U.S. patent application number 11/252350 was filed with the patent office on 2007-05-03 for dynamically ventilated exterior wall assembly.
Invention is credited to Mark Larry Stender.
Application Number | 20070094964 11/252350 |
Document ID | / |
Family ID | 37951574 |
Filed Date | 2007-05-03 |
United States Patent
Application |
20070094964 |
Kind Code |
A1 |
Stender; Mark Larry |
May 3, 2007 |
Dynamically ventilated exterior wall assembly
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 air return conduit(s).
Inventors: |
Stender; Mark Larry;
(Norwood Young America, MN) |
Correspondence
Address: |
DICKE, BILLIG & CZAJA, P.L.L.C.
FIFTH STREET TOWERS
100 SOUTH FIFTH STREET, SUITE 2250
MINNEAPOLIS
MN
55402
US
|
Family ID: |
37951574 |
Appl. No.: |
11/252350 |
Filed: |
October 17, 2005 |
Current U.S.
Class: |
52/302.1 |
Current CPC
Class: |
F24F 2013/221 20130101;
Y02A 30/00 20180101; F24F 7/08 20130101; E04B 1/7069 20130101; Y02B
30/90 20130101; F24F 5/0075 20130101; F24F 2005/0082 20130101 |
Class at
Publication: |
052/302.1 |
International
Class: |
E04B 1/70 20060101
E04B001/70 |
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 wall 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 air 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 air 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 air space 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.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Utility patent application is related to commonly
assigned and concurrently filed Utility patent application Ser. No.
______, entitled EXTERIOR WALL ASSEMBLY having Attorney Docket
Number M420.101.101, and which is herein incorporated by
reference.
BACKGROUND
[0002] Recent improvements in the construction of homes and
buildings have resulted in the fabrication of highly energy
efficient structures. New construction materials, improved
construction methods, and more stringent local and state building
codes have all combined to provide highly energy efficient
structures. In particular, exterior walls that are insulated and
sealed, made according to code, and with the latest construction
materials, increase the energy efficiency of these structures.
[0003] Insulated and sealed wall structures (i.e., "airtight"
structures) reduce 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 wall. Thus, insulated and sealed walls are
airtight and moisture resistant, and are highly energy efficient.
However, since insulated and sealed walls do not "breathe,"
breached or damaged insulated and sealed walls can harbor moisture
and provide nearly ideal breeding grounds for mold and
bacteria.
[0004] 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 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 the air of an interior of the wall structure
naturally migrates to the exterior of the wall structure. Thus,
large gradients in outside and inside air temperatures can lead to
an accumulation of moisture within even an insulated and sealed
wall.
[0005] The opposite conditions occur during the summer months, when
the air 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 natural 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.
[0006] Moisture includes bulk liquid, such as rain or rain
droplets, and moisture vapor, such as in warm and humid air.
Moisture, whether bulk 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
enters 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.
[0007] In general, moisture accumulation within a wall, whether in
the form of bulk liquid or in the form of moisture vapor,
structurally damages the wall and can lead to health and safety
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 accelerated in hot and humid environments.
[0008] This undesirable moisture penetration and accumulation
within a wall 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 building
structure, and for the removal of moisture that potentially
collects within an exterior wall assembly.
SUMMARY
[0009] One aspect of the present invention is related to a
dynamically ventilated 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 unit 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 conduit(s) to the exterior wall assembly and remove
humidity from the exterior wall assembly through the air return
conduit(s).
[0010] Another aspect of the present invention relates to 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
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 air space.
[0011] 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 exterior wall assembly is
provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The accompanying drawings 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.
[0013] FIG. 1 illustrates a cross-sectional view of a structure
including a dynamically ventilated exterior wall system according
to one embodiment of the present invention.
[0014] FIG. 2 illustrates a cross-sectional view of an above-grade
exterior wall assembly according to one embodiment of the present
invention.
[0015] FIG. 3 illustrates a cross-sectional view of a below-grade
exterior wall assembly according to one embodiment of the present
invention.
[0016] FIG. 4A illustrates a cross-sectional view of a flexible
moisture grid according to one embodiment of the present
invention.
[0017] FIG. 4B illustrates a perspective view of another flexible
moisture grid according to one embodiment of the present
invention.
[0018] FIG. 4C illustrates a cross-sectional view of another
flexible moisture grid according to one embodiment of the present
invention.
[0019] FIG. 5 illustrates a perspective view of the flexible
moisture grid illustrated in FIG. 4C.
[0020] FIG. 6 illustrates a flexible grid coupled to a construction
board according to one embodiment of the present invention.
[0021] FIG. 7 illustrates a perspective view of a head end unit
including air supply and return conduits according to one
embodiment of the present invention.
[0022] FIG. 8A illustrates a structure end of an air supply/return
conduit including a single row of orifices formed in a conduit wall
according to one embodiment of the present invention.
[0023] FIG. 8B illustrates a structure end of an air supply/return
conduit including a plurality of orifices disposed helically about
a circumference of the conduit according to one embodiment of the
present invention.
[0024] FIG. 8C illustrates a structure end of an air supply/return
conduit including a plurality of orifices disposed in parallel
columns along the conduit according to one embodiment of the
present invention.
[0025] FIG. 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
[0026] In the following Detailed Description, reference is made to
the accompanying drawings, which form a part 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
Figure(s) 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.
[0027] FIG. 1 illustrates a structure 20 including a dynamically
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 wall
assembly 26. Sealed exterior wall assemblies are structures that
are sealed against the passage of moisture and air and include, for
example, finished exterior wall structures having caulked seams,
sealed seams, fitted flashing, and/or exterior claddings configured
to prevent the transmission of air and moisture through the
wall.
[0028] In one embodiment, the first sealed exterior wall assembly
24 is an 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.
[0029] 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. Air return conduits 34, 36 remove air, for example
relatively humid air, from the sealed above-grade exterior wall
assembly 24 and below-grade exterior 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 suitable locations for humidity sensor 40
along a return path from exterior wall assemblies 24, 26 to head
end unit 28 are also acceptable.
[0030] 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 structure 20, such openings provide a potential pathway
for the entrance of moisture into the sealed exterior wall
assemblies 24, 26.
[0031] 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
surrounds 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, 26.
[0032] FIG. 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 wall 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.
[0033] 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.
[0034] In one embodiment, interior wall portion 60 includes a
sheathing board 70 and an air barrier sheeting 72 attached to
sheathing board 70. In one embodiment, and is best illustrated in
FIG. 2, air barrier sheeting 72 contacts insulation 64.
[0035] 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 of
walls are also acceptable.
[0036] Air barrier sheeting 72 is generally a single layer of
polymeric film suited for adhering to sheathing board 70. In one
embodiment, air barrier sheeting 72 is a polyethylene film,
although other films and construction fabrics suited for covering
sheathing board 70 are also acceptable.
[0037] In 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.
[0038] 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 portion 62. In one embodiment, water barrier sheeting
82 is a flash-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.RTM. house wrap, wax coated fabrics, tarpaper and the like,
although other suitable materials and/or fabrics are
acceptable.
[0039] Exterior cladding 84 includes suitable exterior insulation
and finish systems (EIFS) 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.
[0040] 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.
[0041] FIG. 3 illustrates a cross-sectional view of below-grade
exterior wall assembly 26 according to one embodiment of the
present invention. In one embodiment, exterior wall assembly is a
below-grade wall assembly forming a portion of a foundation of
structure 20 (shown in FIG. 1). Exterior wall assembly 26 includes
an interior wall portion 90, an opposing exterior wall portion 92,
insulation 94, and a flexible grid 96 disposed within an opening 98
formed between insulation 94 and exterior wall portion 92.
[0042] In one embodiment, interior wall portion 90 includes a
sheathing board 100 and an air barrier sheeting 102 attached to the
sheathing board 100. Sheathing board 100 and air barrier sheeting
102 are highly similar to sheathing board 70 and air barrier
sheeting 72 described with reference to FIG. 2. With this in mind,
air barrier sheeting 102 is attached to sheathing board 100 and
contacts insulation 94.
[0043] In one embodiment, exterior wall portion 92 forms a
foundation of structure 20 (shown in FIG. 1) and includes concrete
blocks 104, 106, 108. 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.
[0044] Insulation 94 is highly similar to insulation 64. As
illustrated in FIG. 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.
[0045] FIG. 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
FIG. 2) and flexible grid 96 (shown in FIG. 3). In this regard,
flexible grid 110 includes a first surface 112, an opposing second
surface 114, and a core 116 disposed between first surface 112 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 air containing moisture vapor, can
be transported (dynamically and/or passively) through the flexible
grid.
[0046] In one embodiment, flexible grid 110 is a single layer
structure formed of a random distribution of fibers in a matt or
fabric-like sheeting. In one exemplary embodiment, flexible grid
110 is a nonwoven sheeting including a fibrous core 116. For
example, in one embodiment flexible grid 110 is a nonwoven web of
randomly distributed polyolefin 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.
[0047] 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. In another embodiment, core 116 defines an air space
configured to permit air and moisture transport.
[0048] 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 core 116. The surface energy-reducing additive is
melt-added to the fibers during formation in one embodiment. In
another embodiment, the surface energy-reducing additive is added
topically to the fibers after formation.
[0049] FIG. 4B illustrates a perspective view of a flexible grid
117 according to one embodiment of the present invention. Flexible
grid 117 includes strands 118a-118e, and strands 119a-119f
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 channels M1-M5
longitudinally along core 121, and air channels N1-N4 laterally
along core 121. In one embodiment, strands 118 and 119 are each
approximately 0.125 inch wide and 0.125 inch thick, such that
overlapping strands 118/119 combine to form a core 121 having a
0.250-inch thickness. Other suitable dimensions for strands 118/119
are also acceptable.
[0050] 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-M5 and N1-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 M1-M5 and N1-N4 provide air passageways that are
approximately orthogonal to the air passageways through the core
defined by the voids.
[0051] In one embodiment, air channels M1-M5 are vertical air
channels and air channels N1-N4 are horizontal air channels. In one
exemplary embodiment, and with reference to FIG. 2, strands
119a-119f are aligned along respective wall studs (not shown) and
define vertical air channels M1-M5 configured to aerate, for
example, an above-grade exterior wall assembly 24. Strands
118a-118e in this embodiment are aligned horizontally relative to
strands 119a-119f and define horizontal air channels N1-N4 that are
configured to transport air and moisture along, for example,
insulation 64.
[0052] FIG. 4C illustrates a cross-sectional view of another
flexible grid 120 according to one embodiment of the present
invention. Flexible grid 120 is representative of one embodiment of
flexible grid 66 (shown in FIG. 2) and flexible grid 96 (shown in
FIG. 3). In this regard, flexible grid 120 includes a film layer
122, an opposing porous backing 124, and a reticulated core 126
disposed between film layer 122 and porous backing 124. In one
embodiment, flexible grid 120 is a three-layer composite structure
that is pliable. However, it is to be understood that flexible grid
120 can include a single core layer, or multiple layers (i.e., two,
three, or more layers) including more than one core layer.
[0053] 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 122 is in
one embodiment a polymeric film 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
the passage of air, moisture vapor, and water. In another
embodiment, film layer 122 is a mesh netting permeable to air,
moisture vapor, and bulk moisture.
[0054] 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, 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.
[0055] Porous backing 124 is generally configured for contact with
insulation 94 (shown in FIG. 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 backing 124 is a nonwoven
fabric formed of, for example, a polyolefin 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.
[0056] Reticulated core 126 generally separates film layer 122 and
porous backing 124 to form an air passageway configured to fit
within opening 68 (shown in FIG. 2) or opening 98 (shown in FIG.
3). In one embodiment, reticulated core 126 defines a honeycomb
lattice that includes a plurality of chambers 130a, 130b . . . 130z
defined by walls 131. In this regard, chambers 130a-130z extend
between film layer 122 and porous backing 124. Generally,
reticulated core 126 defines a plurality of chambers that form a
network, or air 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.
[0057] In one embodiment, reticulated core 126 is an expanded
polymeric film 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 124 to form an
air spacing therebetween. In this regard, in one embodiment
reticulated core defines a thickness D of between 0.05 inch and 2.0
inches, preferably reticulated core 126 defines a thickness D of
between 0.1 inch and 1.0 inch, and more preferably reticulated core
126 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.
[0058] 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. In
another embodiment, each of the flexible grids 110, 120 is
sufficiently flexible to be folded multiple times and suitable for
delivery to a construction site in, for example, a folded sheet
form.
[0059] FIG. 5 illustrates a perspective view of flexible grid 120
according to one embodiment of the present invention. Film layer
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.
[0060] Porous backing 124 is secured over another end of
reticulated core 126. In one embodiment, film layer 122 and porous
backing 124 are thermoplastically sealed to reticulated core 126.
In an alternate embodiment, film layer 122 and porous backing 124
are adhesively adhered to reticulated core 126. As illustrated in
FIG. 5, in one embodiment reticulated core defines a honeycomb
lattice 132 including the plurality of chambers 130a-130z that
extend between film layer 122 and porous backing 124. Film layer
122 is suitable for adhesively sealing to construction boards, such
as oriented strand boards. As illustrated in FIGS. 4 and 5, in one
embodiment walls 131 are porous to airflow and enable air and
moisture vapor to flow longitudinally and laterally along core
126.
[0061] FIG. 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 FIG. 2), and flexible grid 144 is highly similar to flexible
grid 120 (shown in FIG. 5). Thus, 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.
[0062] 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 forming a sealed
exterior wall assembly, for example exterior wall assembly 24
(shown in FIG. 2). Similar to flexible grid 120 (shown in FIG. 5),
flexible grid 144 includes film layer 146, an opposing porous
backing 148, and a reticulated core 150 disposed between film layer
146 and porous backing 148.
[0063] 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 FIG. 5, the honeycomb
chambers permit airflow through core 150 such that air and moisture
vapor is transported away from sheathing board 142. In one
embodiment, walls 151 are porous to air and moisture vapor and are
configured to permit airflow longitudinally and laterally through
core 150 and along sheathing board 142.
[0064] Flexible grids 110 and 120 provide for a passive
transportation of moisture away from interior surfaces of exterior
wall assemblies 24, 26. In one embodiment, flexible grids 110 and
120 are disposed in an interior opening, for example opening 68
(shown in FIG. 2) or opening 98 (shown in FIG. 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.
[0065] In another embodiment, and as best illustrated in FIG. 6, an
entire exterior wall portion 140 includes sheathing board 142 and
flexible 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 144 and interior wall portion 60 (shown
in FIG. 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.
[0066] FIG. 7 illustrates a perspective view of head end unit 28
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 FIG. 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, head 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.
[0067] With this in mind, in one embodiment head end unit 28 is a
heating ventilation air conditioning (HVAC) unit including a
compressor (not shown) maintained in a compressor side 160, a
blower and a blower motor (neither shown) maintained within a
blower housing 162, air return ducts 164, and humidity sensors 166
aligned with air return ducts 164.
[0068] As illustrated in FIG. 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
computer/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 a humidity level sensed
by humidity sensor 166 for air returned through air return conduits
34, 36.
[0069] 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 FIG. 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 head end unit 28 to an on
configuration where dry, conditioned air is supplied to exterior
wall assemblies 24, 26, and relatively more humid air is removed
from exterior wall assemblies 24, 26 by air return conduits 34, 36
of head end unit 28. Head 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%).
[0070] Thereafter, a blower within head end unit 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 relative 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.
[0071] In one embodiment, head end unit 28 is programmed to cycle
between on and off positions over 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 head end unit 28 in continuously
supplying dry, conditioned air to exterior wall assemblies 24, 26,
useful, for example, in drying exterior wall assemblies in tropical
climates.
[0072] As illustrated in FIG. 7, air supply conduits 30, 32, define
a respective head end side 180a and 180b, and a structure side 182a
and 182b. In a similar manner, air return conduits 34, 36, define a
respective head end side 190a and 190b, and a structure side 192a
and 192b.
[0073] FIG. 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
182a. In one embodiment, the plurality of orifices 202 defines a
single column of orifices aligned along a longitudinal axis of
structure end 182a that is useful in delivering conditioned air
into exterior wall assemblies 24, 26. Orifices 202 are formed
through wall 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.
[0074] Structure 182a defines an outside diameter O.D. and an
inside diameter I.D. In one embodiment, the O.D. of structure 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 air
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.
[0075] Orifices 202 are configured to deliver a flow of air, for
example conditioned air from structure end 182a of air supply
conduit 30 into an exterior wall assembly, such as exterior wall
assembly 24 (shown in FIG. 1). It is to be understood that although
structure end 192a (shown in FIG. 7) of air return 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 FIG. 8A.
[0076] FIG. 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 210 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 I.D. that are highly similar to the outside
diameter and inside diameter described above in FIG. 8A.
[0077] FIG. 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 222. In another embodiment,
orifices 226 define a pair of staggered, parallel columns of
orifices formed in wall 228. Structure end 220 defines an outside
diameter O.D. and an inside diameter I.D. that are highly similar
to the outside diameter and inside diameter described above with
reference to FIG. 8A.
[0078] FIG. 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. With additional reference to
FIG. 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.
[0079] 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 exterior wall assembly, for example
exterior wall assembly 26, is serviced by a single zone. It is to
be understood that structure 20 can include multiple zones within
multiple exterior wall assembly structures, all controlled by head
end unit 28. Reference is made to FIG. 1 in the following
description where air supply conduit 30, and air return conduit 34
combine to define a zone around window 50.
[0080] During use, and with additional reference to FIGS. 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. Orifices 202 are positioned to fluidly
communicate with reticulated core 126 of flexible grid 120 (shown
in FIG. 4C). Dry, conditioned air exits orifices 202 and transports
moisture along an air passageway formed by opening 68 (shown in
FIG. 2). Air return conduit 34 draws the transported moisture away
from window 50 and delivers the relatively humid air back to head
end unit 28.
[0081] With additional reference to FIGS. 1 and 7, humidity sensors
166 sense a humidity level in a zone of an exterior wall structure,
for example exterior wall structure 24. Controllers 170 in
combination with humidity sensors 166 sense a relative humidity of
air returned from exterior wall assembly 24. The sensed humidity
level within exterior wall assembly 24 is compared to a desired
relative humidity level set point, as controlled by controls 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.
[0082] 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 provides 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. In
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.
[0083] With additional reference to process 254, in the case where
the relative humidity level within a zone of exterior wall assembly
24 is not acceptable, process 262 provides for cycling head 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.
[0084] 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 off position, but ready for subsequent
cycling.
[0085] In addition, and with reference to FIG. 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 within 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.
[0086] In contrast, winter seasons and summer seasons can create a
natural humidity gradient across surfaces of structure 20 that
results in frequent cycling 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 will condense on, for example, sheathing
board 70 and air barrier sheeting 72.
[0087] This condensation can lead to moisture accumulation along
air barrier sheeting 72 and insulation 64. Aspects of the present
invention provide for humidity sensors 166 that sense a relative
humidity associated with exterior wall assembly 24. When 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.
[0088] 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 humidity 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.
[0089] Aspects of the present invention have been described that
provide for dynamically venting an exterior wall assembly to remove
moisture from inside a 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 air.
[0090] Other aspects of the present invention provide for a
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 humidity
from the exterior wall assembly.
[0091] 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.
[0092] 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 insulation 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
efficiency 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.
[0093] 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 described 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 that this invention be limited only by the claims
and the equivalents thereof.
* * * * *