WO2008146044A1

WO2008146044A1 - Novel compositions for providing radiation shielding

Info

Publication number: WO2008146044A1
Application number: PCT/GB2008/050384
Authority: WO
Inventors: Nicholas John Hodgkinson; Steven Thomas John
Original assignee: Nicholas John Hodgkinson; Steven Thomas John
Priority date: 2007-05-31
Filing date: 2008-05-28
Publication date: 2008-12-04
Also published as: GB0710421D0; GB2449758A; GB0809628D0; GB2449758A8

Abstract

The present invention provides compositions and products comprising a mix or blend or combination of a first material having insulation properties combined with a second material having electrically conductive properties. The compositions and products are for use in providing building structures with a combination of insulation and radiation shielding effects. The invention also includes a method of providing insulation and radiation shielding to a fixed structure like a building.

Description

NOVEL COMPOSITIONS FOR PROVIDING RADIATION SHIELDING

The present invention relates to compositions and products comprising a mix or blend or combination of a first material having insulation properties combined with a second material having electrically conductive properties. The compositions and products are for use particularly but not exclusively in providing building structures and the like with a combination of insulation and radiation shielding effects. The invention also includes a method of providing insulation and radiation shielding to a fixed structure.

BACKGROUND

There are various types and sources of radiation, including electromagnetic radiation and particle radiation, which can be either ionising or non-ionising radiation. For example, electromagnetic (EM) radiation involves the propagation of a wave of energy with electrical and magnetic components. It is generally classified by the frequency of the wave, referred to as the electromagnetic spectrum. Some typical types of EM radiation are (approximately in order of increasing frequency): electricity power supply waves, radio waves, television waves, mobile communications waves, microwaves, satellite television waves, infra-red waves, visible light, X-rays and gamma-rays. Conversely, particle radiation involves the transmission of energy by means of fast moving particles such as α, β, γ and neutron particles. These particles generally arise from unstable atoms, either naturally or from induced atomic activity. Both EM radiation and particle radiation may be ionising, i.e. they can cause there the addition or removal of electrons from an atom thereby creating ions. Ionising radiation is generally more hazardous and is usually associated with particle radiation. It is known that certain types of radiation, particularly the ionising particle radiation, can be extremely damaging to health. The risks associated with other types of radiation, such as electromagnetic radiation, are less clear and mostly speculative, but are still of concern to the general public, for example the recent possible links to certain disease conditions with EM from mobile phones and associated equipment.

In other situations such as for security purposes it may also be desirable to provide a degree of radiation shielding so as to control radiation from communication devises and the like thereby preventing communication waves penetrating the exterior or interior of a building. Numerous materials or combinations of materials are known from the prior art that can offer a degree of radiation protection or shielding. For example it is known to provide specialist shielding paints, wire mesh screens, aluminium foils and films/curtains to cover windows so as to provide radiation protection. These materials either work by creating a simple barrier or by creating a "Faraday cage" effect by completely or partially enclosing the property. Similarly, these material have been used to provide protection for military/government buildings against breaches of communications security by transmission of EM pulses and EM communications. In the US, in particular, this has been referred to as "Tempest" protection. However, there are several disadvantages associated with the prior art materials and methods of protection, including the high cost, difficulties in application and difficulties associated with retrofit applications i.e. modification of existing structures. Moreover, none of the current materials and methods are suitable for use within the cavities between external and internal walls.

The present invention relates to novel combinations of materials, which have been specifically designed to be conveniently located in, for example and without limitation, cavity walls of buildings so as to provide a degree of shielding to the building whilst concomitantly providing thermal or acoustic insulation. It is envisaged that the novel combination of materials of the present invention and methods of employing them will provide not only thermal or acoustic insulation but also a degree of shielding for radiation arising from various sources, either external to or from within a building, particularly for, but not limited to, electromagnetic radiation.

An advantage of the present invention is to provide a range of electrically conductive materials that can be used in cavity walls and elsewhere to provide radiation shielding whilst maintaining beneficial properties of existing cavity fill materials such as thermal insulation, structural strengthening, cavity tie provision and resistance to moisture penetration.

BRIEF SUMMARY OF THE DISCLOSURE

According to a first aspect of the invention there is provided a composition comprising a first material having insulating properties and a second material having electrically conductive properties wherein the proportion of the first material is greater than the proportion of the second material and wherein the first material acts as a scaffold so as to support the dispersed second material in a three dimensional manner throughout. Preferably, the composition is a solid when formed. Reference herein to "solid" is intended to exclude a gaseous or liquid state but includes a particulate state or semisolid state. The composition of the invention when formed is a solid, it may in some instances be a foam which when cured or left to stand forms a solid and takes a more rigid structure.

The first and second materials may be mixed, bound together, blended or otherwise combined to provide a composition of the present invention. In one embodiment of the invention it is possible that the first and second materials may be 'combined' during the manufacturing process using for example by blowing, drawing or vapourisation.

In the composition of the present invention the first material provides a scaffold or support or matrix structure for supporting the second material which is dispersed throughout the first material, typically in a random manner. That is to say that the second material is dispersed throughout the first material in all three dimensions of x, y and z axes and although the second material is substantially evenly distributed throughout the first material the distances apart from each other are not intended to be strictly identical. The composition of the present invention is not in the form of layers, multilayers or strips.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. Reference herein to insulating properties is intended to include an organic or inorganic material that reduces or prevents the transmission of heat or sound or electricity or any type of particulate or wave energy from one surface to another. In the present invention the surfaces are preferably inner and outer surfaces of a building structure, for example a wall that could either be an interior or exterior wall.

Preferably, the first material having insulating properties has thermal or acoustic or electrical insulating properties or a combination of any one or more of the aforesaid properties.

Preferably, the first material having insulating properties has thermally insulating properties. The first material having thermally insulating properties will herein after also be referred to as an insulating material.

Preferably, the insulating material is derived from an organic source and more preferably is a naturally occurring organic source.

Preferably, the organic source is selected from the group comprising fibres, sheep wool, cellulose fibres, flax fibres, hemp fibres, wood fibres, paper fibres, straw fibres and other organic material that is fibrous and has insulating properties. Alternatively the organic insulating material can be non-fibrous for example fossilised vegetation or cork board in this instance the material can be considered as particulate. The insulating material is not however woven but more in the form of a random mesh.

In another embodiment of the invention the insulating material is derived from an inorganic source.

In the instance where the inorganic source is derived from a naturally occurring inorganic source the material is selected from the group comprising fibreglass, mineral rock, slag, glass wool, foamed glass, expanded volcanic glass, vermiculite and expanded clay. Alternatively, the inorganic source of insulating material can be non-naturally occurring such as aluminium foil which may optionally be plastic coated. In a further embodiment of the invention the insulating material is derived from a non naturally occurring source such as plastics, polystyrene, polyurethane, polyisocyanurate, phenolic material and urea formaldehyde.

In another embodiment of the invention the insulating material can comprise a mix of one or more organic or inorganic materials as hereinbefore described it may also comprise a mix of naturally and non-naturally derived materials. So, for example, the insulating material may comprise a proportion of sheep wool and glass fibres or it may comprise a mixture of polystyrene and mineral rock the specific combinations are not included to limit the scope of the application.

Preferably the insulating material is provided in the form of a fibre or bead or barrier or foam.

It will be appreciated that the insulating material may comprise a mixture of any one or more of the different forms, so for example the insulating material may take the form of a bead and fibre mix, again the specific combinations are not included to limit the scope of the application.

The various insulating materials may also be categorised in terms of the form of material used for insulation. These forms include, loose fibres, fibre bats, fibre rolls, boards, sheets, beads, pellets, foam and the like each of which may apply to the various materials hereinbefore mentioned. However, the various forms of insulating material may conveniently be grouped into four basic categories:

♦ Fibres (which may or may not be formed into for example bats, rolls, boards, pellets and so on)

♦ Beads (which may or may not be formed into for example bats, rolls, boards, pellets and so on etc) ♦ Radiant barriers (which may or may not be fixed to another material for example a foam board)

♦ Foams or other expanded materials (which may or may not be formed into for example boards or attached to other materials such as concrete blocks as they may be injected in -situ) It will be appreciated that although it is intended that the primary application of these materials will be in cavity walls, the use of the materials described in the present invention is not limited to cavity wall applications and will be equally appropriate in other situations. In the case of a building or enclosure, the protection afforded by the compositions of the present invention will also provide a degree of radiation shielding outside the building or enclosure from internal radiation. For example, the use of the materials described in the present invention, will provide a degree of shielding from the electromagnetic waves produced by internal local wireless Internet connections, thereby providing a degree of data security from external access to the electromagnetic Internet communication signals.

A further advantage of the composition of the present invention is that they may be employed in providing radiation shielding in both existing buildings (referred to herein as a retrofit) and also to new constructions.

All the thermally insulating materials of the first material described above, derived from the various sources and in their variety of forms may be mixed, bound, blended or otherwise combined with a second material having electrically conductive properties or they may be made inherently electrically conductive, to provide a degree of radiation shielding.

Preferably, the second material having electrically conductive properties is selected from the group comprising electrically conducting fibres, wires, strands, strings, threads, ribbon, wool, particles and radiation barriers.

In the instance where the electrically conducting material is in the form of fibres, metallic fibres sometimes referred to as "chaff" or wires or strands wool the material is selected from the group comprising copper, steel or other metallic compounds or alloys.

In the instance of the electrically conducting material comprising particles, the particles may be selected from the group comprising aluminium powder or foil fragments sometimes referred to as "glitter" or "chaff", zinc powder or flakes, copper powder or flakes or any other metal that is non-toxic and can be provided in particulate form that retains the property of electrical conductivity. Alternatively, the electrically conducting material may be in the form of carbon- black, polyaniline or carbon nanotubes. In this embodiment of the invention the electrically conducting material has inherent electrically conductive properties.

Preferably, different combinations and combinations of form of the second electrically conductive material may be present in the composition, so for example the electrically conductive material may take the form of a wire or strand or ribbon or glitter or it may be a mix of copper and aluminium, the specific combinations are not included to limit the scope of the application.

Preferably, the percentage of the second material in the composition is less than 50- 30% by weight, more preferably it is less than 25% by weight and more preferably still is less than 20% by weight of the composition. It will be appreciated that the second electrically conductive material can be present in a relatively small amount as compared to the first material for example it may be present in an amount of about 1 -5% by weight and even as small as 0.1 -5% by weight. The compositions of the present invention also includes any integer value between the "small" amount to approximately 50% of the composition by weight. It will be appreciated that for reasons of economy and the environmental it is preferred that the second material is present in a lesser amount than the first material.

The compositions of the present invention advantageously use recycled or reused materials, for example these materials might include recycled paper as the first thermally insulating material component and/or any one of recycled copper wires, aluminium foil, plastic coated aluminium foil, carbon black as the second electrically conductive material.

Preferably, the compositions of the present invention further includes any one or more agent associated with provision of moisture resistance, fire resistance, acoustic insulation, structural support. According to a second aspect of the invention there is provided use of the compositions of the first aspect of the invention, in providing radiation shielding and thermal insulation in a fixed building structure.

Preferably, the use of the second aspect of the invention also includes any one or more of the preferred features of the first aspect of the invention.

Preferably, the electrically conductive material is earthed.

According to a third aspect of the invention there is provide a method of combining a first material having thermally insulating properties and a second material having electrically conductive properties comprising forming a scaffold or support structure with the first material and introducing the second material into the scaffold or support so as to form a three dimensional mesh of electrically conductive material interspersed throughout the first thermally insulating material.

Preferably, the method of the third aspect of the invention also includes any one or more of the preferred features of the first or second aspect of the invention.

According to a fourth aspect of the invention there is provided a method of providing thermal insulation and radiation protection to a fixed building structure comprising introducing into a cavity wall space a first material having thermally insulating properties and a second material having electrically conductive properties so as to form a solid composition of said first and second materials within said cavity space.

Preferably, a proportion of the first composition has already been introduced into a building cavity wall space and the second material is subsequently introduced. This is in effect a retro-fit method and suitable for existing structures. There are two situations that could be described as retro-fit. In the first, a combination of the two materials in introduced into an existing building. In the second the building already has a thermally insulated cavity (comprising the first material) and the second material is subsequently introduced therein. In an alternative embodiment of the invention the first and second materials are pre- mixed and subsequently introduced into the said cavity wall simultaneously.

Preferably, the method of the fourth aspect of the invention also includes any one or more of the preferred features of the previous aspects of the invention.

It may be desirable to allow some electromagnetic waves to enter the shielded building or other enclosure. For example, to allow the building occupants to use their mobile phones, to receive radio or television transmissions or to access area wireless free internet connections. However, the present invention will provide an effective shielding against all such transmissions, thereby preventing their use. This is particularly advantageous to examination halls, concert venues, theatres and the like.

The shielded building or other enclosure could however be fitted with an aerial that receives the signals from outside the shielded building or other enclosure and retransmits the signal inside the building, and visa versa. An improvement on this situation would be to use a 'smart aerial' that selects the frequency or frequencies to be retransmitted, allowing control of the frequencies either entering, and or exiting the shielded building.

DETAILED DESCRIPTION

The present invention describes a number of compositions and methods to create an electrically conductive mesh or medium to provide a degree of radiation shielding, particularly for electromagnetic radiation, by combining the thermally insulating materials as hereinbefore described, with electrically conductive materials as hereinbefore described. The present invention utilises a three-dimensional mesh or medium of conductive material to significantly improve the shielding effect. The three-dimensional mesh will be particularly effective if there is electrical contact between the electrically conductive materials to form a material that is through conductive.

The present invention describes a number of methods of combining the thermally insulating materials with electrically conductive materials, for shielding radiation (particularly, but not limited to electromagnetic radiation), particularly, but not limited to cavity wall installations. The present invention describes four methods of introducing the electrically conductive material, each of which may be introduced to each (or all) of the various different types, sources and forms of thermally insulating material, as follows:

EXAMPLE 1

Table 1 below shows suitable compositions by way of combinations of materials to execute the methods of the present invention.

EXAMPLE 2

Electrically conductive fibres (or wires or strands or ribbons or other such similar fibrous material) may be mixed, blended, bound or otherwise combined with the various types, sources and forms of thermally insulating materials, to create a mesh effect. There are numerous different types of suitable electrically conductive fibrous material, including, but not limited to, fine metal / metallic wires such as copper, non metal / metallic fibres, such as carbon, conductive glass fibres, conductive composite material fibres, conductive polymer fibres, metallised glass fibres etc. In Example 2, fine steel wires (wire wool) were combined with thermally insulating polyurethane foam (PUF), results are shown in Table 2. The weight of wire wool used was approximately 10% by weight of the composition. Ideally, as in the case of 'wire wool' the electrically conducting fibres should have a degree of electrical contact between individual fibres to enhance the three-dimensional 'mesh' effect. However, the present invention also allows for there to be limited or no electrical contact between individual fibres. A series of preliminary trials were carried out using various materials and arrays of electrically conductive fibres. The tests involved surrounding a mobile telephone with each of the materials in turn and monitoring the signal level received by the phone for each material. (A high signal indicates poor shielding effectiveness of the materials at the mobile phone frequency. A low signal indicates good shielding effectiveness at the mobile phone frequency). The results are summarised in Table 2 below:

Table 2

The insulated copper wires were used to represent a situation where electrically conductive wires were held within an electrically non conducting medium, such as rock wool, where there would be little or no electrical contact between adjacent fibres.

The results show that a three-dimensional random array of bare steel wires was the most effective electrically conductive material and arrangement. Further experimentation will be required to investigate the potential shielding effectiveness of other electrically conductive fibres at other concentrations and at other frequencies. The results of these initial trials were then used to focus the development of a prototype composite material combining the shielding effect of the 3-D random array of bare steel wires with a thermally insulating material, for placement in the cavity of a building or other enclosure or similar.

The preferred method was to combine the 3-D random array of bare steel wires with rigid foam, which would maintain the array of wires.

EXAMPLE 3

Electrically conductive particles, or similar discrete particles, may be mixed, blended, bound or otherwise combined with the various types, sources and forms of thermally insulating materials, to create a mesh effect. There are numerous types of suitable electrically conductive particles, including, but not limited to metal / metallic powders or flakes, non metal / metallic powders or flakes or similar such as carbon powder, sometimes referred to as carbon black, and other carbonaceous material, such as carbon nano-tubes. Example 3 shows the use of small pieces of aluminium foil, about 5% by weight of the composition mixed with thermally insulating polyurethane foam (PUF).

A series of experiments were conducted using various arrays of electrically conductive particles or small pieces of electrically conductive radiant barriers. The tests again involved surrounding a mobile telephone with each of the materials in turn and monitoring the signal level received by the phone for each material.

The combination of these electrically conducting materials with thermally insulating materials was represented by mixing the various electrically conducting materials with electrically non conducting powder filler. The results are indicated in Table 3 below.

Table 3

The results show that the small pieces of aluminium foil and plastic coated foil were the most effective electrically conductive materials, although they were not as effective as using electrically conducting fibres, with electrical contact between the fibres.

The results of these experiments were then used to focus the development of a prototype composite material combining the shielding effect of the small pieces of aluminium foil with a thermally insulating material, for placement in the cavity of a building or other enclosure or similar. It was found that the preferred method was to combine the small pieces of aluminium foil with rigid foam, which would maintain the array of foil pieces.

EXAMPLE 4

If a radiant barrier is provided in sheet form this method of providing electrical conductivity is not directly appropriate to retrofit cavity wall situations, but is appropriate to new cavity wall situations and to other types of enclosure not involving cavity wall.

However, if the radiant barrier material is presented in the form of strips, such as 'tinsel', or in small pieces, such as 'glitter' or "chaff", then the radiant material can be readily combined with thermally insulating material in a cavity situation. In the case of small pieces of radiant material the application is not dissimilar to use of electrically conductive particles. This exemplification involves the use of small pieces of aluminium foil mixed with thermally insulating polyurethane foam (PUF).

A series of experiments were carried out to produce a material that was inherently electrically through conductive, rather than material containing electrically conductive materials. The categorisation of a material as inherently electrically through conductive, rather than as a material containing electrically conductive particles or fibres materials is however somewhat arbitrary, as inherent electrical through conductivity may be achieved using extremely fine conductive particles, such as carbon black. Hence, there is a transition from a material containing electrically conductive particles or fibres to a material that is inherently electrically through conductive. The present invention includes all materials within the full range of particle and fibre sizes. For the purpose of these trials the thermally insulating material used as the base material was polyurethane foam (PUF). The present invention however includes the use of all thermally insulating materials, noted previously. For the purposes of these preliminary tests the electrical conductivity was used as an indication of the probable shielding effectiveness, with high electrical conductivity indicating probable high shielding effectiveness.

The results are indicated in Table 4 below:

The term 'Medium' electrical conductivity is used here to indicate electrical resistance across the test beaker of below 10⁶ Ohms. The term 'Low' electrical conductivity is used here to indicate electrical resistance across the test beaker of above 10⁶ Ohms.

EXAMPLE 5

In one embodiment of the invention, alteration of the physical or chemical composition of the thermally insulating material is used to provide inherent electrical conductivity. There are numerous types of suitable electrically conductive compositions, including, intrinsically electrically conductive materials, such as polyacetylene, polypyrrole, polyaniline or carbon nanotubes (CNT), which may be combined either physically or chemically with other materials, such as polyurethane foam to create a through conductive material. A through conductive material, such as a conductive foam, has an advantage over the fibrous mix and particle mix methods described above, in that the three-dimensional conductive structure is significantly improved and the 'mesh' reduces to atomic scale, thereby providing a degree of radiation shielding for very high frequencies. Example 5 exemplifies the use of carbon nano-tubes combined with thermally insulating polyurethane foam (PUF).

Claims

1 . A composition comprising a first material having insulating properties and a second material having electrically conductive properties wherein the proportion of the first material is greater than the proportion of the second material and wherein the first material acts as a scaffold so as to support the dispersed second material in a three dimensional manner throughout.

2. A composition according to claim 1 wherein the composition is a solid and optionally wherein the first and second materials are mixed, bound together, blended or otherwise combined to provide the composition.

3. A composition according to either claim 1 or 2 wherein the first material has thermal acoustic or electrical insulating properties or a combination thereof.

4. A composition according to any preceding claim wherein the first material has thermally insulating properties.

5. A composition according to any preceding claim wherein the first material is derived from an organic source.

6. A composition according to claim 5 wherein the organic source is a naturally occurring organic source.

7. A composition according to either claim 5 or 6 wherein the organic source is selected from the group comprising fibres, sheep wool, cellulose fibres, flax fibres, hemp fibres, wood fibres, paper fibres, straw fibres and other organic material that is fibrous and has insulating properties.

8. A composition according either claim 5 or 6 wherein the first material is non- fibrous.

9. A composition according to any of claims 1 to 4 wherein the first material is derived from an inorganic source.

10. A composition according to claim 9 wherein inorganic source is a naturally occurring inorganic source.

1 1 . A composition according to claim 10 wherein the naturally occurring inorganic source is selected from the group comprising fibreglass, mineral rock, slag, glass wool, foamed glass, expanded volcanic glass, vermiculite and expanded clay.

1 2. A composition according to claim 9 wherein the inorganic source is a non- naturally source.

13. A composition according to claim 1 2 wherein the non-naturally occurring source is selected from the group comprising aluminium or other metallic foil, plastic coated aluminium or other plastic coated metallic foil, plastics, polystyrene, polyurethane, polyisocyanurate, phenolic material and urea formaldehyde.

14. A composition according to any preceding claim wherein the first material comprises a mix of one or more organic or inorganic materials or a mix of naturally and non-naturally derived materials.

1 5. A composition according to any preceding claim wherein the first material is provided in the form of a fibre or bead or pellet or board or barrier or foam.

16. A composition according to claim 15 wherein the first material comprises a mixture of any one or more of the different forms.

17. A composition according to any preceding claim wherein the second material having electrically conductive properties is selected from the group comprising electrically conducting fibres, wires, wool, particles and radiation barriers.

18. A composition according to claim 17 wherein in the instance of the electrically conducting material is in the form of fibres or wires or strands or ribbons or threads or string or wool the material is selected from the group comprising copper, steel or other metallic compounds or alloys.

19. A composition according to claim 17 wherein in the instance of the electrically conducting material comprising particles, the particles are selected from the group comprising aluminium powder or foil fragments, zinc powder or flakes, copper powder or flakes or any other metal that is non-toxic and can be provided in particulate form that retains the property of conducting electricity.

20. A composition according to claim 17 wherein the electrically conducting material is carbon-black, polyaniline or another conductive polymer or carbon nano- tubes.

21 . A composition according to any one of claims 17 to 20 wherein the second material comprises a mix of one or more different electrically conductive materials or a mix of different forms.

22. A composition according to any preceding claim wherein the percentage of the second material in the composition is less than 50-30% by weight.

23. A composition according to claim 22 wherein the percentage of the second material in the composition is less than 25% by weight.

24. A composition according to claim 22 wherein the percentage of the second material in the composition is less than 20% by weight.

25. A composition according to claim 22 wherein the percentage of the second material in the composition is less than 10% by weight.

26. A composition according to claim 22 wherein the percentage of the second material in the composition is at least 1 -5% by weight.

27. A composition according to claim 22 wherein the percentage of the second material in the composition is at least 0.1 -5% by weight.

28. A composition according to any preceding claim further including any one or more of agents associated with provision of moisture resistance, fire resistance, acoustic insulation and structural support.

29. Use of a composition according to claim 1 in providing radiation shielding and thermal insulation in a fixed building structure.

30. Use of a composition according to claim 1 in providing security radiation shielding in a fixed building structure.

31 . Use of a composition according to claim in limiting transmission of EM pulses into or out of a fixed building structure

32. Use according to any one of claims 29 to 31 further including any one or more of the features recited in claims 2 to 27.

33. Use according to any of claims 29 to 31 wherein the second electrically conductive material is earthed.

34. A method of combining a first material having thermally insulating properties and a second material having electrically conductive properties comprising forming a scaffold or support structure with the first material and introducing the second material into the scaffold or support so as to form a three dimensional mesh of electrically conductive material interspersed throughout the first thermally insulating material.

35 A method according to claim 34 further including any one or more of the features recited in claims 2 to 27.

36. A method of providing thermal insulation and radiation protection to a fixed building structure comprising introducing into a cavity wall space of said building structure a first material having thermally insulating properties and a second material having electrically conductive properties so as to form a solid composition of said first and second materials within said cavity space wherein said first material acts as a scaffold so as to support the dispersed second material in a three dimensional manner throughout.

37. A method of providing security protection from radiation to a fixed building structure comprising introducing into a cavity wall space of said building structure a first material having thermally insulating properties and a second material having electrically conductive properties so as to form a solid composition of said first and second materials within said cavity space and wherein said first material acts as a scaffold so as to support the dispersed second material in a three dimensional manner throughout.

38. A method of limiting transmission of EM pulses into or out of a fixed building structure comprising introducing into a cavity wall space of said building structure a first material having thermally insulating properties and a second material having electrically conductive properties so as to form a solid composition of said first and second materials within said cavity space and wherein said first material acts as a scaffold so as to support the dispersed second material in a three dimensional manner throughout.

39. A method according to any one of claims 34 to 38 wherein the first composition is introduced into a building cavity wall space and the second material is subsequently introduced.

40. A method according to any one of claims 34 to 38 wherein the first and second materials are pre-mixed and subsequently introduced into the said cavity wall simultaneously.

41 . A method according to any of claims 34 to 38 further including any one or more of the features recited in claims 2 to 27.