and right hand faces of the window reveal. This seal arrangement needs to permit the insulating sheet 18d and its bottom bar 64 to rise and fall. It may comprise a pair of "U" shaped channels for mounting on the left and right faces of the window reveal, so that the left and right edges of the insulating sheet 18d run in their respective channels.

The thermally insulating blind arrangement of Figure 9 may be used with a louvre blind, as represented in simplified form in Figure 10. Figure 11 provides more constructional detail of this embodiment. The shutters 70 of this embodiment are mounted through hinges 72 to left and right upright internal faces 74 of a window reveal. The insulating blind arrangement 58 is disposed between the shutters 70 and the glazing 76. Seen in Figure 10 are both the aforementioned air gap 68 within the "U" formation of the insulating sheet 18d and the additional airgap 78 between the insulating sheet 18d and the glazing 16.