Field of the Invention

The present invention relates to a component for a building, the component being operative when in use to generate heat. The invention also relates to a building comprising such a component and a method of forming the component.

Background to the Invention It is known to provide under floor heating in homes and offices. According to one approach pipes are disposed such that they follow a tortuous path underneath the floor and hot water is pumped through the pipes to thereby cause the pipes to emit heat. According to another approach electrical heating cable is disposed such that the cable follows a tortuous path underneath the floor. Application of electrical power to the heating cable causes the cable to emit heat.

The present inventor has become appreciative of shortcomings of such known approaches to under floor heating and the present invention has been devised in the light of this appreciation. It is therefore an object for the present invention to provide a component for a building, the component being configured to generate heat. It is a further object for the present invention to provide a building comprising at least one component which is configured to generate heat. It is a yet further object for the present invention to provide a method of forming a component which, in use, is operative to generate heat.

Statement of Invention

In the light of the inventor's above mentioned appreciation and according to a first aspect of the present invention there is provided a building component in the form of a panel configured to form part of a building, the part of the building defining at least in part a habitable space within the building, the building component comprising a heat generating arrangement, the heat generating arrangement comprising at least one sheet of conductive polymer which is configured to generate heat in dependence on application of electrical power to thereby, in use, heat the habitable space. The building component is brought into use by being installed in a part, such as a wall, of a building, the part of the building defining at least in part a habitable space, such as a room, within the building. Electrical power is applied to the heat generating arrangement. Current flowing through the conductive polymer causes the temperature of the conductive polymer to increase whereby the conductive polymer is operative to generate heat. The heat generating arrangement may be operative to radiate heat and the building component may be configured to convey heat radiated by the heat generating arrangement into the habitable space. The present invention offers several advantages over known heating apparatus. In contrast with many central heating configurations the present invention may require no moving parts, such as a pump or motor, and may therefore be more reliable. Furthermore the present invention has an efficiency of about 98% compared with an efficiency of about 88% for gas or oil central heating systems. In addition the present invention may provide a less dry heat than electric heating and yet a drier heat than fuel burning heaters, such as calor gas or paraffin heaters. As is described further below the present invention may be configured to radiate heat from a substantial part of surface, such as a wall, of a room in a building. To achieve a desired temperature in a room the conductive polymer may operate at a lower temperature than a central heating radiator or an individual gas or electric heater. A lower temperature of operation presents less of a risk of injury or fire and is less liable to cause discolouration of walls. The conductive polymer may comprise at least one of a conductive elastomer and a conductive thermoplastic. More specifically the conductive polymer may comprise at least one of: silicone rubber; styrene-butadiene rubber (SBR); linear low density polyethylene (LLDPE); polyurethane (PU); styrenic

thermoplastic elastomer (TES); and olefinic thermoplastic elastomer (TEO). Alternatively or in addition the conductive polymer may comprise polymeric material and conductive matter, the conductive matter being dispersed through the polymeric material. More specifically the conductive matter may be particulate. Alternatively or in addition the conductive matter may be non- metallic. More specifically the conductive matter may comprise carbon, such as carbon black. Carbon black may be advantageous on account of its

comparatively low cost, it being rustproof and the capability to change its conductivity by altering the combustion process used to form the carbon black. The conductivity of the conductive polymer may be changed by changing an amount of conductive matter dispersed through the polymeric material.

The at least one sheet of conductive polymer may comprise a reinforcement structure. The reinforcement structure may be substantially entirely embedded in the at least one sheet of conductive polymer. The reinforcement structure may comprise a polymer and more specifically a polymer comprising an ester functional group in its main chain, such as polyester. The reinforcement structure may comprise a fabric. The reinforcement structure may have the form of a mesh. The reinforcement structure may improve the structural integrity of the at least one sheet of conductive polymer to, for example, provide for ease of handling of the at least one sheet of conductive polymer before attachment to part of the building component.

The building component may comprise a substrate, such as a sheet of plasterboard, and the at least one sheet of conductive polymer may be non- integrally formed with the building component. As described further below the at least one sheet of conductive polymer may be formed separately and then attached when formed to the substrate of the building component. The at least one sheet of conductive polymer may, for example, be attached by adhesive, mechanical fasteners or the like.

The building component may define at least one substantially enclosed space and the at least one sheet of conductive polymer may be received in the at least one substantially space. More specifically the building component may define plural substantially enclosed spaces and the building component may comprise plural sheets of conductive polymer, each of the plural sheets being received in a respective one of the plural substantially enclosed spaces. The building component may be configured such that the plural sheets are electrically coupled to each other, e.g. in a parallel electrical arrangement. The building component may comprise a first plasterboard member and a second plasterboard member disposed in relation to each other to define the

substantially enclosed space therebetween. The building component may further comprise at least one spacer member disposed between the first and second plasterboard members to thereby form a substantially enclosed space between opposing faces of the first and second plasterboard members. A building component comprising first and second plasterboard members may be configured to form at least part of non-load bearing space defining structure of a building, such as a wall of the building. As mentioned above and in contrast to central heating radiators and individual gas or electric heaters the present invention may provide for no intrusion into a space (e.g. room) that is being heated by the conductive polymer.

A conductive polymer according to the invention, such as conductive silicone rubber, may exhibit a positive temperature coefficient (PTC). The conductive polymer may expand upon heating with the expansion causing an increase in resistance. The increase in resistance may moderate further increase in temperature of the conductive polymer to thereby reduce the likelihood of thermal runaway. The space receiving the conductive polymer may therefore be configured to allow for expansion of the conductive polymer. More specifically the space may be configured to allow for an expansion of the conductive polymer of at least substantially 0.5%, 1 %, 2%, 4%, 8% or 16%. The building component may define a space at least in part and the conductive polymer may be received in the space. More specifically the building

component may be configured to define a recess in which the conductive polymer is received. For example and where the building component is configured to form at least a part of a floor, the building component may have a first surface which in use is directed into a room of the building and a second surface comprising the recess, the first and second surfaces being oriented in opposite directions. Thus and in accordance with this example the conductive polymer may be present underneath the floor. In contrast to central heating radiators and individual gas or electric heaters the present invention may provide for no intrusion into the space (e.g. room) that is being heated by the conductive polymer.

The conductive polymer may have a thickness of less than substantially 8 mm, 4 mm or 2 mm. More specifically the conductive polymer may have a thickness of substantially 1 mm. The conductive polymer may have a thickness of more than substantially 0.25 mm, 0.5 mm, 0.75 mm or 1 mm. A thickness of substantially 1 mm has been found to be appropriate for applications where the building component comprises first and second plasterboard members which define a substantially enclosed space and the conductive polymer is received in the substantially enclosed space. Where the thickness of the conductive polymer is substantially 1 mm a spacing (e.g. to an adjacent building

component in the form of another conductive polymer member or other component such as a structural member) around the sides of and above the conductive polymer may be at least 10 mm.

The building component may be configured such that, in use, a temperature of the conductive polymer, e.g. at a surface of the conductive polymer, is less than substantially 100° C, 80° C or 60° C. An environment of the conductive polymer may impose a limit on its operating temperature. Material in the vicinity of the conductive polymer may be liable to degradation or may have its operation compromised if the temperature of the conductive polymer exceeds a threshold temperature. Where, for example, the building component comprises at least one plasterboard member and the plasterboard member is formed to provide for fire retardance the maximum temperature of the plasterboard member may be limited to about 30° C to prevent the fire retardant property of the

plasterboard member being compromised. Therefore a temperature of the conductive polymer may be no more than substantially 40° C to thereby achieve a maximum temperature of about 30° C for the plasterboard member. In other applications, e.g. under floor heating, there may be a higher temperature threshold. Therefore the building component may be configured such that, in use, a temperature of the conductive polymer, e.g. at a surface of the conductive polymer, is less than substantially 300° C, 200° C or 150° C.

Degradation of the conductive polymer may impose a temperature limit. For example certain forms of conductive silicone rubber degrade above about 350° C. Limits with regards to the level of electrical power that may be provided to the conductive polymer may impose a temperature limit. For example conductive polymer in a under floor heating arrangement that is supplied with electrical power from a 240 V RMS mains supply may have an operating temperature of about 100° C.

The conductive polymer may have a resistance of less than substantially 100 Ω per cm ² , 75 Ω per cm ² , 50 Ω per cm ² , 40 Ω per cm ² , 30 Ω per cm ² or 25 Ω per cm ² .

The conductive polymer may be in the form of a mesh. The mesh may define an open structure. A sheet of conductive polymer may therefore have the form of a web. More specifically the openings in the mesh may be substantially evenly spaced and substantially uniform. Alternatively or in addition the conductive polymer may be thin relative to its height and width. The building component may be one of a wall component, floor component or ceiling component. In use the building component may be operative to radiate heat into the space defined at least in part by the building component. Alternatively or in addition the building component may be thin relative to its height and width. Alternatively or in addition the building component may define a substantially planar surface, which in use defines at least in part a space such as a room in the building. The heat generating arrangement may be configured to be electrically coupled to a source of electrical power. The heat generating arrangement may therefore comprise two electrical terminals, e.g. to which a live conductor and a neutral conductor of a mains electricity supply may be connected. Alternatively or in addition the heat generating arrangement may comprise first and second conductors. In use and upon application of electrical power an electrical potential may develop between the first and second conductors. Each of the first and second conductors may be elongate and may extend through the building component. The first conductor may be electrically coupled to the conductive polymer at at least one first location and the second conductor may be electrically coupled to the conductive polymer at at least one second location, the at least one first location being spaced apart from the at least one second location. Electrical connection of the first and second conductors to the conductive polymer in this fashion may cause an electrical current to flow though the conductive polymer with the resistance presented by the conductive polymer causing generation of heat. At least one of the first and second conductors may comprise a metal, such as copper.

According to a second aspect of the present invention there are provided plural building components according to the first aspect of the present invention, each building component comprising two electrical terminals, with corresponding terminals of different building components being configured to mechanically couple with each other to establish an electrical connection such that the plural building components may be provided with electrical power from a single source of electrical power. More specifically a corresponding pair of terminals may comprise a male connector and a female connector. Thus a chain of electrically connected building components may be formed with the chain of building components being connected to a source of electrical power by way of two free terminals.

Further embodiments of the second aspect of the present invention may comprise one or more features of the first aspect of the present invention. According to a third aspect of the present invention there is provided a building comprising at least one building component according to the first or second aspect of the present invention.

Where the building component forms at least part of a floor of the building the building component may comprise a first, substrate layer, e.g. formed from solidified slurry such as cement, a space defining arrangement thereupon, and a second layer, e.g. formed from solidified slurry such as cement, in which the conductive polymer is received in the space defined by the space defining arrangement. Further embodiments of the third aspect of the present invention may comprise one or more features of the first or second aspect of the present invention.

According to a fourth aspect of the present invention there is provided a method of forming a building component according to the first aspect of the present invention, the method comprising: forming the at least one sheet of conductive polymer from solidified fluid material; forming the building component so as to comprise a substrate; and attaching the at least one sheet of formed conductive polymer to the substrate. The at least one sheet of conductive polymer is formed apart from a building component comprising a substrate, such as a sheet of plasterboard. The least one sheet of conductive polymer is formed from solidified fluid material. The least one sheet of conductive polymer may be shaped into a desired form by casting of fluid material or cutting, e.g. by stamping, of solidified fluid material. The formed least one sheet of conductive polymer is attached to the substrate of the building component, such as by adhesion or by mechanical fastening. The step of forming the at least one sheet of conductive polymer may comprise distributing conductive matter through fluid polymeric material. The conductive matter may have a form or composition as described above with reference to the first aspect of the present invention. Alternatively or in addition the step of forming the at least one sheet of conductive polymer may comprise

substantially entirely embedding a reinforcement structure of a form and composition as described above in fluid polymeric material. When formed the at least one sheet of conductive polymer may consist essentially of polymeric material, conductive matter distributed through the polymeric material and a reinforcement structure substantially entirely embedded in the polymeric material. Electrical conductors to provide electrical power to the at least one sheet of conductive polymer may be brought into electrically communication with the at least one sheet of conductive polymer by attachment to the at least one sheet of conductive polymer. The electrical conductors may attached by adhesion or mechanical fastening to provide for sufficient electrical coupling. Alternatively the electrical conductors may be partially embedded in fluid polymeric material.

According to a further aspect of the present invention there is provided a component for a building, the component comprising a heat generating arrangement which is disposed over a substantial part of the component and which is configured to generate heat in dependence on application of electrical power. Embodiments of the further aspect of the present invention may comprise one or more features of any previous aspect of the present invention. Brief Description of Drawings

The present invention will now be described by way of example only with reference to the following drawings, of which: Figure 1 is a block diagram representation of apparatus according to the present invention;

Figure 2 is a first representation of a building component according to the present invention;

Figure 3 is a second representation of the building component of Figure

2; and

Figure 4 provides a detailed view of part of a conductive silicone web. Description of Embodiments

A block diagram representation of apparatus 10 according to the present invention is shown in Figure 1 . The apparatus 10 comprises a supply of mains electricity 12, which is received by a fused switch 14. The apparatus 10 further comprises a transformer 16, which receives a supply of mains electricity, e.g. alternating current at 240 volts RMS, from the fused switch 14 and is operative to provide an alternating current output, e.g. of 30 volts RMS. The transformer 16 is therefore configured in accordance with known practice to achieve the reduction in voltage, e.g. by way of an appropriate ratio of transformer primary to transformer secondary. The electrical output is provided to a building component 18 according to the present invention. As described in more detail below the component 18 is configured to define part of a habitable space, such as a room, in a building. The component 18 comprises plural webs 20 of conductive polymer, which are provided with electrical power by the transformer 16. The component is described in more detail below with reference to Figures 2 and 3.

A first representation of a component 30 according to the present invention is shown in Figure 2. The component 30 of Figure 2 is configured to define part of wall of a room in a building. The component 30 comprises a first plasterboard member 32 of known form. The first plasterboard member 32 is substantially 1200 mm long and substantially 1200 mm wide. The component 30 further comprises eight webs 34 of conductive polymer which are attached to the plasterboard with adhesive and disposed such that they form an array of two columns by four rows. Each web 34 is substantially 180 mm wide and substantially 490 mm long. Adjacent webs 34 in each column are substantially 100 mm apart. The two columns of webs 34 are substantially 40 mm apart. The peripheral edges of the webs are substantially 80 mm from the side edges of the first plasterboard member, substantially 90 mm from the top edge of the first plasterboard member and substantially 170 mm from the bottom edge of the first plasterboard member. The webs of conductive polymer are enclosed in double bagged heat shrink wrap to provide for moisture resistance. The form of a web of conductive polymer is described below with reference to Figure 4. A first live conductor 36 formed from 30 Amp RMS rated tinned copper braid extends from the lower edge of the first plasterboard member 32 around the inner edges of the two columns of webs and is electrically coupled to each of the webs. A second neutral conductor 38 formed from 30 Amp RMS rated tinned copper braid extends from the lower edge of the first plasterboard member 32 around the outer edges of the two columns of webs and is electrically coupled to each of the webs. The first and second conductors 36, 38 are electrically connected at respective first and second locations on each web, with the spacing between the first and second locations being

substantially 470 mm. In use the first and second conductors 36, 38 apply an alternating electrical potential across each web 34. The component 30 further comprises a second plasterboard member 40 of known form, which is substantially 1200 mm long and substantially 1200 mm wide. The function of the second plasterboard member 40 will be described below with reference to Figure 3. In an un-illustrated form, the dimensions and configuration of webs differ. In this un-illustrated form there is a single column of webs. Each web in the column is substantially 500 mm long and substantially 80 mm wide and adjacent webs in the column are spaced apart by substantially 50 mm. It should be appreciated that individual webs can be of practically any size or shape and webs can be variously configured depending on requirements.

A second representation of the component of Figure 2 is shown in Figure 3. Parts of the component of Figure 3 in common with parts of the component of Figure 2 are designated with like reference numerals and the reader's attention is directed to the description provided above with reference to Figure 2 for a description of such common parts. The component 50 as shown in Figure 3 further comprises a third plasterboard member 52 of known form, which is substantially 1200 mm long and substantially 1200 mm wide. The centre of the third plasterboard member 52 is cut out so as to form an aperture of dimensions corresponding to the array of webs 34 and providing for 10 mm clearance around the edges of the webs when the third plasterboard member 52 is placed on the first plasterboard member such that the first and second plasterboard members are coterminous. The third plasterboard member 52 is attached to the first plasterboard member 32 by adhesive. The component 50 also comprises three elongate plasterboard members 54 with each elongate plasterboard member 54 being substantially 1040 mm long by substantially 80 mm wide. Each elongate plasterboard member 54 is positioned between adjacent rows of webs 34 such that the elongate plasterboard member 54 abuts against the opposing faces of the third plasterboard member 52 defining the aperture and such that the edges of the elongate plasterboard member 54 oriented towards the webs are spaced apart from the webs by substantially 10 mm. The three elongate plasterboard members 54 are attached to the first plasterboard member 32 by adhesive. Although not shown in Figure 3 the first and second conductors 36, 38 of Figure 3 are electrically connected to the webs 34 as described above with reference to Figure 2. The first and second conductors 36, 38 are routed to the webs by way of apertures formed in the third plasterboard member 52 and the three elongate plasterboard members 54. Assembly of the component 50 is completed by laying the second plasterboard member 40 over the arrangement hitherto described and such that the second plasterboard member 40 is coterminous with the first plasterboard member 32. The second plasterboard member 40 is attached to the already attached third plasterboard member 52 and the elongate plasterboard members 54 with adhesive. The various plasterboard members therefore define plural substantially enclosed spaces, with each space containing a different web 34.

A detailed view of part of a conductive polymer web 60 is shown in Figure 4. As can be seen from Figure 4 the conductive polymer 62 is in the form of a mesh, which defines an open structure with the openings 64 in the mesh being substantially evenly spaced and substantially uniform. The web is thin at substantially 1 mm relative to its height and width. The conductive polymer is a conductive elastomer comprising silicone rubber and carbon black, which is dispersed through the silicone rubber so as to provide a resistance of substantially 23 to 26 Ω per cm ² . The conductive polymer web 60 further comprises a polyester fabric reinforcement mesh (not shown) which is entirely embedded in the conductive polymer. Silicone rubber and carbon black can be readily obtained from commercial suppliers. On forming the conductive polymer it is important that the silicone rubber and carbon black are mixed thoroughly to ensure that the carbon black is properly dispersed through the silicone rubber. Proper mixing of the silicone rubber and carbon black reduces the likelihood of there being hot spots in the conductive polymer during use. Nevertheless proper mixing of the silicone rubber and carbon black can be achieved by use of readily available mixing apparatus. After mixing the mixture is formed into the desired shape by being poured into a cast containing the polyester fabric reinforcement mesh. The cast structure is then vulcanised. Thereafter the conductive polymer web 60 is attached, as described above, to a plasterboard member. Application of an electrical potential across each web, as described above, causes a current to flow through the web 34 between the first and second conductors 36, 36. The resistance to current flow presented by the conductive polymer causes heat to be generated. The generated heat is emitted by the web and, in turn, by the surrounding plasterboard members. A conductive polymer exhibits a positive temperature coefficient (PTC). More specifically the conductive polymer expands as it heats, with the expansion causing an increase in resistance. The increase in resistance acts as a feedback mechanism which moderates a further increase in temperature of the conductive polymer and thereby reduces the likelihood of thermal runaway. The clearance around the webs in their respective spaces allows for expansion of the conductive polymer to allow the feedback mechanism to function properly. In an un-illustrated form plural components as described above are provided. One half of the plural components comprises a female electrical connector provided on one of the first and second conductors 36, 38 and a male electrical connector provided on the other one of the first and second conductors 36, 38, with the male and female connectors being configured to mechanically couple with each other to thereby establish an electrical connection. The other half of the plural components have their male and female electrical connectors exchanged. The plural components can therefore all be connected to one power supply by disposing components with a male electrical connector on the live conductor next to components with a female electrical connector on the live conductor, e.g. by alternating them, whereby corresponding male and female electrical connectors can be connected to each other to form a daisy chain of electrically coupled components. One or more of the building components 30, 50 described above with reference to Figures 1 to 4 are used to form at least part of a wall of a room in a building. The fused switch 14 is electrically connected to a source of mains electrical power 12 in the building. Upon switch on of the fused switch 14 the conductive polymer of the webs 34 is operative to radiate heat, which is conveyed through the plasterboard of the building component 30, 50 to thereby radiate heat into the room.

In an un-illustrated embodiment the present invention is applied to heat at least a part of a floor of a room. According to a form of this embodiment the webs 34 of conductive polymer are attached to the underside of the floor with adhesive or held by a support structure adjacent the underside of the floor. According to another form of this embodiment a first, substrate layer is formed from solidified slurry such as cement and spacer members are used to define a space on the first layer. The conductive polymer webs are placed in the thus defined space and a second layer is formed thereupon from solidified slurry such as cement. Otherwise operation is as described above.