Note: Descriptions are shown in the official language in which they were submitted.
'.
CA 02556476 2006-08-18
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.
1 D
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.
CA 02556476 2006-08-18
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. . ~ , .
2
CA 02556476 2006-08-18
~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
3
CA 02556476 2006-08-18
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.
4
'
CA 02556476 2006-08-18
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.
5
CA 02556476 2006-08-18
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.
6
CA 02556476 2006-08-18
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
7
CA 02556476 2006-08-18
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
98
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.
CA 02556476 2006-08-18
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
9
CA 02556476 2006-08-18
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
CA 02556476 2006-08-18
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-
8
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
11
CA 02556476 2006-08-18
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
12
CA 02556476 2006-08-18
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
140
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
CA 02556476 2006-08-18
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
14
CA 02556476 2006-08-18
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
CA 02556476 2006-08-18
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
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CA 02556476 2006-08-18
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?
CA 02556476 2006-08-18
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
I8
CA 02556476 2006-08-18
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.
19
CA 02556476 2006-08-18
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
CA 02556476 2006-08-18
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.
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