Structured Insulation Layer Having Differential Convection Cooling Cavities

Abstract

An insulation structure that provides and insulating and cooling effect for permafrost soils includes an insulation material having a top and a bottom. The insulation material defines a plurality of air cavities extending through the insulation material from the top to the bottom. Each air cavity has an upper end at the top of the insulation material and a lower end at the bottom of the insulation material. The air cavities are configured to provide natural convection of air when a temperature above the top surface of the insulation material is less than a temperature below the bottom surface of the insulation material. Sealing material extends across the upper end and the lower end of each air cavity of the plurality of air cavities.

Claims

1. An insulation structure for insulating permafrost, the insulation structure comprising: an insulation material having a top and a bottom, wherein the insulation material defines a plurality of air cavities extending through the insulation material from the top to the bottom, wherein each air cavity has an upper end at the top of the insulation material and a lower end at the bottom of the insulation material, wherein the air cavities are configured to provide natural convection of air when a temperature above the top of the insulation material is less than a temperature below the bottom of the insulation material; and sealing material extending across the upper end and the lower end of each air cavity of the plurality of air cavities.

2. The insulation structure of claim 1, wherein the sealing material comprises a first sheet laminated to the top of the insulation material and a second sheet laminated to the bottom of the insulation material.

3. The insulation structure of claim 1, wherein the structured insulation material is installed within an embankment, wherein the embankment is one of a roadway, a railway, an airport, a pipeline, a building foundation, or a construction pad, wherein the insulation structure is configured to inhibit permafrost foundation soils underlying the embankment from thawing.

4. The insulation structure of claim 1, wherein the plurality of air cavities are arranged in a hexagonal pattern across the insulation material.

5. The insulation structure of claim 4, wherein each air cavity of the plurality of air cavities has a central axis, wherein each air cavity of the plurality of air cavities is positioned a common distance between the central axis of each other adjacent air cavity, and wherein the common distance is from about 5 cm to about 30 cm.

6. The insulation structure of claim 1, wherein each air cavity of the plurality of air cavities is cylindrical.

7. The insulation structure of claim 6, wherein each of the air cavities has a diameter between about 1 cm to about 10 cm and a height between about 5 cm to about 20 cm.

8. The insulation structure of claim 1, wherein the sealing material substantially seals each of the air cavities at the top and bottom by a laminated air-tight layer.

9. The insulation structure of claim 1, wherein the insulation layer has a height between about 5 cm to about 20 cm.

10. The insulation structure of claim 1, wherein the insulation material comprises foam, wherein the foam comprises one of extruded polystyrene, expanded polystyrene, or urethane.

11. The insulation structure of claim 1, wherein the plurality of air cavities have sufficient dimensions to provide for natural convection of air during a period of unstable temperature gradients.

12. An insulation structure configured to be positioned within an embankment, the insulation layer comprising: a sheet of insulation material having a top and a bottom; and a plurality of sealed air cavities extending through the sheet of insulation material from the top to the bottom, wherein each air cavity of the plurality of air cavities is configured to provide natural convection of air within the air cavity during a period of unstable temperature gradients.

13. The insulation structure of claim 12, wherein each of the plurality of air cavities has a cylindrical geometry positioned in a hexagonal pattern through the sheet of insulation material.

14. The insulation structure of claim 13, wherein each air cavity of the plurality of air cavities has a central axis, wherein each air cavity of the plurality of air cavities is positioned a common distance between the central axis of each other adjacent air cavity, and wherein the common distance is from about 5 cm to about 30 cm.

15. The insulation structure of claim 13, wherein each of the plurality of air cavities has a diameter from about 1 cm to about 10 cm and a height from about 5 cm to about 20 cm.

16. The insulation structure of claim 12, wherein the embankment is one of a roadway, a railway, an airport, a pipeline, a building foundation, and a construction pad.

17. The insulation structure of claim 12, wherein the sheet of insulation material has a height between the top and the bottom from about 5 cm to about 20 cm.

18. The insulation structure of claim 12, wherein the sheet of insulation material comprises foam, wherein the foam comprises one of extruded polystyrene, expanded polystyrene, or urethane.

19. The insulation structure of claim 12, further comprising a first sheet laminated to the top of the insulation material and a second sheet laminated to the bottom of the insulation material, wherein the first and second sheets are configured to seal the plurality of sealed air cavities.

20. The insulation structure of claim 19, further comprising a reflective coating on an inwardly facing surface of each of the first and second sheets.

21. An insulation structure configured to be positioned within an embankment, the insulation layer comprising: a sheet of insulation material having a height between about 5 cm to about 20 cm; a plurality of air cavities positioned through the sheet of insulation material, wherein each of the plurality of air cavities is configured to provide natural convection of air within the air cavity during a period of unstable temperature gradients, wherein each of the plurality of air cavities has a cylindrical geometry positioned in a hexagonal pattern through the sheet of insulation material, wherein each of the air cavities are positioned a common distance between cylinder center points, wherein the common distance is between about 5 cm to about 30 cm, and wherein each of the plurality of air cavities has a diameter between about 1 cm to about 10 cm and a height between about 5 cm to about 20 cm; and a seal that seals each of the plurality of air cavities at the top and bottom by a laminated air-tight layer including a reflective surface.

Description

DESCRIPTION OF THE DRAWINGS

[0010] These and other features of the preferred embodiments of the invention will become more apparent in the detailed description in which reference is made to the appended drawings wherein:

[0011] FIG. 1 is a schematic diagram showing a profile view of an embankment with a structured foam insulation layer overlying permafrost foundation soils.

[0012] FIG. 2 is a perspective view of an exemplary insulation structure having cylindrical air cavities positioned in offset rows.

[0013] FIG. 3 is a schematic diagram of an exemplary insulation structure as disclosed herein.

[0014] FIG. 4 is a schematic diagram illustrating convective airflow within air cavities of an exemplary insulation structure during winter months, where an upper surface of the insulation structure is cooler than a lower surface.

[0015] FIG. 5 is a schematic cross sectional diagram of an exemplary insulation structure.

DETAILED DESCRIPTION

[0016] The present invention will be described with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. It is to be understood that this invention is not limited to the particular methodology and protocols described, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

[0017] Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0018] As used throughout, the singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, unless the context dictates otherwise, reference to a cavity provides disclosure of embodiments in which only a single such cavity is provided, as well as embodiments in which a plurality of such cavities are provided.

[0019] All technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs unless clearly indicated otherwise.

[0020] As used herein, the terms optional or optionally mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0021] As used herein, the term at least one of is intended to be synonymous with one or more of. For example, at least one of A, B and C explicitly includes only A, only B, only C, and combinations of each.

[0022] The word or as used herein means any one member of a particular list and, unless context dictates otherwise, can also provide disclosure for alternative embodiments in which any combination of members of that list is provided.

[0023] It is to be understood that unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of aspects described in the specification.

[0024] The description herein supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the apparatus, system, and associated methods of using the apparatus can be implemented and used without employing these specific details. Indeed, the apparatus, system, and associated methods can be placed into practice by modifying the illustrated apparatus, system, and associated methods and can be used in conjunction with any other apparatus and techniques conventionally used in the industry.

[0025] In accordance with the present invention, a horizontal insulation layer (e.g., comprising foam, or formed of foam) can be manufactured with sealed air cavities of sufficient dimension and/or geometry to promote natural convection within the cavities during relatively colder months (e.g., winter months) when a base or bottom surface of the insulation layer is relatively warm compared to an upper or top surface of the insulation layer. Such a temperature difference generates an unstable temperature and density gradient within the air cavities with cold dense air lying above warmer lighter air below. Once the unstable temperature gradient reaches a critical value, air circulation within the cavities can begin and heat transfer from the bottom to the top of the insulation layer will be augmented by this buoyancy-driven natural convection.

[0026] Natural convection, wherein cold air at the top of the cavity circulates and is exchanged with warm air from the bottom of the cavity, is a much more effective heat transfer mechanism than heat conduction through stagnant air or solid foam insulation material. Thus, heat transfer upward through the insulation layer can be greatly enhanced during winter when the unstable temperature and density gradient exists. During summer conditions the upper boundary of the insulation layer is relatively warm compared to the base and the air in the cavities is subjected to a stable temperature gradient wherein warm, light air overlies cold, relatively denser air, so that little or no natural convection occurs. Under these conditions, heat transfer through the layer can be governed by heat conduction through the stagnant air in the cavities which is much less effective than natural convection, and downward heat transfer through the insulation layer during summer is reduced. The overall effect of this behavior is to enhance heat loss and cooling of the materials beneath the insulation layer during winter, and retard heat gain during summer, thus providing an annual cooling influence. This cooling influence reduces average annual temperatures in the permafrost foundation soils helping to abate permafrost layer thaw year-round.

[0027] In order for buoyancy-induced natural convection to occur in a given air cavity, certain conditions of temperature gradient and cavity dimensions must be met. The tendency for convection to occur and convection strength is governed by the Rayleigh number:

[00001]$\mathrm{Ra}=\frac{g{\mathrm{TH}}^3}{}$

where g is the acceleration due to gravity, is the density of the cavity air, is the thermal expansion coefficient of the cavity air, is the dynamic viscosity of the cavity air, is the thermal diffusivity of the cavity air, T is a characteristic temperature difference between the bottom and top of the cavity, and H is the cavity height.

[0028] If T is negative (top of cavity is warmer than bottom), the Rayleigh number is negative and no convection will occur. This would typically be the case during summer conditions. As T increases in the positive direction during winter conditions the Rayleigh number will increase until a critical value is reached, beyond which natural convection begins and the air circulates in the cavity. The properties of air are determined by the temperature of the air in the cavity and cannot be independently adjusted and T is a function of the time of the year and the temperatures imposed on the insulation layer. However H, the cavity height, and other aspects of the cavity geometry can be adjusted as part of the design of the system to ensure that natural convection and air circulation occur during winter in order to enhance cooling. Examples of buoyancy-driven natural convection of pore air are described in commonly assigned U.S. Pat. No. 5,697,730, entitled Roadway Having Convection Cooling for Permafrost Regions, the entire disclosure of which is incorporated by reference herein for all purposes.

[0029] Referring to FIGS. 1-5, an insulation structure 10 can comprise an insulation material 100, such as, for example, an insulation sheet or an insulation layer. The insulation material 100 can have a top 102 and a bottom 104. In some aspects, and as shown, the insulation material 100 can have a predetermined, consistent thickness from the top 102 to the bottom 104. In other aspects, the insulation material 100 can have a varying thickness. For example, in some aspects, the thickness can vary by 25%, or by 20%, or by 15%, or by 10%, or by 5%. The insulation material 100 can define a plurality of air cavities 110 (also called air pockets) that can be configured to perform the behavior described above. In some aspects, the air cavities 110 can extend through the thickness (e.g., height) of the insulation material 100 so that an upper end 112 is at the top 102 of the insulation material, and a lower end 114 is at the bottom 104. Accordingly, the thickness of insulation material 100 can determine the cavity height (H). It is contemplated, therefore, that the thickness of the insulation material can be selected based on a desired amount of insulation, as well as a geometry of the air cavities 110 to achieve convective heat transfer. Although the air cavities 110 have been described as being filled with air, it is contemplated that the air cavities 110 can contain other suitable gasses, such as, for example, nitrogen. Such a gas can have different convection characteristics from air. Accordingly, in some aspects, the air cavities 110 can be configured based on the particular gas to achieve desirable heat transfer properties.

[0030] In one example, the insulation structure 10 can be incorporated into an embankment 200 as shown in FIG. 1. The embankment 200 can comprise embankment fill material 210 positioned on a ground surface 220. The embankment fill material 210 can overlie permafrost foundation soils 230. The embankment 200 can have a top surface 240 that serves as an embankment work surface. The embankment 200 can support a roadway, a railway, an airport, a pipeline, a building foundation, or a construction pad. The insulation structure 10 can be configured to inhibit permafrost foundation soils 230 underlying the embankment 200 from thawing. In some aspects, the insulation structure 10 can be positioned below, but not support the load of, a building foundation. For example, weight of the building can be supported by supports that do not apply load to the insulation structure 10.

[0031] The placement of the insulation structure in the embankment in combination with the annual ambient temperature variations can determine the value of T(T=T.sub.hT.sub.c) at different times of the year. H and T can then combine with the other parameters in the Rayleigh number to determine the presence (or lack thereof) and strength of any convective heat transfer effect. Accordingly, the insulation structure 10 can be positioned within the embankment fill material 210 at a predetermined position between the top surface 240 and the original ground surface 220 in order to provide an optimal T across the insulation structure 10.

[0032] In one embodiment, a plurality of air cavities 110 are provided through the insulation material 100, as shown in FIG. 2. The air cavities 110 can extend from the top 102 of the insulation material 100 to the bottom 104 of the insulation material. In some aspects, the top 102 of the insulation material 100 can correspond to a top surface of the insulation material, and the bottom 104 of the insulation material 100 can correspond to a bottom surface of the insulation material. Accordingly, in some aspects, the air cavities 110 can extend an entire thickness from the top surface to the bottom surface of the insulation material. In other aspects, it is contemplated that the air cavities 110 need not extend through the entire thickness of the insulation material. Rather, the upper end 112 of the air cavities 110 can be slightly below the top surface and/or the lower end 114 of the air cavities 110 can be slightly above the bottom surface of the insulation material 100.

[0033] In one example, each of the air cavities 110 is shaped as a cylinder. In some optional aspects, the air cavities 110 can have a diameter in the range from about 1 cm to about 5 cm. For example, the air cavities 110 can have a major cross-sectional dimension (e.g., optionally, diameter) from about 0.8 cm to about 12 cm, or from about 1 cm to about 10 cm, or from about 1 cm to about 5 cm, or from about 5 cm to about 10 cm, or from about 2 cm to about 8 cm. In additional aspects, the air cavities 110 can have a height from about 5 cm to about 20 cm. For example, the air cavities 110 can have a height from about 5 cm to about 10 cm, or from about 10 cm to about 20 cm. Accordingly, in these aspects, the insulating material can have a thickness from about 5 cm to about 20 cm, or from about 5 cm to about 10 cm, or from about 10 cm to about 20 cm. In additional aspects, the cavities 110 can have any suitable shape. For example, the air cavities 110 can be in the shape of polygonal prisms or elliptical bores. In some aspects, the air cavities 110 can have consistent cross sections from the top 102 of the insulation material 100 to the bottom 104 (e.g., in planes parallel to the top surface). In other aspects, the air cavities 110 can have varying cross sections. For example, the air cavities can be conical.

[0034] The air cavities 110 can be sealed at their respective upper and lower ends 112, 114. For example, a first sheet of material 120 can be laminated against the top 102 of the insulation material 100, and a second sheet of material 122 can be laminated against the bottom 104 of the insulation material. It is contemplated that the air cavities 110 do not extend an entire thickness of the insulation material 100. Accordingly, in some optional aspects, the insulation material 100 between the upper end 112 of the air cavity 110 and the top surface of the insulating material can form the material that seals the cavity. Similarly, in some optional aspects, the insulation material 100 between the lower end 114 of the air cavity 110 and the bottom surface of the insulating material can form the material that seals the cavities at the lower end.

[0035] Optionally, a reflective coating 124 can be applied to one or both of the first sheet of material 120 and the second sheet of material 122. The reflective coating 124 can face inwardly into the respective air cavity 110. In some aspects, the first and second sheets of material can comprise polymer, such as a polymer film. In additional aspects, a single sheet of material can be wrapped around the insulating material 100 so that the single sheet of material seals the upper and lower ends 112, 114 of the air cavities 110. In further aspects, the cavities can be sealed by a geofabric, such as a cloth metallized layer.

[0036] In one example, the air cavities 110 can be cylindrical air cavities that are positioned in a hexagonal pattern such that centrally axes 116 of adjacent cylindrical air cavities are the same distance, x, apart from one another (FIG. 2). In this example, the common distance, x, between cylinder center points may be between about 5 cm to about 30 cm. In another example, the cylindrical air cavities may be positioned in off-set rows. It is noted that the air cavities may include different geometries and the present invention is not limited to a particular geometry such as a cylinder, and the air cavities may be positioned in different patterns and the present invention is not limited to a particular pattern such as a hexagonal pattern or off-set rows. For example, the air cavities can be evenly or unevenly distributed. In some optional aspects, the air cavities can be randomly distributed. In some aspects, the evenly or unevenly distributed air cavities 110 can be spaced from adjacent air cavities by distances from about 5 cm to about 30 cm. In other aspects, the air cavities can be arranged in rows and columns. Optionally, the rows and columns can be evenly or unevenly spaced from adjacent rows and columns. It is contemplated that the air cavities 110 can form from about 5% to about 30%, or from about 10% to about 20% of the insulation structure 10. In various aspects, the ratio of the insulation structure 10 defined by the air cavities 110 can be maximized without compromising structural integrity of the insulation structure. That is, in some aspects, the volume of space occupied by the air cavities 110 can be limited by the structural integrity of the insulation structure 10.

[0037] It is noted that the air cavities 110 can be sealed at the top and bottom to avoid the intrusion of foreign material by using such means as a respective laminated air-tight layer on the top and bottom of the insulation material 100. It is further noted that such lamination could include a reflective coating 124 to further improve thermal performance by reducing thermal radiation across the cavity.

[0038] In one embodiment, the insulation material 100 can comprise foam. Optionally, the insulation material 100 can consist of foam. Optionally, the foam can be closed cell foam. For example, in some aspects, the foam can comprise, or be made of, extruded polystyrene (XPS). In other embodiments, the insulation material 100 can comprise, or be made of, expanded polystyrene (EPS) or urethane. It is noted that the insulation material 100 may comprise or be made of different materials and the present invention is not limited to a particular material. In some aspects, the insulation material 100 can comprise a single layer of foam. In other aspects, the insulation material 100 can comprise a plurality of layers of foam that are stacked together. In some aspects, the air cavities 110 can be formed into the insulation material 100. In other aspects, the insulation material can be formed with the air cavities 110 therein, thereby reducing material waste. In various aspects, the insulation material 100 can further comprise fiber (e.g., fiberglass), mineral wool, cellulose, natural fibers, or any other suitable insulating material.

[0039] The insulation structure 10 further comprises a seal over each of the air cavities (or over the plurality of air cavities) on the top and bottom of each of the air cavities, such that each air cavity is protected from air and moisture external to the air cavity. Accordingly, in some aspects, the seals can be air tight. In one example, the seal may be comprised of a laminate, a polyester film, a transparent film, and/or a transparent film with a metallic coating (e.g., a low-emissivity film), and/or combinations of such examples of a seal that protect the structural and thermal properties of the air cavities.

[0040] In an example, a high-density EPS insulation board is manufactured with closed convective air cavities embedded in the closed-cell insulation matrix and laminated on both sides with a protective woven polyester film barrier and low-emissivity metallized film layer to maintain integrity of the convective air pockets and protect the entire insulation matrix from moisture and structural damage during construction and use. The top laminated barrier may lap over adjoining sheets for reduced installation costs.

[0041] In another example, the process starts with high-density (e.g., 3.0 lb/ft.sup.3, 50 kg/m.sup.3) expanded polystyrene rigid insulation. Next, cylindrical voids are formed in the insulation matrix through its thickness. The specific thickness, geometry and void spacing may be optimized for specific applications and conditions. The voids are then sealed with a woven polypropylene membrane and low-emissivity metallized film barrier laminating both sides of the insulation board to keep pockets free of dirt and water, creating fully-enclosed air pockets inside the rigid insulation matrix, as well as providing a puncture-resistant barrier that does not require bedding sand to protect the insulation during construction.

[0042] FIG. 3 illustrates a simplified configuration of an insulation structure (also called a board) 100 with convective air pockets (also called air cavities or cells) 110.

[0043] FIG. 4 illustrates a convective air cavity (pocket) 110 with air circulation pattern (shown by arrows) inside the air pocket during the winter (cooling) season. During the summer season, the temperature at the top of the insulation Tc is greater than the temperature at the bottom of the insulation Th. The insulation layer acts normally, with the air in closed convective cylinders (cells) remaining stagnant due to stratification (not internally circulating) with warmer temperature on top of the cell. During the winter season, the temperature at bottom of insulation (T.sub.h) is greater than the temperature at the top of the insulation (T.sub.c). The air pockets begin to convectively circulate within the closed air cell due to warmer air at bottom of cell (e.g., at as low as 1 degree Centigrade differential), driving convective heat transfer from bottom (warmer) to top of cell (colder), decreasing the overall insulative effect of the insulation layer to thereby cool the road embankment under the insulation. In other words, this enhanced heat transfer (reduced insulative value) is only active during winter months, promoting active cooling of the road embankment under the insulation structure and maintaining/increasing the permafrost layer at below-freezing conditions, even with increased atmospheric warming and higher air temperatures during summer months.

[0044] In the preceding description, various exemplary embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the scope of the invention as set forth in the claims that follow. For example, certain features of one embodiment described herein may be combined with or substituted for features of another embodiment described herein. In another example, a plurality of insulation structures may be vertically stacked together to provide air cavities that are aligned or not aligned with air cavities that are above or below. The description and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.

[0045] The following references are hereby incorporated by reference herein for all purposes. [0046] Goering, D. J. and P. Kumar. 1996. Winter-time convection in open-graded embankments. Cold Regions Science and Technology, 24 (1): 57 [0047] Goering, D. J. 2000. Passive cooling of permafrost foundation soils using porous embankment structures. American Society of Mechanical Engineers, HTD 366-5, pp. 103.

EXEMPLARY ASPECTS

[0048] In view of the described products, systems, and methods and variations thereof, herein below are described certain more particularly described aspects of the invention. These particularly recited aspects should not however be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the particular aspects are somehow limited in some way other than the inherent meanings of the language literally used therein.

[0049] Aspect 1: An insulation structure for insulating permafrost, the insulation structure comprising: [0050] an insulation material having a top and a bottom, wherein the insulation material defines a plurality of air cavities extending through the insulation material from the top to the bottom, wherein each air cavity has an upper end at the top of the insulation material and a lower end at the bottom of the insulation material, wherein the air cavities are configured to provide natural convection of air when a temperature above the top of the insulation material is less than a temperature below the bottom of the insulation material; and [0051] sealing material extending across the upper end and the lower end of each air cavity of the plurality of air cavities.

[0052] Aspect 2: The insulation structure of aspect 1, wherein the sealing material comprises a first sheet laminated to the top of the insulation material and a second sheet laminated to the bottom of the insulation material.

[0053] Aspect 3: The insulation structure of aspect 1, wherein the structured insulation material is installed within an embankment, wherein the embankment is one of a roadway, a railway, an airport, a pipeline, a building foundation, or a construction pad, wherein the insulation structure is configured to inhibit permafrost foundation soils underlying the embankment from thawing.

[0054] Aspect 4: The insulation structure of aspect 1, wherein the plurality of air cavities are arranged in a hexagonal pattern across the insulation material.

[0055] Aspect 5: The insulation structure of aspect 3, wherein each air cavity of the plurality of air cavities has a central axis, wherein each air cavity of the plurality of air cavities is positioned a common distance between the central axis of each other adjacent air cavity, and wherein the common distance is from about 5 cm to about 30 cm.

[0056] Aspect 6: The insulation structure of aspect 1, wherein each air cavity of the plurality of air cavities is cylindrical.

[0057] Aspect 7: The insulation structure of aspect 6, wherein each of the air cavities has a diameter between about 1 cm to about 10 cm and a height between about 5 cm to about 20 cm.

[0058] Aspect 8: The insulation structure of aspect 1, wherein the sealing material substantially seals each of the air cavities at the top and bottom by a laminated air-tight layer.

[0059] Aspect 9: The insulation structure of aspect 1, wherein the insulation layer has a height between about 5 cm to about 20 cm.

[0060] Aspect 10: The insulation structure of aspect 1, wherein the insulation material comprises foam, wherein the foam comprises one of extruded polystyrene, expanded polystyrene, or urethane.

[0061] Aspect 11: The insulation structure of aspect 1, wherein the plurality of air cavities have sufficient dimensions to provide for natural convection of air during a period of unstable temperature gradients.

[0062] Aspect 12: An insulation structure configured to be positioned within an embankment, the insulation layer comprising: [0063] a sheet of insulation material having a top and a bottom; and [0064] a plurality of sealed air cavities extending through the sheet of insulation material from the top to the bottom, [0065] wherein each air cavity of the plurality of air cavities is configured to provide natural convection of air within the air cavity during a period of unstable temperature gradients.

[0066] Aspect 13: The insulation structure of aspect 12, wherein each of the plurality of air cavities has a cylindrical geometry positioned in a hexagonal pattern through the sheet of insulation material.

[0067] Aspect 14: The insulation structure of aspect 13, wherein each air cavity of the plurality of air cavities has a central axis, wherein each air cavity of the plurality of air cavities is positioned a common distance between the central axis of each other adjacent air cavity, and wherein the common distance is from about 5 cm to about 30 cm.

[0068] Aspect 15: The insulation structure of aspect 13, wherein each of the plurality of air cavities has a diameter from about 1 cm to about 10 cm and a height from about 5 cm to about 20 cm.

[0069] Aspect 16: The insulation structure of aspect 12, wherein the embankment is one of a roadway, a railway, an airport, a pipeline, a building foundation, and a construction pad.

[0070] Aspect 17: The insulation structure of aspect 12, wherein the sheet of insulation material has a height between the top and the bottom from about 5 cm to about 20 cm.

[0071] Aspect 18: The insulation structure of aspect 12, wherein the sheet of insulation material comprises foam, wherein the foam comprises one of extruded polystyrene, expanded polystyrene, or urethane.

[0072] Aspect 19: The insulation structure of aspect 12, further comprising a first sheet laminated to the top of the insulation material and a second sheet laminated to the bottom of the insulation material, wherein the first and second sheets are configured to seal the plurality of sealed air cavities.

[0073] Aspect 20: The insulation structure of aspect 19, further comprising a reflective coating on an inwardly facing surface of each of the first and second sheets.

[0074] Aspect 21: An insulation structure configured to be positioned within an embankment, the insulation layer comprising: [0075] a sheet of insulation material having a height between about 5 cm to about 20 cm; [0076] a plurality of air cavities positioned through the sheet of insulation material, [0077] wherein each of the plurality of air cavities is configured to provide natural convection of air within the air cavity during a period of unstable temperature gradients, [0078] wherein each of the plurality of air cavities has a cylindrical geometry positioned in a hexagonal pattern through the sheet of insulation material, [0079] wherein each of the air cavities are positioned a common distance between cylinder center points, [0080] wherein the common distance is between about 5 cm to about 30 cm, and [0081] wherein each of the plurality of air cavities has a diameter between about 1 cm to about 10 cm and a height between about 5 cm to about 20 cm; and [0082] a seal that seals each of the plurality of air cavities at the top and bottom by a laminated air-tight layer including a reflective surface.