Patent Publication Number: US-9903607-B2

Title: Thermally adaptive enclosure vent

Description:
BACKGROUND 
     1. Field 
     The present invention relates generally to various types of buildings and building materials associated with buildings. More specifically, embodiments of the present invention concern a laminated composite panel used to provide a thermally adaptive structure for a building. 
     2. Discussion of Prior Art 
     Prior art residential and commercial buildings have used a wide array of exterior coverings to protect the structure from being damaged or otherwise degraded by exposure to ambient weather conditions. For instance, various types of conventional exterior siding serve to prevent ambient air and water from entering the interior of the building. Prior art exterior siding also provides limited thermal insulation for the building interior (e.g., when ambient temperatures are extremely hot or extremely cold). 
     Conventional buildings also commonly include an exterior venting structure that can permit gases to selectively flow into and out of the building. For instance, prior art residential homes typically include one or more ridge vents, roof vents, and/or gable vents that serve to vent the attic space of the home. Prior art vents include manually adjusted vents, spring-loaded vents responsive to venting gas flow, and electronically controlled vents. 
     However, prior art building coverings have numerous deficiencies. For instance, the amount of thermal insulation provided solely by conventional exterior siding generally amounts to a small fraction of the thermal insulation provided by the entire wall of the building. For instance, to provide a comfortable living and/or working environment in a building, conventional building walls often include stud walls and insulating material installed within the stud walls. 
     Prior art building vents also have various deficiencies. For example, manual vents and spring-loaded vents are inexpensive but generally do not respond or adjust according to a change in ambient conditions. Electronic vents are cost prohibitive to use in many building applications and are prone to malfunction due to environmental exposure. 
     SUMMARY 
     The following brief summary is provided to indicate the nature of the subject matter disclosed herein. While certain aspects of the present invention are described below, the summary is not intended to limit the scope of the present invention. 
     Embodiments of the present invention provide a thermally adaptive wall covering and thermally adaptive enclosure vent that does not suffer from the problems and limitations of the prior art coverings and vents set forth above. 
     A first aspect of the present invention concerns a enclosure vent operable to be mounted to a building that presents an interior space and to move in response to a change in vent temperature. The enclosure vent broadly includes a vent frame and a laminated composite vent panel. The vent frame is operable to be mounted to the building to define a vent opening that fluidly communicates with the interior space. The vent panel includes outer and inner panel layers and an intermediate connecting structure that connects the panel layers relative to one another along an interface defined between the panel layers. The panel defines an elongated attachment region attached relative to the vent frame. The outer panel layer generally overlies the inner panel layer, with the inner panel layer generally facing the vent opening. The outer and inner panel layers have, respectively, first and second coefficients of thermal expansion that are different from each other and cause expansion and contraction of the corresponding panel layers along the interface. The connecting structure permits expansion and/or contraction of each panel layer in response to the vent temperature change so that the panel flexes. 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the present invention will be apparent from the following detailed description of the embodiments and the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       Preferred embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein: 
         FIG. 1  is a perspective of an enclosed building with an enclosure wall and a wall covering constructed in accordance with a first preferred embodiment of the present invention, with the wall covering including laminated composite panels in overlapping arrangement with one another; 
         FIG. 2 a    is a cross section of the building shown in  FIG. 1 , showing the panels mounted on the wall so that adjacent pairs of upper and lower panels overlap one another, with the panels being flexed into a sealed condition in response to a covering temperature below a normal operating temperature of the panels, where each of the upper panels is in sealing engagement with a corresponding lower panel; 
         FIG. 2 b    is a cross section of the building similar to  FIG. 2 a   , but showing the panels flexed out of the sealed condition to an unsealed condition in response to the covering temperature of the panels rising to the normal operating temperature, with an exposed surface of the panels being generally planar; 
         FIG. 2 c    is a cross section of the building similar to  FIG. 2 b   , but showing the panels flexed to another unsealed condition in response to the covering temperature rising to a temperature above the normal operating temperature, with the exposed surface of the panels being generally concave; 
         FIG. 3 a    is a cross section of an enclosed building with an enclosure wall and a wall covering constructed in accordance with a second preferred embodiment of the present invention, with the wall covering including panels with a foam layer, and showing upper and lower pairs of panels flexed into a sealed condition in response to the covering temperature being below the normal operating temperature of the panels, where each of the upper panels is in sealing engagement with a corresponding lower panel; 
         FIG. 3 b    is a cross section of the building similar to  FIG. 3 a   , but showing the panels flexed out of the sealed condition to an unsealed condition in response to the covering temperature of the panels rising to the normal operating temperature, with the exposed surface of the panels being generally planar; 
         FIG. 3 c    is a cross section of the building similar to  FIG. 3 b   , but showing the panels flexed to another unsealed condition in response to the covering temperature rising to a temperature above the normal operating temperature, with the exposed surface of the panels being generally concave; 
         FIG. 4  is an enlarged fragmentary perspective of one of the panels shown in  FIGS. 1-2   c , showing outer and inner panel layers joined by an intermediate adhesive layer, with a coating layer being applied to an outer surface of the outer panel layer; 
         FIG. 5  is a fragmentary perspective of the wall covering shown in  FIGS. 1-2   c  and  4 , showing one of the panels and corresponding fasteners exploded from the underlying wall; 
         FIG. 5 a    is a fragmentary perspective of one of the panels shown in  FIGS. 1-2   c ,  4 , and  5 , showing a bumper covering a lower corner of the panel; 
         FIG. 5 b    is a fragmentary perspective of one of the panels shown in  FIGS. 1-2   c  and  4 - 5   a , showing a bumper covering a lower corner and lowermost edge of the panel; 
         FIG. 6  is a fragmentary perspective of the wall covering similar to  FIG. 5 , but showing the panels secured to the underlying wall with staples; 
         FIG. 7  is a fragmentary perspective of the wall covering similar to  FIG. 6 , but showing the panels secured to the underlying wall with elongated adhesive strips; 
         FIG. 7 a    is a fragmentary perspective of the wall covering similar to  FIG. 7 , but taken from the opposite side of the wall covering; 
         FIG. 8  is an enlarged perspective of the wall covering shown in  FIGS. 1-2   c  and  4 - 5   b , but showing one of the panels mounted to the wall with alternative fasteners; 
         FIGS. 9-22  are cross sections of laminate composite panels constructed in accordance with other preferred embodiments of the present invention; 
         FIG. 23-35  are fragmentary cross sections of laminate composite panels constructed in accordance with other preferred embodiments of the present invention, and showing various preferred end margin constructions of the panels; 
         FIG. 36  is a fragmentary perspective of an enclosed building with an enclosure wall and a wall covering constructed in accordance with another preferred embodiment of the present invention, with the wall including rows of blocks and the wall covering including panels and fastening brackets to mount the panels to the blocks; 
         FIG. 37  is a fragmentary perspective of the enclosed building similar to  FIG. 36 , but taken from the opposite side of the wall covering; 
         FIG. 38  is an enlarged fragmentary cross section of the enclosed building shown in  FIGS. 36 and 37 , showing one of the panels attached to a corresponding one of the brackets; 
         FIG. 39  is a fragmentary perspective of an enclosed building with a roof and a wall covering constructed in accordance with another preferred embodiment of the present invention, with the wall covering including adjacent pairs of upper and lower panels attached to the roof with fasteners, where each of the upper panels is in sealing engagement with a corresponding lower panel; 
         FIG. 40  is a fragmentary perspective of the enclosed building similar to  FIG. 39 , but showing the panels flexed from the sealed condition to an unsealed condition; 
         FIG. 41  is a fragmentary perspective of an enclosed building with an underlying wall and a wall covering constructed in accordance with another preferred embodiment of the present invention, with the wall covering including multiple webs attached to the underlying wall and further including panels attached to the webs; 
         FIG. 42  is a fragmentary perspective of an enclosed building with a gable roof and an enclosure vent constructed in accordance with another preferred embodiment of the present invention, with the enclosure vent including a vent frame, a vent cover, and vent panels; 
         FIG. 43  is a fragmentary perspective of the enclosed building similar to  FIG. 42 , but with the vent cover exploded from the frame to show the vent panels in a sealed condition; 
         FIG. 44  is a fragmentary perspective of the enclosed building similar to  FIG. 43 , but with the vent panels flexing outwardly from the frame in an unsealed condition; 
         FIG. 45  is a cross section of the enclosed building shown in  FIGS. 42-44 , showing the vent panels in the sealed condition; 
         FIG. 46  is a cross section of the enclosed building similar to  FIG. 45 , but showing the vent panels in the unsealed condition; 
         FIG. 47  is a fragmentary perspective of an enclosed building with a roof and a roof vent constructed in accordance with another preferred embodiment of the present invention, with the roof vent including a vent frame, a vent cover, and a vent panel, and showing the vent cover exploded from the vent frame to depict the vent panel in a sealed condition; 
         FIG. 48  is a fragmentary perspective of the enclosed building similar to  FIG. 47 , but showing the vent panel flexed into an unsealed condition; 
         FIG. 49  is a fragmentary cross section of the enclosed building shown in  FIGS. 47 and 48 , showing the vent panel in the sealed condition; 
         FIG. 50  is a fragmentary cross section of the enclosed building similar to  FIG. 49 , but showing the vent panel flexed into the unsealed condition; 
         FIG. 51  is a fragmentary side elevation of a building including a door and door covering constructed in accordance with another preferred embodiment of the present invention, with the covering including panels that each include an attachment region, an upper flap, and a lower flap; 
         FIG. 52  is a fragmentary side elevation of the building similar to  FIG. 51 , but showing the flaps of the panels flexed away from the door in response to an elevated covering temperature; 
         FIG. 53  is a fragmentary perspective of an enclosed building with a roof and a roof vent constructed in accordance with another preferred embodiment of the present invention, with the roof vent including a vent panel and a vent plug, showing the vent panel in a sealed condition; 
         FIG. 54  is a fragmentary perspective of the enclosed building similar to  FIG. 53 , but showing the vent panel flexed into an unsealed condition; 
         FIG. 55  is a fragmentary perspective of an automobile with a roof and roof vents constructed in accordance with another preferred embodiment of the present invention, with each roof vent including a vent frame and a vent panel, showing the vent panel in a sealed condition; and 
         FIG. 56  is a fragmentary perspective of the enclosed building similar to  FIG. 55 , but showing the vent panel flexed into an unsealed condition. 
     
    
    
     The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the preferred embodiment. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Thermally Adaptive Wall Covering 
     Turning initially to  FIGS. 1-2   c , an exterior thermally adaptive wall covering  100  is configured to adaptively insulate an enclosed building B and is constructed in accordance with a first preferred embodiment of the present invention. As will be explained, the wall covering  100  is preferably attached to enclosure walls W along an exterior of building B to cover at least part of the walls W. When installed on the walls W, the wall covering  100  is configured to move in response to a change in temperature experienced by the covering  100  (which is referred to herein as the covering temperature). 
     While the wall covering  100  is preferably mounted to walls W that are generally stationary, the wall covering  100  could be installed on a wall structure that moves. For instance, as will be shown in a subsequent embodiment, the wall covering  100  could be attached to a door. 
     The illustrated building B comprises a conventional single-family, residential home with stud walls that each include an outer sheath S. However, the principles of the present invention are applicable to various types of buildings. For instance, the wall covering  100  of the present invention could be applied as an adaptive insulation to other residential buildings, such as a garage, shed, shop, lean-to, or barn. Also, the use of wall covering  100  could extend to use on various types of commercial buildings, such as a commercial office, retail building, or warehouse. 
     It will be appreciated that the building B is fully enclosed and includes an interior space that is climate controlled using conventional heating, ventilating, and air-conditioning (HVAC) equipment (not shown). However, it is within the scope of the present invention where the wall covering  100  is installed on a building without HVAC equipment. Furthermore, the wall covering  100  could be installed on a building structure (such as a shed) with one or more building openings that remain open permanently such that the building is only partly enclosed. 
     The outer sheath S installed on building B preferably includes sheets of engineered wood product, such as pressed wood material or plywood, fastened to studs (not shown). However, it is within the scope of the present invention where the wall W includes an alternative sheath S. For instance, the sheath S could include a metal sheet material (e.g., having a metal material such as aluminum, carbon steel, etc.). The illustrated wall W can be variously configured without departing from the scope of the present invention. 
     Turning to  FIGS. 1-2   c  and  4 - 8 , the covering  100  preferably includes laminated composite panels  102  and fasteners  104 . Each laminated composite panel  102  comprises a generally unitary construction that extends along a longitudinal axis A (see  FIG. 1 ) and is configured to flex in response to a covering temperature change. 
     The laminated composite panel  102  preferably includes outer and inner panel layers  106 ,  108  (see  FIGS. 2 a    and  4 ) that are preferably continuous and generally coextensive with one another. The panel  102  also preferably includes an adhesive layer  110  that provides a connecting structure between the panel layers  106 ,  108 . In the illustrated embodiment, the adhesive layer  110  preferably extends continuously between the panel layers  106 ,  108  to bond the panel layers  106 ,  108  to each other. The adhesive layer  110  is preferably formed between the panel layers  106 ,  108  so that the adhesive layer  110  includes substantially no gas pockets or voids. 
     In the illustrated embodiment, the panel layers  106 ,  108  are preferably bonded along an interface  112  (see  FIG. 2 a   ) defined between the panel layers  106 ,  108 . The interface  112  of the illustrated panel  102  extends generally parallel to the panel layers  106 ,  108 , although the interface  112  could be in a nonparallel arrangement relative to at least one of the panel layers  106 ,  108 . 
     Each panel layer  106 ,  108  comprises a unitary and continuous sheet of material. Each panel layer  106 ,  108  is preferably configured to expand and contract in response to any change in covering temperature. Furthermore, each panel layer  106 ,  108  is preferably configured to expand and contract along the interface  112  (i.e., along a direction in which the interface  112  extends). More preferably, each panel layer  106 ,  108  is operable to expand and contract in a width direction H (see  FIG. 2 b   ) associated with the panel  102 , with the width direction H being generally orthogonal to the longitudinal axis A. However, for some aspects of the present invention, the panel  102  could be operable to expand and contract in a direction that is off-axis from the width direction H. 
     The adhesive layer  110  preferably permits expansion and/or contraction of each panel layer  106 ,  108  along the interface  112  and relative to the other panel layer  106 ,  108  in response to the covering temperature change so that the panel  102  flexes. In particular, the adhesive layer  110  preferably permits each panel layer  106 ,  108  to expand and contract relative to the other layers  106 ,  108  along the width direction H. 
     The adhesive layer  110  preferably includes an adhesive material with an adhesive modulus of elasticity. The adhesive modulus of elasticity is preferably less than the modulus of elasticity of the materials forming each panel layer  106 ,  108 . However, for some aspects of the present invention, the adhesive material could have a relatively high modulus of elasticity. For instance, the panel  102  could have an alternative connecting structure that includes an adhesive with a high modulus of elasticity and another layer with a modulus of elasticity less than the modulus of elasticity of both panel layers  106 ,  108 . More preferably, the adhesive material also comprises a viscoelastic damping material that dampens relative movement between the panel layers  106 ,  108 . 
     The adhesive layer  110  preferably includes an adhesive material selected from the group consisting of epoxy resin, elastomeric resin, silicone, and combinations thereof. For instance, it has been found that one suitable adhesive for adhesive layer  110  is a two-component thermosetting epoxy that provides a relatively rigid adhesive layer  110 . One preferred thermosetting epoxy is Loctite® 9433 Hysol® Epoxy Adhesive, supplied by Henkel Corporation. Another suitable adhesive for adhesive layer  110  is a silicone adhesive, such as an RTV silicone adhesive. One preferred silicone adhesive is a two-component adhesive PNS-56228, supplied by Protavic America, Inc. However, it is within the scope of the present invention where the adhesively layer  110  includes an alternative adhesive material. 
     Additionally, for some aspects of the present invention, the panel  102  could include more than one adhesive layer or could be devoid of adhesive (e.g., where the panel layers  106 ,  108  are connected by discrete fasteners). 
     As will be discussed, the panel  102  could include an alternative connecting structure with one or more different types of continuous layers that join the panel layers  106 ,  108  relative to one another. For instance, one alternative connecting structure could include a damping material other than adhesive to dampen relative movement between the panel layers  106 ,  108 . 
     The panel  102  also preferably includes a coating layer  114  applied to and covering the outer panel layer  106 . The coating layer  114  is generally exposed and faces away from the enclosure wall W when an attachment region  116  of the panel  102  is attached to the enclosure wall W. 
     The coating layer  114  preferably comprises an outdoor latex paint. However, the coating layer  114  could alternatively comprise a material selected from the group of enamel paint, latex paint, powder-coated paint, and combinations thereof. 
     The illustrated panel  102  preferably includes the layers  106 ,  108 ,  110 ,  114 . However, as will be discussed in a subsequent embodiment, panel  102  could include a foam layer adhered to an outside surface of the inner panel layer  108 . 
     In the illustrated embodiment, the panel  102  preferably defines a hem margin  118  and a shiftable flap  120  that are integrally formed. The flap  120  is preferably configured to shift relative to the hem margin  118  in response to a covering temperature change. 
     The flap  120  preferably includes an extension section  122 , a flap body  124 , and a lip  126  (see  FIGS. 2 a -2 c    and  4 ). The extension section  122  interconnects the hem margin  118  and the flap body  124  and preferably extends laterally at an oblique angle to the hem margin  118 . The hem margin  118  and the extension section  122  preferably meet along a bend line  125   a . The extension section  122  and the flap body  124  preferably meet along a bend line  125   b.    
     The flap body  124  preferably presents an outwardly facing exposed surface  128 . As will be discussed, the exposed surface  128  is configured to shift between a planar shape (see  FIG. 2 b   ), a convex shape (see  FIG. 2 a   ), and a concave shape (see  FIG. 2 c   ) as the panel  102  flexes in response to a covering temperature change. However, the principles of the present invention are applicable where the exposed surface  128  shifts among an alternative range of shapes. 
     The hem margin  118  preferably provides the attachment region  116  along which the panel  102  is configured to be attached to the enclosure wall W. In the illustrated embodiment, the inner panel layer  108  is preferably folded onto the outer panel layer  106  so that the panel layers  106 ,  108  cooperatively define the hem margin  118 . 
     The hem margin  118  preferably extends along the axis A and presents a generally planar wall engaging surface  130  (see  FIGS. 2 a -2 c   ). When the hem margin  118  is attached to the enclosure wall W, the flap  120  is preferably cantilevered from the hem margin  118  and is shiftable relative thereto. However, as will be shown in subsequent embodiments, the attachment region  116  could be alternatively configured without departing from the scope of the present invention. 
     The panel also preferably presents a lowermost margin  132  opposite the hem margin  118 . The lip  126  is formed by folding the first and second panel layers  106 ,  108  of the lowermost margin  132  onto themselves. However, the margin  132  could be alternatively formed to produce a lip. For instance, only one of the panel layers  106 ,  108  of the lowermost margin  132  could be folded over to form the lip. 
     The illustrated lip  126  presents exposed corners  134  and an exposed lowermost edge  136  (see  FIGS. 2 a -2 c    and  5 ). However, as illustrated in  FIG. 5 a   , the panel could include bumpers  138  fixed to the corners  134  to cover the corners  134  and to restrict a person from being contacted by the corners  134 . 
     Similarly, as illustrated in  FIG. 5 b   , the panel  102  could include a continuous elongated bumper  140  that covers the corners  134  and the lowermost edge  136  and restricts a person from being contacted by the corners  134  and the lowermost edge  136 . 
     Each panel  102  preferably presents a panel width dimension Dl that ranges from about four inches ( 4 ″) to about fourteen inches ( 14 ″) (see  FIG. 2 b   ). More preferably, in the illustrated embodiment, the width dimension D 1  ranges from about six inches ( 6 ″) to about eight inches ( 8 ″). However, the width dimension D 1  could fall outside of these ranges in connection with some aspects of the present invention. Each panel  102  also preferably presents a length dimension (not shown) that ranges from about one foot ( 1 ′) to about forty feet ( 40 ′), although the length dimension could fall outside of this range. 
     The outer and inner panel layers  106 ,  108  preferably have, respectively, outer and inner coefficients of thermal expansion (CTE). The outer and inner coefficients of thermal expansion are different from each other and cause expansion and contraction of the corresponding panel layers  106 ,  108  along the interface  112 . 
     Preferably, the inner coefficient of thermal expansion of the inner panel layer  108  is greater than the outer coefficient of thermal expansion of the outer panel layer  106 . As a result, the flap  120  is preferably configured to shift away from the enclosure wall W in response to an increasing covering temperature and configured to flex toward the enclosure wall W in response to a decreasing covering temperature. 
     In the illustrated embodiment, the outer coefficient of thermal expansion preferably ranges from about negative five (−5) microstrain per degree Celsius to about five (5) microstrain per degree Celsius. A positive value of coefficient of thermal expansion generally refers to a material that expands, in at least one dimension, as the material temperature increases and contracts, in at least one dimension, as the material temperature decreases. A negative value of coefficient of thermal expansion generally refers to a material that contracts, in at least one dimension, as the material temperature increases and expands, in at least one dimension, as the material temperature decreases. 
     Also, the inner coefficient of thermal expansion preferably ranges from about ten (10) microstrain per degree Celsius to about one thousand (1000) microstrain per degree Celsius. However, the coefficients of thermal expansion for the panel layers  106 ,  108  could fall outside of these ranges without departing from the scope of the present invention. 
     Whether or not the inner and outer coefficients of thermal expansion fall within the above-listed ranges, the coefficients of thermal expansion are preferably different from one another so that the panel  102  changes shape in response to a change in temperature. In other words, the panel layers  106 ,  108  preferably exhibit a difference in coefficient of thermal expansion (ΔCTE) that equals the value of inner CTE minus the value the value of outer CTE. The ΔCTE value for the panel  102  preferably ranges from about fifteen (15) microstrain per degree Celsius to about one thousand (1000) microstrain per degree Celsius. 
     The outer panel layer  106  preferably includes a material selected from the group consisting of graphite, epoxy resin, graphene, Invar, and combinations thereof. However, the outer panel layer  106  could include another material consistent with the scope of the present invention. 
     The inner panel layer  108  preferably includes a material selected from the group consisting of aluminum, copper, magnesium, vinyl, stainless steel, and combinations thereof. However, the inner panel layer  108  could include another material consistent with the scope of the present invention. 
     The outer panel layer  106  preferably presents a layer thickness that ranges from about five thousandths of an inch (0.005″) to about ten thousandths of an inch (0.010″). The inner panel layer  108  also preferably presents a layer thickness that ranges from about five thousandths of an inch (0.005″) to about ten thousandths of an inch (0.010″). However, one or both of the layer thicknesses could fall outside of the corresponding range without departing from the scope of the present invention. 
     The principles of the present invention are equally applicable where the panel  102  has an alternative connecting structure that permits expansion and/or contraction of each panel layer  106 ,  108  relative to the other panel layer  106 ,  108  in response to the covering temperature change so that the panel  102  flexes. Preferably, in various alternative embodiments, the connecting structure includes one or more continuous layers that bond the panel layers  106 ,  108  relative to one another. Where the alternative connecting structure includes one or more continuous layers, at least one of the layers preferably includes a material with a modulus of elasticity that is less than the modulus of elasticity of each panel layer  106 ,  108 . 
     In some embodiments, the alternative connecting structure could include a damping material configured to dampen relative movement between the panel layers  106 ,  108 . For instance, as will be shown in a subsequent embodiment, the connecting structure could include an intermediate foam layer (not shown) located between the layers  106 ,  108  and bonded to each panel layer  106 ,  108  with a corresponding layer of adhesive. 
     In such an alternative embodiment, the adhesive of each adhesive layer preferably comprises a damping material and has an adhesive modulus of elasticity less than the modulus of elasticity of the materials forming each panel layer  106 ,  108 . 
     While the illustrated panel  102  preferably only includes two panel layers  106 ,  108 , it is within the ambit of the present invention for the panel  102  to include more than two panel layers  106 ,  108 . For instance, an alternative connecting structure could include a third panel layer located intermediate the outer and inner panel layers  106 ,  108 . In one such alternative embodiment, the intermediate panel layer could have an intermediate coefficient of thermal expansion that is closer to the inner coefficient of thermal expansion than the outer coefficient of thermal expansion. For instance, the intermediate coefficient of thermal expansion could range from about eighty percent (80%) of the inner coefficient of thermal expansion to about one hundred twenty percent (120%) of the inner coefficient of thermal expansion. 
     In another alternative embodiment, the intermediate panel layer could have an intermediate coefficient of thermal expansion that is closer to the outer coefficient of thermal expansion than the inner coefficient of thermal expansion. For instance, the intermediate coefficient of thermal expansion could range from about eighty percent (80%) of the outer coefficient of thermal expansion to about one hundred twenty percent (120%) of the outer coefficient of thermal expansion. 
     Yet further, the panel  102  could have an alternative connecting structure that permits expansion and/or contraction of each panel layer  106 ,  108  relative to the other panel layer  106 ,  108 . For some aspects of the present invention, the panel layers  106 ,  108  could be connected by a mechanical attachment structure (such as mechanical fasteners) that permits relative sliding movement between the panel layers  106 ,  108 . 
     The panel  102  is preferably formed under a normal operating temperature. That is, the panel  102  is shaped during the panel manufacturing process at about the normal operating temperature. When manufactured, the panel  102  is preferably shaped so that the exposed surface  128  is generally planar at the normal operating temperature. The normal operating temperature preferably comprises the average annual temperature for the location where the panel  102  is installed for use. However, the normal operating temperature could be determined in an alternative manner. For instance, the normal operating temperature could be associated with the standard temperature of sixty-eight degrees Fahrenheit (68° F.) according to the National Institute of Standards and Technology (NIST). 
     Again, the flap body  124  preferably presents the outwardly facing exposed surface  128 . The exposed surface  128  is generally planar when the covering temperature is at the normal operating temperature (see  FIG. 2 b   ). 
     Preferably, the flap  120  also flexes so that the exposed surface  128  is concave when the covering temperature is higher than the normal operating temperature (see  FIGS. 2 c   ,  4 , and  5 ). The flap  120  also preferably flexes so that the exposed surface  128  is convex when the covering temperature is lower than the normal operating temperature (see  FIGS. 1 and 2   a ). 
     The flap  120  preferably flexes so that a maximum deflection dimension D 2  is defined between convex and concave positions (see  FIG. 2 c   ). The maximum deflection dimension D 2  preferably ranges from about one half inch (½″) to about four inches (4″). However, the maximum deflection dimension D 2  could be greater than this range (e.g., when the panel  102  presents a larger panel width. 
     As will be discussed, the panels  102  are configured to be arranged into a series of overlapping panels  102  (see  FIG. 1 ). Preferably, each pair of adjacent panels  102  overlaps one another so that an upper panel of each pair of adjacent panels  102  preferably overlaps a lower panel  102  of each pair of adjacent panels  102 . 
     Each of the upper panels  102  is configured to flex into and out of an unsealed condition (see  FIGS. 1, 2   b , and  2   c ), where the flap  120  is spaced from the corresponding lower panel to define an opening O therebetween. Each of the upper panels  102  is also configured to flex into and out of a sealed condition (see  FIGS. 1 and 2   a ), where the flap  120  engages the corresponding lower panel  102 . 
     The elongated hem margin  118  preferably provides the attachment region  116  along which the panel  102  is configured to be attached to the enclosure wall W. The hem margin  118  preferably presents a plurality of slots  142  (see  FIG. 5 ) spaced along the length of the panel  102 . 
     When the hem margin  118  is attached to the enclosure wall W, the outer panel layer  106  generally overlies the inner panel layer  108  and the inner panel layer  108  generally faces the wall W. Again, the hem margin  118  is preferably formed by folding the inner panel layer  108  onto the outer panel layer  106 . 
     However, as will be shown in subsequent embodiments, one or both of the panel layers  106 ,  108  could be alternatively folded to form the hem margin  118  without departing from the scope of the present invention. 
     It is also within the ambit of the present invention where the attachment region  116  has an alternative position and/or configuration. For instance, the attachment region  116  could be spaced between upper and lower margins of the panel  102 . 
     The panels  102  are preferably attached to the enclosure wall W with fasteners  104  of the wall covering  100 . Each fastener  104  preferably includes a wall penetrating nail  144  that presents a nail head  146  (see  FIGS. 2 a -2 c   ). Each fastener  104  also preferably includes a generally oblong washer  148  that is received on the nail  144  and engages the head  146  (see  FIGS. 2 a -2 c   ). 
     The washer  148  has a generally circular disc shape that presents a curved disc edge. However, the washer  148  preferably has a portion of the disc truncated to form a generally straight disc edge. As shown in the illustrated embodiment, the washers  148  are preferably oriented so that the straight disc edges are generally parallel to the axis A. The washers  148  are also preferably oriented so that the straight disc edges are generally parallel to the bend line  125 . 
     The fasteners  104  are spaced along the attachment region  116  and positioned to extend through corresponding slots  142 . Each fastener  104  extends through the attachment region  116  and at least partly through the enclosure wall W to attach the panel  102  to the enclosure wall W. 
     However, the panels  102  could be secured to the enclosure wall W with an alternative fastening structure. For instance, the fasteners could include washers  150  having an alternative oblong shape with opposite straight disc edges (see  FIG. 8 ). 
     Also, the panels  102  could be mounted to the enclosure wall W with staples  152  (see  FIG. 6 ). Yet further, the panels  102  could be secured to the enclosure wall W with continuous fastening strips  154  that each include an adhesive material (see  FIGS. 7 and 7   a ). 
     Preferably, the panels  102  are arranged in a series where each pair of adjacent panels overlaps one another. In the illustrated embodiment, an upper panel  102  of each pair of adjacent panels  102  preferably overlaps a lower panel  102  of each pair of adjacent panels  102 . 
     Again, each of the upper panels  102  is configured to flex into and out of an unsealed condition, where the flap  120  is spaced from the corresponding lower panel  102  to define the opening O therebetween. Each of the upper panels  102  is also configured to flex into and out of a sealed condition, where the flap  120  engages the corresponding lower panel  102  and closes the opening O. In the sealed condition, each pair of upper and lower panels  102  cooperate with the wall W to enclose an air space defined between the upper and lower panels  102  and the wall W. 
     However, for some aspects of the present invention, the panels  102  could have an alternative overlapping arrangement. For instance, the lower panel of each pair of adjacent panels  102  could overlap the corresponding upper panel  102  of each pair of adjacent panels  102  (e.g., where the wall W is constructed to permit each of the upper panels  102  to flex toward the wall W to a position spaced inwardly from the corresponding upper panels  102 ). 
     In the illustrated embodiment, the exposed surface  128  of each panel  102  is generally planar when the covering temperature is at the normal operating temperature (see  FIG. 2 b   ). Also, the flap  120  preferably flexes so that the exposed surface  128  is concave when the covering temperature is higher than the normal operating temperature (see  FIGS. 2 c   ,  4 , and  5 ). Yet further, the flap  120  preferably flexes so that the exposed surface  128  is convex when the covering temperature is lower than the normal operating temperature (see  FIGS. 1 and 2   a ). 
     Each of the upper panels  102  is preferably shiftable between the unsealed condition (see  FIGS. 1, 2   b , and  2   c ), where the flap  120  is spaced from the corresponding lower panel  102  to define the opening O therebetween, and the sealed condition (see  FIGS. 1 and 2   a ), where the flap  120  engages the corresponding lower panel to close the opening O. 
     The panels  102  preferably have a sealing temperature below the normal operating temperature where the upper panels  102  engage and seal the corresponding lower panels  102 . When the covering temperature is above the sealing temperature, the flap  120  is preferably in the unsealed condition (see  FIGS. 1, 2   b , and  2   c ). For instance, the exposed surface  128  could have a slightly convex shape (not shown), a planar shape (see  FIG. 2 b   ), or a concave shape (see  FIGS. 2 c   ,  4 , and  5 ) in the unsealed condition. 
     When the covering temperature is at or below the sealing temperature, the flap  120  is preferably in the sealed condition (see  FIGS. 1 and 2   a ). In the sealed condition, the exposed surface  128  of the flap  120  preferably has a convex shape. 
     In the unsealed condition, the upper and lower panels  102  of each pair of adjacent panels  102  cooperatively define the opening O. In the sealed condition, each pair of adjacent upper and lower panels  102  cooperatively close the opening O. Furthermore, each pair of upper and lower panels  102  cooperate with the wall W to enclose an air space defined between the upper and lower panels  102  and the wall W. 
     In use, the illustrated panels  102  are preferably installed using conventional siding installation techniques and are configured to cover the enclosure walls W. The installed panels  102  each respond to any change in the corresponding covering temperature by shifting the flap  120  toward and away from the enclosure wall W. 
     For instance, as the covering temperature increases (e.g., from the normal operating temperature), the flap  120  shifts away from the enclosure wall W (see  FIG. 2 c   ). In at least some instances, this shifting movement away from the enclosure wall W can cause the flap  120  to move from the sealed condition (see  FIG. 2 a   ) to the unsealed condition (although such a change in conditions is not required). 
     As the covering temperature decreases (e.g., from the normal operating temperature), the flap  120  shifts toward the enclosure wall W. In at least some instances, this shifting movement toward the enclosure wall W can cause the flap  120  to move from the unsealed condition (see, e.g.,  FIGS. 2 b  and 2 c   ) to the sealed condition (although such a change in conditions is not required). 
     Turning to  FIGS. 3 a -3 c    and  FIGS. 9-41 , alternative preferred embodiments of the present invention are depicted. For the sake of brevity, the remaining description will focus primarily on the differences of these alternative embodiments from the preferred embodiment described above. 
     Initially turning to  FIGS. 3 a -3 c   , an alternative wall covering  200  is constructed in accordance with a second embodiment of the present invention. The wall covering  200  is mounted to wall W and includes panels  202  and fasteners  204 . Each panel  202  preferably includes outer and inner panel layers  206 ,  208  and an intermediate adhesive layer  210 . The adhesive layer  210  contacts and bonds the panel layers  206 ,  208  to one another. 
     The panel  200  also preferably includes a foam layer  212  and a second intermediate adhesive layer  214  bonding the inner panel layer  208  and the foam layer  212  to one another. The inner panel layer  208  covers the foam layer  212  when an attachment region  216  is attached to the enclosure wall W. 
     The foam layer  208  preferably includes a conventional closed cell foam material that includes a synthetic resin material with a plurality of small, enclosed, gas pockets suspended within the resin material. More preferably, the closed cell foam material includes a polystyrene material. However, the foam material could include another synthetic resin without departing from the scope of the present invention. 
     The closed cell foam material of the illustrated foam layer  212  is preferable because the material has a relatively large coefficient of thermal expansion. In particular, it has been found that the gas pockets in the foam expand as the temperature of the foam increases. The gas pockets in the foam also contract as the temperature of the foam decreases. As a result, the expansion of the foam layer  212  urges a flap  220  of the panel  202  to flex away from the wall W as the foam temperature increases (e.g., as the foam temperature increases above the normal operating temperature). Similarly, contraction of the foam layer  212  urges the flap  220  of the panel  202  to flex toward the wall W as the foam temperature decreases (e.g., as the foam temperature decreases below the normal operating temperature). In this manner, the foam layer  212  preferably assists with flexing of the panel  202  toward and away from the wall W. 
     The illustrated foam layer  208  includes a series of foam sections  218  that extend generally parallel to each other along the longitudinal axis. Each pair of adjacent foam sections  218  is preferably shiftable toward and away from one another as the panel  202  flexes. 
     Each pair of adjacent foam sections  218  is also preferably in abutting engagement with one another when the covering temperature is at the normal operating temperature. As a result, each pair of adjacent foam sections  218  restricts the flap  220  of the panel  202  from flexing toward the enclosure wall W when the covering temperature is lower than the normal operating temperature. Thus, in the illustrated embodiment, the foam sections  218  cooperatively restrict an exposed surface  222  from shifting to a convex shape. 
     The foam layer  208  also preferably presents a relief cutout  224 . The cutout  224  restricts the foam layer  208  from interfering with flexing of the panel into and out of the sealed condition. 
     Turning to  FIGS. 9-22 , various alternative panel embodiments are illustrated. The panel  300   a  (see  FIG. 9 ) is constructed in accordance with a third embodiment of the present invention and includes outer and inner panel layers  302   a ,  304   a  and a connecting structure  306   a . The panel  300   a  also includes an alternative attachment region  308   a , where the panel layers are preferably unfolded, and a flap  310   a.    
     The connecting structure  306   a  preferably includes an intermediate foam layer  312   a  located between the panel layers  302   a ,  304   a . The connecting structure  306   a  also preferably includes layers of adhesive  314   a ,  316   a  that bond the foam layer  312   a  to the respective panel layers  302   a ,  304   a . The foam layer  312   a  preferably comprises a damping material with a foam modulus of elasticity less than the modulus of elasticity of the materials forming each panel layer  302   a ,  304   a.    
     The adhesive of each adhesive layer  314   a ,  316   a  also preferably comprises a damping material and has an adhesive modulus of elasticity less than the modulus of elasticity of the materials forming each panel layer  302   a ,  304   a.    
     Turning to  FIG. 10 , the panel  300   b  is constructed in accordance with a fourth embodiment of the present invention and includes three (3) sets  301   b  of outer and inner panel layers  302   b ,  304   b  bonded to one another by corresponding adhesive layers  306   b.    
     Each set  301   b  of bonded panel layers  302   b ,  304   b  includes an alternative attachment region  308   b , where the panel layers  302   b ,  304   b  are preferably unfolded, and a flap  309   b . Each set  301   b  of bonded layers  302   b ,  304   b  is adhered to a corresponding backing strip  310   b . The backing straps  310   b  are adhered to corresponding sets  301   a  of bonded panel layers  302   b ,  304   b  with adhesive layers  312   b . The sets  301   b  of bonded panel layers  302   b ,  304   b  cooperatively define insulating spaces  314   b  therebetween. The backing strips  310   b  preferably include a material selected from the group consisting of wood, synthetic resin material, and a combination thereof. 
     Turning to  FIG. 11 , the panel  300   c  is constructed in accordance with a fifth embodiment of the present invention and includes outer and inner panel layers  302   c ,  304   c  bonded to each other by an adhesive layer  306   c.    
     The panel  300   c  includes an alternative attachment region  308   c , where the panel layers are preferably unfolded, and an alternative flap  310   c.    
     The alternative flap  310   c  preferably includes a plurality of longitudinal corrugations  312   c , with an exposed surface  314   c  having a series of longitudinal grooves  316   c . The grooves  316   c  present a groove depth G that ranges from about one quarter inch (¼″) to about one half inch (½″), although the depth G could be outside of this range. The panel  300   c  includes a lip  312   c  formed by folding the panel layers  302   c ,  304   c  around an elongated rod  320   c.    
     Turning to  FIG. 12 , the panel  300   d  is constructed in accordance with a sixth embodiment of the present invention and includes outer and inner panel layers  302   d ,  304   d  bonded to each other by an adhesive layer  306   d . The panel layers  302   d ,  304   d  are formed so that the panel  300   d  includes an attachment region  308   d  and an alternative flap  310   d . The flap  310   d  preferably includes a plurality of longitudinal corrugations  312   d  and presents an exposed surface  314   d  having grooves  316   d.    
     Turning to  FIG. 13 , the panel  300   e  is constructed in accordance with a seventh embodiment of the present invention and includes outer and inner panel layers  302   e ,  304   e  bonded to each other by an adhesive layer  306   e.    
     The panel  300   e  includes an alternative attachment region  308   e  and an alternative flap  310   e . The inner panel layer  304   e  has a first section  312   e  folded over the outer panel layer  302   e  and a second section  314   e  folded over the first section  312   e . The flap  310   e  preferably also includes a plurality of longitudinal corrugations  316   e  and presents an exposed surface  318   e  having protrusions  320   e.    
     Turning to  FIG. 14 , the panel  300   f  is constructed in accordance with an eighth embodiment of the present invention and includes outer and inner panel layers  302   f ,  304   f  bonded to each other by an adhesive layer  306   f . The panel  300   f  preferably includes an alternative attachment region  308   f  and an alternative shiftable flap  310   f . The flap  310   f  includes an extension section  312   f , a flap body  314   f , and a lip  316   f.    
     The flap body  314   f  includes a forward section  318   f , a bend section  320   f  that defines a lowermost margin  322   f  of the flap  310   f , and a rear section  324   f . The rear section  324   f  is spaced behind the forward section  318   f  so that the sections  318   f ,  320   f ,  322   f  cooperatively define an insulating air gap  326   f.    
     The panel layers  302   f ,  304   f  are adhered to a backing strip  328   f . The backing strip  328   f  preferably includes a material selected from the group consisting of wood, synthetic resin material, and a combination thereof. The alternative attachment region  308   f  is preferably configured so that the panel layers  302   f ,  304   f  are unfolded and bonded to the backing strip  328   f  with an adhesive layer  330   f.    
     Turning to  FIG. 15 , the panel  300   g  is constructed in accordance with a ninth embodiment of the present invention and includes outer and inner panel layers  302   g ,  304   g  bonded to each other by an adhesive layer  306   g . The panel  300   g  preferably includes an alternative attachment region  308   g  and an alternative shiftable flap  310   g.    
     The attachment region  308   g  is formed by folding a first section  312   g  of the inner panel layer  304   g  behind a second section  314   g  of the inner panel layer  304   g  to form a hem margin. The sections  312   g ,  314   g  are preferably spaced from each other. 
     The panel  300   g  also preferably includes a foam layer  316   g  bonded to the inner panel layer  304   g  of the flap  310   g  with a second adhesive layer  318   g . The foam layer  316   g  presents a relief cutout  320   g.    
     Turning to  FIG. 16 , the panel  300   h  is constructed in accordance with a tenth embodiment of the present invention and includes outer and inner panel layers  302   h ,  304   h  bonded to each other by an adhesive layer  306   h . The panel  300   h  preferably includes an alternative attachment region  308   h  and an alternative shiftable flap  310   h . The panel  300   h  also preferably includes an alternative foam layer  312   h.    
     The foam layer  312   h  presents a protrusion  314   h  that is bonded to the inner panel layer  304   h  of the flap  310   h  with a second adhesive layer  316   h . Upper and lower regions  318   h ,  320   h  of the foam layer  312   h  are spaced from the inner panel layer  304   h  to form air gaps  322   h.    
     Turning to  FIG. 17 , the panel  300   i  is constructed in accordance with an eleventh embodiment of the present invention and includes outer and inner panel layers  302   i ,  304   i  bonded to each other by an adhesive filler section  306   i . The panel layers  302   i ,  304   i  are formed so that the panel  300   i  comprises a rigid, hollow structure that presents an elongated chamber  308   i . The chamber  308   i  is then preferably filled with adhesive filler material. 
     The panel  300   i  includes an attachment region  310   i  and a flap  312   i . The panel  300   i  presents a thickness dimension T that varies along the width of the panel  300   i . Preferably, the thickness dimension T of the flap  312   i  tapers from a bend line  314   i  adjacent the attachment region  310   i  to a lowermost margin  316   i.    
     Turning to  FIG. 18 , the panel  300   j  is constructed in accordance with a twelfth embodiment of the present invention and includes outer and inner panel layers  302   j ,  304   j  bonded to each other by an adhesive layer  306   j . The panel  300   j  includes an alternative attachment region  308   j  and an alternative flap  310   j . The attachment region  308   j  is formed by folding a first section  312   j  of the inner panel layer  304   j  behind a second section  314   j  of the inner panel layer  304   j . The first and second sections  312   j ,  314   j  are spaced apart and extend generally parallel to one another. The sections  312   j ,  314   j  are interconnected by a third section  316   j  that is orthogonal to both sections  312   j ,  314   j . The attachment region  308   j  is preferably configured to be slidably mounted onto a wall (not shown) that includes blocks or bricks. For instance, the attachment region  308   j  could be slidably mounted onto a section of one of the concrete blocks shown in  FIGS. 36-38 . 
     The panel  300   j  also preferably includes an alternative foam layer  318   j  bonded to the inner panel layer of the flap  310   j  with a second adhesive layer  320   j . The foam layer  318   j  includes a series of foam sections  322   j  that extend generally parallel to each other along the longitudinal axis. Each pair of adjacent foam sections  322   j  is preferably shiftable toward and away from one another as the panel  300   j  flexes. Also, each pair of adjacent foam sections  322   j  restricts the flap  310   j  of the panel  300   j  from flexing toward the enclosure wall when the covering temperature is lower than the normal operating temperature. Thus, in the illustrated embodiment, the foam sections  322   j  cooperatively restrict an exposed surface  324   j  from shifting to a convex shape. 
     Turning to  FIG. 19 , the panel  300   k  is constructed in accordance with a thirteenth embodiment of the present invention and includes outer and inner panel layers  302   k ,  304   k  bonded to each other by an adhesive layer  306   k . The panel  300   k  includes an alternative attachment region  308   k  and an alternative flap  310   k.    
     The panel  300   k  also preferably includes an alternative foam layer  312   k  similar to foam layer  318   j . The alternative attachment region  308   k  preferably includes first, second, and third sections  314   k ,  316   k ,  318   k  similar to attachment region  318   j . However, the third section  318   k  presents a longer width dimension than third section  316   j . The attachment region  308   j  is preferably configured to be slidably mounted onto a wall (not shown) that includes blocks or bricks. For instance, the attachment region  308   j  could be slidably mounted onto a residential stone masonry brick. 
     Turning to  FIG. 20 , the panel  3001  is constructed in accordance with a fourteenth embodiment of the present invention and includes outer and inner panel layers  3021 ,  3041  bonded to each other by an adhesive layer  3061 . The panel  3001  includes an alternative attachment region  3081  and an alternative flap  3101 . 
     The panel  3001  also preferably includes an alternative foam layer  3121  similar to foam layer  312   k . The alternative attachment region  3081  is preferably formed by folding a first section  3141  of the inner panel layer  3041  behind a second section  3161  of the inner panel layer  3041 . The first and second sections  3141 ,  3161  are spaced apart and extend generally parallel to one another. The sections  3141 ,  3161  are interconnected by a bend  3181 . The first section  3141  extends downwardly behind the foam layer  312   k . The first section  3141  and the foam layer  3121  cooperatively define an insulating air gap  3201 . 
     Turning to  FIG. 21 , the panel  300   m  is constructed in accordance with a fifteenth embodiment of the present invention and includes outer and inner panel layers  302   m ,  304   m  bonded to each other by an adhesive layer  306   m . The panel  300   m  includes an alternative attachment region  308   m  and an alternative flap  310   m.    
     The panel  300   m  also preferably includes an alternative foam layer  312   m  similar to foam layers  312   l ,  312   k . The alternative attachment region  308   m  is formed by folding a first section  314   m  of the inner panel layer  304   m  behind a second section  316   m  of the inner panel layer  304   m . The first section  314   m  and the foam layer  312   m  cooperatively define an insulating air gap  318   m.    
     The panel  300   m  further includes multiple intermediate panel layers  320   m  spaced within the air gap  318   m  and bonded to corresponding backing strips  322   m  with adhesive layers  324   m . The panel layers  320  preferably comprise a metallic material, such as aluminum to reflect radiant heat energy away from the corresponding wall. 
     Turning to  FIG. 22 , the panel  300   n  is constructed in accordance with a sixteenth embodiment of the present invention and includes outer and inner panel layers  302   n ,  304   n  bonded to each other by an adhesive layer  306   n . The panel  300   n  includes an attachment region  308   n  and an alternative curved flap  310   n . The flap  310   n  presents an exposed surface  312   n  that is generally convex at the normal operating temperature. The flap  310   n  is preferably shaped to resemble part of an outer log surface (e.g., to present features of a log cabin construction). However, the flap  310   n  also has a curved profile that can be used to represent the general shape of a spanish tile. 
     The panel  300   n  preferably includes an alternative foam layer  314   n  with a series of foam sections  316   n  that extend generally parallel to each other along the longitudinal axis of the panel  300   n.    
     Turning to  FIGS. 23-36 , various alternative embodiments of panels  400   a ,  400   b ,  400   c ,  400   d ,  400   e ,  400   f ,  400   g ,  400   h ,  400   i ,  400   j ,  400   k ,  400   l ,  400   m  with alternative end margins are illustrated. It will be appreciated that the end margin embodiments could be provided as a hem margin and/or a lip of any of the panel embodiments disclosed herein. 
     Each of the alternative panels  400   a ,  400   b ,  400   c ,  400   d ,  400   e ,  400   f ,  400   g ,  400   h ,  400   i ,  400   j ,  400   k ,  400   l ,  400   m  is formed at least partly by outer and inner panel layers  402 ,  404  bonded to each other by an adhesive layer  406 . The panels  400   a ,  400   b ,  400   c ,  400   d ,  400   e ,  400   f ,  400   g ,  400   h ,  400   i ,  400   j ,  400   k ,  400   l ,  400   m  include corresponding end margins  408   a ,  408   b ,  408   c ,  408   d ,  408   e ,  408   f ,  408   g ,  408   h ,  408   i ,  408   j ,  408   k ,  408   l ,  408   m . The panel layers  402 ,  404  of end margin  408   a  are preferably unfolded to present exposed panel layer edges (see  FIG. 23 ). 
     End margins  408   b ,  408   c ,  408   d  (see  FIGS. 24-26 ) preferably include a clip element  410   b ,  410   c ,  410   d  that covers the corresponding edges of panel layers  402 ,  404 . End margins  408   e ,  408   g ,  408   i ,  408   m  (see  FIGS. 27, 29, 31, and 35 ) are formed by folding the corresponding outer and inner layers  402 ,  404  onto one another to present corresponding fold configurations. 
     End margins  408   f ,  408   h ,  408   j  (see  FIGS. 28, 30, and 32 ) are formed by folding the outer and inner layers  402 ,  404  onto one another to present corresponding fold configurations. The panels  400   f ,  400   h ,  400   j  also include a corresponding bead  412   f ,  412   h ,  412   j  of adhesive material applied along the corresponding end margin  408   f ,  408   h ,  408   j  to cover a seam  414 . End margins  408   k ,  408   l  are formed by bending the outer and inner layers  402 ,  404  around a rod  416  (see  FIGS. 33 and 34 ). 
     Turning to  FIGS. 36-38 , an alternative wall covering  500  is constructed in accordance with a seventeenth embodiment of the present invention. The wall covering  500  is configured to be installed on a concrete block wall W of a building B. In the usual manner, the block wall W includes multiple rows of blocks K stacked and secured to one another with mortar joints M. 
     The wall covering  500  preferably includes alternative panels  502  and alternative fastening brackets  504 . The fastening brackets  504  serve as fasteners to mount the panels  502  onto corresponding rows of blocks B. 
     Each bracket  504  comprises a unitary and elongated beam structure that includes tabs  506  that project into openings of the blocks B (see  FIG. 37 ). Each bracket  504  also includes a channel section  508  (see  FIG. 36 ) that presents a groove  510  (see  FIG. 38 ) and a plurality of holes  512  (see  FIG. 36 ). Each panel  502  includes outer and inner panel layers  514 , 516  bonded by an adhesive layer  518  (see  FIG. 38 ). The panel  502  also includes an attachment region  520  and a flap  522 . 
     The attachment region  520  includes a finger  524  that is formed as part of the inner panel layer  516  and is sprung to project into a gap  526  defined between first and second sections  528 ,  530  of the attachment region  520  (see  FIG. 38 ). The first section  528  is configured to be slidably inserted into the groove  510  so that each finger  524  snaps into a corresponding one of the holes  512 . The end of the finger  524  extends upwardly to engage the corresponding hole  512  and restricts removal of the panel  502  from the bracket  504 . 
     Turning to  FIGS. 39 and 40 , an alternative wall covering  600  is constructed in accordance with an eighteenth embodiment of the present invention. The wall covering  600  preferably includes alternative panels  602  and fasteners  604 . 
     Each panel  602  is generally similar to the panel  102  except that the panel  602  presents multiple transverse slots  606  that extend across the width of a flap  608 . The slotted panel construction permits the panels  602  to be installed on a roof R of the enclosed building B as shingles. The panels  602  are mounted on the roof R with fasteners  604 . The panels  602  are each configured to move in response to a change in covering temperature experienced by the panel  602 . Each of the panels  602  preferably has length and width dimensions similar to conventional composite shingles. 
     Turning to  FIG. 41 , an alternative wall covering  700  is constructed in accordance with a nineteenth embodiment of the present invention. The wall covering  700  preferably includes alternative panels  702  and a web  704  of fastening material. The web  704  preferably includes a continuous sheet  706  of woven fabric material that is wound into a roll  708 . The web  704  also preferably includes a series of adhesive strips  710  that are spaced along the fabric sheet  706 . 
     The web  704  extends vertically along an enclosure wall W of a building B and is secured to the enclosure wall W with fasteners (not shown). With the web  704  mounted on the wall W, each panel  702  is configured to be mounted to a corresponding one of the adhesive strips  710 . 
     Turning to  FIGS. 51 and 52 , a fire-resistant door  800  is constructed in accordance with a twentieth embodiment of the present invention. The door  800  is provided as part of a building B and preferably includes a door wall  802  and a door covering  804 . The door wall  802  presents an upright door surface  806 . 
     The door covering  804  includes a plurality of panels  808  that each include an attachment region  810 , an upper flap  812 , and a lower flap  814 . The attachment region  810  extends laterally and is fixed to the door  800 . For instance, where the door  800  comprises a steel door construction, the attachment regions  810  could be welded directly to the surface  806 . However, the attachment regions  810  could be alternatively attached to the door body  802  (e.g., with threaded fasteners, adhesive, etc.). 
     The flaps  812 ,  814  are shiftable into and out of an unflexed position at a normal operating temperature, where the flaps  812 ,  814  extend vertically along the surface  806  and are generally parallel to and immediately adjacent the surface  806  (see  FIG. 51 ). The flaps  812 ,  814  are also shiftable into and out of a flexed position at a temperature above the normal operating temperature (see  FIG. 52 ). 
     In the flexed position, the flaps  812 ,  814  are generally spaced outwardly from the surface  806  so that the flaps  812 ,  814  and surface  806  cooperatively define insulating air gaps  816 . Thus, in the event that a space  820  facing the surface  806  includes elements that are being consumed by fire, the increased temperature due to the fire causes the flaps  812 ,  814  to deploy into the flexed position. 
     If the building B has a ceiling-mounted, fire sprinkler system (not shown) to suppress a fire within the space  820 , the upper flaps  812  are configured to collect water (not shown) along the surface  806 . That is, with the upper flaps  812  deployed into the flexed position, the upper flaps  812  are configured to catch water from the sprinkler system and cooperate with the surface  806  to funnel and hold the water within the gaps  816 . As a result, the door  800  collects water to cool the door  800  and to suppress fire from consuming the door  800 . 
     Thermally Adaptive Enclosure Vent 
     Turning to  FIGS. 42-50 and 53-56 , various enclosure vent embodiments are illustrated. As will be shown, each of these vent embodiments includes a panel structure similar to panels shown in the previous embodiments. 
     Turning to  FIGS. 42-46 , a gable vent  900  is constructed in accordance with a twenty-first embodiment of the present invention. The gable vent  900  is illustrated as being mounted on a gable wall  902  of the enclosed building B. In the usual manner, the gable wall  902  defines part of an interior attic space  904  of the building B (see  FIGS. 45 and 46 ). Similar to the previous panel embodiments, the gable vent  900  is configured to move in response to a change in temperature experienced by the gable vent  900  (which is referred to herein as the vent temperature). The gable vent  900  is preferably configured to permit air flow F to move into and out of the space  904 . 
     The gable vent  900  preferably includes a vent frame  905 , a vent cover  906 , and laminated composite vent panels  908 . The vent frame  904  is mounted to the gable wall  902  and cooperates with the gable wall  902  to define a vent opening  910 . The vent opening  910  fluidly communicates with the interior attic space  904 . The vent cover  906  is removably mounted to the vent frame  904  and presents an open chamber  912  and side openings  914  that fluidly communicate with the chamber  912 . 
     Each vent panel  908  includes outer and inner panel layers  916 ,  918  and an intermediate adhesive layer (not shown) that bonds the panel layers  916 ,  918  relative to one another along an interface (not shown) defined between the panel layers  916 ,  918 . The outer and inner panel layers  916 ,  918  have corresponding coefficients of thermal expansion that are different from each other and cause expansion and contraction of the corresponding panel layers  916 ,  918  along the interface. 
     Each vent panel  908  defines an elongated attachment region  924  that is attached to the vent frame  904  and a flap  926  that includes a lowermost lip  928 . Each vent panel  908  also preferably includes a foam layer  930  that is bonded to the inner panel layer  918  with another adhesive layer (not shown). The foam layer  930  preferably includes a series of foam sections  934  that extend generally parallel to each other along the longitudinal axis of the vent panel  908 . Each pair of adjacent foam sections  934  is preferably shiftable toward and away from one another as the panel  908  flexes. Also, each pair of adjacent foam sections  934  restricts the flap  926  of the corresponding vent panel  908  from flexing toward the vent opening  910  from an unflexed position (see  FIG. 45 ). 
     The gable vent  900  further includes elongated coil spring elements  936  that present opposite upper and lower ends  936   a,b  attached respectively to the attachment region  924  and the lip  928  (see  FIGS. 43 and 44 ). 
     The flaps  926  are preferably shiftable into and out of the unflexed position. The flaps  926  are preferably in the unflexed position when the vent panel  908  is at a normal operating temperature. In the unflexed position, the flaps  926  extend vertically along the vent opening  910  and are generally parallel to and immediately adjacent the vent opening  910  (see  FIGS. 43 and 45 ). 
     In the unflexed position, the spring elements  936  are preferably elongated from a relaxed condition so that the spring elements  936  are stretched. With the spring elements  936  stretched, the spring elements  936  preferably urge the flaps  926  to shift toward a flexed position (see  FIGS. 44 and 46 ). In particular, the spring elements  936  apply generally upward spring forces to the lip  928  to urge the lip to move upwardly and away from the vent opening  910 . 
     At the normal operating temperature, the structure of the vent panel  908  preferably exerts a force, which is partly due to the weight of the vent panel, that counteracts and is larger than the combined spring forces. Thus, at the normal operating temperature, the vent panel  908  remains in the unflexed position. 
     The flaps  926  are also shiftable into and out of the flexed position at a temperature above the normal operating temperature (see  FIGS. 44 and 46 ). In the flexed position, the flaps  926  are generally spaced outwardly from the vent opening  910  so that air can pass into and out of the attic space  904 . 
     In the flexed position, the spring elements  936  are preferably stretched to a smaller degree compared to the unflexed position. Furthermore, in some instances, the spring elements  936  could assume the relaxed condition when the flaps  926  are flexed. 
     Turning to  FIGS. 47-50 , a roof vent  1000  is constructed in accordance with a twenty-second embodiment of the present invention. The roof vent  1000  is illustrated as being mounted on a roof wall  1002  of the enclosed building B. In the usual manner, the roof wall  1002  defines part of an interior attic space  1004  of the building B (see  FIGS. 49 and 50 ). Similar to the previous panel embodiments, the roof vent  1000  is configured to move in response to a change in temperature experienced by the roof vent  1000 . The roof vent  1000  is preferably configured to permit air flow F to move into and out of the space  1004 . 
     The roof vent  1000  preferably includes a vent frame  1006 , a vent cover  1008 , and a laminated composite vent panel  1010 . The vent frame  1006  is mounted to the roof wall  1002  and cooperates with the roof wall  1002  to define a vent opening  1012  (see  FIGS. 49 and 50 ). The vent opening  1012  fluidly communicates with the interior attic space  1002 . The vent frame  1006  presents an open chamber  1014  and side openings  1016  that fluidly communicate with the chamber  1014 . 
     The vent panel  1010  is similar to the vent panel  908  and includes outer and inner panel layers  1018 ,  1020  and an intermediate adhesive layer (not shown) that bonds the panel layers  1018 ,  1020  relative to one another. The vent panel  1010  also preferably includes a foam layer  1024  (see  FIGS. 49 and 50 ) that is bonded to the inner panel layer  1020  with another adhesive layer  1026 . The foam layer  1024  preferably includes a series of foam sections  1028  (see  FIGS. 49 and 50 ) that extend generally parallel to each other along the longitudinal axis of the vent panel  1010 . 
     Each vent panel  1010  defines an elongated attachment region  1030  that is attached to the vent frame  1006  and a flap  1032 . The flap  1032  is shiftable into and out of the unflexed position at a normal operating temperature where the flap  1032  is in abutting engagement with the frame  1006  to extend generally parallel to the vent opening  1012  (see  FIGS. 47 and 49 ). 
     The flap  1032  is also shiftable into and out of the flexed position at a temperature above the normal operating temperature (see  FIGS. 48 and 50 ). In the flexed position, the flap  1032  is generally spaced outwardly from the frame  1006  and the vent opening  1012  so that air flow F can pass into and out of the attic space  1004 . 
     Turning to  FIGS. 53 and 54 , a roof vent  1100  is constructed in accordance with a twenty-third embodiment of the present invention. The roof vent  1100  is illustrated as being mounted on the roof wall  1102  of the enclosed building B. The roof wall  1102  presents a roof opening  1104  and defines part of an interior space  1105 . Similar to the previous panel embodiments, the roof vent  1100  is configured to move in response to a change in temperature experienced by the roof vent  1100 . The roof vent  1100  is preferably configured to permit air flow F to move into and out of the space  1105 . 
     The roof vent  1100  preferably includes a laminated composite vent panel  1106  and a vent plug  1108 . The vent panel  1106  includes outer and inner panel layers  1110 ,  1112  and an intermediate adhesive layer  1114 . The vent panel  1106  also includes a foam layer  1118  bonded to the inner panel layer  1112  with another adhesive layer  1120 . 
     The vent panel  1106  defines an attachment region  1122  and a flap  1124 . The attachment region  1122  is secured to the wall  1102  with threaded fasteners  1126 . The flap  1124  is shiftable into and out of the unflexed position at a normal operating temperature where the flap  1124  extends generally parallel to and engages a surface  1128  of the roof wall  1102  (see  FIG. 53 ). Also, the vent plug  1108  is preferably removably received by the opening  1104 . 
     The flap  1124  is also shiftable into and out of the flexed position at a temperature above the normal operating temperature (see  FIG. 54 ). In the flexed position, the flap  1124  is generally spaced outwardly from the roof opening  1104  so that air flow F can pass into and out of the attic space  1105 . 
     Turning to  FIGS. 55 and 56 , an automobile roof vent  1200  is constructed in accordance with a twenty-fourth embodiment of the present invention. The roof vent  1200  is illustrated as being mounted on the roof wall  1202  of a vehicle V. The illustrated vehicle V comprises an automobile with a rolling chassis and a drive train (not shown). 
     In the usual manner, the roof wall  1202  defines part of an interior vehicle space  1204  of the vehicle V. The roof vent  1200  is configured to move in response to a change in temperature experienced by the roof vent  1200 . The roof vent  1200  is preferably configured to permit air flow F to move into and out of the space  1204  (e.g., as the vehicle V is being advanced in a forward travel direction N. 
     The roof vent  1200  preferably includes a vent frame  1206  and a series of laminated composite vent panels  1208 . The vent frame  1206  is mounted to the roof wall  1202  and defines a vent opening  1210 . Each vent panel  1208  includes an outer panel layer  1212 , an inner panel layer (not shown), and an intermediate adhesive layer (not shown) bonding the panel layers to each other. 
     Each vent panel  1208  defines an attachment region  1218  fixed to the roof wall  1202  and a flap  1220  (see  FIG. 55 ). The flap  1220  is shiftable into and out of the unflexed position at a normal operating temperature where the flap  1220  extends generally parallel to and engages a surface  1222  of the roof wall  1202  (see  FIG. 55 ). 
     The flap  1220  is also shiftable into and out of the flexed position at a temperature above the normal operating temperature (see  FIG. 56 ). In the flexed position, the flap  1220  is generally spaced outwardly from the vent opening  1210  so that air flow F can pass into and out of the interior vehicle space  1204 . 
     Although the above description presents features of preferred embodiments of the present invention, other preferred embodiments may also be created in keeping with the principles of the invention. Such other preferred embodiments may, for instance, be provided with features drawn from one or more of the embodiments described above. Yet further, such other preferred embodiments may include features from multiple embodiments described above, particularly where such features are compatible for use together despite having been presented independently as part of separate embodiments in the above description. 
     The preferred forms of the invention described above are to be used as illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventor hereby states his intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.