CA2556476A1

CA2556476A1 - Dynamically ventilated exterior wall assembly

Info

Publication number: CA2556476A1
Application number: CA002556476A
Authority: CA
Inventors: Mark Larry Stender
Original assignee: MOISTURE MANAGEMENT LLC
Current assignee: MOISTURE MANAGEMENT LLC
Priority date: 2005-10-17
Filing date: 2006-08-18
Publication date: 2007-04-17
Also published as: US20070094964A1

Abstract

A dynamically ventilated exterior wall includes a sealed exterior wall assembly and a ventilation assembly fluidly coupled to the exterior wall assembly. The exterior wall assembly includes an interior wall portion and an opposing exterior wall portion, and insulation and a flexible porous grid disposed between the interior and exterior wall portions. The ventilation assembly includes a head end unit coupled to air supply conduit(s) and air return conduit(s), where each of the conduits communicates with the porous grid of the exterior wall assembly. The head and unit is configured to supply conditioned air through the air supply conduit(s) to the exterior wall assembly and remove humidity from the exterior wall assembly through the sir return conduit(s).

Description

'.

DYNAMICALLY VENTILATED EXTERhOR WALL ASSEMBLY
Cross-Reference to Related Applications This Utility Patent Application is related to commonly assigned and concurrently filed Utility Patent Application Serial Number XX/3~X,XXX, entitled EXTERIOR WALL ASSEMBLY having Attorney Docket Number M420.101.101, and which is herein incorporated by reference.

Background Recent improvements in the construction of homes and buildings have resulted in the fabrication of highly energy e~cient structures. New construction materials, improved construction methods, and more shingent local 15 and state building codes have all combined to provide highly energy e~cieut structures. In particular, exterior walls that are insulated and sealed, made according to code, and with the latest construction materials, increase the energy e~ciency of these structures.
Insulated and sealed wall structures (i.e., "airtight" structures) reduce .
20 heat loss by substantially preventing drafts that remove heat from the wall structure. In addition, insulated and sealed wall structures are constructed to prevent the passage of moisture through the we'll. Thus, insulated and sealed walls are airtight and moisture resistant, and are highly energy e~cient.
However, since insulated and sealed walls do not "breathe,' breached or 25 damaged insulated and sealed walls can.harbor moisture and provide nearly ideal breeding gTOUnds for mold and bacteria.
In addition, environmental climate changes can create temperature differences between the internal and external spaces of the insulated and sealed walls that can contribute to the formation of condensate on interior surfaces of 30 the walls. For example, during northern cold winter months, the air outside of an insulated and sealed wall is cold and dry, and the air inside of the wall is warm and humid. Thus, a natural humidity gradient is formed where moisture vapor in 1.

the air of an interior of the wall structure naturally raigrstes to the exterior of the wall structure. Thus, large gradients in outside and inside sir temperatures can lead to an accumulation ofmoisture within even an insulated and sealed wall The opposite conditions occur during the summer months, when ~e sir outside the structure is warm and humid, and the air inside the structure is conditioned to be cooler and dryer. Thus, during summer months a ~nattusl, gradient exists driving warm humid air toward an interior of an insulated and sealed wall. Consequently, moisture can accumulate within an insulated and sealed wall due to normal, climate-induced temperature and humidity gradients.
Moisture includes~bulk liquid, such as rain or rain droplets, and moisture vapor, such as in warm and humid air. Moisture, 'whether bulls or in the form of moisture vapor, can accumulate on surfaces of an insulated and sealed wall, as described above. In some cases, moisture is the result of natural condensation, but may also be the result of wind driven water that eaters the wall along a window or door seam. For example, forming a window or a door in an exterior wall provides locations where water can enter the wall assembly and accumulate behind the wall covering. In some cases, moisture entering in the form of water is the result of poor workmanship, or alternately, a deterioration of flashing or sealants around the window/door.
In general, moisture accumulation within a wall, whether in the form of bulk liquid'ar in the form of moisture vapor; structurally damages the wall and .can lead to health and safely issues for the occupants of the structure. In particular, moisture within a wall is known to create a breeding ground for insects, and can form other health hazards, such as the growth of molds and/or bacteria. The deleterious effects of moisture accumulation within a wall are' accelerate6 in hot and humid environments:
This undesirable moisture penetration and accumulation within a Mall assembly in new building structures has created challenges for the construction and insurance industries. Thus, there is a need for a system and a method to prevent moisture from accumulating in a sealed exterior~wall assembly of a bui3ding structure, and for the removal of moisture that potentially collects within an exterior wall assembly. . ~ , .

~tlInnlarV
One aspect of the present invention is related to a dynamically ven#ilated exterior wall system. The dynamically ventilated exterior wall system includes a sealed exterior wall assembly and a ventilation assembly fluidly coupled to the.
exterior wall assembly. The sealed exterior wall assembly includes an interior wall portion and an opposing exterior wall portion, and insulation and a flexible porous grid disposed between the interior and exterior wall portions. The ventilation assembly includes a head end unif coupled to at least one air supply conduit and at least one air return conduit, where each of the conduits communicates with the porous grid of the exterior wall assembly. The head and unit is configured to supply conditioned air through the air supply conduits) to the exterior wall assembly and remove humidity from the exterior wall assembly through the air return conduit(s).
Another aspect of the present invention relates to a method of IS dynamically ventilating a sealed exterior wall that includes an interior wall portion and an opposing exterior wall portion and insulation adjacent to the interior wall portion. The method includes disposing a porous grid between the insulation and the exterior wall portion to define an air space within the sealed exterior wall. The method additionally provides supplying conditioned air through the air space. The method ultimately provides for removing humidity from the sir space.
Another aspect of the present invention relates to an exterior wall system.
The system includes an exterior wall assembly and means for transporting moisture out of the exterior wall assembly. The exterior wall assembly includes an interior wall portion and an opposing exterior wall portion, and a flexible porous grid disposed between the interior and exterior wall portions. In this regard, means for transporting moisture through the flexible porous grid and out of the ea~terior wall assembly~is provided.
. . Brief Description of the Drawings The accompanying dravs~ings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles of the invention. Other embodiments of the present invention, and many of the intended advantages of the present invention, will be readily appreciated as they become better understood by reference to the following detailed description.
The elements of the drawings are not necessarily to scale relative to each other.
Like reference numerals designate corresponding similar parts.
Figure 1 illustrates a cross-sectional view of a structure including a dynamically ventilated exterior wall system according to one embodiment of the present invention.
Figure 2 illustrates a cross-sectional view of an above-grade exterior wall assembly according to one embodiment of the present invention.
Fioure 3 illustrates a cross-sectional view of a below-grade exterior wall assembly according to one embodiment of the present invention.
Figure 4A illustrates a cross-sectional view of a flexible moisture grid according to one embodiment of the present invention.
Figwe 9B illustrates a perspective view of another flexible moisture grid according to one embodiment of the present invention.
Figure 4C illustrates a cross-sectional view of another flexi'bIe moisture grid according to one embodiment ofthe present invention.
Figuie 5 illustrates a perspective view of the flexible moisture grid illustrated in Figure 4C.
Figure 6 illustrates a flexible grid coupled to a construction board according to one embodiment of the present invention.
Figure 7 illustrates a perspective view of a head end unit including air supply and return conduits according to one embodiment of thepresent invention.
Figure 8A illustrates a structure end of an air supply/return conduit including o single row~of orifices fozzned in a conduit wall~according to one embodiment of the present invention.

' Figure ~8B illustrates a structure end of an air supplylreturn conduit including a plurality of orifices disposed helically about a circumference of the conduit according to one embodiment of the present invention.
Figure 8C illustrates a structure end of an air supply/reiurn conduit including a plurality of orifices disposed in parallel columns along the conduit according to one embodiment of the present invention, Fi~ure 9 illustrates a system flow chart directed to the removal of moisture from a zoned structure according to one embodiment of the present invention. .
Detailed Description In the following Detailed Description, reference is made to the accompanying drawings, which form a pari hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as "top," "bottom,"
"front," "back," "leading," "trailing," etc., is used with reference to the orientation of the Figures) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a Limiting sense, and the scope of the present invention is defined by the appended claims.
Figwe 1 illustrates a structure 20 including a dynamicaiiy ventilated exterior wall system 22 according to one embodiment of the present invention.
Structure 20 includes a first sealed exterior wall assembly 24, and a second sealed exterior waD assembly 26. Sealed exterior wall assemblies are structures chat are sealed against the passage of moisture and air and include, for example, finished exterior wall structures having caulhe;d sums, sealed seams, fitted flashing, andlor exterioi claddings configured to prevent the transmission.of sir and moisture through the wall.

In one embodiment, the first sealed exterior wall assembly 24 is as above-grade exterior wall, and second sealed exterior wall assembly 26 is a below-grade exterior wall. The ventilation assembly 22 is fluidly coupled to the exterior wall assemblies 24, 26, and in one embodiment, includes a head end unit 28, air supply conduits 30, 32, and air return conduits 34, 36, where the conduits 30-36 extend from head end unit 28 into an interior of the sealed exterior wall assemblies 24, 26.
For example, in one embodiment head end unit 28 supplies conditioned dry air through air supply conduits 30, 32 into above-grade exterior wall assembly 24 and below-grade exterior wall assembly 26. Aix return conduits 34, 36 remove air, for example relatively humid air, from the sealed above-grade exterior wall assembly 24 and below-grade exie:rior wall assembly 26, and deliver the return air to head end unit 28. In one embodiment, a humidity sensor 40 is coupled between air return conduit 38 and head end unit 28, although other I S suitable locations for humidity sensor 40 along a return path from exterior wall assemblies 24, 26 to head end unit 28 are also acceptable.
In one embodiment, desired structural openings, such as a window 50 and a door 52, are formed in the exterior wall assemblies 24, 26 that provide a pathway for the ingress of moisture into structure 20. While it is desirable to have window 50 and door 52 formed in structture 20, such openings provide a potential pathway for the entrance of moisture into the sealed exterior wall assemblies 24, 26.
In one embodiment, air supply conduit 30 is disposed in a zone adjacent' to window 50, and air supply conduit 32 is disposed in a zone adjacent to door 52, to supply these potential.moisture entry areas with conditioned, dry air.
In another embodiment, air supply conduit 30 surrounds window 50, and air supply conduit 32 siurounds door 52. In any regard, air supply conduits 30, 32 supply conditioned, dry air to exterior wall assemblies 24, 26, and air return conduits 34, 36 remove air (at a typically higher humidity) from exterior wall assemblies 24, 26 and deliver the humid air back to head and unit 28 to cyclically condition exterior wall assemblies 24, 2b.

Fiwre 2 illustrates a cross-sectional view of above-grade exterior wall.
assembly 24 according to one embodiment of the present invention. Exterior wall assembly 24~includes an interior wall portion 60, an opposing exterior wall portion 62,~insulation 64, and a flexible grid 66. In one embodiment, insulation 64 is disposed adjacent to interior waD portion 60 and defines an opening 68 between insulation 64 and exterior wall portion 62: In one embodiment, flexible grid 66 is disposed within opening 68 to form an air passageway between exterior wall portion 62, and insulation 64.
Insulation 64 is a thermally insulating.filler configured for placement in an exterior wall. In one embodiment, insulation 64 is a fiberglass insulation.
In another embodiment, insulation 64 is.a blown fibrous insulation. In general, insulation 64 is disposed between studs used to frame exterior wall assembly 24, and can include rolls or sheets of insulating material.
In one embodiment, interiox wall portion 60 includes a sheathing board 70 and an aar barrier sheeting 72 attached to sheathing board 70. In one embodiment, and is best illustrated in Figure 2, air barrier sheeting 72 contacts insulation b4.
Sheathing board 70 is generally a structural board suited for construction of new homes and commercial buildings. In one embodiment, sheathing board 70 is an oriented strand board, although other structural boards suited for the .
construction ofwalls are also acceptable.
A.ir barrier sheeting 72 is generally a single layer of polymeric film suited foi adhering to sheathing board 70. In one embodiment, air barrier sheeting ~72 is a polyethylene film, although other $lms and construction fabrics suited for covering sheathing board 70 are also acceptable.
1.n one embodiment, exterior wall portion 62 includes a second sheathing board 80, a water barrier sheeting 82 attached to sheathing board 80, and exterior cladding 84 attached to the water barrier sheeting 82.
Sheathing board 80 is highly similar to sheathing board 70. Water barrier sheeting 82 is attached to an exterior face of sheathing board 80 to provide a level of weather resistance for exterior wall pbr~on 62. In one embodiment, water barrier sheeting ~82 is a ~.~ash-spun polyethylene nonwoven fabric that is adhered, for example by stapling, to the exterior face of sheathing board 80.
' Exemplary materials for water barrier sheeting 82 include Tyvek~ house wrap, wax coated fabrics, tarpaper and the like, although other suitable materials and/or fabrics are acceptable.
Exterior cladding 84 includes suitable extezior iusulaiion and finish systems (ElfS) such as, for example, stucco finishes, shakes including cedar shakes, vinyl and metal siding, plastic and wood siding, and the other suitable exterior wall coverings.
In one embodiment, flexible grid 66 is disposed within opening 68 and bounded by sheathing board 80 on one side and by insulation 64 on an opposing side. In this manner, flexible grid 66 provides an air passageway between .
insulation 64 and exterior wall portion 62, and is configured to transport moisture that accumulates within exterior wall assembly 24 along opening 68 and away from insulation 64 and exterior wall portion 62.
Figure 3 illustrates a cross-sectional view of below-grade exterior wall assembly 26 according to one embodiment of the present invention. In one embodinoent, exterior wall assembly is a below-= ade wall assembly forming a portion of a foundation of structure 20 (shown in Figure 1). Exterior wall assembly 26 includes an interior wall portion 90, an opposing exterior wall portion 92, insulation 94, and a flexible grid 9_6 disposed within an opening formed between insulation 94 and exterior wall portion 92.
In- one embodiment, interior wall portion 90 includes a sheathing board 3 00 and an air barrier sheeting 7 02 attached to the sheathing board 100.
Sheathing board 100 and air barrier sheeting l, 02 are highly similar to sheathing board 70 and air barrier sheeting 72 described with reference to Figwe 2. With this in mind, air barrier sheeting 102 is attached to sheathing board 100 and contacts insulation 94.
In one embodiment, exterior wall portion. 92 forms a foundation of structure 20 (shov,~n in Figure 1) and includes concrete blocks 104, 106, 1.08. In another embodiment, exterior wall portion 92 is formed of a continuous concrete wall, although other suitable below-grade foundation materials can also be employed.

Insulation 94 is highly similar to insulation 64. As illustrated in Figure 3, flexible grid 96 defines an air passageway between insulation 94 and exterior wall portion 92 and is configured to transport moisture along opening 98 and away from insulation 94 and exterior wall portion 92.
~ Figure 4A illustrates a cross-sectional view of a flexible grid 110 according to one embodiment of the present invention. Flexible grid 110 is representative of flexible grid 66 (shown in Figure 2) and flexible grid 96 (shown in Figure 3). In this regard, flexible grid 110 includes a first surface 112, an opposing second surface 1 I4, and a core 1 I6 disposed between first surface 1 l2 and second surface 114. Flexible grid 110 is, in general, pliable and porous to air flow. In this Specification, porous to air flow means that air and moisture vapor, and sir containing moisture vapor, can be; transported (dynamically and/or passively) through the flexible grid.
In one embodiment, flexible grid 110 is a single layer structure formed of a random distribution of fbers in a matt or fabric-h7ce sheeting. In one exemplary embodiment, flexible grid 110 is.a nonwoven sheeting including a fibrous core I 16. For example, in one embodiwent flexible grid 110 is a nonwoven web of randomly distributed polyolefm fibers where first surface 112 and second surface 114 are thermally treated (e.g., by embossing, or calendering, or by hot can treating) to define a relatively smooth and flat surface.
Generally, core 116 defines a plurality of chambers that form a network, or air space, between first surface 112 and second surface 114. In one .
embodiment, core 116 defines a "dead" air space. Tn another embodiment, wire 116 defines an air space configured to permit air and moisture transport.
In one embodiment, flexible grid 110 is permeable to moisture vapor and impermeable to liquid water, and includes a surface energy-reducing additive, such as a fluorochemical, added to fibrous care 1 l6. The surface energy-reducing additive is melt-added to the ~bers during formation in one embodiment. In another embodiment, the surface energy-reducing additive is added topically to the fibers after formation.
Fiwre 4B illustrates a perspective view of a flexj'ble grid 117 according to one embodiment of the present invention. F)exible grid 117 includes strands 118a-118e, and strands 119a-Il9f overlapping and contacting strands 118a-.118e to define a core 121. Strands 118 and 119 overlap to form voids between the strands, where the voids permit airflow through core 121. In addition, the overlapping strands 118 and 119 defining air cbanuels Ml MS longitudinally along core 121, and air channels Nl-N4 laterally along core 12I. In one embodiment, strands I I 8 and 119 are each approximately 0.125 inch wide and 0.125 inch thick, such that overlapping strands 1 I8/I 19 combine to form a core 12I having a 0.250-inch thiclaiess: Other suitable dimensions for strands 118/119 are also acceptable.
In one embodiment, strands 118 are aligned in a first direction, for . example a horizontal orientation, and strands 119 are aligned in a second direction not equal to the first direction, for example, a vertical orientation. In this manner, air channels M1-MS and NI-N4 are defined in at least two orientations. In one embodiment, the voids formed by the overlapping strands 118/119 provide air passageways extending through core 121, and air channels MI-MS and Nl-N4 provide air passageways that are approximately orthogonal to the air passageways through the core defined by the voids.
In one embodiment, air channels MI-MS are vertical air channels and air channels Nl-N4 are horizontal air channels. In one exemplary embodiment, and with reference to Figwe 2, strands 119a-119f are aligned along respective wall studs (not shown) and define vertical air channels Iv,~l-MS configured to aerate, for example, an above-grade exterior wall assembly 24. Strands 118x-1 I $e in this embodiment are aligned horizontally relative to strands I 19a-119f and define horizontal air channels Nl-N4 that are configured to transport air and . " 25 moisture_along, for example, insulation 64.
Figure 4C illustrates a cross-sectional view of another flexible grid I20 - -according to one embodiment ofthe present invention. Flexible grid 120 is representative of one embodiment of #lexible grid b6 (shown in Figure 2) and flexible grid 96 (shown in Figure 3). In thiswegard, flexible grid 120 includes a film layer 122, an opposing porous backing 124, and a reticulated core 126., disposed between ~Im layer 122 and porous.backing 124. In one embodiment, flexible grid I20 is a three-layer composite structure that.is pliable.
However, it is to be understood that flexible grid I20 can include a single cure layer, or multiple layers {i.e., two, three, or more layers) including more than one core layer.
Film layer 122 is generally a substantially continuous surface and is suitable for contact and/or adhesive attachment to a solid construction surface.
In this regard, film layer I22 is in one embodiment a polymeric fihm that is permeable to moisture vapor and impermeable to liquid water. In another embodiment, film layer 122 is a polymeric film that is mechanically perforated to permit ~~e passage~of air, moisture vapor, and water. In another embodiment, film layer I22 is a mesh netting permeable to air, moisture vapor, and bulk moisture.
As described above, film.layer 122 is permeable to moisture vapor and impermeable to liquid water, according to one aspect of the present invention.
In one embodiment film layer 122 includes a surface energy-reducing additive, IS such as a fluorochemical, a wax, a silicone, or an oil. In one aspect of the present invention, the surface energy reducing additive (for example, a carbon-fluorochemical) is applied. as a topical additive to film layer 22; in another embodiment, the surface energy reducing additive is a melt additive added to film layer 122 during processing of film layer 122.
Porous backing 124 is generally configured for contact with insulation 94 (shown in Figure 3). In this regard, porous backing 124 generally defines a highly open structure that permits free air exchange. In one embodiment, porous backing 124 is a plastic mesh netting. In another embodiment, porous backing 124 is a woven fabric. In another embodiment, porous baclting I24 is a ' nonwoven fabric formed of, for example, a polyoIefin material such as polyethylene or polypropylene. In any regard, porous backing 124 is highly porous to air flow and is configured to abut against insulation 94 and impede an entrance of insulation 94 into flexible grid 120.
Reticulated core 126 generaDy separates film layer 122 and porous backing 124 to form an air passageway conf~wred to fit within opening 68 (shown in Figure 2) or opening 98 (shown in Figure 3). In one embodiment, reticulated core 126 defines a honeycomb lattice that incluc'es a plurality of chambers 130a,130b . . . 130z defined by walls 131. In this regard, chambers I30a-1302 extend between h3.m layer 122 and porous backing 124. Generally, reticulated core 126 defines a plurality of chambers that form a network, or au space, between film layer 122 and porous backing 124., In one embodiment, the network defines a "dead" air space. In another embodiment, the network defines an air space configured to permit passive and/or dynamic air and moisture transport.
In one embodiment, reticulated core 126 is an expanded.polymeric fttm that is porous to air and liquid. In another embodiment, reticulated core 126 is a felted network of fibers. In general, reticulated core 126 provides a measurable degree of separation between film layer 122 and porous backing I24 to form an air spacing therebetween, In this regard, in ane embodiment reticulated core defwes a thickness D of between 0.05 inch and 2.0 inches, preferably reficiilated core 126 defines a thickness D ofbetween 0.1 inch and I.0 inch, and more preferably reticulated core I26 defines a Thickness D of between 0.25 and 0.75 inch. To this end, a thickness of flexible grid 120 is compatible with insertion of grid 120 into an exterior wall assembly such that the wall assembly will comply with building and construction codes.
In one embodiment, each of the flexible grids 110, 120 is sufficiently flexible to be rolled onto a core and suitable for delivery to a construction site in, for example, roll form. Iin another embodiment,.each of the flexible grids 110, 120 is sufficiently flexible io be folded multiple times and suitable for delivery to a construction site in, for example, a folded sheet form.
Figure 5 illustrates a perspective view of flex~'bIe grid 120 according to one embodiment of the present invention. Film Iayer 122 forms a substantially continuous surface against which one end reticulated core 126 is supported.
.In one embodiment, film layer 122 is porous to air and moisture vapor. For example, in one embodiment film layer 122 includes macroporous holes or .
orifices that enable the grid 120 to be "breathable" and transport air and moisture vapor between film layer 122 and porous backing 124.
Porous backing 124 is secured over another end of reticulated core 126.
In one embodiment, fivm layer J22 arid porous backing 124 are themo~lastically sealed to reticulated core 126. In an alternate embodiment, film layer 122 and porous backing I24 are adhesively adhered to reticulated core 126. As illustrated in Figure 5, in one embodiment reticulated core defines a honeycomb .lattice I32 including the plurality of chambers 130a-1302 that extend between film layer 122 and porous backing I24. Film layer 122 is suitable for adhesively sealing to construction 'boards, such as oriented strand boards. As illustrated in Figures 4 and S, in one embodiment walls 131 are porous to airflow and enable air and moisture vapor to flow longitudinally and laterally along core 126.
Figure 6 illustrates a perspective view of an exterior wall portion 140 according to one embodiment of the present invention. Exterior wall portion includes a sheathing board 142 and a flexible grid 144 attached to sheathing board 142. In this regard, sheathing board 142 is highly similar to sheathing board 80 (shown in Figure 2), and flexible grid 144 is highly similar to flexible grid 120 (shown in Figure 5). T'lius, optionally, sheathing board 142 includes a water barrier sheeting, for example a plastic film, attached to a side of board 142 opposite flexible grid 144.
In one embodiment, flexible grid 144 is adhesively attached to sheathing board 122. In this manner, exterior wall portion 140 is suitable for use in the construction trades in foaming a sealed exterior wall assembly, for example ., exterior wall assembly 24 (shown in Figure 2). Similar to flexible grid 120 (shown in Figure 5), ..flexible grid L44~.includes film layer 146, an opposing porous backing 148, and a reticulated core 150 disposed between film layer 146 and porous backing 148.
In one embodiment, reticulated core 150 includes a honeycomb lattice of chambers defined by walls 151 that extend away from sheathing board 142. In a manner analogous to Figure 5, the honeycomb chambers permit air_Dow through core l 50 such that air and moisture vapor is transported away from sheathing board 142. In one embodiment, walls I 51 are porous to air and moisture vapor and are configured to permit airflow longitudinally and lateraDy through core I50 and along sheathing board 142.
Fleu'ble grids l 10 and 120 provide for a passive transportation of moisture away from interior surfaces of exterior wall assemblies 24, 26. In one i3 embodiment, flexible grids I 10 and 120 are disposed in,an interior opening, for example opening 68 (shown in Figure 2) or opening 98 (shown in Figure 3), to form a moisture-transporting air passageway inside the sealed and insulated exterior wall assemblies 24, 26. Moisture is transported along the air passageway formed by flexible grids 110 and 120, thus removing moisture from interior wall portions, exterior wall portions, and insulation inside the assemblies 24, 26.
In another embodiment, and as best illustrated in Figure 6, an entire exterior wall portion 140 includes sheathing board 142 and flexrble grid 144 attached to sheathing board 142. During the construction of an exterior wall assembly, exterior wall portion 140 can be erected in one step, such that upon finishing the interior portion of the wall assembly, insulation is simply unrolled over flexible grid 744 and interior wall portion 60 (shown in Fiwre 2), for example, is fixed in place. The exterior wall portion 140 can provide one-step erection of a sheathing board 142 and moisture-transporting flexible grid 144.
Figure 7 illustrates a perspective view ofhead end unit 2$ according to one embodiment of the present invention. Head end unit 28 generally supplies conditioned air through air supply conduits, for example air supply conduits 30, 32, and receives air removed from a structure, for example exterior wall assemblies 24, 26 (shown in Figure 1). In one embodiment, head end unit 28 is a stand-alone unit configured to supply dry, conditioned air to exterior wall assemblies 24, 26, and configured to remove relatively humid air from exterior wall assemblies 24, 26. In another embodiment, bead end unit 28 is electrically coupled to an existing forced air heating and cooling system (not shown) within structure 20, such that head end unit 28 cooperates with the existing forced air heating and cooling system to supply dry, conditioned air to exterior wall assemblies 24, 26, and remove relatively humid air from exterior wall assemblies 24, 26.
With this in mind, in one embodiment bead end unit 28 is a heating ventilation air conditioning (HVAC) unit including a compressor (nit shoam) maintained in a compressor side J 60, a blower and a blower motor (neither shown) maintained within a blower housing 162, air return ducts 164, and humidity sensors l 66 aligned with air return ducts 164.
As illustrated in Figure 7, air return conduits 34, 36 couple with air return ducts 164, and humidity sensors 166 fluidly communicates with air-return conduits 34, 36. A plurality of controls 170 is provided on head end unit 28 to enable an automated control of air conditioning delivered through supply conduits 30, 32 and moisture removal pulled through return conduits 34, 36. In -one embodiment, a programmable controller (not shown) is coupled to controls 170 (internal to head end unit 28) to permit a cornputer/logic-controlled operation air supply and return. Controls 170 can be selectively adjusted to cycle conditioned air through air supply conduits 30, 32 in response to s humidity level sensed by humidity sensor 166 for air returned through air retuai conduits 34, 36. .
In one embodiment, controls 170 are set: to a desired set point to maintain a relative humidity level within exterior wall assemblies 24, 26 (shown in Figure 1). For example, in one embodiment controls 170 are set to maintain a relative humidity within exterior wall assemblies 24, 26 of approximately 70%. In this embodiment, controls 170 cycle bead end unit 28 to an on configuration where dry, conditioned air is supplied to exterior wall assemblies 24, 26, and.ielatively more humid air is removed from exterior wall assemblies 24, 26'by air return conduits 34, 36 ofhead end unit 28. Tlea.d.end unit 28 remains in the on configuration until humidity sensor 166 communicates a relative humidity in the return air of less than the desired humidity set point (i.e., 70%).
.Thereafter, a blower within head end tout 28 continues to remove air from exterior wall assemblies 24, 26 to enable humidity sensor 166 to continue sensing a relative humidity within the exterior wall assemblies 24, 26. In one embodiment, consecutive readings of the ielative humidity by the humidity sensor 166 indicating that air extracted from exterior wall assemblies 24, 26 is below the desired humidity set point will activate head end unit 28 to an off position. .
In one embodiment, head end unit 28 is programmed to cycle between on and off positions fiver a set time interval (e.g., every 30 minutes). In another embodiment, head end unit 28 is programmed to cycle between on and off positions based upon a relative humidity reading from within.exterior wall assemblies 24, 26 by a separate humidity sensor (not shown) within exterior wall assemblies 24, 26. One aspect of the present invention provides for a continuous operation of bead end unit 28 in continuously supplying dry; conaitioned air to exterior wall assemblies 24, 26, useful, for example, in drying exterior wall assemblies in tropical climates.
As illustrated in Figure 7, air supply conduits 30, 32, define a respective head end side 180a and 180b, and a structure side 1$2a and 182b. In a similar manner, air return conduits 34, 36, define a respective head end side I90a and 190b, and a structure side 192a and 192b.
Figure 8A illustrates a perspective view of structure side 182a of air supply conduit 30 according to one embodiment of the present invention.
Structure side 182a defines a closed end 200 and a plurality of orifices 202 formed in a wall 204 of structure end 182x. . In one embodiment, the plurality of orifices 202 defines a single column of orifices aligned along a longitudinal axis of structwe end 182a that is useful in delivering conditioned air into exterior wall assemblies 24, 26. Orifices 202 are formed through wah 204 and communicate with an interior portion of air supply conduit 30. That is to say, in one embodiment conduit 30 defines an annular structure and a single column of orifices 202.
Structure 182a defwes an outside diameter O.D. and an inside diameter LD. In one embodiment, the O.D. of structwe end 182a is between 0.1 inch and 1.0 inch, preferably the O.D. of structure end 182a is between 0.2 inch and 0.5 inch. For example, in one embodiment a 0.25 inch thick flexible grid 120 is secured within exterior wall assembly 24, and a structure end 182a of sir supply conduit 30 having a 0.25 inch O.D. is coupled to flexible grid 120. Wall 204 defines a thickness that is suited for supplying air through conduit 30.
Orifices 202 are configured to deliver a flow of sir, for example conditioned air from structure end 182a of sir supply conduit 30 into an exterior wall assembly, such as exterior wall assembly 24 (shown in Figure 1). It is to be understood that altbough structure end 192a (shown in Figwe 7) of airretuin conduit 34 is not illustrated, structure end 192a of air return conduit 34 is, in one embodiment, similar to structure end 182a of air supply conduit 30 illustrated in Figure 8A.
Figure 8B illustrates another embodiment of a structure end 210 of an air supply conduit 212 according to one embodiment of the present invention.
Structure end 2I0 defines a closed end 214 and a plurality of orifices 216 formed circumferentially in a wall 218 of air supply conduit 212. In one embodiment, orifices 216 are formed in wall 218 in a helical pattern about a circumference of structure end 210. Structure end 210 defines an outside diameter O.D. and an inside diameter LD. that are highly similar to the outside diameter and inside diameter described above in Figure 8A.
Figure 8C illustrates yet another embodiment of a structure end 220 of an air supply conduit 222 according to one embodiment of the present invention.
Structure end 220 defines a closed end 224 and a plurality of orifices 226 formed in a wall 228. In one embodiment, orifices 226 are formed in parallel columns along structure end 220 of air supply conduit 2'~. In another embodiment, orifices 226 define a pair of staggered, parallel columns of orifices fonned in wall 228. Structure end 220 defines an outside diameter O.D. and an inside diameter LD, that are highly similar to the outside diameter and inside diameter described above with reference to Figure 8A.
Figure 9 illustrates a system flow chart 250 directed to the removal of moisture from a zoned structure according to one embodiment of the present invention. V~ith additional reference to Figure 1, a zone is defined by at least one air supply conduit, at least one air return conduit, and at least one humidity sensor communicating with the_ air return conduit. For example, air supply ' ~ conduit 30, air return conduit 34, and humidity sensor 40 combine to define one zone in structure 20.
Structure 20 can include a plurality of zones, for example a zone directed to removing moisture from around a window, and a separate second zone for removing moisture from around a door. In another embodiment, an entire ea~terior wall assembly, for example exterior wall assembly 26, is serviced by a single zone. 1t is to be under stood that structure 20 can include multiple zones . 1?

within multiple exterior wall assembly structures, aII controlled by head end unit 28. Reference is made to Figure 1 in the following description where air supply conduit 30, and air return conduit 34 combine to define a zone around window 50.
During use, and with additional reference to Figures 1 and 8A, air supply conduit 30 is extended away from head end unit 28 and positioned to drive moisture away from a potentially moist area, for example window 50. Ori.$ces 202 are positioned to fluidly communicate with reticulated core 126 of flexi'bIe grid 120 (shown in Figure 4C). Dry, conditioned air exits orifices 2Q2 and transports moisture along an air passageway formed by opening 68 (shown in Figure 2). Air return conduit 34 draws the transported moisture away from window 50 and delivers the relatively humid sir back to head end unit 28.
With additional reference to Figures 1 and 7, humidity sensors 166 sense a humidity level in a zone of an exterior wall structure, for example exterior wall I S structure 24. ControDers 170 in combination with humidity sensors 166 sense a relative humidity of air returned from exterior mall assembly 24. The sensed humidity level within exterior wall assembly 24 is compared to a desired relative humidity level set point, as controlled by contrals 170. The process for comparing the sensed humidity level within exterior wall assembly 24 to the relative humidity set point is provided by process 252.
Process 254 queries whether the relative humidity level within a zone of exterior wall assembly 24 is acceptable. If the relative humidity level is acceptable, process 256 pxovides for sensing a humidity level in a next zone of the exterior wall assembly 24 or of structure 20. In an iterative manner, process 258 provides for sensing a humidity level in a last zone of an exterior wall assembly 24/structure 20 where prior zones of the structure were evaluated to have an acceptable relative humidity level. 1n the case where each zone of structure 20 has an acceptable relative humidity level, process 260 provides for a timed out wait period prior to cycling system 250.
With additional reference to process 254, in .the case where the relative humidity level urithin a zone of exterior wall assembly 24 is not acceptable, process 262 provides for cycling bead end unit 28 to supply conditioned dry air through air supply conduits 30, 32. Thus, head end unit 28 supplies conditioned air to the zone having a relative humidity level that is above the set point, and process 266 provides for sensing the relative humidity of air returning through air return conduits 34, 36 extracted from the too humid zone. A further query is made of the zone in process 254, consistent with one drying cycle of system 250.
In one embodiment, and in particular during periods of relatively dry weather, process 260 signals ~to head end unit 28 that conditioned air is not called for by any zone. Thus, head end unit 28 does not cycle between the on and off positions, but rather is maintained in an offposition, but ready for subsequent cycling.
In addition, and with reference to Figure 2, during periods in which head end unit 28 does not cycle, flexible grid 66 provides for a continual passive transport of moisture vapor away from interior wall portion 60 and exterior wall portion 62. In other words, flexible grid 66 forms an air passageway williin opening 68 that permits the transport of moisture vapor away from the interior surfaces of exterior wall assembly 24 without cycling head end unit 28.
In contrast, winter seasons and summer seasons can create a natural humidity gradient across surfaces of structure 20 that results in frequent cycliag of head end unit 28. For example, during winter months associated with cold ' and dry exterior air temperatures and relatively warm interior air temperatures, the large temperature and humidity gradients between the interior air of structure .20 and the environment outside of structure 20 combine to cause moisture vapor in the air to condense upon surfaces of exterior wall assemblies 24, 26. Thus, during winter months, humid air within structure 20 wi71 condense on, for example, sheathing board '70 and air barrier sheeting 72.
This condensation can lead to moisture accumulation along air barrio sheeting 72 and insulation 64. Aspects of the present invention provide for humidity. sensors 166 that sense a relative hurnidity associated with exterior wall assembly 24. l~Then the relative humidity within exterior wall assembly 24 ~ exceeds a Desired set point, head end unit 28 is activated to an on condition, supplying condition dry air through air.supply conduits 30, 32, and removing moisture from within exterior wall assembly 24 via air return conduits 34, 36.

Thus, moisture within exterior wall assembly 24 is driven to opening 68 and transported through flexible grid 66, to be conditioned by head end unit 28.
With the above in mind, in one embodiment head end unit 28 cycles between on and off settings periodically (e.g., every fifteen minutes) to maintain the desired relative hunudity within wall assembly 24. In contrast, during relatively dry months, head end unit 28 might not cycle to the on position for periods of greater than one week.
Aspects of the present invention have been described that provide for dynamically venting an exterior wall assembly to remove moisture from inside a I O sealed and insulated exterior wall. In particular, sealed exterior wall assemblies have been described that can accumulate moisture either through natural condensation processes or through a failure in weather proofing or sealing of, for example, doors and windows in an exterior wall assembly. Embodiments of the present invention provide for dynamically ventilating conditioned air through the flexible grid within the exterior wall assembly to displace humid moisture within the exterior wall assembly with conditioned dry sir.
Other aspects of the present invention provide for 8 flexible grid that provides an air passageway within the exterior wall assembly for the passive removal of moisture. Embodiments of the present invention provide for statically ventilating the exterior wall assembly via the flexible grid to remove bumidity_from the exterior wall assembly.
A sealed exterior wall assembly that is highly energy efficient and in compliance with local and state housing codes has been described that provides for dynamically, and/or passively (statically), venting moisture from the sealed exterior wall assembly.
In one embodiment, the dynamic, and/or passive, venting of moisture from a sealed exterior wall assembly improves the overall energy efficiency of the wall assembly and its associated structure. The removal of moisture from a wall assembly results in increasing the "R-value," or insulafiion value of the wall assembly. Since the wall assembly does not retain the potentially harmful moisture, the insulation performs better, .the insulating quality is improved, and moisture that otherwise might conduct heat out of the wall assembly is reduced or eliminated, thus increasing the energy eff ciency of the wall assembly.
Embodiments of dynamically, and/or passively vented exterior wall assemblies as described above will remain warmer in winter, cooler in summer, and can cost-effectively satisfy even the most stringent 'building codes.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent~implementations may be substituted for the specific embodiments shown and descnbed without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended chat this invention be limited only by the claims and the equivalent thereof.

Claims

1. A dynamically ventilated exterior wall system comprising:
a sealed exterior wall assembly including an interior wall portion and an opposing exterior wall portion, and insulation and a flexible porous grid disposed between the interior and exterior wall portions; and a ventilation assembly fluidly coupled to the exterior wall assembly, the ventilation assembly including a head end unit coupled to at least one.air supply conduit and at least one air return conduit, each of the conduits communicating with the porous grid, wherein the head end unit is configured to supply conditioned air through the at least one air supply conduit to the exterior wail assembly and remove humidity from the exterior wall assembly through the at least one air return conduit.

2. The dynamically ventilated exterior wall system of claim 1, wherein the insulation is disposed within the wall assembly adjacent to the interior wall portion, and the porous grid is disposed between the insulation and an inner surface of the exterior wall portion.

3. The dynamically ventilated exterior wall system of claim 1, wherein the flexible porous grid comprises:
a core defining at least one air passageway communicating between the insulation and the exterior wall portion and at least one sit passageway extending along the core between the interior and exterior wall portions.

4. The dynamically ventilated exterior wall system of claim 3, wherein the at least one air supply conduit and at least one air return conduit communicate with the core of the flexible porous grid.

5. The dynamically ventilated exterior wall system of claim 1, wherein the ventilation assembly defines a plurality of zones, each zone comprising at least one air supply conduit, at least one air return conduit, and at least one humidity sensor communicating with the at least one air return conduit.

6. The dynamically ventilated exterior wall system of claim 5, wherein each humidity sensor of each zone is coupled to the head end unit, and further wherein the head end unit is configured to control a supply of conditioned air through the air supply conduits to control a relative humidity of the exterior wall assembly.

7. The dynamically ventilated exterior wall system of claim 1, wherein the head end unit comprises a heating ventilating air conditioning (HVAC) unit.

8. A method of dynamically ventilating a sealed exterior wall that includes an interior wall portion and an opposing-exterior wall portion and insulation adjacent to the interior wall portion, the method comprising:
disposing a porous grid between the insulation and the exterior wall portion to define an air space within the sealed exterior wall;
supplying conditioned air through the air space; and removing humidity from the air space.

9. The method of claim 8, wherein disposing a porous grid between the insulation and the exterior wall portion comprises disposing a flexible porous grid including a core defining at least one air passageway communicating between the insulation and the exterior wall portion, and at least one of a longitudinal and a lateral air channel extending along the core.

10. The method of claim 9, wherein supplying conditioned air through the sir space and removing humidity from the air space are performed by a ventilation assembly having a head end unit coupled to at least one air supply conduit and at least one air return conduit, the conduits communicating with the core.

11. The method of claim 10, wherein the ventilation assembly comprises a zoned ventilation assembly, each zone including:
at least one air supply conduit extending between a blower of the head end unit and the core;
at least one air return conduit extending between the core and the head end unit; and a humidity sensor coupled between the at least one air return conduit and the head end unit.

12. The method of claim 11, wherein removing humidity from the air space comprises removing humidity from the air space of one zone, including:
pressurizing the porous grid by blowing air from the head end unit through the air supply conduit into the core;
removing air from the air space through the air return conduit;
sensing a humidity level of the air removed from the airspace with the humidity sensor; and controlling a flow of low humidity conditioned air from the head end unit through the air supply conduit into the core.

13. The method of claim 12, wherein controlling a flow of low humidity conditioned air through the air supply conduit comprises:
cycling from a first zone to a second zone of a plurality of zones in the sealed exterior wall a flow of low humidity conditioned air from the head end unit into the core of a respective one of the plurality of zones.

14. An exterior wall system comprising:
an exterior wall assembly including an interior wall portion and an opposing exterior wall portion, and a flexible porous grid disposed between the interior and exterior wall portions; and means for transporting moisture through the flexible porous grid and out of the exterior wall assembly.

15. The exterior wall system of claim 14, wherein the means for transporting moisture through the flexible porous grid comprises a ventilation assembly including a pressurized air source coupled to the porous grid.

16. The exterior wall system of claim 14, wherein the means for transporting moisture through the flexible porous grid comprises a ventilation assembly including a driven air return conduit coupled to the porous grid.

17. The exterior wall system of claim 14, wherein the exterior wall assembly forms an insulated exterior wall of a building, the building including a heating ventilating air conditioning (HVAC) system, and the means for transporting moisture through the flexible porous grid fluidly couples the HVAC system to the porous grid.

18. The exterior wall system of claim 14, wherein the means for transporting moisture through the flexible porous grid comprises a ventilation assembly including at least one humidity sensor configured for sensing a relative humidity level between the interior and exterior wall portions.

19. The exterior wall system of claim 18, further comprising:
a programmable controller coupled to the at least one humidity sensor, the programmable controller configured to activate an air conditioning head end unit of the ventilation assembly in response to data read from the at least one humidity sensor.

20. The exterior wall system of claim 18, wherein the means for transporting moisture through the flexible porous grid comprises a ventilation assembly including at least one air supply conduit, at least one air return conduit, and at least one humidity sensor communicating with the air return conduit.