GB2499293A

GB2499293A - Lintel comprising discontinuities to provide thermal break

Info

Publication number: GB2499293A
Application number: GB1222523.1A
Authority: GB
Inventors: Sean Coyle
Original assignee: Keystone Lintels Ltd
Current assignee: Keystone Lintels Ltd
Priority date: 2011-12-13
Filing date: 2012-12-13
Publication date: 2013-08-14
Anticipated expiration: 2032-12-13
Also published as: GB2499293B; GB201121408D0; GB201222523D0

Abstract

The lintel, made from a metal or an alloy such as steel, comprising an inner flange 23, an outer flange 27 and, what would be in use, a cavity bridging component. The cavity bridging component comprising a number of discontinuities 5 creating a thermal barrier by forming a tortuous path for heat transfer between the two flanges. The lintel may include an elongate slot 31 substantially extending the length of the lintel such as to create a lintel made up of two parts, which are bridged by reinforcing elements 33 at intervals along the lintel s length. The discontinuities may be rows of elongate slots staggered such that the gap between slots on one row coincides with a slot on an adjacent row and vice versa. The discontinuities may also be circular, zig-zag or any shape capable of providing a discontinuity in order to retard heat transfer from one flange to the other. A base plate may be welded to connect the two flanges of the lintel. An insulation member may be placed on at least one exposed flange of the lintel.

Description

A COMPONENT FOR IMPROVING THERMAL EFFICIENCY

The present invention relates to a component to reduce the cold bridging effect and to improve thermal efficiency of the component and in particular to a steel lintel.

5 Support structures are used in all forms of constructions from buildings to vehicles such as ships and aeroplanes. A common form of support structure used above a door or window opening in a wall is a lintel. The support structure is required to take the weight of the material above the aperture to provide structural support to the wall to avoid this material collapsing into the aperture. Traditionally, lintels have been manufactured from the likes of 10 reinforced concrete and steel. Lintels have been provided in a multitude of configurations from traditional unitary components to multiple components coupled together with insulation there between.

Thermal conductivity of steel is measured in Watts per meter Kelvin (W/m. K). Steel lintels are characterized with high thermal conductivity, allowing the transfer of heat from the 15 interior section of a lintel through the material to its exterior section. When steel lintels are employed to bridge the cavity between the inner and outer leaf of masonry, the heat inside the building finds a path through this bridge to escape to the cold environment outside. This problem, often referred to as the cold bridging effect, creates efficiency issues with regard to heating inside the building. Most of the prior art attempts to solve this problem involve 20 utilizing a two section lintel and putting a material of low thermal conductivity between these two sections to prevent heat transfer from the inside of the building to the outside. However, this solution provides a lintel with overall reduced structural strength compared with unitary steel lintels of the same size and gauge. Composite Glass-reinforced Plastic (GRP) lintels are also known in prior art but while they do solve the issue of thermal conductivity caused 25 by steel to some extent, they are expensive to manufacture and are structurally weaker than steel lintels of the same size and gauge.

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It is an object of the present invention to obviate or mitigate the problem of cold bridging associated with a component made up of metal or metal alloy, particularly, a steel lintel as mentioned above.

Accordingly, the present invention provides a lintel of metal or metal alloy comprising 5 an inner flange, a cavity bridging component and an outer flange where a temperature differential is formable between the two flanges of the lintel, the cavity bridging component comprising a plurality of discontinuities acting as a thermal barrier by creating a tortuous path for heat transfer between the two flanges.

Preferably, the cavity bridging component comprises at least one elongate non-planar 10 cavity bridging member which extends between the inner flange and outer flange, defining a void beneath the cavity bridging member.

Preferably, the discontinuities are provided through the cavity bridging component.

Ideally, the lintel of metal or metal alloy comprises elongate planar members.

Preferably, the cavity bridging component comprises a plurality of elongate planar 15 bridging members.

Where a plurality of cavity bridging members exist, the discontinuities are provided through a single cavity bridging member, all cavity bridging members, or any combination of cavity bridging members.

Ideally, the discontinuities are positioned between a first longitudinal edge and a 20 second longitudinal edge of the cavity bridging component.

Preferably, the cavity bridging component comprises an upstand, an upper bridging component and a downstand locatable within a cavity.

Ideally, the inner flange of the lintel is contactable with an atmosphere at a first temperature.

25 Preferably, the outer flange of the lintel is contactable with an atmosphere at a second different temperature.

Various tests/experiments have shown that it is possible to significantly reduce the thermal conductivity value of a metal component by creating a plurality of discontinuities in it

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at different carefully selected locations when compared to the thermal conductivity value of a component having similar size and gauge without discontinuities. Use of the term discontinuity encompasses all forms of openings/gaps/holes/apertures through the structure of the metal or metal alloy component.

5 Advantageously, by interrupting the normal path of heat flow between two longitudinal edges of the cavity bridging component where a temperature differential exists and reducing the material content, the discontinuities in the cavity bridging component slow down the heat transfer across it. Thus, thermal conductivity of a metal or metal alloy component, provided with discontinuities to create a tortuous path for heat flow, is significantly reduced compared 10 to a similar component without discontinuities.

According to Fourier's law of heat conduction the rate of heat transfer from the hot side to the cold side of a solid component is directly proportional to the temperature difference between two sides, as well as, the cross-sectional area 'A' (geometry of the component) across which the heat flows. It is inversely proportional to the thickness 'B' of the 15 component. Mathematically, it can be shown as: q = kA(T1 - T2)/B; where 'k' is a constant, the thermal conductivity of a material. It is true that heat will flow through the path of least resistance according to this principle. Thus, maximum heat transfer will take place through that portion of any irregular shaped component which offers maximum surface area and minimum thickness compared to any other portion of the same component exposed to heat. 20 To start with, the direction of net heat transfer is perceived in a direction normal to the exposed surface area but then, inside the metal, the heat energy follows a path of least resistance.

Preferably, the discontinuities are provided in one or more of the upstand, the upper bridging component or the downstand.

25 Ideally, the cavity bridging component has discontinuities with a uniform pattern.

Preferably, the cavity bridging component has discontinuities with a non-uniform pattern.

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Ideally, the discontinuities are provided proximal to the periphery/boundary of the cavity bridging component.

Preferably, the discontinuities are provided by elongated slots.

Alternatively, the discontinuities can be provided by circular or zig-zag shaped slots. It 5 will of course be appreciated that any geometric shape or any combination of geometric shape of discontinuity can be formed in the cavity bridging component which is capable of acting to retard heat transfer from one edge to another edge where a temperature differential exists.

Preferably, the discontinuities are formed in more than one row, the rows being in a 10 spaced apart configuration running in a direction traversing the direction of flow of heat from one edge of the cavity bridging component to another edge where a temperature differential exists.

Ideally, the discontinuities in adjacent rows are staggered to create a tortuous path for the heat energy to travel. Advantageously, the path can be designed so that the heat transfer 15 is significantly reduced.

Preferably, metal or metal alloy material between discontinuities in one row is in alignment with a discontinuity in an adjacent row, the direction of alignment being with respect to the direction of travel of the heat from a first edge of the cavity bridging component to a second edge of the cavity bridging component. In this arrangement there is no direct 20 path for heat to travel along the path of least resistance to the flow of heat.

Ideally, the length of metal or metal alloy material between discontinuities is less than the length of the aligned discontinuity in an adjacent row. Advantageously, this configuration of elongate discontinuities aligned with shorter portions of material between discontinuities in adjacent rows creates a tortuous path for the heat to travel from one edge of the cavity 25 bridging component to the other edge of the cavity bridging component thereby reducing the cold bridging effect.

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Further alternatively, the discontinuities are provided or supplemented by at least one longitudinal slot formed in the cavity bridging component, the longitudinal slot being divided and bridged by further reinforcement means at intervals along its length.

Ideally, the reinforcement means are reinforcement tabs.

5 Ideally, the longitudinal slot divides a unitary lintel into two separate lintel sections.

Preferably, the reinforcement tabs are formed integrally with the cavity bridging component.

Advantageously, the longitudinal slot and reinforcement tabs can be provided and the lintel can be formed from a unitary sheet of material.

10 Alternatively, the reinforcement tabs are separate reinforcement tabs attachable to the cavity bridging component.

Ideally, the reinforcement tabs are metallic.

Alternatively, the reinforcement tabs are plastic.

Advantageously, the larger discontinuity provided by the elongate slot impedes the 15 heat transfer along the cavity bridging component in a direction between the flanges while still maintaining its structural integrity due to the reinforcement tabs.

Ideally, flange reinforcement means are provided between the inner and outer flanges.

Ideally, the flange reinforcement means are flange reinforcement tabs. 20 Preferably, the flange reinforcement tabs are formed integrally with the inner and/or outer flanges.

Advantageously, the flange reinforcement tabs are created from the material of the inner and/or outer flange and the cut-out that results from the formation of the flange reinforcement tabs provides a discontinuity at the same time.

25 Alternatively, the flange reinforcement tabs are separate tabs attachable at a first end to the inner flange and at a second end to the outer flange.

Ideally, the flange reinforcement tabs are metallic.

Alternatively, the flange reinforcement tabs are plastic.

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Preferably, the cavity bridging component is formed from a single sheet of material.

Ideally, the lintel is formed from a single sheet of material.

Advantageously, the ability to form the cavity bridging component or lintel from a single sheet reduces manufacturing time, manufacturing cost, and labour requirements to 5 produce the lintel.

Further advantageously, forming the cavity bridging component or lintel from a single sheet of material reduces the weaknesses introduced by component joints.

Preferably, the lintel is made of steel.

Preferably, a base plate is welded to connect the two flanges of the lintel. 10 It will of course be appreciated that the plurality of discontinuities can be formed in any configuration in the cavity bridging component of the lintel provided structural integrity of the lintel is retained. The size, pattern and overlap of the discontinuities can be varied for different cavity bridging components in order to find the most effective balance between reduced thermal conductivity and strength of the cavity bridging component. 15 Preferably, an insulation member is provided on at least one exposed flange of the perforated lintel. Advantageously, the insulation member provides extra insulation to reduce heat transfer across the metal or metal alloy lintel.

Ideally, the insulation member is manufactured from wood, foam, plastic or GRP.

A method of manufacturing a metal or metal alloy lintel comprising the steps of 20 forming elongate planar members comprising an inner flange, a cavity bridging component and an outer flange, forming a plurality of discontinuities in the cavity bridging component, the discontinuities being formed for acting as a thermal barrier by creating a tortuous path for heat transfer across the cavity bridging component.

Ideally, the method comprising punching, cutting or casting a plurality of 25 discontinuities on at least part of the body of the cavity bridging component.

The invention will now be described with reference to the accompanying drawings which show by way of example only one embodiment of an apparatus in accordance with the invention. In the drawings:

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Figure 1 is a vertical section of a traditional lintel bridging a cavity wall;

Figure 2 is a schematic drawing of part of a cavity bridging component with a plurality of discontinuities formed in it;

Figure 3 is a second view of Figure 2 showing a thermal image of heat attempting to cross 5 the cavity bridging component;

Figure 4 is a vertical section of a lintel with the cavity bridging component of Figures 2 and 3.

Figure 5 is a sectional view of a lintel having a longitudinal thermal break spanned by reinforcement tabs and having a further flange tabs spanning between the inner and outer 10 flanges; and

Figure 6 is a perspective view of a lintel having a longitudinal thermal break spanned by reinforcement tabs and having a further flange tabs spanning between the inner and outer flanges.

In the drawings, and initially referring to Figure 1, there is shown a prior art steel lintel 15 L employed to bridge the cavity C between the inner I and outer O leaf of masonry. The heat energy H inside the building IB finds a path along the inner flange IF, the upstand U, the down slope D, the down stand DS and out through the outer flange OF to the outside atmosphere A. This problem, often referred to as the cold bridging effect, creates efficiency issues with regard to loss of heating inside the building. This problem is exacerbated on 20 these types of Lintels L where a base plate B is welded across the gap between the inner flange IF and outer flange OF to improve the resistance to warping of the lintel L during loading. The heat H has a shorter path directly across the cavity C through the base plate B.

Referring to the drawings and now to Figures 2 and 3, there is shown an upper bridging component of a cavity bridging component indicated generally by the reference 25 numeral 1 of metal or metal alloy having a first longitudinal edge 2 in contact indirectly with an outside atmosphere 4 at a first temperature and a second longitudinal edge 3 in contact

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indirectly with an inside atmosphere 13 at a second higher temperature creating a temperature differential between the two longitudinal edges 2, 3 of the upper bridging component 1. The upper bridging component 1 has seven discontinuities 5 positioned between the first longitudinal edge 2 and the second longitudinal edge 3 of the upper 5 bridging component 1. The discontinuities 5 act as a thermal barrier as clearly illustrated in Figure 3 by creating a tortuous path for heat transfer between the two edges 2, 3 of the upper bridging component 1.

Various tests/experiments have shown that it is possible to significantly reduce the thermal conductivity value of a metal or metal alloy upper bridging component 1 by creating a 10 plurality of discontinuities 5 in it at different carefully selected locations when compared to the thermal conductivity value of a component having similar size and gauge without discontinuities. Use of the term discontinuity 5 encompasses all forms of openings/gaps/holes/apertures through the structure of the metal or metal alloy upper bridging component 1. Advantageously, by interrupting the normal path of heat flow between 15 the two edges 2, 3 of the upper bridging component 1 having a thermal gradient and reducing the material content, the discontinuities 5 in the upper bridging component 1 slow down the heat transfer across it. Thus, thermal conductivity of a metal upper bridging component 1, provided with discontinuities 5 to create a tortuous path for heat flow, is significantly reduced compared to a similar component without discontinuities. 20 The upper bridging component 1 has discontinuities 5 with a uniform pattern although it will of course be appreciated that the upper bridging component 1 can be provided with discontinuities with a non-uniform pattern provided they sufficiently retard heat transfer. The discontinuities 5 are provided proximal to the periphery/boundary 6 of both longitudinal edges 2, 3, 7 and both lateral edges of the upper bridging component 1 and in the space 12 25 between the two longitudinal edges 2, 3, 7. The discontinuities 5 are provided by elongated slots. Alternatively, the discontinuities can be provided by circular or zig-zag shaped slots. It will of course be appreciated that any geometric shape or any combination of geometric shape of discontinuity can be formed in the upper bridging component 1 which is capable of

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acting to retard heat transfer from one edge 3 to another edge 2 of the component 1 where a temperature differential exists whilst retaining the required structural integrity of the upper bridging component 1.

The discontinuities 5 are formed in three rows 11 and the rows 11 are in a spaced 5 apart configuration running in a direction traversing the direction of flow of heat from one edge 3 of upper bridging component 1 to the other edge 2 of the upper bridging component 1. The discontinuities 5 in adjacent rows 11 are staggered to create a tortuous path for the heat energy to travel. Advantageously, the path for the heat to travel can be designed so that the heat transfer is significantly reduced. Metal or metal alloy material 14 bridging between 10 discontinuities 5 in one row 11 is in alignment with a discontinuity 5 in an adjacent row 11, the direction of alignment being with respect to the direction of travel of the heat from a first edge 3 of the upper bridging component 1 to a second edge 2 of the upper bridging component 1. In this arrangement there is no direct path for heat to travel along the path of least resistance to the flow of heat.

15 The length of metal or metal alloy material 14 bridging between discontinuities 5 is less than the length of the aligned discontinuity 5 in an adjacent row. Advantageously, this configuration of elongate discontinuities 5 aligned with shorter portions of material 14 bridging between discontinuities 5 in adjacent rows 11 creates a tortuous path for the heat to travel from one edge 2 of the upper bridging component to the other edge 3 of the 20 component 1 thereby reducing the cold bridging effect. The reduced steel material content and the pattern of the perforations or slots 5 causes a bottle neck effect coupled with a direct barrier effect which slows the heat transfer giving a reduced thermal conductivity compared with a similar component with no perforations or slots.

Referring to the drawings and now to Figure 4, the upper bridging component 1, 25 is 25 shown as part of a cavity wall lintel 21. The lintel 21 is made up of a single piece of metal or metal alloy comprising an inner flange 23, an up stand 24, an upper bridging component 1 being a top slope 25, a down stand 26 and an outer flange 27. A base plate 28 is welded to connect the two flanges 23, 27 of the lintel 21. The plurality of discontinuities 5 are provided

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in the upper bridging component 1/top slope 25. It will of course be appreciated that the plurality of discontinuities 5 can be provided in either or both of the upstand 24 and downstand 26 as well as or instead of the plurality of discontinuities 5 in the upper bridging component 1, 25.

5 It will of course be appreciated that the plurality of discontinuities 5 can be formed in any configuration provided structural integrity of the lintel 21 is retained. The size, pattern and overlap of the discontinuities 5 can be varied for different upper bridging components 1 in order to find the most effective balance between reduced thermal conductivity and strength of the lintel 21.

10 The lintel 21 is formed from a single sheet of material which reduces manufacturing time, manufacturing cost, and labour requirements to produce the lintel 21. Additionally, forming the lintel 21 from a single sheet of material reduces the weaknesses introduced by component joints.

Referring to figures 5 and 6, a further embodiment of the invention is shown wherein 15 the discontinuities 5 are supplemented by one longitudinal slot 31 formed in the cavity bridging component 32, the longitudinal slot 31 being divided and bridged by further reinforcement tabs 33 at intervals along its length. The longitudinal slot 31 divides a unitary lintel into two separate lintel sections 34, 35.

The reinforcement tabs 33 are separate reinforcement tabs 33 attached to the each 20 of the separate lintel sections 34, 35 and the larger discontinuity provided by the longitudinal slot 31 impedes the heat transfer along the cavity bridging component 32 in a direction between the flanges 23, 27 while still maintaining its structural integrity due to the reinforcement tabs 33.

Flange reinforcement tabs 36 are also provided between the inner and outer flanges 25 23 , 27 and are attachable at a first end 37 to the inner flange 23 and at a second end 38 to the outer flange 27.

In relation to the detailed description of the different embodiments of the invention, it will be understood that one or more technical features of one embodiment can be used in

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combination with one or more technical features of any other embodiment where the transferred use of the one or more technical features would be immediately apparent to a person of ordinary skill in the art to carry out a similar function in a similar way on the other embodiment.

5 In the preceding discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of the said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, 10 is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value.

The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of a means for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or 15 in any combination of such features be utilised for realising the invention in diverse forms thereof.

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Claims

1. A lintel of metal or metal alloy comprising an inner flange, a cavity bridging component and an outer flange where a temperature differential is formable between

5 the two flanges of the lintel, the cavity bridging component comprising a plurality of discontinuities acting as a thermal barrier by creating a tortuous path for heat transfer between the two flanges.

2. A lintel as claimed as claim 1, wherein the discontinuities are provided through the cavity bridging component.

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3. A lintel as claimed as claim 1 or claim 2, wherein the lintel of metal or metal alloy comprises elongate planar members.

4. A lintel as claimed in any one of the preceding claims, wherein the cavity bridging component comprises a plurality of elongate planar bridging members.

5. A lintel as claimed in claim 4, wherein the discontinuities are provided through a

15 single cavity bridging member, all cavity bridging members, or any combination of cavity bridging members.

6. A lintel as claimed in any one of the preceding claims, wherein the discontinuities are positioned between a first longitudinal edge and a second longitudinal edge of the cavity bridging component.

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7. A lintel as claimed in any one of the preceding claims, wherein the cavity bridging component comprises an upstand, an upper bridging component and a downstand locatable within a cavity.

8. A lintel as claimed in claim 7, wherein the discontinuities are provided in one or more of the upstand, the upper bridging component or the downstand.

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9. A lintel as claimed in any one of the preceding claims, wherein the cavity bridging component has discontinuities with a uniform pattern.

10. A lintel as claimed in any one of claims 1 to 8, wherein the cavity bridging component has discontinuities with a non-uniform pattern.

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11. A lintel as claimed in any one of the preceding claims, wherein the discontinuities are provided proximal to the periphery/boundary of the cavity bridging component.

12. A lintel as claimed in any one of the preceding claims, wherein the discontinuities are provided by any one of or any combination of elongated slots, circular or zig-zag

5 shaped slots or any geometric shape or any combination of geometric shape of discontinuity which is capable of acting to retard heat transfer from one edge to another edge where a temperature differential exists.

13. A lintel as claimed in any one of the preceding claims, wherein the discontinuities are formed in more than one row, the rows being in a spaced apart configuration running

10 in a direction traversing the direction of flow of heat from one edge of the cavity bridging component to another edge where a temperature differential exists.

14. A lintel as claimed in any one of the preceding claims, wherein the discontinuities in adjacent rows are staggered to create a tortuous path for the heat energy to travel.

15. A lintel as claimed in claim 14, wherein metal or metal alloy material between

15 discontinuities in one row is in alignment with a discontinuity in an adjacent row, the direction of alignment being with respect to the direction of travel of the heat from a first edge of the cavity bridging component to a second edge of the cavity bridging component.

16. A lintel as claimed in claim 14 or 15, wherein the length of metal or metal alloy

20 material between discontinuities is less than the length of the aligned discontinuity in an adjacent row.

17. A lintel as claimed in any one of the preceding claims, wherein the discontinuities are provided or supplemented by at least one longitudinal slot extending along all or a substantial part of the length of the cavity bridging component, the longitudinal slot

25 being divided and bridged by further reinforcement means at intervals along its length.

18. A lintel as claimed in claim 17, wherein the longitudinal slot divides a unitary lintel into two separate lintel sections.

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19. A lintel as claimed in claim 17, wherein the reinforcement means are formed integrally with the cavity bridging component.

20. A lintel as claimed in any one of claims 17 to 19, wherein flange reinforcement means are provided between the inner and outer flanges.

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21. A lintel as claimed in any one of the claims 1 to 17, 19 or 20, wherein the cavity bridging component is formed from a single sheet of material.

22. A lintel as claimed in any one of the claims 1 to 17, 19, 20, 21 wherein the lintel is formed from a single sheet of material.

23. A lintel as claimed in any one of the preceding claims, wherein the lintel is made of 10 steel.

24. A lintel as claimed in any one of the preceding claims, wherein a base plate is welded to connect the two flanges of the lintel.

25. A lintel as claimed in any one of the preceding claims, wherein an insulation member is provided on at least one exposed flange of the perforated lintel.

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26. A lintel as claimed as claim 1, wherein the cavity bridging component comprises at least one elongate non-planar cavity bridging member which extends between the inner flange and outer flange, defining a void beneath the cavity bridging member.

27. A lintel substantially as hereinbefore described with reference to and/or as shown in the accompanying drawings of Figures 2 to 6.

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•.'????.• INTELLECTUAL

*.*. .V PROPERTY OFFICE

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Application No: GB 1222523.1 Examiner: Mr Kunal Saujani

Claims searched: 1-27 Date of search: 28 May 2013

Patents Act 1977: Search Report under Section 17 Documents considered to be relevant: