IE87204B1 - Door leaf and door frame assemby - Google Patents

Abstract

A door leaf (3) comprising a thermally insulating core (15) located between a first thermally conducting sheet (16) defining a first face of the door leaf and a second thermally conducting sheet (18) defining a second face of the door leaf is provided. The first sheet (16) and the second sheet (18) are connected by a first door edge element (17) which forms at least part of a first edge of the door leaf (3). The first door edge element (17) comprises a thermally broken portion (17B) that is disposed within the door leaf (3) and is covered over by a thermally conducting part of the door leaf (3). The thermally broken portion (17B) is arranged to mitigate heat transfer between the first (16) and second (18) sheets. <Figure 1>

Description

Door leaf and door frame assembly Field of the Invention The present invention relates to door leaves and door frames, and to door leaf and door frame assemblies. More particularly, but not exclusively this invention concerns thermally broken doors and thermally broken door and door frame assemblies.

Background of the Invention It is very well known to use metals such as steel as construction materials for doors and door frames due to their superior mechanical and weather resisting properties and their cost.

A problem with known metallic doors and door frames is that they are thermally conducting and, as such, they may act as thermal bridges which can conduct heat from inside a building into the outside environment. This can adversely affect the overall thermal insulation of a building .

The present invention seeks to provide an improved door .

Summary of the Invention The present invention provides, according to a first aspect, a door leaf comprising a thermally insulating core located between a first thermally conducting sheet defining a first face of the door leaf and a second thermally conducting sheet defining a second face of the door leaf, - 2 wherein the first sheet comprises a first door edge element which connects the first sheet and the second sheet and which forms a first exposed edge of the door leaf, and wherein the first door edge element comprises a part extending within the door leaf, adjacent to the second sheet, so that the part is disposed within the door leaf and is covered over by the second sheet, and wherein the thermally broken portion is provided in the part so that the thermally broken portion is disposed within the door leaf and is not exposed to the outside environment, the thermally broken portion comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sheets.

The thermally broken portion of the door leaf is able to limit the conduction of heat from one thermally conducting face of the door leaf to the other whilst still providing a mechanical connection between those parts but is itself able to be protected by the part of the door leaf covering over the thermally broken portion.

The first and second thermally conducting sheets preferably extend over substantially all of the area of the first and second faces of the door leaf respectively. That improves both the aesthetic and practical characteristics of the door. As will be understood, the thermally broken element is provided partway between the first and second faces and spaced from the faces.

The first and second thermally conducting sheets may be sheet metal. The first door edge element may be of sheet metal. The sheet metal may be sheet steel.

The thermally insulating core may be mineral wool. - 3 The thermally broken portion is broken by a multiplicity of apertures spaced along the portion and defining bridging portions between them. Such a thermally broken portion can be formed economically and provide an effective thermal break. Since it is covered over by another part of the door leaf, there is no need for it to be aesthetically pleasing and it need not be relied upon to form a barrier to, for example, moisture entering into the thermally insulating core of the door leaf. The multiplicity of apertures may be arranged along a linear path. The apertures may each be of substantially the same size and shape and may be equispaced. The apertures may be of rectangular shape defining bridging portions between them.

The spacing of adjacent bridging portions is preferably greater than the spacing of adjacent apertures. Thus, in the region of the apertures, the apertures occupy a greater area than the bridging portions, it being understood that spacing refers to edge to edge spacing rather than centre to centre spacing. The spacing of adjacent bridging portions may be more than three times greater than the spacing of adjacent apertures. The spacing of adjacent bridging portions may be more than six times greater than the spacing of adjacent apertures. In an embodiment of the invention described below the spacing of adjacent bridging portions is ten times greater than the spacing of adjacent apertures.

The thermally broken portion preferably extends along substantially the whole length of the first door edge element. The first door edge element may extend along the whole length of an edge of the door leaf. - 4 The thermally broken portion of the first door edge element may be disposed substantially in a plane adjacent to and parallel to the second face of the door leaf. The second sheet may overlie the thermally broken portion of the first door edge element.

The first door edge element and the second sheet may be provided with complementary U shaped lips which interengage. A layer of thermally insulating material may be placed between adjacent surfaces of the interengaging U shaped lips.

Whilst reference is made above to a first door edge element, it should be understood that it is within the scope of the broadest aspect of the invention for the first door edge element to be the only door edge element. In a preferred form of the invention, the door leaf further comprises a second door edge element, wherein the first sheet and the second sheet are also connected by the second door edge element which forms at least part of a second edge of the door leaf. The second edge of the door leaf may be opposite the first edge of the door leaf. The second door edge element may comprise a thermally broken portion that is disposed within the door leaf and is covered over by a thermally conducting part of the door leaf so that the thermally broken portion is not exposed to the outside environment, the thermally broken portion of the second door edge element comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second - 5 sheets. The second door edge element may have any of the features defined above of the first door edge element. The second door edge element may be substantially the same as the first door edge element.

The door leaf may further comprise a third door edge element, wherein the first sheet and the second sheet are also connected by the third door edge element which forms at least a part of a third edge of the door leaf. The third edge of the door leaf may be transverse to the first edge of the door leaf. The third door edge element may be made of a thermally conducting material, for example sheet metal. The third door edge element may comprise a thermally broken portion that is disposed within the door leaf and is covered over by a thermally conducting part of the door leaf so that the thermally broken portion is not exposed to the outside environment, the thermally broken portion of the third door edge element comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sheets. The thermally broken portion of the third door edge element may have any of the features defined above of the thermally broken portion of the first door edge element. For example it may be formed of apertures and bridging portions which may be arranged along the length of the third door edge element.

It should be understood that whilst reference is made to a third door edge element, it is not essential for the second door edge element to be present when the third door edge element is present.

The third door edge element may be formed as a separate member from the first and second sheets. The - 6 third door edge element may be of generally U shaped cross section, with the limbs of the U connected to the first and second sheets. The thermally broken element may be provided in the base of the U. The recess defined by the U shaped cross section may contain thermally insulating material.

A further separate member may be fixed to the third door edge element covering over the thermally broken element of the third door edge element so that the thermally broken element is not exposed to the outside environment. The further separate member may be of generally U shaped cross-section and may fit inside the third door edge element with limbs of the U of the further member disposed adjacent to limbs of the U shaped third door edge element and extending towards the base of the U shaped third door edge element.

The door leaf may further comprise a fourth door edge element, wherein the first sheet and the second sheet are also connected by the fourth door edge element which forms at least a part of a fourth edge of the door leaf. The fourth edge of the door leaf may be opposite the third edge of the door leaf. The fourth door edge element may comprise a thermally broken portion that is disposed within the door leaf and is covered over by a thermally conducting part of the door leaf, the thermally broken portion of the fourth door edge element being arranged to mitigate heat transfer between the first and second sheets.

The fourth door edge element may have any of the features defined above of the third door leaf element. The fourth door edge element may be arranged in substantially the same way as the third door edge element. - 7 The door leaf may further comprise a thermally conducting internal stiffening member connected between the first and second sheets, wherein the internal stiffening member comprises a thermally broken portion comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sheets. The thermally broken portion may have any of the features defined above of the thermally broken portion of the first door edge element. For example it may be formed of apertures and bridging portions which may be arranged along the length of the stiffening member.

The internal stiffening member may extend in a direction substantially parallel to the first door edge element.

The internal stiffening member may comprise a web which spans the space between the first and second faces of the door. The stiffening member may comprise a first flange connected to the first sheet and a second flange connected to the second sheet. A layer of thermally insulating material may be provided between each flange and the sheet to which it is connected.

There may be a plurality of stiffening members spaced apart from one another and each extending substantially parallel to the first door edge element.

The door leaf may have a length greater than its width and the first door edge element may extend along the length of the door. The door leaf may be of rectangular shape. The third and fourth edge elements may extend along opposite ends of the door. In use the door is typically mounted with the first door edge element vertical. - 8 The present invention provides, according to a second aspect, a door and frame assembly comprising a door leaf according to the first aspect of the invention and a thermally broken door frame, the door leaf being hinge-mounted upon the door frame and moveable between an open and a closed position, wherein the door frame comprises a first side spaced apart from a second side and a stop located between the first and second sides of the frame which is arranged to abut a face of the door leaf when the door leaf is in the closed position, such that when the door leaf is in the closed position, the frame extends around the door leaf, wherein the door frame further comprises a thermally broken portion comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sides of the frame.

The sides of the frame may be of a thermally conducting material such as sheet metal, for example sheet steel. The thermally broken portion may have any of the features defined above of the thermally broken portion of the first door edge element.

The frame may extend around part or all of the door leaf. In an embodiment of the invention described below, the frame extends around a top and opposite sides of a door leaf .

The thermally broken element of the frame may be arranged to mitigate heat transfer between one of the first and second sides of the frame and the stop. - 9 Description of the Drawings Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: Figure 1 is a front elevation view of a door and frame assembly according to a first embodiment of the invention; Figure 2 is a cross-sectional view of a U-shaped channel which forms a vertical edge of the door ; Figure 3 is a horizontal cross-sectional view of the door and frame assembly along the crosssection labelled 'X' in Figure 1; Figure 4 is a vertical cross-sectional view of the door and frame assembly along the cross-section labelled Ύ' in Figure 1; Figure 5 is an isometric view of the U-shaped channel shown in Figure 2 which forms a vertical edge of the door; Figure 6 is an isometric view of a section of door frame member; Figure 7 is a front elevation view of a door and frame assembly according to a second embodiment of the invention; and Figure 8 is a horizontal cross-sectional view of the door and frame assembly along the crosssection labelled 'Z' in Figure 7.

Detailed Description A door and frame assembly 1 according to a first embodiment of the invention is shown in Figure 1. The - 10 door and frame assembly comprises a thermally broken door leaf 3 and a thermally broken door frame 5. Both the door and frame comprise a number of thermally broken structural elements which are arranged to mitigate heat transfer across the door and frame arrangement, usually from the inside to the outside of a building. Each of the thermally broken elements comprise sections of sheet metal which are thermally broken by a number of apertures, as will be explained below. The door and frame are both constructed such that, in use, the thermally broken elements are covered over, and therefore are not exposed to the outside environment.

As can be seen from the cross-sectional views in Figure 3 and Figure 4, the thermally broken door leaf 3 is formed by an outer panel 7, an inner panel 9, a top edge member 11 and a bottom edge member 13. The panels 7, 9, and the top and bottom edge members 11, 13 surround and enclose a thermally insulating mineral wool core 15. Apart from the mineral wool core 15, all the parts which form the thermally broken door comprise pieces of sheet metal which have been punched, where appropriate, using a CNC turret punch before being folded and pressed into shape using a variety of CNC folding machines.

The outer panel 7, which defines a first side of the door, forms an outside face sheet 16 of the door leaf 3 (the outside face being the face of the door leaf 3 that is located on the outside of the building when the door 3 is closed) and the opposite vertical edges of the door leaf 3. The panel 7 consists of a single piece of sheet metal, equal in vertical length to the height of the door 3, which has been folded along its vertical length at both vertical edges to create a U-shaped channel 17 which runs along each of the opposite vertical edges of the - 11 door leaf 3. Each U-shaped channel 17, one of which is shown in detail in Figure 2 and in Figure 5, is formed such that it comprises an outer arm 17A which forms part of the outside face sheet 16, and an inner arm 17B, located opposite the outer arm 17A, which is connected to the back of an inside face sheet 18 (the inside face being the face of the door 3 that faces the inside of the building when the door 3 is closed). The outer arm 17A and inner arm 17B are connected by a side section 17C which spans the thickness of the door 3 and forms a vertical edge of the door 3.

As can be seen from Figure 2 and Figure 5, the inner arm 17B, which extends at 90 degrees from the side section 17C, comprises a multiplicity of apertures which have been punched into the sheet metal to form a plurality of thermal break slots 19 which are spaced along the vertical length of the door leaf 3. The thermal break slots 19 are approximately 30 mm in vertical length, 6 mm in width and are vertically spaced by 3 mm. The outer panel 7 is therefore arranged such that the inside face sheet 18 is connected to the outside face sheet 16 via a thermally broken element 17B which comprises a multiplicity of 3 mm x 6 mm bridging members 20 which are formed between the thermal break slots 19.

The distal end of each of the inner arms 17B is folded 180 degrees back on itself into a U shape to form a lip 21, each of the outer panel lips 21 being engaged with a corresponding lip 23, the corresponding lips 23 being formed by the inner panel 9, as will be discussed below.

The inner panel 9, which defines the second side of the door, forms the inside face sheet 18 and is constructed from a single piece of sheet metal equal in - 12 vertical length to the height of the door 3. The inner panel 9 has been folded 180 degrees back on itself along each of its vertical edges to create a lip 23 along each of the vertical edges of the inside face sheet 18. To mount the inner panel 9 upon the outer panel 7, the inner panel 9 must be positioned end-to-end with the outer panel 7 such that the inner panel lips 23 are positioned to interlock with their corresponding outside panel lips 21, the panels 7, 9 must then be moved relative to one another along the vertical axis of the door leaf 3 such that the panels 7, 9 slidingly engage and the lips 21, 23 interlock. A layer of insulating foam tape 25 is placed between the lip 23 of the inner panel 9 and the arm 17B of the outer panel 7 such that the panels 7, 9 cannot directly come into contact with one another as direct contact between the panels in this region would bypass the thermal break slots 19. With the outer panel 7 and inner panel 9 positioned in this way, the door 3 is partially formed with an outside face sheet 16, an inside face sheet 18, and vertical edges 17C.

A top edge member 11 and a bottom edge member 13 of the door leaf 3, represented by dotted lines in Figure 1, are sandwiched between the inside face sheet 18 and outside face sheet 16 and span the top and bottom edges of the door. The top and bottom edge members 11, 13 are identical and, as can be seen in Figure 4, are arranged such that, when they are contained within the door, they are mirror images of each other about a horizontal symmetry line across the centre of the door leaf. The edge members 11, 13 will now be described with reference to the top edge member 11 only, like parts on the bottom edge member are identically numbered in Figure 4 with the prefix '13' instead of ΊΓ . - 13 The top edge member 11 is generally in the shape of a hollow beam with a square cross-section. The top edge member 11 is formed by a U-shaped channel capping member 112 which is sat within a U-shaped internal channel member 111, the top edge member 11 being oriented such that the internal channel member 111 sits fully within the door leaf 3 and the channel capping member 112 forms the top edge of the door leaf 3. Each of the internal channel member 111 and the channel capping member 112 have two arms connected by a connecting portion to form the U-shape. The distance between the arms of the internal channel member 111 is slightly larger than the distance between the arms of the channel capping member 112, thereby allowing the channel capping member 112 to be positioned within the internal channel member 111 to form the top edge member 11 with a square cross-section. To install the top edge member into the door leaf 3, firstly the internal channel member 111 is positioned between the inside face sheet 18 and outside face sheet 16 at the top edge of the door leaf 3 such that it spans the width of the door leaf 3. The internal channel member 111 is then spot welded to the inside face sheet 18. The channel capping member 112, which has been filled with an insulating mineral wool core 15, is then installed within the internal channel member 111 at the top edge of the door leaf 3 such that it spans the width of the door leaf 3, with an edge of the channel capping member 113 forming the top edge of the door.

The channel capping member 112 is secured to the internal channel member 111 using a plurality of screw fasteners 116, one of which is shown in Figure 4. The threaded shaft of each fastener is pushed through a hole in the channel capping member 111, through the insulating - 14 mineral wool core 15 contained within the top edge member 11 and into screw threaded engagement with a hole in the internal channel member 111, and with the distal end of the screw extending into the thermally insulating mineral wool core 15 contained between the inner 18 and outer 16 face sheets.

The arms of internal channel member 111 are prevented from directly contacting the arms of the channel capping member 112 by a layer of thermally insulating foam tape 113 which is placed between the arms of internal channel member 111 and the arms of the channel capping member 112, the thermally insulating foam tape thereby acts as a thermal break between the outer internal channel member 111 and channel capping member 112. Further insulating capacity is provided by a number of apertures which are punched along the base of the internal channel member 111 which spans between the two arms of the internal channel member 111, the apertures acting as thermal break slots 114. As can be seen from Figure 3, the thermal break slots 114 span the width of the door and are arranged in the same way as the thermal break slots 19 that run along the vertical length of the inner arm 17B. The two arms of the internal channel member 111 are therefore connected by a thermally broken element which comprises a number of 3 mm χ 6 mm bridging members 115 located between the thermal break slots 114. As can be seen from Figure 3 and Figure 4, the top edge member 11 is oriented such that the thermal break slots 114 are positioned within the interior of the door.

The top edge member 11 is secured to the outside face sheet 16 via a layer of thermally insulating foam tape 117 placed between the arm of the internal channel member 111 and the outside face sheet 16. - 15 The door leaf 3 is filled with a thermally insulating mineral wool core 15. To increase the stiffness of the door leaf 3, three vertical stiffeners 27 are spaced across the width of the door leaf 3 and run the vertical length of the door leaf 3. The stiffeners 27, represented by dotted lines in Figure 1, are shown in detail in Figure 3. The stiffeners 27 have a U-shaped cross-section consisting of an inside flange 27A which is bonded to the inside face sheet 18, an outside flange 27B which is bonded to the outside face sheet 16, and a web 27C which spans the thickness of the door 3 and connects the inside and outside flanges. One of the bonds between a flange and a face sheet is achieved using a layer of thermally insulating foam tape while the other is achieved using adhesive. As can be seen from Figure 3 the web of each stiffener comprises a number of thermal break slots 29, these are arranged along the vertical length of the stiffener 27 in the same way as the thermal break slots 19 that run along the vertical length of the inner arm 17B shown in Figure 5. Each stiffener is therefore arranged such that the inside flange 27A is connected to the outside flange 27B via a number of 3 mm x 6 mm bridging members (which are identical to the bridging members 20 shown in Figure 5) which are located between the thermal break slots 29.

The procedure for assembling the thermally broken door from its separate component parts will now be described.

Apertures are punched into the parts which make up the inner panel 9, outer panel 7, thermally broken stiffeners 27, the top edge member 11, and bottom edge member 13 using a CNC turret punch. The parts are then pressed into shape using CNC folding machines. - 16 The outer panel 7 is laid down horizontally with its inner face uppermost and is reinforced for hinges and any other ironmongery before the thermally broken stiffeners 27 and top and bottom internal channel members 111, 131 are bonded in place using a thermally insulating foam based adhesive tape. The foam based adhesive tape is positioned between the flanges of the stiffeners 27 and the outside face sheet 16, and between the arms of the top and bottom edge members 111, 131 and the outside face sheet 16. The insulating mineral wool core is then added and a polyurethane adhesive is applied to the flanges of the thermally broken stiffeners which will contact the inside face sheet 18. The inner panel 9 is then slidingly engaged with the outer panel 7, as described above .

The top and bottom internal channel members 111 and 131 are then spot welded to the inside panel 9. Layers of insulating foam tape are applied to the internal channel members 111, 131, before the top channel capping member 112 is screwed into the top of the door leaf 3, and the bottom channel capping member 132 is screwed into the bottom of the door leaf 3, the layers of insulating foam tape being positioned between the arms of each internal channel member 111, 131 and channel capping member 112, 132 such that the internal channel members 111, 131, do not come into direct contact with the channel capping members 112, 132. The assembled door leaf is then subjected to heat and pressure to cure the polyurethane adhesive. The door leaf 3 is then prepared for hardware items before a polyester powder coating (PPC) finish is applied and the required ironmongery is installed on the door leaf. - 17 The thermally broken door leaf 3 is mounted within a thermally broken doorframe 5 via three hinges 31, as shown in Figure 1 and Figure 3. The door frame is formed by two side members 501, which in use are positioned vertically on opposite sides of the door, and a crossbeam member 502 which spans the gap between the two side members, at the top of the door. A section of the thermally broken doorframe 5 is shown in Figure 6. Each of the side members 501 and the crossbeam member 502 of the door frame 5 is formed from a single piece of sheet metal which has been folded to form an inside jamb 503, a stop 504, and an outside jamb 505. An elastomeric door seal 33, which can be seen in Figure 3 and Figure 4, is contained within a door seal channel 507 which runs around both the side members 501 and the crossbeam member 502 of the door frame, being formed between the stop 504 and the outside jamb 505. As can be seen from Figure 6, a number of thermal break slots 509 are spaced along the length of each of the door frame members 501, 502, in the region where the outside jamb 505 meets the stop 504. The thermal break slots 509 are arranged in the same way as the thermal break slots 19 that run along the vertical length of the inner arm 17B. The door frame is therefore arranged such that the inside jamb 503 and stop 504 are connected to the outside jamb 505 via a number of 3 mm χ 6 mm bridging elements 511 which are located between the thermal break slots 509.

Figure 7 shows a door and frame assembly according to a second embodiment of the invention. The door and frame assembly shown in Figure 7 is similar to the door and frame assembly 1 of the first embodiment of the invention but comprises two door leaves 1000, 2000 and a door frame 3000 which is dimensioned to accommodate a - 18 double door leaf configuration. The presently described embodiment of the invention has many features in common with the door and frame assembly 1 of the first embodiment of the invention; as such, like features have been labelled with like numbers but adding the prefix 100 or 200 to indicate which door leaf they belong to .

The door and frame assembly shown in Figure 7 comprises an active leaf 2000 and an inactive leaf 1000. In normal use, the inactive leaf 1000 remains shut and the active leaf 2000 is opened and closed to gain access to the building to which the door and frame assembly is fitted. However, both leaves 1000, 2000 may be opened if necessary. Figure 8 shows a cross-sectional view of the inactive and active leaves 1000, 2000 in the region where the leaves 1000, 2000 meet. As can be seen, the thickness of a section 1070 of the inactive door leaf 1000 has been locally reduced in the region where the two door leaves 1000, 2000 meet and the active door leaf is arranged with an overlapping portion 2080 which projects widthways out of the vertical edge of the door leaf 2000, parallel with the outside face sheet 2016, towards the inactive leaf 1000. The overlapping portion 2080 is arranged to overlap with the inactive leaf 1000 and sit against the section 1070 when the doors are closed, the local thickness reduction of the section 1070 being such that when the doors are closed, the outside face sheet 2016 of the active leaf 2000 sits flush with the outside face sheet 1016 of the inactive leaf 1000.

Claims (5)

Claims

1. A door leaf comprising a thermally insulating core located between a first thermally conducting sheet defining a first face of the door leaf and a second thermally conducting sheet defining a second face of the door leaf, wherein the first sheet comprises a first door edge element which connects the first sheet and the second sheet and which forms a first exposed edge of the door leaf, and wherein the first door edge element comprises a part extending within the door leaf, adjacent to the second sheet, so that the part is disposed within the door leaf and is covered over by the second sheet, and wherein a thermally broken portion is provided in the part so that the thermally broken portion is disposed within the door leaf and is not exposed to the outside environment, the thermally broken portion comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sheets.

2. A door leaf according to claim 1, wherein the first and second thermally conducting sheets and the first door edge element are sheet metal.

3. A door leaf according to claim 1 or 2, wherein the thermally insulating core is mineral wool.

4. - A door leaf according to any preceding claim, wherein the spacing of adjacent bridging portions is more than three times greater than the spacing of adjacent apertures. 5. A door leaf according to any preceding claim, wherein the thermally broken portion of the first door edge element is disposed substantially in a plane adjacent to and parallel to the second face of the door leaf. 6. A door leaf according to any preceding claim, wherein the first door edge element and the second sheet are provided with complementary U shaped lips which interengage. 7. A door leaf according to any preceding claim, further comprising a second door edge element, wherein the first sheet and the second sheet are also connected by the second door edge element which forms at least part of a second edge of the door leaf, the second edge of the door leaf is opposite the first edge of the door leaf, and the second door edge element comprises a thermally broken portion that is disposed within the door leaf and is covered over by a thermally conducting part of the door leaf so that the thermally broken portion is not exposed to the outside environment, the thermally broken portion of the second door edge element comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to - 21 mitigate heat transfer between the first and second sheets . 8. A door leaf according to any preceding claim, further comprising a third door edge element, wherein the first sheet and the second sheet are also connected by the third door edge element which forms at least a part of a third edge of the door leaf, the third edge of the door leaf is transverse to the first edge of the door leaf, and the third door edge element comprises a thermally broken portion that is disposed within the door leaf and is covered over by a thermally conducting part of the door leaf so that the thermally broken portion is not exposed to the outside environment, the thermally broken portion of the third door edge element comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sheets. 9. A door leaf according to claim 8, wherein the third door edge element is formed as a separate member from the first and second sheets. 10. A door leaf according to claim 9, wherein a further separate member is fixed to the third door edge element covering over the thermally broken element of the third door edge element so that the thermally broken element is not exposed to the outside environment. 11. A door leaf according to any of claims 8 to 10, further comprising a fourth door edge element, wherein the first sheet and the second sheet are also connected by the fourth door edge element which 5 forms at least a part of a fourth edge of the door leaf, the fourth edge of the door leaf is opposite the third edge of the door leaf, and the fourth door edge element comprises a thermally broken portion that is disposed within the door leaf and is covered 10 over by a thermally conducting part of the door leaf so that the thermally broken portion is not exposed to the outside environment, the thermally broken portion of the fourth door edge element comprising a multiplicity of apertures spaced along the portion 15 and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sheets . 20 12. A door leaf according to any preceding claim, further comprising a thermally conducting internal stiffening member connected between the first and second sheets, wherein the internal stiffening member comprises a thermally broken portion 25 comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sheets. 30 13. A door leaf according to claim 12, wherein the internal stiffening member extends in a direction - 23 substantially parallel to the first exposed edge of the door leaf. 14. A door leaf according to any preceding claim, wherein the door leaf has a length greater than its width and the first door edge element extends along the length of the door. 15. A door and frame assembly comprising a door leaf according to any preceding claim and a thermally broken door frame, the door leaf being hinge-mounted upon the door frame and moveable between an open and a closed position, wherein the door frame comprises a first side spaced apart from a second side and a stop located between the first and second sides of the frame which is arranged to abut a face of the door leaf when the door leaf is in the closed position, such that when the door leaf is in the closed position, the frame extends around the door leaf, wherein the door frame further comprises a thermally broken portion comprising a multiplicity of apertures spaced along the portion and defining bridging portions between them, the thermally broken portion thereby being arranged to mitigate heat transfer between the first and second sides of the frame . 16. A door and frame assembly according to claim 15, wherein the thermally broken portion of the frame is positioned between one of the first and second sides of the frame and the stop, the - 24 thermally broken portion of the frame thereby being arranged to mitigate heat transfer between the one of the first and second sides of the frame and the stop.

5. F.F. GORMAN & CO.