CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 62/467,878, filed March 7, 2017, and entitled "Pre-Case Concrete Flooring Systems and Methods of Use," the content of which is herein incorporated by reference in its entirety.

BACKGROUND

Most multi-story buildings are very wasteful of the space between the finished ceiling of one level and the finished floor of the level above it. This volume is referred to as the "sandwich volume." Various building systems are routed through the sandwich volume, including HVAC, electrical, communications, plumbing, and fire protection.

To make the design process simpler, the design team often allocates an independent volume to each of the systems. FIG. 1 illustrates a typical example of the sandwich volume. The structural, HVAC and lighting systems have been given their own volumes, having a horizontal extent equal to the footprint of the building and a vertical dimension great enough to accommodate the deepest component of each system. In this process, vast amounts of the interstitial volume are filled only with air. The overall height of the interstitial space is typically 5 to 6 feet in multistory office buildings.

Accordingly, there is a need in the art for a flooring system that allows for more efficient use of the sandwich volume.

BRIEF SUMMARY

Various implementations include an elongated pre-cast concrete floor support unit. The floor support unit comprises a first wall, a second wall, a third wall, a first web extending between the first wall and the second wall, and a second web extending between the first wall and the third wall. The second and third walls are coplanar and lie in a plane that is parallel and spaced apart from the first wall. The first and second webs are spaced apart from each other. And, the first wall and the first and second webs define a channel therebetween.

In some implementations, the floor support unit further comprises a first flange and a second flange. The first flange extends from an intersection of the first wall and the first web in the plane of the first wall, and the second flange extends from an intersection of the first wall and the second web in the plane of the first wall.

In some implementations, the first wall includes a first surface and a second surface. The first and second surfaces are opposite and spaced apart from each other. The first surface faces a first vertical direction, and the second surface faces a second vertical direction that is opposite from the first vertical direction. Each of the first and second webs has a first surface and a second surface. The first and second surfaces of the webs are opposite and spaced apart from each other, and the first surfaces of the first and second webs and the first wall define the channel. Each of the second and third walls has a first surface that faces the first vertical direction and a second surface that is opposite and spaced apart from the first surface of each of the second and third walls and faces the second vertical direction. And, thermally insulating material is disposed on at least a portion of the first surfaces of the first and second webs and the first, second, and third walls. For example, in some implementations, the thermally insulating material comprises at least one of a fiber reinforcing polymer material or sprayed foam insulation.

In some implementations, the unit has a first edge and a second edge, and first and second surfaces of each wall and web extend between the first edge and the second edge. The first edge of the channel is in fluid communication with a return air duct for a heating, ventilation, and air conditioning (HVAC) system, and the return air is received through the channel.

In some implementations, the first web lies at an angle of between 90° and 135° to the first wall.

In some implementations, the second web lies at an angle of between 90° and 135° to the first wall.

In some implementations, the concrete comprises pre-stressed tendons.

Various other implementations include a pre-cast concrete floor support system that comprises at least a first elongated floor support unit and a second elongated floor support unit. Each unit includes: a first wall; a second wall; a third wall; a first web extending between the first wall and the second wall; and a second web extending between the first wall and the third wall. The second and third walls are coplanar and lie in a plane that is parallel and spaced apart from the first wall, and the first and second webs are spaced apart from each other. The first wall and the first and second webs define a channel therebetween. A distal edge of the third wall of the first elongated floor support unit abuts against a distal edge of the second wall of the second elongated floor support unit, and the distal edges of the second and third walls are spaced apart from the first and second webs, respectively. The channel defined by the first wall and the first and second webs of each elongated floor support unit is a first channel and faces a first vertical direction, and a second channel is defined by the third wall and the second web of the first elongated floor support unit and the abutting second wall and the first web of the second elongated floor support unit. The second channel faces a second vertical direction that is opposite from the first vertical direction.

In some implementations, each elongated floor support unit further comprises a first flange and a second flange. The first flange extends from an intersection of the first wall and the first web in the plane of the first wall, and the second flange extends from an intersection of the first wall and the second web in the plane of the first wall.

In some implementations, the first wall of each elongated floor support unit includes a first surface and a second surface. The first and second surfaces are opposite and spaced apart from each other. The first surface faces a first vertical direction, and the second surface faces a second vertical direction that is opposite from the first vertical direction. Each of the first and second webs of each elongated floor support unit has first surface and a second surface, and the first and second surfaces of the webs are opposite and spaced apart from each other. The first surfaces of the first and second webs and the first wall define the channel. Each of the second and third walls of each elongated floor support unit has a first surface that faces the first vertical direction and a second surface that is opposite and spaced apart from the first surface of each of the second and third walls and faces the second vertical direction, and thermally insulating material is disposed on at least a portion of the first surfaces of the first and second webs and the first, second, and third walls.

In some implementations, the second channel distributes supply air from a heating, ventilation, and air conditioning (HVAC) system for a second level of a building, and the first channel receives return air for the HVAC system from a first level of the building, the first level being vertically below and adjacent the second level.

In some implementations, each elongated floor support unit has a first edge and a second edge, and first and second surfaces of each wall and web of each elongated floor support unit extend between the first edge and the second edge. One of the first or second edges of the first channel is in fluid communication with at least one return air inlet for the HVAC system, and the return air flows through the first channel. One of the first or second edges of the second channel is in fluid communication with at least one supply air outlet for the HVAC system, and the supply air flows through the second channel.

In some implementations, the first web of each elongated concrete floor support unit lies at an angle of between 90° and 135° to the first wall.

In some implementations, the second web of each elongated concrete floor support unit lies at an angle of between 90° and 135° to the first wall.

In some implementations, the concrete comprises pre-stressed tendons.

In some implementations, each flange defines a plurality of recessed portions along a distal edge of each flange. The distal edge extends a first distance from the web from which the flange extends, and each recessed portion has a distal edge that extends a second distance from the web from which the flange extends. The first distance is greater than the second distance. The distal edge of the second flange of the second elongated concrete floor support unit abuts the distal edge of the first flange of the first elongated concrete floor support unit, and the recessed portions defined by each edge align and define an opening through which supply air flows.

In some implementations, each of the second wall and third wall defines a plurality of recessed portions along a distal edge of each of the second wall and the third wall. The distal edge extends a first distance from the web from which the second or third wall extends, and each recessed portion has a distal edge that extends a second distance from the web from which the second or third wall extends. The first distance is greater than the second distance. The distal edge of the second wall of the second elongated concrete floor support unit abuts the distal edge of the first wall of the first elongated concrete floor support unit, and the recessed portions defined by each distal edge align and define an opening through which supply air flows.

In various other implementations, an elongated pre-cast concrete floor support unit includes: a first wall; a second wall; a third wall; a fourth wall; a first web extending between the first wall and the second wall; a second web extending between the first wall and the third wall; and a third web extending between the third wall and the fourth wall. The second and third walls are coplanar, the first and fourth walls are coplanar, the first, second, and third webs are spaced apart from each other, the second and third walls lie in a plane that is parallel and spaced apart from the first and fourth walls, the first and second webs and the first wall define a first channel therebetween, and the third wall and the second and third webs define a second channel therebetween. The first channel opens in a first vertical direction, and the second channel opens in a second vertical direction that is opposite of the first vertical direction.

In some implementations, the unit further comprises a first flange and a second flange. The first flange extends from an intersection of the first wall and the first web in the plane of the first wall, and the second flange extends from an intersection of the first wall and the second web in the plane of the first wall.

In some implementations, the unit further comprises a third flange that extends from an intersection of the fourth wall with the third web in the plane of the fourth wall.

In some implementations, the first, second, third, and fourth walls each include a first surface and a second surface. The first and second surfaces are opposite and spaced apart from each other. The first surface faces a first vertical direction, and the second surface faces a second vertical direction that is opposite from the first vertical direction. Each of the first, second, and third webs has a first surface and a second surface. The first and second surfaces of the webs are opposite and spaced apart from each other, and the first surfaces of the first and second webs and the first wall define the first channel, and the second surfaces of the second and third webs and the third wall define the second channel. Thermally insulating material is disposed on at least a portion of the first surfaces of the first, second, and third webs and the first, second, third, and fourth walls.

In some implementations, the unit has a first edge and a second edge, and first and second surfaces of each wall and web extend between the first edge and the second edge. One of the first or second edges of the first channel is in fluid communication with at least one return air inlet for a heating, ventilation, and air conditioning (HVAC) system, and the return air is received through the first channel. And, one of the first or second edges of the second channel is in fluid communication with a supply air outlet for the HVAC system, and supply air is received through the second channel. In some implementations, the second channel provides supply air to a second level of a building, and the first channel receives return air from a first level of the building, wherein the first level is vertically adjacent and below the second level.

In some implementations, the first web lies at an angle of between 90° and 135° to the first wall. In some implementations, the second web lies at an angle of between 90° and 135° to the first wall.

In some implementations, the third web lies at an angle of between 90° and 135° to the fourth wall.

In some implementations, the unit further includes a fifth wall and a fourth web, the fifth wall being coplanar with the second and third walls, wherein fourth web is spaced apart from the first, second, and third webs, the fourth web extends between the fourth wall and the fifth wall, and the third and fourth webs and the fourth wall define a third channel therebetween that opens in the first vertical direction. In some implementations, the fourth web lies at an angle of between 90° and 135° to the fourth wall.

In some implementations, the unit further includes a fourth flange that extends from an intersection of the fourth wall with the fourth web in the plane of the fourth wall.

And, in some implementations, the concrete comprises pre-stressed tendons.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a typical sandwich volume in a building according to the prior art.

FIG. 2 illustrates an end view of a floor support unit according to one implementation.

FIG. 3 illustrates a partial cross-sectional view of two of the floor support units shown in FIG. 2 disposed horizontally adjacent each other.

FIG. 4 illustrates a cross sectional view of two floor support units shown in FIG. 2 disposed horizontally adjacent each other.

FIG. 5 illustrates a perspective view of a plurality of the floor support units shown in FIG. 2 installed in a building according to one implementation.

FIG. 6A illustrates a partial perspective view of a plurality of floor support units installed in a building according to another implementation.

FIG. 6B illustrates a cross sectional view of two of the floor support units shown in FIG. 6A as taken through the B-B line shown in FIG. 6A.

FIG. 6C illustrates a cross sectional view of two of the floor support units shown in FIG. 6A as taken through the A-A line shown in FIG. 6A.

FIG. 7A illustrates a partial perspective view of a plurality of floor support units installed in a building according to one implementation. FIG. 7B illustrates a cross sectional view of two of the floor support units shown in FIG. 7A as taken through the A-A line shown in FIG. 7A.

FIG. 7C illustrates a cross sectional view of two of the floor support units shown in FIG. 7A as taken through the B-B line shown in FIG. 7A.

FIG. 8 illustrates the floor support units shown in FIG. 6A and a pedestal floor system.

FIG. 9 illustrates the floor support units and pedestal floor system of FIG. 8 and supply and return ducts installed adjacent one end of a building, according to one implementation.

FIG. 10 illustrates the floor support units and pedestal floor system of FIG. 8 and supply and return ducts installed adjacent a side of a building, according to one implementation.

FIG. 11 illustrates the floor support units and pedestal floor system of FIG. 8 and supply and return ducts installed within an interior volume in a building, according to one implementation.

FIG. 12 illustrates a floor support unit according to another implementation.

FIG. 13 illustrates a floor support unit according to another implementation.

DETAILED DESCRIPTION

Various implementations include a corrugated concrete floor system that includes a plurality of elongated pre-cast concrete floor support units disposed in a horizontal arrangement relative to each other. The concrete floor support units are disposed between floors of a multi-story building. The units define a plurality of supply air plenums and return air plenums that are arranged alternately in the sandwich space between each floor. The supply air plenums are in fluid communication with the building level above them, and the return air plenums are in fluid communication with the building level below them. By having the supply-air plenum and the return-air plenum share the volume occupied by concrete floor support units, the height of the sandwich space is reduced.

In addition, various implementations of the floor system provide thermal comfort and good air quality by providing a continuous supply air plenum that delivers fresh, thermally conditioned air upward through the floor surface to the occupied space above and a continuous return air plenum that removes stale air through the ceiling of the occupied space below. In the occupied spaces, gently rising ventilation air assures comfort and maximizes air quality by taking off the most contaminated air at the ceiling.

The height of the sandwich space is also reduced by providing a top flange cross sectional area and an extensive bottom flange cross sectional area that provides a favorable cross-sectional area for the floor unit. The top flange increases the section modulus and moment of inertia of the floor unit and provides a working surface for construction activities and a support surface on which to mount an elevated access flooring that is used to enclose the supply plenum and provide a level, finished floor for the building occupants. In addition, the top flanges may be coupled together intermittently to complete the floor diaphragm. By reducing the sandwich space, each floor of the building can have higher ceilings, and/or the overall height of the building can be reduced. Higher ceilings can provide lighter, more cheerful spaces and deeper penetration of natural light, which can reduce lighting electricity consumption. And, a lower building height decreases the cost of the building envelope area, reduces energy operating costs associated with energy losses through a thermal envelope of the building, and reduces the cost of additional structure that may be required to resist overturning moments due to wind and/or seismic activity.

In addition, by forming the units with concrete, the units provide full fire separation between building stories. Thus, no separate concrete topping layer is required. And, the system is compatible with steel-frame and pre-cast concrete-frame construction, which eliminates site-cast concrete and simplifies and speeds up the construction process.

Various implementations of the concrete floor system are applicable to any multi-story building. For example, the concrete floor system may be used in commercial, retail, residential, or industrial buildings.

FIG. 2 illustrates an elongated pre-cast concrete floor support unit 10 that includes a first wall

12, a second wall 14, a third wall 16, a first web 18, and a second web 20. The second 14 and third walls 16 are coplanar and lie in a plane that is parallel and spaced apart from the first wall 12. The first web 18 extends between the first wall 12 and the second wall 14, and the second web 20 extends between the first wall 12 and the third wall 16. The first web 18 and the second web 20 are spaced apart from each other, and the first wall 12 and the first 18 and second webs 20 define a channel 26 therebetween. In some implementations, each of the first web 18 and second web 20 lies at an angle Θ of between 90° and 135° to the first wall 12.

The first wall 12 includes a first surface 32 and a second surface 34, and the first 32 and second surfaces 34 are opposite and spaced apart from each other. The first surface 32 faces a first vertical direction, and the second surface 34 faces a second vertical direction that is opposite from the first vertical direction. In addition, each of the first 18 and second webs 20 has a first surface 36 and a second surface 38, and the first 36 and second surfaces 38 of the webs 18, 20 are opposite and spaced apart from each other. The first surfaces 36 of the first 18 and second webs 20 and the first surface 32 of the first wall 12 define the channel 26. Furthermore, each of the second 14 and third wall 16 has a first surface 40 that faces the first vertical direction and a second surface 42 that is opposite and spaced apart from the first surface 40 and faces the second vertical direction.

The floor support unit 10 also includes a first flange 28 and a second flange 30. The first flange 28 extends from an intersection of the first wall 12 and the first web 18 in the plane of the first wall 12 in a first horizontal direction, and the second flange 30 extends from an intersection of the first wall 12 and the second web 20 in the plane of the first wall 12 in a second horizontal direction that is opposite of the first horizontal direction. The first 28 and second flanges 30 have second surfaces 44 that are coextensive with second surface 34 of the first wall 12.

As shown in FIGS. 3 and 4, thermally insulating material 51 is disposed on at least a portion of the first surfaces 36 of the first 18 and second webs 20, the first surface 32 of the first wall 12, and the first surfaces 40 of the second 14 and third walls 16. For example, the thermally insulating material includes a fiber reinforcing polymer material, sprayed foam insulation, and/or soy-based material.

Furthermore, in some implementations, the concrete of the floor support unit 10 may include pre-stressed tendons.

FIG. 5 illustrates a plurality of the floor support units 10 shown in FIGS. 2-3 disposed horizontally adjacent each other on support beams. Each floor support unit 10 is elongated, and each floor support unit 10 has a first edge 46 and a second edge 48. The first surfaces 32, 36, 40 and second surfaces 34, 38, 42 of each wall 12, 14, 16 and web 18, 20, respectively, extend between the first edge and the second edge.

FIGS. 6A-6C illustrates a plurality of support units 210a, 210b disposed upon horizontal support beams, according to another implementation. The support units 210a, 210b are similar to support unit 10 except as noted. As shown in this implementation, each flange 228, 230 defines a plurality of recessed portions 262 along a distal edge 264 of each flange 228, 230. The distal edge 264 extends a first distance Dl from the respective web 218, 220 from which the flange 228, 230 extends, and each recessed portion 262 has a second edge 266 that extends a second distance D2 from the respective web 218, 220 from which the flange 228, 230 extends. The first distance Dl is greater than the second distance D2. And, the distal edge 264 of the second flange 230 of the second elongated concrete floor support unit 210b abuts the distal edge 264 of the first flange 228 of the first elongated concrete floor support unit 210a, and the recessed portions 262 defined by each edge 264 align and define an opening through which supply air flows from the adjacent supply channel 258. The second edge 266 may define a stepped portion 266b as shown in FIG. 6C. The stepped portion 266b may receive a vent cover. For example, a horizontal portion of the stepped portion 266b may provide support for the vent cover, and a vertical portion of the stepped portion 266b prevents the vent cover from sliding horizontally. A depth of the vertical portion of the stepped portion 266b may be similar to a height of the vent cover so that an upper surface of the vent cover is flush with the second surfaces 244 of the respective flanges 228, 230.

The implementation shown in FIGS. 7A-7C is similar to the implementation shown in FIGS. 6A-6C but each of the second wall 214' and third wall 216' defines a plurality of recessed portions 270' along the distal edge 254' of the second wall 214' and the distal edge 256' of the third wall 216'. The distal edges 254', 256' extend a first distance Dl' from the web 218', 220' from which the second 214' or third wall 216' extends, respectively. And each recessed portion 270' has a distal edge 272' that extends a second distance D2' from the web 218', 220' from which the second 214' or third wall 216' extends. The first distance Dl' is greater than the second distance D2', and the distal edge 254' of the second wall 214' of the first elongated concrete floor support unit 210a' abuts the distal edge 256' of the third wall 216' of the second elongated concrete floor support unit 210b'. The recessed portions 270' align and define openings 274' through which supply air flows into the adjacent supply channel 258' from the plenum 25 disposed below the recessed portions 270'.

As shown in FIGS. 8-11, the first channels 226 on a particular level of a building are in fluid communication with one or more return trunks 250 for the particular level, and the return trunk(s) 250 for each level are in fluid communication with one or more return chases 252, which return the air to heating, ventilation, and air conditioning (HVAC) system for conditioning. Similarly, the second channels 258 on a particular level of the building are in fluid communication with one or more supply trunks 253 for the particular level, and the supply trunk(s) 253 for each level are in fluid communication with one or more supply chases 260, which supplies conditioned air to the supply trunks 253 from the HVAC system.

In the implementation shown in FIGS. 8-9, the supply trunks 253 are disposed adjacent the first edges 246 of the second channels 258, and the return trunks 250 are disposed adjacent the first edges 246 of the first channels 226. The supply chase(s) 260 and the return chase(s) 252 are also disposed adjacent an exterior side of the building adjacent the first edges 246 of the channels 226, 258.

In other implementations, the supply and return trunks and the supply and return chases may be disposed adjacent other exterior sides of the building or extend through interior portions of the building (e.g., spaced inwardly from exterior sides). For example, in the implementation shown in FIG. 10, the return air trunks 150 and the supply air trunks 153 are disposed adjacent the distal edge 254 of the second wall 214 of a unit 210 that is disposed along an exterior side of the building, between the first edges 246 and second edges 248 of the units 210. The return air chase 152 and supply air chase 160 are also disposed along that exterior side of the building. And, in the implementation shown in FIG. 11, the return and supply trunks and the return chase 252 and supply chase 260 extend through an interior portion of the building.

As shown in FIGS. 8-11, in some implementations, a pedestal access flooring layer 280 is disposed over the second surface 234 of the first wall 212 and the second surfaces 244 of the first 228 and second flanges 230. The pedestal access flooring layer 280 includes a horizontal surface 282 supported by a plurality of adjustable pedestals 284 that are supported by the second surfaces 234, 244. The height of each pedestal 284 is adjustable to provide a level, finished floor sub-surface for installation of the flooring material (e.g., carpet, hardwood, laminate, etc.) for the level of the building. The flooring layer 280 also defines the supply air plenum with the channels 258 below the flooring layer 280. The flooring layer 280 further defines a plurality of vents 286 through which supply air flows into the level of the building. The vents 286 are adjustable to control the supply air flowing into the level of the building adjacent the vents 286. Furthermore, baffles or other air directing structures may be disposed within the supply air plenum defined between the flooring layer and the second surfaces 234, 244 of the floor support units 210 to direct air flow through the supply air plenum.

In addition, a dropped ceiling may be disposed below the floor support units 210. The dropped ceiling defines a plurality of vents through which return air flows into the return air plenum defined between the dropped ceiling and the first surfaces 240, 232, and 236 and channel 226 of the floor support units 210.

FIG. 12 illustrates another implementation of a floor support unit 110. Each unit 110 includes a first wall 112, a second wall 114, a third wall 116, a first web 118, and a second web 120, which are similar to the units 10, 210', 210 described above in relation to FIGS. 2-11. However, the

implementation shown in FIG. 12 also includes a fourth wall 174 and a third web 178. The third web 178 is spaced apart from the first web 118 and the second web 120. In addition, the first 112 and fourth walls 174 are coplanar. The second 114 and third walls 116 lie in a plane that is parallel and spaced apart from the first 112 and fourth walls 174. The first 118 and second webs 120 and the first wall 112 define a first channel 126 therebetween, and the third wall 116 and the second 120 and third webs 178 define a second channel 158 therebetween. The first channel 126 opens in a first vertical direction, and the second channel 158 opens in a second vertical direction that is opposite of the first vertical direction.

Similar to units 10, 210', 210, each unit 110 includes a first flange 180 and a second flange 182. The first flange 180 extends from an intersection of the first wall 112 and the first web 118 in the plane of the first wall 112, and the second flange 182 extends from an intersection of the first wall 112 and the second web 120 in the plane of the first wall 118. However, unit 110 also includes a third flange 184 that extends from an intersection of the fourth wall 174 with the third web 178 in the plane of the fourth wall 174.

The first 112, second 114, third 116, and fourth walls 174 each include a first surface 132 and a second surface 134. The first 132 and second surfaces 134 are opposite and spaced apart from each other, and the first surface 132 faces a first vertical direction and the second surface 134 faces a second vertical direction that is opposite from the first vertical direction. The first 118, second 120, and third webs 178 have a first surface 136 and a second surface 138. The first 136 and second surfaces 138 of the webs 118, 120, 178 are opposite and spaced apart from each other. The first surfaces 136 of the first 118 and second webs 120 and first surface 132 of the first wall 112 define the first channel 126, and the second surfaces 138 of the second 120 and third webs 178 and the second surface 134 of the third wall 116 define the second channel 158. In some implementations, thermally insulating material 151 is disposed on at least a portion of the first surfaces 136 of the first 118, second 120, and third webs 178 and the first surfaces 132 of the first 112, second 114, third 116, and fourth walls 174. The unit 110 also includes a first edge and a second edge, and first 132 and second surfaces 134 of each wall 112, 114, 116, 174 and the first 136 and second surfaces 138 of each web 118, 120, 178 extend between the first edge and the second edge.

FIG. 13 shows another implementation of a floor support unit 410. The unit 410 is similar to unit 110 but further incudes a fifth wall 486 and a fourth web 488. The fifth wall 486 is coplanar with the second 414 and third walls 416. The fourth web 488 is spaced apart from the first 418, second 420, and third webs 478. The fourth web 488 extends between the fourth wall 474 and the fifth wall 486. The third 478 and fourth webs 488 and the fourth wall 474 define a third channel 494 therebetween that opens in the first vertical direction. In addition, the unit 410 includes a fourth flange 496 that extends from an intersection of the fourth wall 474 with the fourth web 488 in the plane of the fourth wall 474.

The first 412, second 414, third 416, fourth 474, and fifth walls 486 each include a first surface 432 and a second surface 434. The first 432 and second surfaces 434 are opposite and spaced apart from each other, and the first surface 432 faces a first vertical direction and the second surface 434 faces a second vertical direction that is opposite from the first vertical direction. The first 418, second 420, third webs 478 and fourth webs 488 have a first surface 436 and a second surface 438. The first 436 and second surfaces 438 of the webs 418, 420, 478, 488 are opposite and spaced apart from each other. The first surfaces 436 of the first 418 and second webs 420 and the first surface 432 of the first wall 412 define the first channel 426, the second surfaces 438 of the second 420 and third webs 478 and the second surface 434 of the third wall 416 define the second channel 458, and the first surfaces 436 of the third 478 and the fourth webs 488 and the first surface 432 of the fourth wall 474 define the third channel 494. In some implementations, thermally insulating material 451 is disposed on at least a portion of the first surfaces 436 of the first 418, second 420, third 478, and fourth webs 488 and the first surfaces 432 of the first 412, second 414, third 416, fourth 474, and fifth walls 486. The unit 410 also includes a first edge and a second edge, and first 432 and second surfaces 434 of each wall 412, 414, 416, 474 and the first 436 and second surfaces 438 of each web 418, 420, 478 extend between the first edge and the second edge.

The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The implementation was chosen and described to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various implementations with various modifications as are suited to the particular use contemplated.