Above-ground wildfire shelter with steel a-frame structure

Abstract

An above-ground, A-frame wildfire shelter designed to withstand extreme wildfire conditions is disclosed. The structure is fireproof and is fabricated entirely from non-combustible metals to ensure durability under severe thermal exposure. The A-frame roof configuration offers significant advantages, including reduced gravitational load and inherent angular bracing, as the opposing rafters support one another. Roofing panels are mounted directly to the rafters for structural integrity. To address prolonged exposure to temperatures approaching 1,000° C., the design incorporates passive cooling through hollow, rectangular rafters. These rafters facilitate airflow, drawing cooler air from near ground level and discharging heated air above the roofline. Additionally, the A-frame geometry can be scaled to accommodate an integrated off-grid electrical system, enabling geothermal cooling to mitigate soak-back heat within the shelter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Ser. No. 63 / 770,560, filed on Mar. 12, 2025, which is incorporated herein by reference.TECHNICAL FIELD

[0002] This present disclosure relates to disaster survival shelters. More particularly, the present disclosure relates to wildfire shelters.BACKGROUND

[0003] Wildfires pose a severe and growing threat to human life, property, and infrastructure, particularly in forested regions and areas where urban development meets wildland environments. Despite established guidelines for access control, forest management, removal of combustible materials, and fire-resistant building practices, these measures are often inadequately implemented. As a result, the frequency and intensity of destructive wildfires continue to increase.

[0004] Current recommendations for surviving a wildfire frequently emphasize sheltering in place. However, most residential structures are constructed from combustible materials, making them highly vulnerable to ignition and structural failure under extreme fire conditions. Effective refuge from wildfire hazards requires an enclosed environment composed of non-combustible materials capable of withstanding flame-radiated surface temperatures exceeding 1,000° C. Existing solutions, such as portable, foil-wrapped fiberglass cocoons, have been employed by firefighters for short-term exposure, but offer limited protection and comfort during extended fire events.

[0005] Alternative approaches include underground shelters that leverage the earth's stable, cooler temperature as a thermal barrier. While these designs can provide longer-term protection, they present significant drawbacks: they must be sealed against water and smoke infiltration, are costly and complex to install, and often create accessibility challenges for individuals with physical limitations. Additionally, underground shelters can induce feelings of confinement and discomfort during prolonged occupancy.

[0006] Above-ground concrete shelters have also been introduced in the art, but typically offer minimal interior space for survival supplies and equipment, reducing their practicality for extended stays. Larger above-ground disaster structures incorporating steel canopy shields have been disclosed in the prior art as well; however, while these designs may be suitable for some disasters, these designs lack provisions for maintaining structural integrity under sustained exposure to extreme heat, high winds, and other environmental stresses associated with wildfire conditions.

[0007] Accordingly, there is a need for an above-ground shelter capable of withstanding the extreme conditions associated with wildfires, including peak radiated thermal energy, high winds, and potential flooding. There is also a need for a system that maintains structural integrity by preventing excessive heat buildup in load-bearing components. In addition, such a shelter should incorporate integrated power and support systems to enhance safety and comfort during extended periods of isolation. Current technologies fail to provide adequate protection for firefighters, essential equipment, and residential communities at risk from wildfires. A comprehensive solution should ensure durability under severe thermal exposure, resist environmental intrusions, and support occupant survivability and operational functionality under prolonged emergency conditions. The present disclosure seeks to solve these and other problems.SUMMARY OF EXAMPLE EMBODIMENTS

[0008] In some embodiments, a wildfire structure comprises an A-frame structure manufactured entirely of metal and / or other non-combustible components, resulting in a fireproof shelter. In some embodiments, the roof may comprise a plurality of layered metal sheets, such as stainless steel or other high-strength alloys. The metal sheets may be configured to provide one or more insulating layers and air flow channels to dissipate heat. The metal sheets may comprise a reflective surface to withstand elevated temperatures without excessive discoloration. In some embodiments, the wildfire structure comprises hollow steel rafters that are open-ended to allow for the passage of air and smoke therethrough.

[0009] In some embodiments, the wildfire structure further comprises a soil heat exchanger and a cooled compartment. In some embodiments, the roof is sized to provide adequate surface area for solar power to operate equipment inside the shelter, including an electric coolant pump for geothermal cooling of individuals and equipment therein.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a chart depicting a typical wildfire with burn temperature as a function of time;

[0011] FIG. 2 is a perspective view of a wildfire shelter;

[0012] FIG. 3 is a chart showing the yield strength of several metals that may be used to implement a wildfire shelter;

[0013] FIG. 4 is perspective view of a wildfire shelter showing the different metallic components and layers used in the A-frame shelter structure;

[0014] FIG. 5A is a front elevation cross-sectional view of a wildfire structure;

[0015] FIG. 5B is a cross-section taken along lines A-A of FIG. 5A illustrating a hollow, structural steel rafter as the basic load-carrying element of the wildfire shelter structure;

[0016] FIG. 5C is a detailed view of a hollow steel rafter and heating and cooling methods associated therewith;

[0017] FIG. 6 illustrates a front elevation cross-sectional view of a sheet spacer and mounting post (e.g., threaded standoffs) for attaching the metal sheets to the rafters;

[0018] FIG. 7 is a cross-sectional elevation view which shows the thermal paths and methods for transmitting heat from the rafters to an exhaust plume and from the rafters to the soil below;

[0019] FIG. 8 is a top plan view of an aluminum rail base for easy field assembly and maximum conduction of heat into the soil, comprising a geothermal cooling system;

[0020] FIG. 9A illustrates a front perspective view of a wildfire shelter having a first façade;

[0021] FIG. 9B illustrates a front perspective view of a wildfire shelter having a second façade;

[0022] FIG. 9C illustrates a first wildfire shelter coupling to a second wildfire shelter;

[0023] FIG. 10 is a perspective view of a wildfire shelter comprising a fire-resistant solar panel coupled to the sloped A-frame roof;

[0024] FIG. 11 illustrates a rear elevation cross-sectional view of the wildfire shelter comprising an off-grid electrical power system with solar charge controller, temperature-tolerant batteries, an optional DC to AC inverter, and cooling system comprising coiled tubes and / or vertical plate heat exchangers; and

[0025] FIG. 12 illustrates a rear elevation cross-sectional view of the wildfire shelter comprising an off-grid electrical power system with solar charge controller, temperature-tolerant batteries, an optional DC to AC inverter, and shallow cooling system comprising a horizontal plate heat exchanger.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0026] The following descriptions depict only example embodiments and are not to be considered limiting in scope. Any reference herein to “the invention” is not intended to restrict or limit the invention to exact features or steps of any one or more of the exemplary embodiments disclosed in the present specification. References to “one embodiment,”“an embodiment,”“various embodiments,” and the like, may indicate that the embodiment(s) so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment,” or “in an embodiment,” do not necessarily refer to the same embodiment, although they may.

[0027] Reference to the drawings is done throughout the disclosure using various numbers. The numbers used are for the convenience of the drafter only and the absence of numbers in an apparent sequence should not be considered limiting and does not imply that additional parts of that particular embodiment exist. Numbering patterns from one embodiment to the other need not imply that each embodiment has similar parts, although it may.

[0028] Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Unless otherwise expressly defined herein, such terms are intended to be given their broad, ordinary, and customary meaning not inconsistent with that applicable in the relevant industry and without restriction to any specific embodiment hereinafter described. As used herein, the article “a” is intended to include one or more items. When used herein to join a list of items, the term “or” denotes at least one of the items, but does not exclude a plurality of items of the list. For exemplary methods or processes, the sequence and / or arrangement of steps described herein are illustrative and not restrictive.

[0029] It should be understood that the steps of any such processes or methods are not limited to being carried out in any particular sequence, arrangement, or with any particular graphics or interface. Indeed, the steps of the disclosed processes or methods generally may be carried out in various sequences and arrangements while still falling within the scope of the present invention.

[0030] The term “coupled” may mean that two or more elements are in direct physical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.

[0031] The terms “comprising,”“including,”“having,” and the like, as used with respect to embodiments, are synonymous, and are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including, but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes, but is not limited to,” etc.).

[0032] As discussed earlier herein, there is a need for an above-ground, fireproof shelter capable of withstanding the extreme conditions associated with wildfires, including peak radiated thermal energy, high winds, and potential flooding. There is also a need for a system that maintains structural integrity by preventing excessive heat buildup in load-bearing components. In addition, such a shelter should incorporate integrated power and support systems to enhance safety and comfort during extended periods of isolation. The wildfire shelter disclosed herein solves these problems and others.

[0033] Generally, an above-ground, A-frame wildfire shelter designed to withstand extreme wildfire conditions is disclosed. The structure is fabricated entirely from non-combustible metals to ensure durability under severe thermal exposure. The A-frame roof configuration offers significant advantages, including reduced gravitational load and inherent angular bracing, as the opposing rafters support one another, and do not require purlins. Roofing panels are mounted directly to the rafters for structural integrity. To address prolonged exposure to temperatures approaching 1,000° C., the design incorporates passive cooling through hollow, rectangular rafters. These hollow rafters facilitate airflow, drawing cooler air from near ground level and discharging heated air above the roofline. Additionally, the A-frame geometry can be scaled to accommodate an integrated off-grid electrical system, enabling geothermal cooling to mitigate soak-back heat within the shelter. It will be appreciated that as used herein, “fireproof” means capable of withstanding temperatures approaching 1,000° C. for at least 30 minutes.

[0034] Referring now to FIG. 1, a chart is shown illustrating a wildfire burn profile. As understood, the burn profile has two components: a short-term, higher temperature fire “A” created by combustion of the foliage at the tops of larger trees, and a longer-term, lower temperature fire “B” of brush closer to the ground.

[0035] Referring to FIG. 2, a wildfire shelter 100 is shown comprising an A-frame assembly 102. The A-frame assembly 102 comprises a metal pitched roof 104 having two opposing sides with the same slope, with an open “V”103 at the top, replacing a standard apex. As will be explained more herein, the open V 103 allows for heat to escape from within hollow rafters of the A-frame assembly 102. In some embodiments, the wildfire shelter 100 is constructed entirely of metal and is configured to use the soil 106 as a heatsink. The A-frame assembly 102 eliminates high temperature interfaces which are open to smoke and ashes and are difficult to seal. Additionally, the wildfire shelter 100 needs no eaves or overhangs which can trap burning debris. Because the A-frame assembly 102 is all metal, and preferably stainless steel, heat radiation, shown at arrows 114, is reflected therefrom to aid in heat reduction.

[0036] FIG. 3 is a chart that illustrates the yield strength versus temperature for candidate material metals. These include stainless steel alloys, which may be used for an outer reflective surface. Stainless steel can provide reflectivity of 85% while maintaining enough strength to be self-supporting up to 1200° C. Stainless steel may use specially designed fastening methods, such as shown and described later herein with reference to FIG. 6. Stainless steel sheets, which are readily available and cost-effective, may be used in paneling and roofing for the wildfire shelter 100. Higher-performance steels, such as Inconel (nickel-chromium-based superalloy), may be used without departing herefrom.

[0037] Continuing with the chart of FIG. 3, the best load-carrying steels are structural steels which have a useful operating temperature up to 600° C. These structural steels may be used as rafters and, as discussed in more detail herein, are best utilized when configured to stay below 600° C.

[0038] The components that transmit thermal energy into the soil 106 must have high thermal conductivity relative to that of the soil 106. Aluminum alloys may be used, but should not be used above 400° C. Thermal resistance (degree / Watt) of major shelter structural components is calculated as R=L / k / A, where L is the length of the heat transfer path, k is the thermal conductivity, and A is the heat transfer surface area. The thermal heat transfer characteristics of the major components of the wildfire shelter 100 are, in some embodiments, as follows:Conductivity-Length-DeltaUseMaterialk = W / (m*° C.)mR = L / k / A(° C. / W)° C.° C.ReflectiveStainless16<0.001001100RoofSteelThermalAir Layers0.07@800 C.0.10.076500600InsulationUnderlaymentStainless16<0.00100600SteelRafter RibsStructural450.00150.01684516SteelInner RoofAluminum2500.0030.022116400ShellHeatsinkSoil,1.01.10.07638020MoistTotal0.1901080

[0039] Referring now to FIG. 4, an assembly of the wildfire shelter 100 is shown. As shown, the wildfire shelter 100 comprises a metal pitched roof 104 forming an A-frame assembly 102 with an open V 103 at the top. The metal pitched roof 104 may comprise a plurality of layers, including a first, outer panel 108 that is reflective and forms the roof, a second, intermediate steel panel 110 as underlayment, and a third, inner aluminum panel 112. The first, outer panel 108 is directly exposed to radiated thermal energy flux, illustrated at arrow 114, at levels as high as 100 KW / Square Meter and 1200° C., and is therefore preferably manufactured from stainless steel or other high-heat resistant materials. Generally, stainless steel can tolerate these high heats if isolated from induced mechanical stresses. Additionally, the surface is ideally reflective so as to aid in reflecting the thermal energy, as shown by arrow 114. A first air-insulation gap 116 is interposed between the first, outer panel 108 and the second, intermediate panel 110 to act as another barrier for radiated heat, as discussed below.

[0040] The first air-insulation gap 116 provides a high reliability insulator with no manufactured materials or organic binders. In some embodiments, the first air-insulation gap 116 comprises several layers and an overall height selected to limit heat flow as needed to reduce the temperature into the load-bearing structural steel components to less than 600° C. For example, the first, outer panel 108 may be a corrugated steel reflective panel 118 that forms the top of first air-insulation gap 116 having a total height (i.e., practical air gap) of 0.10 meters. This limits heat flow to Q=k*A*(T1-T2 / L=0.07*22.3*500 / 0.1=7,800 Watts, which is the common factor for defining the temperature drops for the heat transfer path at arrow 120 from the first, outer panel 108 to the second, intermediate panel 110 (e.g., steel underlayment). Arrow 122 shows the heat transfer path from the second, intermediate panel 110 (e.g., steel panel) to the inner panel 112 (e.g., aluminum panel) and hollow steel rafters 124, which may be heated to approximately 600° C. without failing, and supporting maximum roof loads at maximum wildfire temperatures of 1200° C.

[0041] The hollow steel rafters 124 are each open-ended to allow for convection, wherein cooler air enters at the bottom end 105 and flows up through each hollow rafter 124 to the top end at the open V 103, the open V 103 formed by the hollow steel rafters 124 on opposing sides abutting one another on their lower sides. As the air inside the hollow rafters 124 is heated, its density decreases, and the air rises through the rafters 124 to exit at the top, open V 103. The resulting airflow cools the inside walls of the hollow rafters 124 so as not to exceed their high-temperature strength limit. The hollow rafter 24 air inlets and exits are aerodynamically designed for smooth flow streamlines, minimum pressure drop, and maximum cooling flow. The hollow steel rafters 124 are coupled to the inner panel 112, which, in some embodiments, is preferably manufactured from aluminum. The inner panel 112 assists in transferring heat via the path shown at arrow 126 to the soil 106. In other words, the soil 106 acts as a heatsink for the wildfire shelter 100 via the aluminum inner panel 112, which extends directly into the soil 106.

[0042] FIG. 5A illustrates, in some embodiments, a front elevation cross-section of a wildfire shelter 100, partially disassembled (e.g., lacking exterior insulative portion 129, discussed later, on the right side) for ease of understanding. FIG. 5B illustrates a cross-section along the lines A-A of FIG. 5A, and FIG. 5C illustrates a partial view of the A-frame assembly 102 illustrating thermal paths. Referring to FIG. 5A, the A-frame assembly 102 is formed via a plurality of hollow steel rafters angled to abut one another in an “A” formation, with a first hollow steel rafter 124A on a first side and a second hollow steel rafter 124B on a second side. Each hollow steel rafter 124A-B is open-ended. In other words, the bottom end comprises a bottom opening 125A-B, and the top end comprises a top opening 127A-B.

[0043] As shown, the hollow steel rafters 124A-B form an open V 103 at the top of the A-frame assembly 102, where heat is able to escape to the environment (arrows 142 illustrating the heat escape path). FIG. 5B also illustrates heat convection 143 traveling through the hollow rafter 124B. A respective inner panel 112 is coupled to each rafter 124A-B, with an intermediate panel 110 coupled on the exterior side of the rafters 124A-B. In other words, the rafters 124A-B are interposed between the inner panel 112 and the intermediate panel 110. The outer panel 108 may then be coupled to the intermediate panel 110 and the rafter 124A via a plurality of fasteners 144 (only one shown for ease of understanding), which are preferably made of stainless steel or other metal. As mentioned earlier, the outer panel 108 and intermediate panel 110 is configured to comprise an air gap therebetween, functioning as insulation. Likewise, the width of the hollow rafters 124A-B form another insulative air gap between the intermediate panel 110 and the inner panel 112.

[0044] The outer panel 108 is preferably reflective, which aids in reflecting heat (thermal influx), as shown at arrows 114. In some embodiments, as shown in FIGS. 5A-B, additional layers between the outer panel 108 and the intermediate panel 110 may be used. For example, one or more metal sheets 128A-C may be interposed between the outer panel 108 and intermediate panel 110. In some embodiments, the metal sheets 128A-C may be made of stainless steel and configured to retain about 80% of their strength at 1,000° C. In some embodiments, the metal sheets 128A-C are rolled and corrugated and thereby provide additional insulation, both in metal and air gaps between each sheet 128A-C and between the outer panel 108 and intermediate panel 110. While three metal sheets 128A-C are shown in FIG. 5A, it will be appreciated that more or fewer may be used without departing herefrom.

[0045] Additionally, the inner layers 128A-C may also be replaced with steel separating members, such as steel beams, which may be hollow, to create insulative air gaps between the outer panel 108 and the intermediate panel 110. Further, an additional inside insulative layer 113 (ideally steel corrugated sheets) may be positioned between the inner panel 112 and the interior compartment 132, further protecting the interior compartment 132 from outside heat. While the thickness of the various panels 108-112 and sheets 128A-C may vary in the Figures, it will be appreciated that they need not vary and may be the same thickness, and that differing shadings and line thickness in the drawings are for ease in understanding the various components disclosed herein.

[0046] It will be appreciated that the plurality of panels 108-112 and sheets 128A-C may be coupled using threaded standoffs or other standard securement mechanisms, such as bolts, screws, or any other suitable fastening means, forming the exterior insulative portion 129 (FIG. 5B). Metal caps 130A-B may be coupled at the top and bottom of the A-frame assembly 102. These metal caps 130A-B seal the seams of the various panels to prevent ash or other debris from entering. It will be appreciated that the wildfire shelter 100 may be sized according to a user's needs. In some embodiments, the size of the interior compartment 132 is sufficient to provide two individuals with oxygen for a minimum of one day. Further the interior compartment 132 provides for a temperature-controlled space for personnel, emergency communication equipment, portable solar panels, and electric escape vehicle charging.

[0047] The A-frame assembly 102 is directly coupled to the soil via vertical heat transfer plates 134A-B, which may be made of aluminum or other thermally conductive material. In a preferred embodiment, the vertical heat transfer plates 134A-B are integral to the inner panel 112. In other words, a single aluminum panel on each side is shaped to form both the inner panel 112 and the vertical heat transfer plates 134A-B (one continuous metal sheet). However, the vertical heat transfer plates 134A-B may also be separate components that are coupled to the inner panel 112, such as through bolts, screws, or other fasteners. Further, while two heat transfer plates 134A-B are shown in FIG. 5A, it will be appreciated that the heat transfer plates 134A-B may be continuous or otherwise coupled to extend around the entire bottom perimeter under the A-frame assembly 102, similar to a foundation. However, in some embodiments, a concrete foundation 196 may also be used, although not required. In such instances, the heat transfer plates 134A-B may be coupled to the concrete foundation 196, such as through screws or other fasteners. Additionally, inner insulative layer 113 (e.g., stainless steel corrugated sheets) may be coupled to the inner panel 112, with an air gap therebetween, to provide an additional layer of insulation to the compartment 132. The inner insulative layer 113 may be coupled to aluminum brackets 117 that function as a further heat sink to the soil.

[0048] As a result, heat travels down the inner panel 112 and down inner insulative layer 113, via conduction, shown at heat transfer path 136, where it may be absorbed into the cool soil 106, shown at arrows 138 in FIG. 5A, via the vertical heat transfer plates 134A-B. As a result, the soil 106 functions as a natural heatsink. Likewise, and as best seen in FIGS. 5B-5C, exterior heat is not only reflected (e.g., arrow 114), but may travel upwardly, shown at arrow 140, through the hollow rafter 124B, where it may exit at the top opening 127B of the hollow rafter 124B at the top open V 103, indicated at arrow 142, or through a draft or the various insulative gaps between the panels 108-112. Smoke may also take this same path of upward travel, forming an exit plume at arrow 142.

[0049] The rafters 124A-B are ideally manufactured to be monolithic and smooth on the inside to enhance the induction of convective cooling flows and not to impede the heat transfer path (e.g., 136, 140) along the hollow rafters 124A-B. This dual heat transfer approach (i.e., convection and conduction) helps ensure that the hollow rafters 124A-B stay below the 600° C. limit.

[0050] Control of the temperature of the hollow steel rafters 124A-B to a safe limit is determined primarily by the ratio of the roof insulation resistance to the heat transfer plate to soil resistance. This should ideally be designed to be close to unity for the rafter temperature to be half of the roof outer metal temperature. This requires the maximum practical thermal resistance and insulation depth for the roof. It also requires a large soil heat exchanger plate area. The standard length (L) to dissipate thermal energy in soil is usually taken as 1.1 meters. This is implemented in the present disclosure by sinking a heat transfer plate 134 along the complete circumference of the shelter base (i.e., where the shelter 100 meets the soil 106) to a depth required to realize the minimum soil heat transfer. The maximum plate depth of the heat transfer plate 134 is chosen to be achievable during field assembly with automated methods, such as those utilized for electrical cable burial. Ideally, the vertical heat transfer plate 134 is integral to the aluminum inner panel 112 which is bolted directly to the hollow rafters 124A-B. The circumferential vertical heat transfer plate 134 further provides an integral lightweight, portable foundation for the shelter 100. As an example, bury this circumferential heat transfer plate 134 into the soil one meter to get the area required: A=4*W*D=4*12*0.3048=14.6 Meters Sq.

[0051] Referring to FIG. 6, in some embodiments, the fastening mechanism for the exterior insulative portion 129 and hollow rafters 124 may comprise a plurality of threaded standoffs 144, each comprising a spring washer 146 and / or flat washer, and may be secured via a head 148. The spring washer 146 controls the bolt load on the insulative portion 129 so that each layer is secured, but can move without damage during thermal expansion from fire temperature changes. In other words, the load applied to the steel sheets (e.g., outer panel 108) is controlled by the spring washer 146 and threaded standoff 144 to set loads and allow relative motion between layers of the exterior insulative portion 129. The holes in each layer for receiving the threaded standoffs 144 are drilled oversized to accommodate this movement and to provide for drilling tolerances so as not to buckle the metal sheets (e.g., 108, 128A-C, and 110). Overall, the combined depth of the standoffs 144 provides the desired air gap insulation value. In other words, an air-insulation gap is formed between each layer (108-112) via the threaded standoffs 144.

[0052] As discussed previously, the hollow steel rafter 124 is the core of the passive thermal management system. As the fire starts to locally subside, ground and air temperatures cool to below that of the hollow metal rafter 124 and A-frame assembly 102. This temperature difference creates a free convective flow through each hollow rafter 124 and upward over the smooth roof surface. This draws in cooler ground air, through bottom opening 125A-B, where it flows through the hollow rafter 124, which cools down the whole wildfire shelter 100 (e.g., the chimney effect) during the longer soak back period. This updraft cooling (e.g., flow from arrows 140 to 142) complements the structure conductive cooling (e.g., 136 to soil).

[0053] Referring now to FIG. 7, in some embodiments, the path for structure cooling by convection of heat from the bottom opening 125A of the hollow rafter 124 and inner panel 112 to the soil 106 is shown. The inner panel 112 is preferably made from highly conductive metals such as aluminum, and may have one or more insulative layers 113 coupled thereto, such as stainless steel corrugated sheets. An optional outer foundation comprises a mounting bracket 150 and additional vertical heat exchanger plates 134A. The bracket 150 is coupled (e.g., bolted) to the inner panel 112 and to the bottom of the hollow rafters 124, and extends along the sides of the wildfire shelter 100. The vertical heat exchanger plates 134A are coupled to the bracket 150 and also extend along the sides of the wildfire shelter 100. The bracket 150 and vertical heat exchanger plates 134A are inserted in a narrow trench about one meter deep (although depth may vary) to maximize the surface area for heat transfer to the soil 106. While bracket 150 is shown and described, it will be appreciated that it is not required, and that the heat exchanger plates 134A-B may be coupled to, or integrally manufactured with, the inner panel 112.

[0054] Additionally, in some embodiments, a conduit 152 brings rainwater from under the eaves (where bottom opening 125A is located) to the inner floor surface to enhance cooling heat transfer. The A-frame assembly 102 may be bolted to a base 154, which is preferably made from aluminum (e.g., aluminum beams) for the fieldable versions of the wildfire shelter 100, as will be discussed with regard to FIG. 8. The A-frame assembly 102 may be coupled to the base 154 to make a rigid triangular structure which does not require additional braces and is easily field transportable. In some installations, a standard concrete slab foundation may be used, instead of, or in addition to, the base 154.

[0055] Referring now to FIG. 8, in some embodiments, the base 154 may be fabricated from standard, purchased channel, T, or L sections of aluminum 155 and can be cut-to-size and coupled together using corner brackets 156. Horizontal metal heat exchanger plates 158 provide partial floors (or are otherwise incorporated therein) and serve as braces, and are all surrounded by a plurality of vertical heat transfer plates 134. While cooling has been discussed as being passive, it will be appreciated that active cooling may be used as well. For example, coolant water from a geothermal pump (not shown in this Fig.) is brought to the horizontal metal heat exchanger plates 158 through fittings 160. Finned aluminum posts 162 may provide additional thermal conductivity, functioning as heatsinks, and may likewise extend into the soil 106.

[0056] The base 154 is modular and portable, and may be easily assembled onsite. The horizontal metal heat exchanger plates 158 are ideally made of aluminum (or other lightweight, thermally conductive material) and contact the soil to function as a heatsink, thereby helping to maintain a cooler interior for occupants. The horizontal metal heat exchanger plates 158 may function as the floor inside the compartment 132.

[0057] Referring to FIGS. 9A-B, it will be appreciated that the exterior façade may vary, depending on the desired aesthetics. For example, as shown in FIG. 9A, the front end 164 may comprise another outer panel 108 and a door 166 therein, with the front end 164 and door 166 constructed in a manner similar to the A-frame assembly 102 (i.e., multi-layered panels with insulative air gaps therebetween). Door frames may be made manufactured from the same steel hollow rafters 124 (e.g., HSS) as the roof. The door 166 may be machined flat after assembly and fitted with fireproof ceramic rope which is pressed into a groove machined into the door frame. While the back end is not shown, it will be appreciated that it may be constructed similarly, with or without a door. It will also be appreciated that the door 166, or a plurality of doors, may be sized for different purposes. For example, people ingress / egress vs. equipment / vehicle ingress / egress.

[0058] Referring to FIG. 9B, the façade may be altered for a different aesthetic. For example, the front end 164 may comprise painted steel siding 168. The door 166 may comprise windows 170 with fireproof glass. In some embodiments, the windows 170 may further comprise hinged metal plates to further protect against extreme heat. The cool soil 106 provides short-term passive cooling via vertical heat transfer plates 134 with geothermal cooling as an option.

[0059] FIG. 9C illustrates a plurality of wildfire shelters 100A-B being horizontally coupled to one another, increasing the available compartment 132 space. This increase in size may be for additional occupancy, or may simply provide for additional oxygen and space. As shown, each wildfire shelter 100A-B may be a complete standalone shelter that is couplable to the other, such as via bolts or other fasteners, and may have overlapping sheet metal to cover any joint or seam between the two. The inner walls (e.g., steel siding 168) and door 166 may aid in both heat reduction and smoke prevention between the two compartments. However, it will be appreciated that the door 166 and / or wall (with steel siding 168) may be removed to create one compartment without departing herefrom.

[0060] Referring to FIG. 10, in some embodiments, the wildfire shelter 100 may comprise solar panels 172. The slope 174 of the A-frame assembly 102 may be selected to maximize absorption of solar radiation during short days. The slope 174 may also aid in self-cleaning of snow from panels 172. The solar panels 172 may be mounted on the A-frame assembly 102, preferably on the sunny and downwind side, and may be supplemented by portable solar panels stored inside of the wildfire shelter 100. The solar panels 172 may be removably coupled to the outer panel 108 of the A-frame assembly 102 using steel brackets 176. The solar panels 172 are sturdily secured to withstand heavy roof loads and high winds.

[0061] In some embodiments, a wire grate 178 may be positioned over the solar panels 172 to prevent damage by flying debris. The solar panels 172 may be mounted high enough to avoid damage by grass fires, but low enough to be replaced from the ground. The slope 174 may be configured to concentrate rainwater runoff to the side of the wildfire shelter 100 for wetting the soil 106 in a trench 180 for improving the efficiency of the heat exchanger plates 134, 158 and geothermal cooling system conduit / piping 152, 160.

[0062] Referring to FIG. 11, in some embodiments, the wildfire shelter 100 may house necessary electrical equipment which utilizes power from the roof solar panels 172. For example, power from the solar panels 172 may be routed to a charge controller 182 and then to one or more batteries 184 and directly to the geothermal pump 186, which may draw water or coolant through one or more in-ground coils 188 for cooling one or more horizontal metal heat exchanger plates 158 via fittings 160. While in-ground coils 188 are shown, it will be appreciated that cooling reservoirs or other heat-exchangers (e.g., radiator systems) may be used without departing herefrom.

[0063] A small inverter / charger 190 can provide AC power to equipment 192, such as communication equipment, an air supply / cooling system 194, and / or a portable satellite internet system, among others. Because the wildfire shelter 100 is made of metals, it may be used as a heatsink for all devices, eliminating the requirement for unreliable cooling fans. FIG. 11 also shows a preferred location of the trench 180 located in the soil 106 under the shade of the A-frame assembly 102.

[0064] Further, FIG. 11 illustrates an optional concrete foundation 196. As shown, the inner panel 112 extends into the soil 106 (thereby operating as vertical heat exchanger plates) and may be coupled (e.g., screwed, bolted, etc.) to the foundation 196 to provide for additional structural integrity, where needed. While only shown with hollow rafters 124, inner panel 112, and inside insulative layers 113, this is only for convenience and it will be appreciated that other layers, such as outer panel 108 and others, are included. One or more metal seals 115 may be placed at joint of the two inside insulative layers 113 and / or at the joint of the inner panels 112.

[0065] Referring to FIG. 12, a wildfire shelter 100 may comprise horizontal metal heat exchanger plates 158, which may be in contact with a floor 159 (or may function as the floor, in some embodiments). A plurality of heat exchanger members 161 may allow for conductivity with the soil 106. Additionally, as shown, the inner panel 112 may be configured to extend into the soil to form the vertical heat transfer plates. Additional layers, such as inside insulative layers 113 (e.g., corrugated stainless steel sheets), may be coupled to the interior side of inner panel 112, with an air gap therebetween, to provide for additional insulation and smoke prevention to the compartment 132. Further, one or more brackets 117 (e.g., aluminum brackets) may be used to add stability at the bend and to provide a heatsink mechanism to the inside insulative layer 113 to the soil 106. As appreciated, the wildfire shelter 100 may be easily assembled onsite, and may be installed into the ground using a trencher or similar device for embedding the vertical heat transfer plates (e.g., 134 and / or 112) into the soil 106.

[0066] The wildfire shelter 100 comprises a shelter to soil thermal resistance that is equal to, or smaller than, the roof insulation thermal resistance; a large soil heat transfer surface that is integral to the inner aluminum panel 112 and extends around the perimeter of the shelter, which may function as the foundation as well. Heat and smoke may be reduced by packing gaps, such as between the heat transfer plate and soil, with sand (the sand may also be selected to have a higher heat transfer coefficient than common soil types as well).

[0067] It will be appreciated that the wildfire shelter 100 disclosed herein may be assembled on site using metal fasteners (e.g., 144), without the use of seams, caulk, or welding, and may be modular for ease of portability. In other words, sections of the wildfire shelter 100 may be preassembled and / or transported and then easily assembled onsite via power tools, such as drills, to fasten the sections together. The foundation may be formed from the vertical heat transfer plates 134A-B, which are lightweight and may be inserted into the ground using a trencher or similar device. As assembled, the wildfire shelter 100 does not require caulking at the seams, and may instead rely on slip-fit configurations that are fastened via the standoffs 144 (or other fasteners). Adjoining panels are centered on the hollow rafters 124 to cover any seam and are tightly and individually fastened to the hollow rafters 124, such as via the standoffs 144. Differential expansion is accommodated by the spring-loaded seams (e.g., spring washer 146 and assembly shown in FIG. 6) on the outer surface.

[0068] Accordingly, it will be appreciated from the foregoing that the wildfire shelter 100 disclosed herein solves the need for an above-ground, fireproof shelter capable of withstanding the extreme conditions associated with wildfires, including peak radiated thermal energy, high winds, and potential flooding. It also solves the need for a system that maintains structural integrity by preventing excessive heat buildup in load-bearing components, and further incorporates integrated power and support systems to enhance safety and comfort during extended periods of isolation.

[0069] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage, and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention.

[0070] Exemplary embodiments are described above. No element, act, or instruction used in this description should be construed as important, necessary, critical, or essential unless explicitly described as such. Although only a few of the exemplary embodiments have been described in detail herein, those skilled in the art will readily appreciate that many modifications are possible in these exemplary embodiments without materially departing from the novel teachings and advantages herein. Accordingly, all such modifications are intended to be included within the scope of this invention.

Examples

Embodiment Construction

[0026]The following descriptions depict only example embodiments and are not to be considered limiting in scope. Any reference herein to “the invention” is not intended to restrict or limit the invention to exact features or steps of any one or more of the exemplary embodiments disclosed in the present specification. References to “one embodiment,”“an embodiment,”“various embodiments,” and the like, may indicate that the embodiment(s) so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment,” or “in an embodiment,” do not necessarily refer to the same embodiment, although they may.

[0027]Reference to the drawings is done throughout the disclosure using various numbers. The numbers used are for the convenience of the drafter only and the absence of numbers in an apparent sequence should not be considered limiting...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Ser. No. 63 / 770,560, filed on Mar. 12, 2025, which is incorporated herein by reference.TECHNICAL FIELD

[0002] This present disclosure relates to disaster survival shelters. More particularly, the present disclosure relates to wildfire shelters.BACKGROUND

[0003] Wildfires pose a severe and growing threat to human life, property, and infrastructure, particularly in forested regions and areas where urban development meets wildland environments. Despite established guidelines for access control, forest management, removal of combustible materials, and fire-resistant building practices, these measures are often inadequately implemented. As a result, the frequency and intensity of destructive wildfires continue to increase.

[0004] Current recommendations for surviving a wildfire frequently emphasize sheltering in place. However, most residential structures are constructed from combustible materials, making them highly vulnerable to ignition and structural failure under extreme fire conditions. Effective refuge from wildfire hazards requires an enclosed environment composed of non-combustible materials capable of withstanding flame-radiated surface temperatures exceeding 1,000° C. Existing solutions, such as portable, foil-wrapped fiberglass cocoons, have been employed by firefighters for short-term exposure, but offer limited protection and comfort during extended fire events.

[0005] Alternative approaches include underground shelters that leverage the earth's stable, cooler temperature as a thermal barrier. While these designs can provide longer-term protection, they present significant drawbacks: they must be sealed against water and smoke infiltration, are costly and complex to install, and often create accessibility challenges for individuals with physical limitations. Additionally, underground shelters can induce feelings of confinement and discomfort during prolonged occupancy.

[0006] Above-ground concrete shelters have also been introduced in the art, but typically offer minimal interior space for survival supplies and equipment, reducing their practicality for extended stays. Larger above-ground disaster structures incorporating steel canopy shields have been disclosed in the prior art as well; however, while these designs may be suitable for some disasters, these designs lack provisions for maintaining structural integrity under sustained exposure to extreme heat, high winds, and other environmental stresses associated with wildfire conditions.

[0007] Accordingly, there is a need for an above-ground shelter capable of withstanding the extreme conditions associated with wildfires, including peak radiated thermal energy, high winds, and potential flooding. There is also a need for a system that maintains structural integrity by preventing excessive heat buildup in load-bearing components. In addition, such a shelter should incorporate integrated power and support systems to enhance safety and comfort during extended periods of isolation. Current technologies fail to provide adequate protection for firefighters, essential equipment, and residential communities at risk from wildfires. A comprehensive solution should ensure durability under severe thermal exposure, resist environmental intrusions, and support occupant survivability and operational functionality under prolonged emergency conditions. The present disclosure seeks to solve these and other problems.SUMMARY OF EXAMPLE EMBODIMENTS

[0008] In some embodiments, a wildfire structure comprises an A-frame structure manufactured entirely of metal and / or other non-combustible components, resulting in a fireproof shelter. In some embodiments, the roof may comprise a plurality of layered metal sheets, such as stainless steel or other high-strength alloys. The metal sheets may be configured to provide one or more insulating layers and air flow channels to dissipate heat. The metal sheets may comprise a reflective surface to withstand elevated temperatures without excessive discoloration. In some embodiments, the wildfire structure comprises hollow steel rafters that are open-ended to allow for the passage of air and smoke therethrough.

[0009] In some embodiments, the wildfire structure further comprises a soil heat exchanger and a cooled compartment. In some embodiments, the roof is sized to provide adequate surface area for solar power to operate equipment inside the shelter, including an electric coolant pump for geothermal cooling of individuals and equipment therein.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a chart depicting a typical wildfire with burn temperature as a function of time;

[0011] FIG. 2 is a perspective view of a wildfire shelter;

[0012] FIG. 3 is a chart showing the yield strength of several metals that may be used to implement a wildfire shelter;

[0013] FIG. 4 is perspective view of a wildfire shelter showing the different metallic components and layers used in the A-frame shelter structure;

[0014] FIG. 5A is a front elevation cross-sectional view of a wildfire structure;

[0015] FIG. 5B is a cross-section taken along lines A-A of FIG. 5A illustrating a hollow, structural steel rafter as the basic load-carrying element of the wildfire shelter structure;

[0016] FIG. 5C is a detailed view of a hollow steel rafter and heating and cooling methods associated therewith;

[0017] FIG. 6 illustrates a front elevation cross-sectional view of a sheet spacer and mounting post (e.g., threaded standoffs) for attaching the metal sheets to the rafters;

[0018] FIG. 7 is a cross-sectional elevation view which shows the thermal paths and methods for transmitting heat from the rafters to an exhaust plume and from the rafters to the soil below;

[0019] FIG. 8 is a top plan view of an aluminum rail base for easy field assembly and maximum conduction of heat into the soil, comprising a geothermal cooling system;

[0020] FIG. 9A illustrates a front perspective view of a wildfire shelter having a first façade;

[0021] FIG. 9B illustrates a front perspective view of a wildfire shelter having a second façade;

[0022] FIG. 9C illustrates a first wildfire shelter coupling to a second wildfire shelter;

[0023] FIG. 10 is a perspective view of a wildfire shelter comprising a fire-resistant solar panel coupled to the sloped A-frame roof;

[0024] FIG. 11 illustrates a rear elevation cross-sectional view of the wildfire shelter comprising an off-grid electrical power system with solar charge controller, temperature-tolerant batteries, an optional DC to AC inverter, and cooling system comprising coiled tubes and / or vertical plate heat exchangers; and

[0025] FIG. 12 illustrates a rear elevation cross-sectional view of the wildfire shelter comprising an off-grid electrical power system with solar charge controller, temperature-tolerant batteries, an optional DC to AC inverter, and shallow cooling system comprising a horizontal plate heat exchanger.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0026] The following descriptions depict only example embodiments and are not to be considered limiting in scope. Any reference herein to “the invention” is not intended to restrict or limit the invention to exact features or steps of any one or more of the exemplary embodiments disclosed in the present specification. References to “one embodiment,”“an embodiment,”“various embodiments,” and the like, may indicate that the embodiment(s) so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment,” or “in an embodiment,” do not necessarily refer to the same embodiment, although they may.

[0027] Reference to the drawings is done throughout the disclosure using various numbers. The numbers used are for the convenience of the drafter only and the absence of numbers in an apparent sequence should not be considered limiting and does not imply that additional parts of that particular embodiment exist. Numbering patterns from one embodiment to the other need not imply that each embodiment has similar parts, although it may.

[0028] Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Unless otherwise expressly defined herein, such terms are intended to be given their broad, ordinary, and customary meaning not inconsistent with that applicable in the relevant industry and without restriction to any specific embodiment hereinafter described. As used herein, the article “a” is intended to include one or more items. When used herein to join a list of items, the term “or” denotes at least one of the items, but does not exclude a plurality of items of the list. For exemplary methods or processes, the sequence and / or arrangement of steps described herein are illustrative and not restrictive.

[0029] It should be understood that the steps of any such processes or methods are not limited to being carried out in any particular sequence, arrangement, or with any particular graphics or interface. Indeed, the steps of the disclosed processes or methods generally may be carried out in various sequences and arrangements while still falling within the scope of the present invention.

[0030] The term “coupled” may mean that two or more elements are in direct physical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.

[0031] The terms “comprising,”“including,”“having,” and the like, as used with respect to embodiments, are synonymous, and are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including, but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes, but is not limited to,” etc.).

[0032] As discussed earlier herein, there is a need for an above-ground, fireproof shelter capable of withstanding the extreme conditions associated with wildfires, including peak radiated thermal energy, high winds, and potential flooding. There is also a need for a system that maintains structural integrity by preventing excessive heat buildup in load-bearing components. In addition, such a shelter should incorporate integrated power and support systems to enhance safety and comfort during extended periods of isolation. The wildfire shelter disclosed herein solves these problems and others.

[0033] Generally, an above-ground, A-frame wildfire shelter designed to withstand extreme wildfire conditions is disclosed. The structure is fabricated entirely from non-combustible metals to ensure durability under severe thermal exposure. The A-frame roof configuration offers significant advantages, including reduced gravitational load and inherent angular bracing, as the opposing rafters support one another, and do not require purlins. Roofing panels are mounted directly to the rafters for structural integrity. To address prolonged exposure to temperatures approaching 1,000° C., the design incorporates passive cooling through hollow, rectangular rafters. These hollow rafters facilitate airflow, drawing cooler air from near ground level and discharging heated air above the roofline. Additionally, the A-frame geometry can be scaled to accommodate an integrated off-grid electrical system, enabling geothermal cooling to mitigate soak-back heat within the shelter. It will be appreciated that as used herein, “fireproof” means capable of withstanding temperatures approaching 1,000° C. for at least 30 minutes.

[0034] Referring now to FIG. 1, a chart is shown illustrating a wildfire burn profile. As understood, the burn profile has two components: a short-term, higher temperature fire “A” created by combustion of the foliage at the tops of larger trees, and a longer-term, lower temperature fire “B” of brush closer to the ground.

[0035] Referring to FIG. 2, a wildfire shelter 100 is shown comprising an A-frame assembly 102. The A-frame assembly 102 comprises a metal pitched roof 104 having two opposing sides with the same slope, with an open “V”103 at the top, replacing a standard apex. As will be explained more herein, the open V 103 allows for heat to escape from within hollow rafters of the A-frame assembly 102. In some embodiments, the wildfire shelter 100 is constructed entirely of metal and is configured to use the soil 106 as a heatsink. The A-frame assembly 102 eliminates high temperature interfaces which are open to smoke and ashes and are difficult to seal. Additionally, the wildfire shelter 100 needs no eaves or overhangs which can trap burning debris. Because the A-frame assembly 102 is all metal, and preferably stainless steel, heat radiation, shown at arrows 114, is reflected therefrom to aid in heat reduction.

[0036] FIG. 3 is a chart that illustrates the yield strength versus temperature for candidate material metals. These include stainless steel alloys, which may be used for an outer reflective surface. Stainless steel can provide reflectivity of 85% while maintaining enough strength to be self-supporting up to 1200° C. Stainless steel may use specially designed fastening methods, such as shown and described later herein with reference to FIG. 6. Stainless steel sheets, which are readily available and cost-effective, may be used in paneling and roofing for the wildfire shelter 100. Higher-performance steels, such as Inconel (nickel-chromium-based superalloy), may be used without departing herefrom.

[0037] Continuing with the chart of FIG. 3, the best load-carrying steels are structural steels which have a useful operating temperature up to 600° C. These structural steels may be used as rafters and, as discussed in more detail herein, are best utilized when configured to stay below 600° C.

[0038] The components that transmit thermal energy into the soil 106 must have high thermal conductivity relative to that of the soil 106. Aluminum alloys may be used, but should not be used above 400° C. Thermal resistance (degree / Watt) of major shelter structural components is calculated as R=L / k / A, where L is the length of the heat transfer path, k is the thermal conductivity, and A is the heat transfer surface area. The thermal heat transfer characteristics of the major components of the wildfire shelter 100 are, in some embodiments, as follows:Conductivity-Length-DeltaUseMaterialk = W / (m*° C.)mR = L / k / A(° C. / W)° C.° C.ReflectiveStainless16<0.001001100RoofSteelThermalAir Layers0.07@800 C.0.10.076500600InsulationUnderlaymentStainless16<0.00100600SteelRafter RibsStructural450.00150.01684516SteelInner RoofAluminum2500.0030.022116400ShellHeatsinkSoil,1.01.10.07638020MoistTotal0.1901080

[0039] Referring now to FIG. 4, an assembly of the wildfire shelter 100 is shown. As shown, the wildfire shelter 100 comprises a metal pitched roof 104 forming an A-frame assembly 102 with an open V 103 at the top. The metal pitched roof 104 may comprise a plurality of layers, including a first, outer panel 108 that is reflective and forms the roof, a second, intermediate steel panel 110 as underlayment, and a third, inner aluminum panel 112. The first, outer panel 108 is directly exposed to radiated thermal energy flux, illustrated at arrow 114, at levels as high as 100 KW / Square Meter and 1200° C., and is therefore preferably manufactured from stainless steel or other high-heat resistant materials. Generally, stainless steel can tolerate these high heats if isolated from induced mechanical stresses. Additionally, the surface is ideally reflective so as to aid in reflecting the thermal energy, as shown by arrow 114. A first air-insulation gap 116 is interposed between the first, outer panel 108 and the second, intermediate panel 110 to act as another barrier for radiated heat, as discussed below.

[0040] The first air-insulation gap 116 provides a high reliability insulator with no manufactured materials or organic binders. In some embodiments, the first air-insulation gap 116 comprises several layers and an overall height selected to limit heat flow as needed to reduce the temperature into the load-bearing structural steel components to less than 600° C. For example, the first, outer panel 108 may be a corrugated steel reflective panel 118 that forms the top of first air-insulation gap 116 having a total height (i.e., practical air gap) of 0.10 meters. This limits heat flow to Q=k*A*(T1-T2 / L=0.07*22.3*500 / 0.1=7,800 Watts, which is the common factor for defining the temperature drops for the heat transfer path at arrow 120 from the first, outer panel 108 to the second, intermediate panel 110 (e.g., steel underlayment). Arrow 122 shows the heat transfer path from the second, intermediate panel 110 (e.g., steel panel) to the inner panel 112 (e.g., aluminum panel) and hollow steel rafters 124, which may be heated to approximately 600° C. without failing, and supporting maximum roof loads at maximum wildfire temperatures of 1200° C.

[0041] The hollow steel rafters 124 are each open-ended to allow for convection, wherein cooler air enters at the bottom end 105 and flows up through each hollow rafter 124 to the top end at the open V 103, the open V 103 formed by the hollow steel rafters 124 on opposing sides abutting one another on their lower sides. As the air inside the hollow rafters 124 is heated, its density decreases, and the air rises through the rafters 124 to exit at the top, open V 103. The resulting airflow cools the inside walls of the hollow rafters 124 so as not to exceed their high-temperature strength limit. The hollow rafter 24 air inlets and exits are aerodynamically designed for smooth flow streamlines, minimum pressure drop, and maximum cooling flow. The hollow steel rafters 124 are coupled to the inner panel 112, which, in some embodiments, is preferably manufactured from aluminum. The inner panel 112 assists in transferring heat via the path shown at arrow 126 to the soil 106. In other words, the soil 106 acts as a heatsink for the wildfire shelter 100 via the aluminum inner panel 112, which extends directly into the soil 106.

[0042] FIG. 5A illustrates, in some embodiments, a front elevation cross-section of a wildfire shelter 100, partially disassembled (e.g., lacking exterior insulative portion 129, discussed later, on the right side) for ease of understanding. FIG. 5B illustrates a cross-section along the lines A-A of FIG. 5A, and FIG. 5C illustrates a partial view of the A-frame assembly 102 illustrating thermal paths. Referring to FIG. 5A, the A-frame assembly 102 is formed via a plurality of hollow steel rafters angled to abut one another in an “A” formation, with a first hollow steel rafter 124A on a first side and a second hollow steel rafter 124B on a second side. Each hollow steel rafter 124A-B is open-ended. In other words, the bottom end comprises a bottom opening 125A-B, and the top end comprises a top opening 127A-B.

[0043] As shown, the hollow steel rafters 124A-B form an open V 103 at the top of the A-frame assembly 102, where heat is able to escape to the environment (arrows 142 illustrating the heat escape path). FIG. 5B also illustrates heat convection 143 traveling through the hollow rafter 124B. A respective inner panel 112 is coupled to each rafter 124A-B, with an intermediate panel 110 coupled on the exterior side of the rafters 124A-B. In other words, the rafters 124A-B are interposed between the inner panel 112 and the intermediate panel 110. The outer panel 108 may then be coupled to the intermediate panel 110 and the rafter 124A via a plurality of fasteners 144 (only one shown for ease of understanding), which are preferably made of stainless steel or other metal. As mentioned earlier, the outer panel 108 and intermediate panel 110 is configured to comprise an air gap therebetween, functioning as insulation. Likewise, the width of the hollow rafters 124A-B form another insulative air gap between the intermediate panel 110 and the inner panel 112.

[0044] The outer panel 108 is preferably reflective, which aids in reflecting heat (thermal influx), as shown at arrows 114. In some embodiments, as shown in FIGS. 5A-B, additional layers between the outer panel 108 and the intermediate panel 110 may be used. For example, one or more metal sheets 128A-C may be interposed between the outer panel 108 and intermediate panel 110. In some embodiments, the metal sheets 128A-C may be made of stainless steel and configured to retain about 80% of their strength at 1,000° C. In some embodiments, the metal sheets 128A-C are rolled and corrugated and thereby provide additional insulation, both in metal and air gaps between each sheet 128A-C and between the outer panel 108 and intermediate panel 110. While three metal sheets 128A-C are shown in FIG. 5A, it will be appreciated that more or fewer may be used without departing herefrom.

[0045] Additionally, the inner layers 128A-C may also be replaced with steel separating members, such as steel beams, which may be hollow, to create insulative air gaps between the outer panel 108 and the intermediate panel 110. Further, an additional inside insulative layer 113 (ideally steel corrugated sheets) may be positioned between the inner panel 112 and the interior compartment 132, further protecting the interior compartment 132 from outside heat. While the thickness of the various panels 108-112 and sheets 128A-C may vary in the Figures, it will be appreciated that they need not vary and may be the same thickness, and that differing shadings and line thickness in the drawings are for ease in understanding the various components disclosed herein.

[0046] It will be appreciated that the plurality of panels 108-112 and sheets 128A-C may be coupled using threaded standoffs or other standard securement mechanisms, such as bolts, screws, or any other suitable fastening means, forming the exterior insulative portion 129 (FIG. 5B). Metal caps 130A-B may be coupled at the top and bottom of the A-frame assembly 102. These metal caps 130A-B seal the seams of the various panels to prevent ash or other debris from entering. It will be appreciated that the wildfire shelter 100 may be sized according to a user's needs. In some embodiments, the size of the interior compartment 132 is sufficient to provide two individuals with oxygen for a minimum of one day. Further the interior compartment 132 provides for a temperature-controlled space for personnel, emergency communication equipment, portable solar panels, and electric escape vehicle charging.

[0047] The A-frame assembly 102 is directly coupled to the soil via vertical heat transfer plates 134A-B, which may be made of aluminum or other thermally conductive material. In a preferred embodiment, the vertical heat transfer plates 134A-B are integral to the inner panel 112. In other words, a single aluminum panel on each side is shaped to form both the inner panel 112 and the vertical heat transfer plates 134A-B (one continuous metal sheet). However, the vertical heat transfer plates 134A-B may also be separate components that are coupled to the inner panel 112, such as through bolts, screws, or other fasteners. Further, while two heat transfer plates 134A-B are shown in FIG. 5A, it will be appreciated that the heat transfer plates 134A-B may be continuous or otherwise coupled to extend around the entire bottom perimeter under the A-frame assembly 102, similar to a foundation. However, in some embodiments, a concrete foundation 196 may also be used, although not required. In such instances, the heat transfer plates 134A-B may be coupled to the concrete foundation 196, such as through screws or other fasteners. Additionally, inner insulative layer 113 (e.g., stainless steel corrugated sheets) may be coupled to the inner panel 112, with an air gap therebetween, to provide an additional layer of insulation to the compartment 132. The inner insulative layer 113 may be coupled to aluminum brackets 117 that function as a further heat sink to the soil.

[0048] As a result, heat travels down the inner panel 112 and down inner insulative layer 113, via conduction, shown at heat transfer path 136, where it may be absorbed into the cool soil 106, shown at arrows 138 in FIG. 5A, via the vertical heat transfer plates 134A-B. As a result, the soil 106 functions as a natural heatsink. Likewise, and as best seen in FIGS. 5B-5C, exterior heat is not only reflected (e.g., arrow 114), but may travel upwardly, shown at arrow 140, through the hollow rafter 124B, where it may exit at the top opening 127B of the hollow rafter 124B at the top open V 103, indicated at arrow 142, or through a draft or the various insulative gaps between the panels 108-112. Smoke may also take this same path of upward travel, forming an exit plume at arrow 142.

[0049] The rafters 124A-B are ideally manufactured to be monolithic and smooth on the inside to enhance the induction of convective cooling flows and not to impede the heat transfer path (e.g., 136, 140) along the hollow rafters 124A-B. This dual heat transfer approach (i.e., convection and conduction) helps ensure that the hollow rafters 124A-B stay below the 600° C. limit.

[0050] Control of the temperature of the hollow steel rafters 124A-B to a safe limit is determined primarily by the ratio of the roof insulation resistance to the heat transfer plate to soil resistance. This should ideally be designed to be close to unity for the rafter temperature to be half of the roof outer metal temperature. This requires the maximum practical thermal resistance and insulation depth for the roof. It also requires a large soil heat exchanger plate area. The standard length (L) to dissipate thermal energy in soil is usually taken as 1.1 meters. This is implemented in the present disclosure by sinking a heat transfer plate 134 along the complete circumference of the shelter base (i.e., where the shelter 100 meets the soil 106) to a depth required to realize the minimum soil heat transfer. The maximum plate depth of the heat transfer plate 134 is chosen to be achievable during field assembly with automated methods, such as those utilized for electrical cable burial. Ideally, the vertical heat transfer plate 134 is integral to the aluminum inner panel 112 which is bolted directly to the hollow rafters 124A-B. The circumferential vertical heat transfer plate 134 further provides an integral lightweight, portable foundation for the shelter 100. As an example, bury this circumferential heat transfer plate 134 into the soil one meter to get the area required: A=4*W*D=4*12*0.3048=14.6 Meters Sq.

[0051] Referring to FIG. 6, in some embodiments, the fastening mechanism for the exterior insulative portion 129 and hollow rafters 124 may comprise a plurality of threaded standoffs 144, each comprising a spring washer 146 and / or flat washer, and may be secured via a head 148. The spring washer 146 controls the bolt load on the insulative portion 129 so that each layer is secured, but can move without damage during thermal expansion from fire temperature changes. In other words, the load applied to the steel sheets (e.g., outer panel 108) is controlled by the spring washer 146 and threaded standoff 144 to set loads and allow relative motion between layers of the exterior insulative portion 129. The holes in each layer for receiving the threaded standoffs 144 are drilled oversized to accommodate this movement and to provide for drilling tolerances so as not to buckle the metal sheets (e.g., 108, 128A-C, and 110). Overall, the combined depth of the standoffs 144 provides the desired air gap insulation value. In other words, an air-insulation gap is formed between each layer (108-112) via the threaded standoffs 144.

[0052] As discussed previously, the hollow steel rafter 124 is the core of the passive thermal management system. As the fire starts to locally subside, ground and air temperatures cool to below that of the hollow metal rafter 124 and A-frame assembly 102. This temperature difference creates a free convective flow through each hollow rafter 124 and upward over the smooth roof surface. This draws in cooler ground air, through bottom opening 125A-B, where it flows through the hollow rafter 124, which cools down the whole wildfire shelter 100 (e.g., the chimney effect) during the longer soak back period. This updraft cooling (e.g., flow from arrows 140 to 142) complements the structure conductive cooling (e.g., 136 to soil).

[0053] Referring now to FIG. 7, in some embodiments, the path for structure cooling by convection of heat from the bottom opening 125A of the hollow rafter 124 and inner panel 112 to the soil 106 is shown. The inner panel 112 is preferably made from highly conductive metals such as aluminum, and may have one or more insulative layers 113 coupled thereto, such as stainless steel corrugated sheets. An optional outer foundation comprises a mounting bracket 150 and additional vertical heat exchanger plates 134A. The bracket 150 is coupled (e.g., bolted) to the inner panel 112 and to the bottom of the hollow rafters 124, and extends along the sides of the wildfire shelter 100. The vertical heat exchanger plates 134A are coupled to the bracket 150 and also extend along the sides of the wildfire shelter 100. The bracket 150 and vertical heat exchanger plates 134A are inserted in a narrow trench about one meter deep (although depth may vary) to maximize the surface area for heat transfer to the soil 106. While bracket 150 is shown and described, it will be appreciated that it is not required, and that the heat exchanger plates 134A-B may be coupled to, or integrally manufactured with, the inner panel 112.

[0054] Additionally, in some embodiments, a conduit 152 brings rainwater from under the eaves (where bottom opening 125A is located) to the inner floor surface to enhance cooling heat transfer. The A-frame assembly 102 may be bolted to a base 154, which is preferably made from aluminum (e.g., aluminum beams) for the fieldable versions of the wildfire shelter 100, as will be discussed with regard to FIG. 8. The A-frame assembly 102 may be coupled to the base 154 to make a rigid triangular structure which does not require additional braces and is easily field transportable. In some installations, a standard concrete slab foundation may be used, instead of, or in addition to, the base 154.

[0055] Referring now to FIG. 8, in some embodiments, the base 154 may be fabricated from standard, purchased channel, T, or L sections of aluminum 155 and can be cut-to-size and coupled together using corner brackets 156. Horizontal metal heat exchanger plates 158 provide partial floors (or are otherwise incorporated therein) and serve as braces, and are all surrounded by a plurality of vertical heat transfer plates 134. While cooling has been discussed as being passive, it will be appreciated that active cooling may be used as well. For example, coolant water from a geothermal pump (not shown in this Fig.) is brought to the horizontal metal heat exchanger plates 158 through fittings 160. Finned aluminum posts 162 may provide additional thermal conductivity, functioning as heatsinks, and may likewise extend into the soil 106.

[0056] The base 154 is modular and portable, and may be easily assembled onsite. The horizontal metal heat exchanger plates 158 are ideally made of aluminum (or other lightweight, thermally conductive material) and contact the soil to function as a heatsink, thereby helping to maintain a cooler interior for occupants. The horizontal metal heat exchanger plates 158 may function as the floor inside the compartment 132.

[0057] Referring to FIGS. 9A-B, it will be appreciated that the exterior façade may vary, depending on the desired aesthetics. For example, as shown in FIG. 9A, the front end 164 may comprise another outer panel 108 and a door 166 therein, with the front end 164 and door 166 constructed in a manner similar to the A-frame assembly 102 (i.e., multi-layered panels with insulative air gaps therebetween). Door frames may be made manufactured from the same steel hollow rafters 124 (e.g., HSS) as the roof. The door 166 may be machined flat after assembly and fitted with fireproof ceramic rope which is pressed into a groove machined into the door frame. While the back end is not shown, it will be appreciated that it may be constructed similarly, with or without a door. It will also be appreciated that the door 166, or a plurality of doors, may be sized for different purposes. For example, people ingress / egress vs. equipment / vehicle ingress / egress.

[0058] Referring to FIG. 9B, the façade may be altered for a different aesthetic. For example, the front end 164 may comprise painted steel siding 168. The door 166 may comprise windows 170 with fireproof glass. In some embodiments, the windows 170 may further comprise hinged metal plates to further protect against extreme heat. The cool soil 106 provides short-term passive cooling via vertical heat transfer plates 134 with geothermal cooling as an option.

[0059] FIG. 9C illustrates a plurality of wildfire shelters 100A-B being horizontally coupled to one another, increasing the available compartment 132 space. This increase in size may be for additional occupancy, or may simply provide for additional oxygen and space. As shown, each wildfire shelter 100A-B may be a complete standalone shelter that is couplable to the other, such as via bolts or other fasteners, and may have overlapping sheet metal to cover any joint or seam between the two. The inner walls (e.g., steel siding 168) and door 166 may aid in both heat reduction and smoke prevention between the two compartments. However, it will be appreciated that the door 166 and / or wall (with steel siding 168) may be removed to create one compartment without departing herefrom.

[0060] Referring to FIG. 10, in some embodiments, the wildfire shelter 100 may comprise solar panels 172. The slope 174 of the A-frame assembly 102 may be selected to maximize absorption of solar radiation during short days. The slope 174 may also aid in self-cleaning of snow from panels 172. The solar panels 172 may be mounted on the A-frame assembly 102, preferably on the sunny and downwind side, and may be supplemented by portable solar panels stored inside of the wildfire shelter 100. The solar panels 172 may be removably coupled to the outer panel 108 of the A-frame assembly 102 using steel brackets 176. The solar panels 172 are sturdily secured to withstand heavy roof loads and high winds.

[0061] In some embodiments, a wire grate 178 may be positioned over the solar panels 172 to prevent damage by flying debris. The solar panels 172 may be mounted high enough to avoid damage by grass fires, but low enough to be replaced from the ground. The slope 174 may be configured to concentrate rainwater runoff to the side of the wildfire shelter 100 for wetting the soil 106 in a trench 180 for improving the efficiency of the heat exchanger plates 134, 158 and geothermal cooling system conduit / piping 152, 160.

[0062] Referring to FIG. 11, in some embodiments, the wildfire shelter 100 may house necessary electrical equipment which utilizes power from the roof solar panels 172. For example, power from the solar panels 172 may be routed to a charge controller 182 and then to one or more batteries 184 and directly to the geothermal pump 186, which may draw water or coolant through one or more in-ground coils 188 for cooling one or more horizontal metal heat exchanger plates 158 via fittings 160. While in-ground coils 188 are shown, it will be appreciated that cooling reservoirs or other heat-exchangers (e.g., radiator systems) may be used without departing herefrom.

[0063] A small inverter / charger 190 can provide AC power to equipment 192, such as communication equipment, an air supply / cooling system 194, and / or a portable satellite internet system, among others. Because the wildfire shelter 100 is made of metals, it may be used as a heatsink for all devices, eliminating the requirement for unreliable cooling fans. FIG. 11 also shows a preferred location of the trench 180 located in the soil 106 under the shade of the A-frame assembly 102.

[0064] Further, FIG. 11 illustrates an optional concrete foundation 196. As shown, the inner panel 112 extends into the soil 106 (thereby operating as vertical heat exchanger plates) and may be coupled (e.g., screwed, bolted, etc.) to the foundation 196 to provide for additional structural integrity, where needed. While only shown with hollow rafters 124, inner panel 112, and inside insulative layers 113, this is only for convenience and it will be appreciated that other layers, such as outer panel 108 and others, are included. One or more metal seals 115 may be placed at joint of the two inside insulative layers 113 and / or at the joint of the inner panels 112.

[0065] Referring to FIG. 12, a wildfire shelter 100 may comprise horizontal metal heat exchanger plates 158, which may be in contact with a floor 159 (or may function as the floor, in some embodiments). A plurality of heat exchanger members 161 may allow for conductivity with the soil 106. Additionally, as shown, the inner panel 112 may be configured to extend into the soil to form the vertical heat transfer plates. Additional layers, such as inside insulative layers 113 (e.g., corrugated stainless steel sheets), may be coupled to the interior side of inner panel 112, with an air gap therebetween, to provide for additional insulation and smoke prevention to the compartment 132. Further, one or more brackets 117 (e.g., aluminum brackets) may be used to add stability at the bend and to provide a heatsink mechanism to the inside insulative layer 113 to the soil 106. As appreciated, the wildfire shelter 100 may be easily assembled onsite, and may be installed into the ground using a trencher or similar device for embedding the vertical heat transfer plates (e.g., 134 and / or 112) into the soil 106.

[0066] The wildfire shelter 100 comprises a shelter to soil thermal resistance that is equal to, or smaller than, the roof insulation thermal resistance; a large soil heat transfer surface that is integral to the inner aluminum panel 112 and extends around the perimeter of the shelter, which may function as the foundation as well. Heat and smoke may be reduced by packing gaps, such as between the heat transfer plate and soil, with sand (the sand may also be selected to have a higher heat transfer coefficient than common soil types as well).

[0067] It will be appreciated that the wildfire shelter 100 disclosed herein may be assembled on site using metal fasteners (e.g., 144), without the use of seams, caulk, or welding, and may be modular for ease of portability. In other words, sections of the wildfire shelter 100 may be preassembled and / or transported and then easily assembled onsite via power tools, such as drills, to fasten the sections together. The foundation may be formed from the vertical heat transfer plates 134A-B, which are lightweight and may be inserted into the ground using a trencher or similar device. As assembled, the wildfire shelter 100 does not require caulking at the seams, and may instead rely on slip-fit configurations that are fastened via the standoffs 144 (or other fasteners). Adjoining panels are centered on the hollow rafters 124 to cover any seam and are tightly and individually fastened to the hollow rafters 124, such as via the standoffs 144. Differential expansion is accommodated by the spring-loaded seams (e.g., spring washer 146 and assembly shown in FIG. 6) on the outer surface.

[0068] Accordingly, it will be appreciated from the foregoing that the wildfire shelter 100 disclosed herein solves the need for an above-ground, fireproof shelter capable of withstanding the extreme conditions associated with wildfires, including peak radiated thermal energy, high winds, and potential flooding. It also solves the need for a system that maintains structural integrity by preventing excessive heat buildup in load-bearing components, and further incorporates integrated power and support systems to enhance safety and comfort during extended periods of isolation.

[0069] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage, and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention.

[0070] Exemplary embodiments are described above. No element, act, or instruction used in this description should be construed as important, necessary, critical, or essential unless explicitly described as such. Although only a few of the exemplary embodiments have been described in detail herein, those skilled in the art will readily appreciate that many modifications are possible in these exemplary embodiments without materially departing from the novel teachings and advantages herein. Accordingly, all such modifications are intended to be included within the scope of this invention.

Examples

Embodiment Construction

[0026]The following descriptions depict only example embodiments and are not to be considered limiting in scope. Any reference herein to “the invention” is not intended to restrict or limit the invention to exact features or steps of any one or more of the exemplary embodiments disclosed in the present specification. References to “one embodiment,”“an embodiment,”“various embodiments,” and the like, may indicate that the embodiment(s) so described may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Further, repeated use of the phrase “in one embodiment,” or “in an embodiment,” do not necessarily refer to the same embodiment, although they may.

[0027]Reference to the drawings is done throughout the disclosure using various numbers. The numbers used are for the convenience of the drafter only and the absence of numbers in an apparent sequence should not be considered limiting...

Claims

1. An above-ground wildfire shelter, comprising:an all metal, fireproof A-frame assembly, comprising:a plurality of hollow steel rafters, each hollow steel rafter open on a top end and open on a bottom end,an outer reflective steel panel,an intermediate steel panel, andan inner aluminum panel;one or more vertical heat transfer plates coupled to the A-frame assembly and extending into soil, wherein the one or more vertical heat transfer plates and the soil cooperate as a heatsink, the one or more vertical heat transfer plates further forming a foundation for the all metal, fireproof A-frame assembly; andwherein the all metal, fireproof A-frame assembly forms an inner compartment.

2. The above-ground wildfire shelter of claim 1, wherein the plurality of hollow steel rafters are interposed between the intermediate steel panel and the inner aluminum panel.

3. The above-ground wildfire shelter of claim 1, wherein the outer reflective steel panel is corrugated stainless steel.

4. The above-ground wildfire shelter of claim 1, further comprising an air-insulation gap between at least the outer steel panel and the intermediate steel panel.

5. The above-ground wildfire shelter of claim 1, further comprising one or more stainless steel sheets interposed between the outer steel panel and the intermediate steel panel.

6. The above-ground wildfire shelter of claim 5, comprising an air-insulation gap between the outer steel panel and a first stainless steel sheet, a second air-insulation gap between the first and second stainless steel sheets, a third air-insulation gap between the second and third stainless steel sheets, and a fourth air-insulation gap between the third stainless steel sheet and the intermediate panel.

7. The above-ground wildfire shelter of claim 6, wherein a height of each air-insulation gap is configured via a respective threaded standoff.

8. The above-ground wildfire shelter of claim 1, further comprising one or more inside insulative layers coupled to the inner aluminum panel with an air gap therebetween.

9. The above-ground wildfire shelter of claim 1, further comprising a base comprises a plurality of aluminum structural beams.

10. The above-ground wildfire shelter of claim 1, further comprising a plurality of horizontal heat exchanger plates configured as a floor.

11. The above-ground wildfire shelter of claim 10, further comprising one or more conduits to transport rainwater.

12. The above-ground wildfire shelter of claim 1, further comprising solar panels coupled to the outer reflective steel panel.

13. The above-ground wildfire shelter of claim 12, further comprising a charge controller, at least one battery, and an inverter.

14. The above-ground wildfire shelter of claim 1, further comprising a geothermal pump configured to cool a horizontal heat exchanger plate at a floor.

15. An above-ground wildfire shelter, comprising:an all-metal A-frame assembly configured to dissipate heat upwardly through a draft; andone or more vertical heat transfer plates coupled to the A-frame assembly and extending into soil, the one or more vertical heat transfer plates and the soil cooperating as a heatsink.

16. The above-ground wildfire shelter of claim 15, wherein the all-metal A-frame assembly comprises an exterior insulative portion comprising a plurality of layers with a respective air-insulation gap between each layer.

17. The above-ground wildfire shelter of claim 15, wherein the all-metal A-frame assembly comprises a plurality of hollow steel rafters, each hollow steel rafter open-ended.

18. The above-ground wildfire shelter of claim 15, further comprising solar panels coupled to an outer panel of the all-metal A-frame assembly, a charge controller, at least one battery, and an inverter.

19. The above-ground wildfire shelter of claim 15, further comprising a geothermal pump configured to cool a horizontal heat exchanger plate in a floor.

20. A method of using an above-ground wildfire shelter to dissipate heat in a wildfire, the method comprising:utilizing an all-metal A-frame structure, wherein the all-metal A-frame structure comprises at least one air-insulation gap and a plurality of hollow rafters, each hollow rafter open-ended;reflecting heat from the A-frame structure by using a reflective outer surface on an outer panel;directing heat upwardly through the plurality of hollow rafters; anddissipating heat downwardly into soil via one or more vertical heat transfer plates that extend into the soil.

Images