GB2079415A - Thermal insulation - Google Patents

Abstract

A building structure can be thermally insulated with a layer of insulating material formed from enclosures (4) of low thermal conductivity. These enclosures (4) may have heat-reflecting internal surfaces and are preferably formed from a fire resistant or fire retardant water impermeable material. They may be flexible plastics pockets filled with air or other gas of low thermal conductivity. Alternatively they may be rigid-walled pockets which may be evacuated or gas-filled. These rigid- walled pockets can be formed as separate glass balls or as pockets vacuum moulded in plastics sheeting (3). Where the enclosures (4) contain air or other gas this preferably is of lower density than atmospheric air. The insulating material may be applied to the surfaces of ceilings, floors or partitions, inserted into wall cavities, provide left insulation in spaces between joists, or be applied as lagging around pipes and water tanks. <IMAGE>

Description

SPECIFICATION thermal insulation This invention relates to thermal insulation materials particularly although not exclusively for use for cladding or lagging and for insulating cavities and partitions in buildings.

Mineral fibres are widely used for insulation purposes in buildings, for example as loft insulation in domestic residences. However such material relies for its insulating properties on the formation of a network of interconnected air-trapping spaces between fibres and is therefore not always wholly satisfactory in so far as such network is inevitably permeable to condensation and may therefore permit accumulation of moisture on, for example, adjacent wooden joists thereby facilitating rotting thereof. Also, a considerable quantity or thickness of fibrous material may be required to provide adequate insulation which may be costly or inconvenient.

An object of the present invention is to provide a material which may be of an inexpensive and convenient form yet which can afford effective thermal insulation without necessarily giving rise to condensation problems.

According to one aspect of the invention therefore there is provided a method of insulating a building structure by application thereto of a layer of an insulation material comprising a plurality of discrete enclosures of low thermal conductivity.

With this arrangement, the insulation material can be manufactured and utilised in a particularly simple inexpensive and convenient manner, and may be capable of providing satisfactory thermal insulation properties without necessitating an unduly extensive or thick layer of the insulating material and without necessarily being such as to permit ready ingress and accumulation of moisture.

In particular, the enclosures may comprise sealed thin-walled pockets, either being flexible-walled and inflated with a fluid substance of low thermal conductivity or being rigid-walled and evacuated or filled with a fluid substance of low thermal conductivity, whereby the bulk of such material can be composed largely or substantially wholly of the thermally insulating evacuated orfluid-filled spaces within the pockets, the intermediate retaining structure defined by the pocket walls being relatively insubstantial and therefor unlikely to be responsible [ or appreciable heat losses especially if such walls are formed from a material of low thermal conductivities such as plastics sheeting or glass. It may even be possible to use enclosures filled with polystyrene or other solid substance.

Moreover, such sealed enclosures can form a vapour barrier.

Where fluid-filled enclosures are used the fluid substance may be of any suitable nature and may be a liquid or gas. Preferably, however, a gas is utilised.

Although such gas may be air, most preferably a gas of lower density than atmospheric air, being for example low pressure air or a gas of low density (such as a freon), is used since such substance may be particularly advantageous with regard to the reduction of heat loss due to convection as well as conduction. The discrete enclosures may be utilised in the form of wholly separate bodies defining a fluent mass, or alternatively may be linked, being, for example, formed at spaced positions on or being attached to a rigid or flexible sheet or strip or other support or being embedded in a body of resin or other material or being bonded together. The enclosures may be spherical or dome-shaped or of any other suitable form. The size of the enclosures will be selected in accordance with thermal insulation requirements.

Any suitable plastics material or combination of materials may be utilised in the formation of the enclosures including thin flexible sheeting of polyethylene, polyvinylchloride, polyester, and the like. Most preferably the insulation material is fireresistant or fire-retardant, and in the case where the enclosures are formed from plastics material such property may be a consequence of the inherent characteristics thereof and/or due to the incorporation therein or application thereto of a suitable substance or substances. Preferably also, the enclosures are utilised in conjunction wth a heat-reflective surface such as a film or layer of shiny aluminium which may be applied directly to the walls of the enclosures andlorto a backing sheet supporting said enclosures or used in conjunction therewith.The said layer of insulation material used in accordance with the invention may be used alone or in conjunction with other thermal insulation materials.

In accordance with the first aspect of the invention, the insulation material thereof may be applied to any suitable building structure in any suitable manner.

Thus, the insulation material may be inserted into wall cavities, applied as lagging around pipes and water tanks, or applied to the surfaces of ceilings, floors, partitions and the like. Where the insulation is to be inserted into wall cavities, such insulation will preferably be in the form of separate said enclosures which can conveniently be poured or blown or otherwise caused to flow into the cavity. Such separate enclosures may also be used in other circumstances for example as a deposited layer on a horizontal surface (as loft insulation), or as a layer contained within a flexible bag or rigid container or sandwiched between constraining sheets or walls or the like.Where the insulation material is provided in sheet or strip form it can conveniently be applied, as for example from a roll thereof, to spaces between joists in loft insulation or on other horizontal surfaces, or such material may be applied as by bonding or otherwise to supporting surfaces, for example, such material may be incorporated in or secured such as by bonding to rear surfaces of structural boards such as plaster board, chipboard or the like.

Where reference is made to buildings it is to be understood that this includes domestic residences, industrial and commercial premises and other habitable residences such as caravans and the like.

In accordance with a second aspect of the present invention, there is provided insulation material suitable for use in performing the method of the first aspect of the invention comprising a plurality of discrete pockets enclosing a region of low thermal conductivity having a density below that of atmospheric air.

The pockets may be flexible or rigid thin-walled sealed structures as described above in connection with the method of the first aspect of the invention.

In one embodiment of the second aspect of the invention the pockets comprise bulbs or globules formed from glass and preferably separate from each other. Such bulbs or globules may be of any suitable size and shape. For example glass spheres of about 5mm diameter may be used.

The pockets may be provided internally and/or externally with a heat-reflective surface defined for example by a layer of shiny alumium, and if desired an outer protective coating of a plastics or resin material may be provided.

In an alternative embodiment of the second aspect of the invention the enclosures are defined by sealed thin-walled rigid pockets moulded in plastics sheeting.

Said material of the second aspect of the invention may additionally incorporate any one or more of the features of the material used in the method of the first aspect of the invention as appropriate.

The insulation material of the second aspect of the invention may be utilised as described above in relation to the first aspect or alternatively for any other suitable purpose.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which: Figure I is a perspective view of one form of insulation material according to the invention; Figure 2 is a sectional view of the material of Figure 1; Figure 3 is a sectional view through a mould showing the method of manufacture of an alternative form of material according to the invention; Figure 4 is a diagrammatic perspective view of a moulded sheet obtained with the mould of Figure 3; Figure 5 is a diagrammatic perspective view of insulating material made with the sheet of Figure 4; Figure 6 is a diagrammatic sectional view of multiple layers of the material of Figure 5.

As shown in Figures 1 and 2, insulation material in sheet form is manufactured from two flexible plastics films 1, 2 each of which has fire-resistant or retardant properties and at least one of which is highly reflective in that it has thereon a deposited shiny aluminium coating.

The films 1,2 are disposed in superimposed relationship and are heat-welded together around the peripheries 3 of multiple circular regions whilst trapping air therebetween. Multiple side-by-side regularly-spaced dome-shaped enclosures 4 of say 2 cm or 3 cm diameter are thereby defined, such domes 4 being firmly inflated with air.

The resulting sheet material can be readily rolled or folded for storage and transport purposes and when required for use can be unrolled or unfolded and laid out on a support surface. In particular, the sheet can be laid on top of a ceiling between joists in a loft of a domestic residence.

The sheet may be laid with the domes 4 directed downwardly and/or with multiple sheets one on top of the other so that air is also trapped between the domes 4.

The sheet provides excellent thermal insulation due to the reflective properties thereon and also dus to the low thermal conductivity of the trapped air. In particular good thermal insulation can be achieved with a relatively small thickness of insulation mate rial. Further, the sheet is simple and inexpensive to manufacture and convenient to install; and also the sheet provides a vapour barrier preventing passage and accumulation of moisture.

In the case where separate enclosures are required, the above-described heat-welding process may be extended by prolonged or excess heating or by a cutting step to effect separation of the enclosed regions from the sheet.

With reference to Figures 3 to 6 insulation material is manufactured from extruded plastics sheeting (preferably having fire-resistant or retardant properties) of say 0.5mm thickness. As shown in Figure 3 a rectangular sheet 5 of this plastics material is introduced into a vacuum forming mould between a heater 6 and a shaped mould surface 7. The sheet 5 is softened by heating and the mould is evacuated through an outlet 8 to cause the sheet 5 to be drawn into intimate contact with the mould surface thereby to adopt the shape of same. The resulting shaped sheet 5 as shown in Figure 4 has a plurality of hemispherical depressions 9 at evenly spaced positions considered in mutually perpendicular directions parallel to the sheet sides.The depressions 9 are linked by part-cylindrical channels 10 and at least one corner depression 9 has a freely projecting part-cylindrical channel 11 extending along a projecting edge extension of the sheet. Two like said moulded sheets 5 are positioned in superimposed relationship and are sealed together by heat-welding at the confronting flat portion between the depressions 9 and passages 10 so as to define a structure as shown in Figure 5 having substantially spherical pockets linked by cylindrical passages defined by confronting pairs of depressions 9 and channels 10.

Also the structure has one or more outlet passages 12 defined by one or more confronting pairs of said projecting channels 11, it being understood that each sheet 5 is of appropriate shape (say square) or has an appropriate number of projecting channels to obtain said one or more confronting pairs with superimposed said sheets.

The pockets in the structure are rigid-walled ands can be collectively evacuated via the passages 12, such passages 12 then being heat-sealed. The interconnecting passages 13 can also be heat-sealed and if desired it is even possible to separate the sealed evacuated pockets from the sheeting.

As shown in Figure 6, a number (say three) of like structures can be assembled in superimposed relationship with the pockets on one structure fitting respectively between the pockets of the next adjacent structure. The structure may be secured together and a heat-reflective metallised layer may be applied to the underside of the assembly.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiments which are described by way of example only.

In particular although reference is made in relation to the embodiment of Figures 1 and 2 to the use of air as the fluid inflating the pockets, in practice it may be preferable to use a fluid of lower density than atmospheric air, for example freon, such low density fluid minimising transmission of heat by way of convection.

With regard to the embodiment of Figures 3 to 6, if desired, the pockets may be filled with a fluid, particularly a low density gas, ratherthan being evacuated.

Where pockets which are evacuated or filled with a low density gas are used the density of the pocket walls may be selected such that the entire insulating material is lighter than air, this facilitating, for example, attachment of the material to a ceiling or other overhead structure.

The material may be used in transparent or translucent form, i.e. without the heat-reflective layer, so as to be suitable for insulating for example windows or the like.

Claims (32)

1. A method of thermally insulating a building structure by application thereto of a layer of an insulation material comprising a plurality of discrete enclosures of low thermal conductivity.

2. A method according to claim 1, wherein said discrete enclosures are utilised as separate bodies defining a fluent mass.

3. A method according to claim 1, wherein said discrete enclosures are utilised as interconnected bodies.

4. A method according to claim 3, wherein said interconnected bodies define a flexible sheet or strip structure.

5. A method according to any one of claims 1 to 4, wherein said insulation layer includes a heatreflective surface.

6. A method according to claim 5, wherein said heat-reflective surface is provided on walls of said enclosures.

7. A method according to any one of claims 1 to 6, wherein said insulating material has fire-retardant or resistant properties.

8. A method according to any one of claims 1 to 7, wherein said enclosures are secured to a supporting surface of said building structure.

9. A method according to any one of claims 1 to 8, wherein said enclosures comprise sealed thinwalled pockets.

10. A method according to claim 9, wherein said pockets are flexible-walled and are inflated with a fluid substance of low thermal conductivity.

11. A method according to claim 9, wherein said pockets are rigid-walled and are evacuated or filled with a fluid substance of low thermal conductivity.

12. A method according to claim 10 or 11, wherein said pockets are filled with a gas of density lower than atmospheric air.

13. A method according to any one of claims 9 to 12, wherein said pockets are formed from plastics sheeting.

14. A method according to claim 1, substantially as hereinbefore described with reference to the accompanying drawings.

15. Insulation material for use in performing the method of claim 1, comprising a plurality of discrete pockets enclosing a region of low thermal conductivity having a density below that of atmospheric air.

16. Insulation material according to claim 15, wherein said pockets comprise sealed thin-walled structures.

17. Material according to claim 16, wherein said pockets are wholly separate and define collectively a fluent mass.

8. Material according to claim 16, wherein said pockets are interconnected in sheet form.

19. Material according to any one of claims 16 to 18, wherein said pockets are flexible-walled and are inflated with a fluid substance of low thermal conductivity which is less dense than atmospheric air.

20. Material according to claim 19, wherein said thin-walled pockets are formed from flexible plastics sheeting.

21. Material according to any one of claims 16 to 18, wherein said pockets have rigid walls and are evacuated or contain a substance of low thermal conductivity which is less dense than atmospheric air.

22. Material according to claim 21, wherein said pockets are formed from glass.

23. Material according to claim 21, when dependent on claim 18, wherein said pockets are moulded in plastics sheeting.

24. Material according to claim 23, wherein said sheeting is formed from two moulded sheets secured together in superimposed relationship and having said pockets defined between same.

25. Material according to claim 23 or 24, wherein said pockets are at least generally of spherical form.

26. Material according to any one of claims 23 to 25, wherein said pockets are disposed at evenly spaced positions considered in each of two mutually perpendicular directions.

27. Material according to any one of claims 23 to 26, comprising a plurality of layers of said pocketed sheeting disposed one on top of anotherwith the pockets of each layer fitting respectively in spaces between pockets of the next adjacent layer.

28. Material according to any one of claims 15 to 27, which has fire-retardant or resistant properties.

29. Material according to any one of claims 15 to 28, having a heat-reflective surface applied thereto.

30. Insulating material substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

31. A building structure when insulated in accordance with the method of any one of claims 1 to 14.

32. A building structure when insulated with insulating material according to any one of claims 15 to 30.