Note: Descriptions are shown in the official language in which they were submitted.
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EFFICIENT HOUSE: AN EFFICIENT, HEALTHFUL AND DURABLE BUILDING SYSTEM
USING DIFFERENTIAL AIRFLOW AND HEAT CONTROL ACROSS AN AIR PERMEABLE
HEAT REFLECTIVE EXTERNAL ENVELOPE ASSEMBLY
FIELD OF THE INVENTION
This efficient house invention relates generally to buildings using
differential flow of
air through air-permeable exterior walls and ceilings that also incorporate a
reflective material, to
capture, reflect, and control heat being transferred through the envelope, to
improve energy
conservation, durability of the structure, and provide fresh air to such a
building.
BACKGROUND OF THE INVENTION
Control of heat losses and gains in houses has been attempted from the time of
earliest shelter. Today's buildings are 'tight (reducing air leakage) and well-
insulated (reducing
heat losses and gains) but relatively inefficient, unstable and unhealthy. For
example, costly
special mechanical devices such as heat recovery ventilators (HRVs) are needed
to supply
tempered fresh air for indoor air quality to reduce the risk of unsafe indoor
conditions, and these
often break down or perform poorly during their lifetime. Also air tight
designs promote mold and
mildew when humidity levels become high and contamination occurs when
pollutants are not
sufficiently diluted (Forest 2004). Structural deterioration and mold and
mildew are common
problems that occur when moisture becomes trapped, and normal fiber insulation
becomes
ineffective as humidly levels within insulated assemblies (e.g. exterior wall
cavities) become
elevated (Swinton, Brown and Chown,1995) .
For about 30 years it has been known that fresh 'dynamic air' moving slowly
inwards through the envelope (e.g. exterior walls) of buildings could recover
conductive heat
normally lost in the heating season and provide the fresh air required for
healthful indoor air
quality. Beginning in the late1970s, experimental houses were constructed in
Sweden using the
idea and a 'depressurization of the house' approach. In the 1980s experimental
houses using a
similar approach were constructed in Canada, under the guidance of Dr. John
Timusk, one
constructed in Ontario in 1981 and 1982, and two in Alberta between 1983 and
1987, funded by
Alberta's Innovative Housing Grants Program. Reports of these early
experimental houses are
in the public record (e.g., Thoren 1982; Anderlind and Johansson 1983; Levon
1986; Timusk
1987; and Mackay 1990).
However, with the price of oil remaining low though the 1980s, interest waned
and there appears to have been a general lack of interest and lack of
development from 1987
to recently, when the idea was picked up by two groups: one from Lakehead
University, Canada
and the other from University of Aberdeen, Scotland. Each has taken a
different approach to the
basic idea, the former goes back to first principles of engineering physics to
develop a new
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approach using existing materials in novel ways and the latter focuses on a
composite panel.
One reason for the apparent period of inactivity is, despite the potential of
the idea, results from
early houses were disappointing, with much less than predicted heat recovery
and insufficient
fresh air supply. Besides air quality concerns, heat recovery was only
approximately 50% of the
predicted value with high incremental costs. The 1986 Report T5 of the Swedish
Building
Council concluded that "... the energy goals were not satisfied" (as quoted in
Timusk, 1987 p.
3). Although air quality was improved over existing houses, the fresh air
supply proved
insufficient to satisfy Canadian building code requirements and needed to be
supplemented.
This could be done by using heat recovery ventilator appliances, but added to
cost of
construction and introduced other problems including failure of most of these
appliances to
operate properly within a few years of installation.
Timusk later had come to the conclusion that depressurizing the wall cavities
made more sense than depressurizing the building from both an energy
conservation and air
quality standpoint, and he relayed this information to those interested, for
example Timusk sent
a sketch of this idea to Dr Bryan Poulin of Lakehead University, who shared
this idea with Dr.
Tony Gillies. Since then, Bryan Poulin and Dr. Tony Gillies have explored and
extended this
and other ideas and, building on their own experience, invented the efficient
house system that
they laboratory and field tested, together with the assistance of students and
the Innovation
Office of Lakehead University, on a confidential basis.
The apparent lack of development from 1987 to date in efficient housing
suitable
for the North may have been due to a combination of factors that included lack
of interest in
energy conservation because of relatively low energy prices, less than optimal
performance due
to technical difficulties that were not resolved, and no serious
commercialization effort due to the
right team not being assembled. Reasons for the disappointing results of
previous attempts to
harness the idea may have been a combination of wrong approach (depressurizing
the house to
pull in the fresh air), uncontrolled air infiltration (at doors and windows
and between
assemblies), thermal bridging (e.g., heat conducting through the solid wood
assemblies) and
inadequate and impractical inventions, including overly complex and/or fault
prone devices to
supplement fresh air requirements (e.g., heat recovery ventilator units)
(DeProphetis 2006).
Besides technical problems, there may have been other problems with the
innovation process, including inadequate testing of prototypes to find out
what worked well and
what did not, and inadequate commercialization effort. For example, reflective
coatings are
commonly used to reflect radiant heat for windows but not exterior walls.
Technology and
commercialization problems encountered, in early attempts at using the idea,
appear not to
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have been adequately addressed by any inventions to date, each having been
piecemeal while
it appears that a comprehensive and systematic approach was required.
Recently Brown, lmbabi, Murphy and Peacock (2008) discuss a "dynamic
breathing building" in similar terms although the present invention contains
unique features
found in no other system including that of Brown, lmbabi, Murphy and Peacock.
These unique
features include the differential handling of air drawn through exterior walls
and ceiling, and the
special control system to handle the collection and distribution of fresh air.
Also the current
invention uses or adapts existing materials for the exterior wall and ceiling
assemblies, unlike
the proprietary wall panel described by the Brown lmbabi, Murphy and Peacock
approach. In
addition, refinements suggested by the testing of the current invention and
its various
components in the Lakehead University bike shack and testing from 2006 to
2010, including the
specific testing of certain aspects such as the efficacy of the reflective
material applied to the
exterior envelope, make the entire system uniquely suitable for building
conditions in Northern
Canada and similar climatic conditions elsewhere.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided an efficient
building
using airflow across one or more exterior walls to counteract heat transfer
thereacross, said one
or more exterior walls each having a dynamic wall structure comprising:
a stud wall layer comprising a series of wall studs spaced along a length of
the
wall structure with stud cavities between adjacent studs and air-permeable
wall insulation
material disposed within the stud cavities;
an air-permeable external insulation layer comprising rigid insulation panels
fixed
to the wall stud layer on an exterior side thereof facing outwardly away from
an interior space of
the building toward an external environment outside the building;
a building wrap layer disposed on an exterior side of the rigid air-permeable
insulation panels facing away from the wall studs; and
heat reflecting material arranged within the wall structure to reflect radiant
heat
back away from the wall in both directions.
According to another aspect of the invention there is provided an efficient
building
comprising:
a plurality of exterior dynamic wall structures surrounding an interior space
of the
building, the dynamic wall structures being air permeable to allow airflow
therethrough from an
external environment outside the building;
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at least one depressurization source fluidly communicated with internal spaces
of
the dynamic wall structures and operable to depressurize the internal spaces
of the dynamic wall
structures relative to the external environment to induce the airflow through
the dynamic wall
structure from the external environment; and
a monitoring system configured to monitor conditions associated with each of
the
exterior dynamic wall structures;
a control system linked to the monitoring system and configured to control the
depressurization of the internal space of each dynamic wall structure in order
to control airflow
through each dynamic wall structure in response to measured values of the
monitored conditions.
According to yet another aspect of the invention there is provided a sheathing
panel for an air permeable wall assembly, the sheathing panel comprising:
a sheathing panel body having a length, a width and a thickness defining two
opposite ends, two opposite sides and two opposite faces of the body;
a plurality of holes formed in the sheathing panel body to extend fully
therethrough
from one of the two opposite faces to the other; and
a plurality of hollow inserts received in respective ones of the plurality of
holes,
each hollow insert being hollow between opposite open ends thereof and having
an outer size
and shape arranged to fit against the sheathing panel body at the perimeter of
the respective hole
to reinforce an open condition thereof between the opposite faces of the
sheathing panel body.
According to a further aspect of the invention there is provided an efficient
building
comprising:
a plurality of exterior dynamic wall structures surrounding an interior space
of the
building, the dynamic wall structures being air permeable at exteriors thereof
to allow airflow
between internal spaces of the dynamic wall structures and an external
environment outside the
building;
at least one depressurization source fluidly communicated with internal spaces
of
the dynamic wall structures and operable to depressurize the internal spaces
of the dynamic wall
structures relative to the external environment to induce the airflow through
the dynamic wall
structure from the external environment; and
an air distribution system coupled to the dynamic wall structures to fluidly
communicate with the internal spaces thereof, the air distribution system
having at least one
discharge that opens into the interior space of the building; and
a control system switchable between a heating mode, in which the internal
space
of at least one of the dynamic wall structures is depressurized to draw air
into the air distribution
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system from the external environment through the dynamic wall structure for
release into the
interior space of the building via the discharge, and a cooling mode in which
inside air from a
lower level of the building's interior space enters the dynamic wall
structures through the air
distribution system and is forced out of the building through the dynamic wall
structures.
5 BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate exemplary embodiments of the
present invention,
Figure 1A is a schematic sectional view of an efficient house according to a
first
embodiment of the present invention operating during the heating season, and
illustrates how the
three mechanisms of heat gain are optimally treated.
Figure 1B is a schematic sectional view of an efficient house according to a
first
embodiment of the present invention operating during the cooling season.
Figures 2A and 2B are schematic close up sectional views of a portion of the
efficient house of Figures 1A and IB, marked as Detail 1 in Figure 1A, and
illustrate alternate
ceiling and exterior wall structure details as exterior air flows through the
structure in the heating
season.
Figure 3 is a schematic illustration of an inlet/distribution chamber of an
air
distribution system of the efficient house of Figure 1A.
Figure 4 is a schematic illustration of the exhaust heat recovery unit or heat
exchanger connected between the air distribution system and an exhaust air
collector of the
efficient house of Figure 1A.
Figure 5 is a schematic illustration of a control system of the efficient
house of
Figure 1A.
Figure 6 is a schematic overhead view of an efficient building according to a
second embodiment of the present invention in a demonstration building
constructed and tested
at Lakehead University.
Figure 7 is a partial schematic sectional view of the efficient building of
Figure 6,
illustrating ceiling and exterior wall structure thereof.
Figure 8 is a schematic face view of a sheathing panel used in the wall
structure of
Figure 7 and Figure 8.
Figure 9A is a schematic illustration demonstrating operation of an alternate
embodiment control system for the efficient house of Figure 1 in a default
night-time mode of
operation.
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Figure 9B is a schematic illustration demonstrating operation of the alternate
embodiment control system in a daytime a.m. or morning mode of operation.
Figure 90 is a schematic illustration demonstrating operation of the alternate
embodiment control system in a daytime p.m. or afternoon-evening mode of
operation.
Figure 9D is a schematic illustration demonstrating operation of the alternate
embodiment control system in a daytime peak mode of operation.
DETAILED DESCRIPTION
Figure 1A shows an efficient house 1 having four exterior side walls with a
ceiling
disposed thereover to enclose an interior space 2 of the house over a
foundation thereof. An attic
space 4 is defined between the ceiling structure 6 and a roof structure 8
disposed thereover with
a floor/ceiling structure 10 dividing the interior space 2 of the house 1 into
an upper level 2A and
a lower level 2B. Each exterior side wall structure 12, two oppositely facing
ones of which can be
seen in cross-section in each of Figures 1A and 1B, is air permeable at the
exterior face thereof
exposed to the outside environment surrounding the house 1 and has a hollow
airspace 14
defined within it as illustrated in Figure 2A. On the interior side of the
wall structure 12, the hollow
airspace 14 defined therein is in fluid communication with ductwork 16 that is
closed off from the
surrounding interior space 2 of the house and connects to an air distribution
system 18 in the
lower level, or basement, 2B of the house 1. Alternately outside air is drawn
through the exterior
insulated stud wall cavity directly to the ductwork 16 without the hollow
airspace 14 as illustrated
in Figure 2B. The air distribution system includes an inlet/distribution
chamber 20 that
establishes the connection to the ductwork 16 and also connects to a
conditioning unit 22, which
in turn feeds a discharge 24 that finally releases the airflow through the
distribution system 18 into
the interior space 2 of the house 1.
When operated during the heating season, or winter, a heating fan within the
conditioning unit 22 is operated to draw air into the distribution system 18,
defined in part thereby,
through the ductwork 16 from the hollow airspace 14 within each of the
exterior side walls 12.
This depressurizes the airspace 14 relative to the outside environment so as
to draw fresh
outside into the airspace 14 through the air permeable exterior side of the
wall structure 12. The
fan further draws the air through the ductwork 16 into the inlet/distribution
chamber 20 of the air
distribution system 18 and onward into the conditioning unit 22, which in the
first embodiment
includes a heating device, such as a furnace or heat pump. Fresh air thus
enters through walls
and ceiling and is carried by ducts as shown, such that the fresh outside air
is drawn into the
conditioning unit 22 without any substantial mixing with the air of the
interior space 2 of the
house, due to the closed nature of the ductwork except for its communication
with the distribution
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system 18 at the inlet/distribution chamber 20 thereof, and is warmed by the
heating device for
subsequent release of this heated outside air into the interior space 2
through the discharge
portion 24 of the distribution system 18. The conditioning unit 22 may be
further equipped with a
filter to filter outside air drawn into the distribution system prior to
release into the interior space 2
of the house 1.
During the inward flow of air described in the preceding paragraph, the
outside air
is warmed or preheated as it as it is drawn into the depressurized airspace 14
within the wall
structure 12 by outward flowing heat that otherwise would be lost to the
outside environment from
the heated interior 2 of the house 1 by transfer through a conventional wall
structure. The sealing
off, as much as possible, of the interconnected hollow airspaces 14 within the
walls, ductwork 16
connected thereto and distribution system receiving air therefrom from the
interior space 2 of the
house means that only the hollow airspaces 14 need to be depressurized
relative to the outside
environment surrounding the house 1 to draw fresh outside air into the house.
In other words, the
provision of an air permeable wall assembly depressurized by a central fan
avoids the need to
depressurize the entire house to draw air thereinto. Furthermore, with the
airspace
depressurized below both the air pressure outside and inside the house, any
leakage at the
interior finish of the exterior walls 12 that in a conventional building
structure would potentially
allow leakage of warm air from the interior space 2 of the house instead just
feeds back into the
heating system through the ductwork 16 from the airspace 14 it has leaked into
along with the
inward flow of fresh outside air.
As shown in Figure 1A, the ceiling structure 6 defining, with the exterior
side walls
12, part of the envelope enclosing the interior space 2 of the house 1, is
also taken advantage of
as a site for recovering heat that would otherwise simply be allowed to escape
into the attic space
4, as the ceiling structure 6 also includes a respective hollow airspace 14C
therein that is fluidly
connected to the ductwork 16. The attic space 4 is ventilated in a known
manner, for example by
soffit ventilation between the exterior side of the exterior side walls and
the outer edges or eaves
of the roof 8, so that outside air entering the attic space 4 is drawn into
the ceiling airspace 14C 6
by the depressurization thereof by operation of the conditioning unit heating
fan to draw air from
the hollow airspace 14 through the ductwork 16. The fresh outside air entering
the ceiling
airspace 14C thus absorbs heat transferring outward from the heated interior
space 2 through the
ceiling structure 6. With this heat recovery occurring differentially at all
walls exposed to the air of
the outside environment, i.e. each exterior side wall 12 and the ceiling
structure 6, heat loss or
waste is significantly reduced relative to conventional housing construction.
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In the illustrate embodiment, the aforementioned hollow airspace 14 within
each of
the external side walls 12 is disposed entirely within an elevation range
corresponding to the
upper level 2A of the house's interior space 2 above the floor/ceiling
structure 10 dividing the two
levels. A separate and additional lower level or basement hollow airspace 14B
is defined within
each exterior side wall 12 within an elevation range defined below the floor
ceiling structure.
These additional lower level hollow airspaces 14B are connected to the
distribution system 18 by
additional ductwork 16B to draw fresh outside air thereinto in the same
manner, so as to pick up
heat that would otherwise be lost through the lower level portions of the
external walls during the
heat season.
During the above-described operation of the heating system during the heating
season to draw in fresh outside air while picking up waste heat that would
otherwise be
dissipated from the house by heat loss through the exterior side walls 12 and
ceiling 6, the
outside air being drawn into the distribution system 18 by operation of the
heating fan in the
conditioning unit 22 flows through one fluid-path of a two-stream heat
exchanger 26 on its way
from the inlet/distribution chamber, or IDC, 20 to the conditioning unit 22.
The other fluid path of
the two-stream heat exchanger 26 is fed by an exhaust air collection system
28, that at an inlet
end 28A on one side of the heat exchanger 26 receives exhaust air from a
kitchen or bathroom,
for example under operation of a bathroom exhaust fan or kitchen exhaust hood,
and at the
discharge or exhaust end 28B on the opposite side of the heat exchanger
discharges to the
outside environment. So connected between the exhaust air collector 28 and the
air distribution
system 18, the heat exchanger facilitates heat transfer from exhaust air, that
is typically
discharged straight to the outside environment without any heat recovery in a
conventional
housing structure running an exhaust fan, to the outside air being drawn into
the conditioning unit
22 by the heating fan thereof. Not only does this use of the heat exchanger as
an exhaust heat
recovery unit, or EHRU, improve on conventional exhaust systems where heat,
such as that
developed during running of a hot shower in the bathroom or cooking in the
kitchen, is simply
wasted during direct exhaust to the outside environment, but it also improves
on prior art heat
recovery systems by using the heat being discharged from the interior space of
the house 2
through the exterior side walls 12 and ceiling 6 to preheat the outside air
being drawn into the
house and defining the heat exchanger's cold stream. Having the outside air
warmed during its
passage inward through the walls before entering the heat exchanger reduces or
eliminates
dependency on a defrost cycle to ensure proper and efficient operation of the
heat exchanger and
less probability of breakdown. An alternative is to eliminate the heat
exchanger, where there is
very high cost of maintenance and service, for example in the far North of
Canada.
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Having been warmed during passage through the walls externally exposed to the
outside air, including the ceiling, and subsequently flowing through the heat
exchanger 26, the
outside air is further heated in the conditioning unit 22, for example by a
furnace or heat pump or
electric coil thereof, and finally released into at least one area of the
interior space 2 of the house
through a discharge portion 24 of the distribution system, for example through
conventional duct
and register arrangements such as those commonly used in conventional forced-
air heating
systems. Heat loss to the outside environment during the heating season is
greatly reduced
relative conventional housing structures, not merely by trying to block or
slow heat transfer
outward through the walls but by instead by making use of such heat transfer,
which typically
amounts to wasted heat, along with heat typically discharged directly to the
outside environment
by exhaust systems, to warm an incoming supply of fresh outside air.
Reflective properties of the
Delta Dry, if used, or separate reflective materials within the exterior
facing walls and ceiling will
reflect heat back into and away from the interior of the building.
As shown in Figure 1B, the operation of the system can be reversed from that
shown in Figure 1A to run in a cooling mode in the cooling season. An air
intake conduit 30
extends through at least one of the exterior side walls 12 to communicate the
interior space 2 of
the house 1 directly with the outside environment when one or more dampers 30A
are opened
during the cooling season. The conditioning unit 22 in the lower level 2B of
the house 1 features
an inlet 22A through which air is drawn into the conditioning 22 during
operation of a cooling fan
thereof. This cooling fan and the heating fan used during the heating season
may be defined by
the same fan unit, operable to rotate in opposite directions to effect the
necessary air flow
direction through the distribution system depending on whether heating or
cooling of the interior
space 2 is required. During the cooling mode operation, a damper 32 closes off
the connection
between the heat exchanger 26 and the conditioning unit 22 while another
damper 34 is opened
to fluidly connect the conditioning unit 22 with the inlet/distribution
chamber 20 of the air
distribution system 18 and the ductwork 16, 16B connected thereto while
bypassing the heat
exchanger 26. Opposite to the heating fan, which operates to draw air into the
conditioning unit
22 of the distribution system 18 through the inlet/distribution chamber 20
thereof from the
ductwork 16 communicating with the hollow airspaces 14, 14C in the external
side walls 12 and
ceiling 6, the cooling fan draws air into the conditioning unit 22 through the
inlet 22A thereof and
forces it outward from the conditioning unit 22 into the ductwork 16, 16B
through the
inlet/distribution chamber 20, but not by way of the heat exchanger due to the
closed condition of
damper 32. This airflow into the ductwork 16, 16B continues onward into the
hollow airspaces
14, 14C communicating therewith and thus subsequently outward through the air
permeable
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outer sides of the exterior side walls 12 and ceiling 6. Air flows from inside
to outside through air
permeable wall assembly, opposite the airflow created during heating mode
operation. Since the
outside environment is warmer than the interior space 2 of the house 1 in the
cooling season,
heat transfer through the walls is inward, opposite the direction of heat loss
in the heating season.
5 The
forced outward flow of air through the permeable wall and ceiling structures
thus opposes
this inward flow of heat, absorbing the heat and carrying it outward back to
the outside
environment, thereby reducing or preventing heat transfer into the interior
space 2 of the house 1.
In addition to reducing heat transfer into the interior space 2 by carrying
heat
outward with out-flowing air, and reflective coated materials, the cooling
mode operation of the
10
system also distributes cooler air from the lower level 2B of the house 1 into
the upper level 2A,
which will naturally tend to be warmer due to the higher buoyancy of warm air
relative to that of
cooler air. The forcing of cool air upward into the upper level 2A occurs by
opening a damper 36
within at least one branch of the discharge arrangement 24 that discharges
into the upper level
2A of the house 1. With this damper 36 open, air from the conditioning unit 22
is forced by the
cooling fan, not only through the ductwork 16, 16B to the hollow airspaces 14,
14B, 14C in the
exterior side walls 12 and ceiling 6, but also through this branch of the
discharge arrangement 24.
Cool air from the lower level is thus not only forced outward through the air
permeable wall
structures, including the ceiling, to oppose heat transfer into the interior
space 2 through these
structures, but is also forced into the upper level 2A of the interior to
provide a cooling effect.
Lower level air is thus distributed by fan, with this cooling mode operation
also bringing fresh
outside air into the house through the intake 30 for subsequent distribution
once entering the
conditioning unit 22 through the inlet 22A thereof.
During cooling mode operation, the heat exchanger 26 is inactive, unlike
during
heating mode operation. As shown in Figure 1B, in addition to closing the
connection between
the heat exchanger 26 and the conditioning unit 22 by way of damper 32 to
close the cold stream
path through the heat exchanger, the warm stream path may also be closed by
closing dampers
37 at the exhaust or discharge end 28B of the exhaust air collector 28 and
instead opening an
alternate exhaust air discharge conduit 38 that releases exhaust air, for
example from the kitchen
or bathroom, directly to the outside environment without passage through the
heat exchanger 26.
Alternatively, the envelope may transfer all the heat necessary for efficient
operation, without the need for a separate heat exchanger.
Referring to Figure 2A, each exterior side wall 12 features, from inside to
outside
the house 1, an interior wall finish 40 (e.g. drywall), vapour barrier or
retarder 42, the hollow air
space 14, insulation 44 (e.g. fiberglass or rock wool insulation) within the
cavities of the exterior
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stud wall, air permeable sheathing/insulation 46 (e.g. insulating polystyrene
sheathing equipped
with holes to admit exterior air during the heating season) and an air-
barrier/strapping/exterior-
finish arrangement 48 or other rain-screen sub-system. In addition, the wall
includes a reflective
material within the wall (e.g. either a reflective coating at the exterior
facing building wrap or a
reflecting material within the cavity such as aluminum foil). The vapour
barrier or retarder 42, is
typically located under the interior finish of the wall at the interior side
of the hollow airspace or
cavity in the wall. An alternative installation 50, is shown on the other side
of the hollow airspace
14 at the interior face of the insulated stud wall 44. A plenum 52 is
supported at the interior face
of the wall 12 with its hollow interior in fluid communication with the hollow
airspace within the
wall 12 via a series of openings 54 extending through the interior wall finish
40 at spaced
positions therealong near the top of the wall 12. A stack effect can be
expected to help draw air
upwards through the exterior wall and this may allow sufficient air flow
directly to duct without the
need for the hollow wall cavity 14 behind the interior face of the exterior
wall, as shown in Figure
2B. Operation of the heating fan during the heating season lowers pressure in
the plenum 52 and
wall cavity 14 to lower than outside and inside air to draw air from the
outside environment into
the hollow airspace 14 and collect any inside air leaking into the wall from
the interior space 2. It
will be appreciated that plenums may be incorporated into some walVceiling
designs and
eliminated as separate external structures.
The ceiling structure is similar in function, consisting of, from the interior
space 2 of
the house 1 outward, an interior finish 56, vapour barrier 58, the hollow
ceiling airspace or plenum
14C, an air permeable membrane 60 and insulation 62, the ceiling's hollow
airspace 14C opening
into the ductwork through intentionally provided gaps, breaks or openings in
the interior finish. As
suggested by the solid-headed arrows in Figure 2, the outside air drawn into
the hollow airspaces
14, 14C in the exterior side walls and ceiling 6 during heating mode operation
is guided onto the
inlet/distribution chamber 20 by the ductwork 16. As shown strapping 64 set
perpendicularly
crosswise to the ceiling joists may be used in a conventional manner for
support of the ceiling's
interior finish 56, with staggering of the strapping 64 in its lengthwise
direction perpendicular to
the floor joists providing gaps to allow for airflow within the hollow
airspace 14C in which the
strapping 64 is disposed, between the vapour barrier 58 and the air permeable
membrane 60.
Figure 3 schematically illustrates the inlet/distribution chamber 20 of the
air
distribution system 18 during operation of the efficient house 1 in the
heating season, as
represented in Figure 1A. The ductwork 16, 16B connecting the hollow airspaces
14, 14C within
the exterior side walls 12 and ceiling 6 includes ceiling branch 16C, north
wall branch 16N, south
wall branch 16S, east wall branch 16E and west wall branch 16W connected to
the ceiling
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structure 6 and north, south, east and west exterior side walls of the house 1
respectively. Each
branch of the ductwork 16, 16B connects separately and distinctly to the
inlet/distribution
chamber 20 of the distribution system 18. The upper level ductwork 16 in the
upper level 2A of
the interior space 2 of the house 1 in Figures 1A and 1B thus actually
represents five separate
ducts each defining a sealed air path from a respective one of the four
exterior side walls and
ceiling of the house 1 to the inlet/distribution chamber 20 of the
distribution system 18, carrying
air from a respective one of the hollow airspaces 14, 140 to the
inlet/distribution chamber 20
without mixing with air from another airspace or air from within other parts
of the interior space 2
of the house 1. The lower level ductwork 16 in the lower level 2B of the
interior space 2 of the
house 1 is similarly four separate ducts each fluidly communicating in a
sealed manner with the
lower level hollow airspace 14B of a respective one of the four exterior side
walls. Each lower
level duct may connect with the respective one of the five upper level ducts
communicating with
the upper level hollow airspace 14 of the same wall, these two connected ducts
thus forming one
of the wall-connected ductwork branches 16N, 16S, 16E, 16W of Figure 3.
Five inlet control dampers 66C, 66N, 66S, 66E, 66W are installed on the five
ductwork branches 16C, 16N, 16S, 16E, 16W and are operable to control the flow
of air into
inlet/distribution chamber 20 during operation of the heating fan in the
heating mode operation.
For example, in Figure 3 each of the five inlet control dampers 66C, 66N, 66S,
66E, 66W is
shown in an open position (schematically illustrated in solid lines) fully
allowing flow of air into the
inlet/distribution chamber 20 from the respective ductwork branch under
operation heating fan in
the conditioning unit 22 to induce such a flow of fresh outside air from the
outside environment
through the air permeable external side of the respective exterior side wall
or ceiling. Each of the
five inlet control dampers 660, 66N, 66S, 66E, 66W however is pivotable into a
closed position
(schematically shown in broken lines) sufficiently obstructing flow from the
respective ductwork
branch so as to substantially prevent any airflow between the hollow airspace
of the respective
exterior side wall or ceiling and the distribution system 18. First heating
duct 68 also connects to
the inlet/distribution chamber 20 of the distribution system 18, defining a
sealed path from the
inlet/distribution chamber 20 to the inlet side of the cold stream path of the
heat exchanger 26
during heat mode operation to define an exit from the inlet/distribution
chamber 20 for outside air
flowing thereinto through the ductwork 16 when at least one of the inlet
control dampers 66C,
66N, 66S, 66E, 66W is open.
Figure 5 schematically illustrates a control system, or CS, 70 used in the
house 1
to control operation of the overall system in the heating and cooling modes of
Figures 1A and 1B.
The control system 70 receives input signals from outside temperatures wall
sensors N, S, E, W
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each mounted to the house 1 in or near the outside environment to monitor the
temperature at or
near the respective one of the north, south, east and west external side
walls, for example to
detect temperature differences at different sides of the house caused by, for
example solar gains.
Other types of sensors or gauges may also or alternatively be included, for
example to monitor
wind pressure or speed at the different sides of the house or air flow within
the ducts and the
control system will use the data to from the flow and temperature sensors to
optimally balance the
system. The input signals received by the control system are used to control
the inlet control
dampers 66C, 66N, 66S, 66E, 66W during heat mode operation to control the
airflow into the
inlet/distribution chamber 20 of the distribution system 18 from each of the
ductwork branches
connected to the exterior side walls. The control system 70 also receives
signals from flow
sensors installed on the ductwork branches 16C, 16N, 16S, 16E, 16W and from
additional
temperatures sensors within the interior space 2 of the house to control
operation of the overall
system.
As an example, looking at Figure 1B, although only one air intake conduit 30
is
shown, each exterior side wall is provided with a respective air intake
conduit in the first
embodiment to facilitate entry of air during cooling mode operation from
selective locations. The
control system 70 operates the dampers of these intake conduits, for example,
to only intake
outside air from the cool side of the house 1 as determined by comparison of
the signals from the
exterior wall temperature sensors to identify the exterior side wall having
the lowest temperature.
Figure 1B shows the dampers 30A of the one illustrated air intake conduit 30
open with air
entering the lower level 2B from the detected cool side of the house. The
control system will
balance conditions including drawing fresh air (in heating season) and
exhausting air (in cooling
season) with just the right amount of air passing through the exterior facing
walls and ceiling to
counter heat flow by conduction and also to provide fresh air required for
healthy occupancy.
The 'brains' behind the system is the control system (CS) box that contains a
site specific
computer and software optimizing the data obtained at each building by, for
example using a
'genetic algorithm' approach (McGrew in Sechbech and Gordon, 2009). This data
may include
measures on the unique environmental conditions facing the building (e.g.
measures of outside
temperature, temperatures within each of the exterior stud wall cavities and
the ceiling assembly.
Locations in the far North of Canada, or other remote areas, may necessitate a
simpler and less
complex control system than the one illustrated in Figures 9A, 9B, 9C and 9D.
For example, the
control system may be as simple as one controlling fan speed, with a simple
forward and reverse
switch, triggered by outside temperature for summer and winter operation.
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Figure 6 illustrates an exemplary layout of ductwork within an efficient
building 100
which shows a single story building.
Multi-storey buildings (e.g. two story houses) are
conceptually the same with ducting at the top of each wall, led to a single
distribution chamber
and controlled by a system control box and sensors, and similar to the single
story house with a
basement. Like the house 1 of Figures 1A and 1B, the demonstration building
Figure 6 has four
exterior side walls, which are labeled 12N, 12S, 12E, 12W in accordance with
their respective
north, south, east and west outwardly facing orientations.
The ductwork features four
corresponding side wall branches 16N, 16S, 16E, 16W each fluidly communicating
with the
hollow airspace defined within a respective one of the side walls 12N, 12S,
12E, 12W. Due to the
elongated rectangular floor plan of the demonstration building, significantly
longer in one direction
than the other, the ceiling structure is divided into equal sized sections in
the elongated direction
of the building, the sections having one single hollow airspace under the
interior side of the
exterior facing ceiling with the air led to the air collection and
distribution chamber by way of two
ceiling ducts defined therein each fluidly communicating with a respective one
of two ceiling
branches 16C1, 16C2 of the ductwork 16.
Figure 7 shows the wall structure used in the efficient building construction
of
Figure 6. A stud wall assembly, having the cavities between adjacent vertical
studs filled with
insulation as shown schematically at 44 in the figure, has horizontal
strapping, or furring, 102
fastened perpendicularly across the vertical studs at the interior side of the
stud wall. Drywall, or
other interior finish, 40 is fixed to the strapping 102 on the side or face
thereof opposite the stud
wall, the resulting open space between the stud wall and the drywall 40
defining the hollow
airspace 14 within the wall structure, with the battens creating the air space
staggered, so as not
to impede the free flow of air in the cavity space. Vapour barrier is
installed on the interior side of
the airspace, as described herein above for the efficient house 1 with
reference to Figure 2. On
the exterior side of the stud wall is an insulating sheathing layer 46, which
in the embodiment of
Figures 6 to 8 is made up of a series of beadboard (expanded polystyrene, or
EPS) panels 106,
the sheathing layer 46 in turn having a layer of building wrap 108 (e.g. Delta
Dry) installed over
the outside face thereof. Finally, the outer side of the wall structure 12E is
completed with
breathable/air-permeable exterior siding 110.
To improve airflow between the outside environment and the hollow airspace 14
defined within the wall structure 12E, the panels 106 of the sheathing layer
46 are each provided
with a series of holes 112 punched therethrough from one panel face to the
opposite panel face,
thereby defining channels through which air can flow across the panel 106. As
shown in Figure
8, the holes 112 may be arranged in staggered parallel rows 114, 116, each row
extending in an
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elongate vertical dimension of the panel 106 defined between opposite ends
thereof. In the
illustrated embodiment of the panel 106, the spacing between any two adjacent
holes in the same
row is the same and the inter-hole spacing of one row is equal to that of the
other row. The rows
114, 116 are offset from one another in their parallel elongate directions by
one-half this common
5
straight line distance between any two holes in the same row, such that in the
parallel direction
defined by the rows, each hole is spaced from a corresponding hole in the
other row by one-half
of the distance between two adjacent holes in the same row. Cross-sectionally
round and hollow
cylindrical liners or inserts 118 of plastic, each having a circular
cylindrical inner and outer shape,
are inserted into the holes 112 in the panel 110 to help retain the shape and
open condition of the
10
holes 112 by reinforcing the panel around each hole 112 therein. Testing was
performed with
three beadboard panels (each sixteen inches wide and two inches thick with
height of 96 inches)
arranged long side edge to long side edge and equipped with fifty holes
(seventeen in each of
two end panels and sixteen in the middle panel between the outside panels)
each of five
millimeters in diameter and each fitted with a five millimeter diameter
plastic drinking straw insert
15 of
two and one-eight inches in length. The holes were arranged two staggered rows
per panel
with the holes of one row spaced vertically from those of the other by six
inches and the two rows
horizontally spaced by seven inches and centered over the panel's sixteen inch
width. Compared
to flow pressure through the same panel assembly when equipped with one
hundred non-
reinforced holes, the reinforced arrangement with the plastic inserts (formed
by adding the inserts
and taping over half of the one hundred original holes) was found to provide a
greater flow
pressure at a the same inside pressure and the entry of air with the 50
reinforced holes exceeded
that of standard air permeable building wraps such as Tyvek, and thus was
judged to be a
superior arrangement in supplying fresh area to the building through the
exterior walls. This
reinforced arrangement would also be suitable for other insulated sheathing
materials.
With further reference to Figure 7, each half of the ceiling structure 6' of
the
efficient building 100 is similar to the ceiling structure 6 of the efficient
house of Figures 1A, 1B
and 2. Ceiling insulation 62 (e.g. fiberglass insulation) is fitted between
adjacent ceiling joists
with an air permeable membrane 60 (e.g. Tyvek) separated therebeneath from the
vapour barrier
58 (e.g. 6 mil polyethylene sheet) that is applied next to the interior finish
(e.g. drywall). The
hollow airspace 14C is defined by spacing of the interior finish (e.g.
drywall) downward from the
joists by strapping 64 extending perpendicular to the ceiling joists in a
staggered fashion to leave
spacing between strapping pieces in their lengthwise direction to allow
airflow across the
strapping within the airspace 14C. Like the walls, the ceiling also
incorporates a layer of
reflective material therein. Alternately, installation of a dimpled semi-
rigid, air permeable material
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such as Delta Dry, if perforated may provide an all-in-one solution: air space
between the fiber
ceiling insulation, required air permeability and required reflectivity. As
shown at 126, the hollow
airspaces within the wall and the ceiling 14, 14C are separated from one
another along edge
defined by the meeting of the interior finishes of the wall 12E and ceiling 6.
The other half of the
ceiling structure 6' of the efficient building 100 is of similar construction,
the hollow airspaces of
the two halves being separated from one another so that each communicates with
a respective
one of the two ceiling braches 16C1, 16C2 of the ductwork 16.
As shown in Figures 6 and 7, the ductwork 16 may be connected with the hollow
airspaces 14, 14C of the exterior side walls 12N, 12S, 12E, 12W and ceiling 6'
by way of duct
boots 128 connecting each duct branch 16N, 16S, 16E, 16W, 16C1, 16C2 to the
hollow airspace
defined within the respective wall or portion of the ceiling structure at
spaced points along the
duct branch. The boots of each of the side wall duct branches 16N, 16S, 16E,
16W extend
horizontally from a portion of the branch extending along the respective
exterior side wall parallel
and proximate thereto near the upper edge thereof within the interior space of
the building, while
the boots of each of the ceiling duct branches 16C1, 16C2 extend vertically
upward from a portion
of the branch extending parallel and proximate to the ceiling within the
interior space. In the
efficient demonstration building of the second embodiment, the portions of the
two ceiling duct
branches 1601, 16C2 equipped with duct connections to the hollow airspaces of
the two ceiling
sections are parallel and extend across (i.e. along the short dimension) of
the elongate building.
These two parallel portions of the ceiling duct branches 16C1, 16C2 are
equally spaced along the
building (i.e. in the direction of the building's elongate dimension) from
respective end walls 12N,
12S also extending across the building 100 and are spaced apart from one
another by
approximately one half of the lengthwise dimension of the building's interior
space. This
corresponds to division of the two ceiling sections along an axis cross-wise
to the building 100
half way therealong, so that each ceiling duct branch 1601, 16C2 can be
considered to operate
with a respective half of the overall ceiling structure.
As shown in Figure 6, the side wall branches 16N, 16S, 16E, 16W of the
ductwork
16 may extend along the perimeter of the interior space of the building to
connect to the
inlet/distribution chamber, or !DC, 20 of the distribution system in a common
space defined
somewhere along a respective one of the exterior side walls, illustrated as
the east wall 12E in
Figure 6. Although parallel portions of the different duct branches 16N, 16S,
16E, 16W, 16C1,
16C2 are shown as being horizontally spaced from one another in Figure 6 to
prevent overlap
and improve clarity of the illustration, these duct portions extending toward
the inlet/distribution
chamber 20 may instead be vertically spaced or stacked as illustrated by the
south and east wall
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duct branches 16S, 16E in Figure 7 so as to minimize the inward distance from
the walls
occupied by the wall branches of the ductwork 16.
The demonstration building prototype based on the embodiment of Figures 6 to 8
was constructed, being a building twenty-two feet and eight inches wide and
thirty-eight feet long
using four inch diameter ducts with two inch diameter boots or other such
means as establishing
communication with the airspaces approximately seven feet up the walls. The
linear segments of
the ceiling ducts, each communicating with the respective ceiling airspace at
spaced locations
along the segment and extending cross-wise to the elongate floor-plan, are
proposed to be
positioned ten feet inward of the shorter exterior sides of the building so as
to each serve a
respective half of the overall ceiling structure as explained herein above
with reference to Figure
6.
Figure 9 schematically illustrates operational modes of an alternate
embodiment
control system that switches between different operation modes based on both
time and
monitored conditions for an efficient dynamic-wall house or building of the
type described above.
Four exterior walls NW, SW, EW, WW face north, south, east and west
respectively and each
have the dynamic wall structure described herein above, and a dynamic ceiling
of the type
disclosed above communicates with outside air via the attic space. Again,
ductwork connects
each dynamic wall or ceiling to a heat exchanger 26 acting as a heat recovery
ventilator (HRV) or
energy recovery ventilator (ERV) in an air distribution system of the
building. Such as in the
inlet/distribution chamber of Figure 3, the distribution system features
dampers 66C, 66N 66S,
66E, 66W each operational to control airflow into the air distribution system
via the ductwork
feeding thereinto from the dynamic ceiling and walls. Temperature sensors are
again used, but
unlike the control system of Figure 5, they are located within the building
and monitor airflow
temperatures Tc, TNw, Ts, TEw, Tww in the ductwork between the dynamic ceiling
and walls and
the dampers 660, 66N 66S, 66E, 66W rather than outside air temperatures. That
is, they provide
ongoing monitoring of the incoming outside air after, not before, the heat
transfer that occurs as
the incoming air passes through the dynamic ceiling and walls.
Each air circulation branch duct from the tributary external wall, ceiling or
sub-floor
cavity (e.g. air drawn to recover conduction heat from an unheated crawl
space) features
temperature sensing of the airflow and an adjustable damper. For the purposes
of the
explanation, the dampers are assumed to have two selectable settings, LOW flow
and HIGH flow.
The dampers are adjustable, for example, each unit being individually
motorized unit, or some
being slaves to a master control motor and controlled via a signal feed from
the master controller,
which may be located remotely from one or more of the dampers. In one
embodiment, a single
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motor may control multiple dampers that are mechanically linked. The
illustrated system utilizes a
single central circulation fan operable to draw air through the ducts from all
the dynamic
structures, which for the purpose of Figure 9 is an integral part of the heat
recovery ventilator 26,
although it will be appreciated that the fan may alternatively be part of a
furnace or other air
distribution component into which the supply air from the heat recovery unit
is fed. The fan has
multiple switchable or adjustable speed settings, controlled via another
signal output from the
master controller. For the purposes of this exemplary embodiment, the fan has
three settings
denoted LOW, MEDIUM and HIGH.
The switching between operational modes can be triggered by one or more of
three different input options (1) Damper (Opening setting) / Flow (HRV/ERV fan-
speed)
parameters preset in master controller are switched based on time-of-day and
calendar date
reflecting seasonal variations; (2) Damper / Flow switching based on
temperatures sensed in the
flow in the individual ducts from each tributary area (wall or ceiling)
compared to a target setpoint
sensed/coded into the controller; and (3) Damper/Flow switched based on wind-
speed and
direction as provided to the controller from the weather station at the
facility or provided from a
remote source such an online public weather bureau. Wind information is fed to
the control unit
such and dampers are opened further or closed off more on sides exposed to
wind currents
and/or fan-speed is controlled in such a way as to optimize the system and
keep it in balance.
Figure 9A shows a DEFAULT MODE of operation of the system. The circulation
fan is operated on the LOW setting and the dampers are each partially closed
into their LOW
airflow position, and the resulting airflow is the minimum required to meet
the flow requirements
for adequate air changes in the building as supplied by each tributary
wall/ceiling/sub-floor zone.
The system may be arranged to employ this default mode of operation during a
night time period,
either through manual switching into and out of this mode in the evening and
morning by an
operator, or automatic switching into and out of this mode when a clock of the
controller reaches
particular hours of the day, which may be preset or user selectable,
programmable, or adjustable.
Figure 9B shows a DAYTIME A.M. or MORNING mode of operation into which the
system may be switched from the NIGHTTIME or DEFAULT mode of operation.
Flow is
increased from selected zones based on which walls are expected to be exposed
to morning
sunlight (e.g. in the northern hemisphere, walls facing east, south-east and
south). Thus in the
drawing, dampers 66S, 66E of the south and east walls SW, EW are opened
further from their
partially closed positions of the default night-mode operation into their HIGH
airflow positions and
the fan speed at the heat recovery ventilator 26 is increased to MEDIUM. This
draws in more air
from the sides of the building expected to be heated by the sun in the morning
hours. The
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setting for the ceiling damper 660 will be low or high, "LJH" depending on,
for example,
temperature readings from the sensors in the externally facing cavities and/or
ducts, and the
requirements of the interior building space.
Figure 9C shows a DAYTIME P.M. or AFTERNOON/EVENING mode of operation
into which the system may be switched from the DAYTIME A.M. mode of operation.
Flow is
reduced from one or more selected zones to default (LOW airflow) and increased
in others to
HIGH and based on the expected change of walls exposed in the afternoon and
evening
compared to the morning (i.e. in the northern hemisphere, the shift of
sunlight exposure from the
wall(s) facing east and south or southeast to the wall(s) facing west and
south or southwest), and
the fan speed is left at MEDIUM. Thus in the drawing, damper 66W of the west
wall WW is
opened further from its previous partially closed position of the night and
daytime a.m. modes of
operation into its HIGH airflow position, while the damper 66E of the east
wall EW is return to its
default partially closed LOW flow position and damper 66S of the south wall WW
is left its HIGH
airflow position. Like in the daytime a.m. or morning mode, more air is drawn
in from the sides of
the building expected to be heated by the sun in the morning hours, thereby
increasing the heat
energy being brought into the building interior space at the dynamic walls. As
shown, the damper
66C for the airflow from the ceiling may also be opened to its HIGH flow
position to increase
airflow from the ceiling on the expectation that the roof's exposure to
sunlight will cause heating
of the attic space, providing more heat available to be drawn into the main
interior space of the
building by the incoming air.
The control system may be operable to change the hours of the day at which the
operation mode switches, whether through user-programmability or automated
adjustment of the
mode switching times through use of a calendar used to monitor the current
date for correlation
with season changes, daylight savings time changes.
Figure 9D shows a DAYTIME PEAK mode of operation into which the system may
automatically switch from DAYTIME A.M. or DAYTIME P.M. mode upon detecting
that one or
more of the airflow temperatures Tc, TNw, Tsw, TEw, Tww coming in from the
respective dynamic
ceiling and wall structures exceeds a setpoint temperature. The damper for
each airflow detected
as being warmer than the setpoint temperature (i.e. dampers 660, 66S, 66W for
the illustrated
example) is set to its HIGH flow position and the fan-speed is likewise
increased to HIGH, thereby
drawing in more air from this warmer zone.
It will be appreciated that may be possible to have more incremental fan-
speeds
and damper degree-of-opening positions so that the flow could be continuously
variable in both
volume and in draw from individual discrete source zones.
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The efficient control system can functionto: (1) control and balance air flow
to
optimize heat transfer and meet indoor air quality standards (i.e. bring in a
sufficient collective
volume of air from the dynamic structures to adequately ventilate the building
to such standards,
while using monitored temperatures or expected sun exposure to increase the
volume of air
5 where more heat energy is available to reduce heating costs), (2) daily
and seasonally control air
temperature according to user requirements and setpoints, (3) possibly collect
air quality,
temperature and energy usage data, for example at regular intervals, such as
every hour, (4)
possibly report data to one or more third parties every day for analysis via
telecommunication,
and (5) possibly monitor the system and transmit alarm notifications or
signals to third parties or
10 remote locations in case of failure.
It will be appreciated that control over air pressure within the airspaces of
the wall
and ceiling relative to the outside air pressure of the outside environment
and the inside air
pressure of the interior space of the building may be controlled by systems
other than a single
centralized fan-based system within the conditioning unit of the distribution
system. For example,
15 the airspace of each wall could have its own respective fan installed in
fluid communication
therewith, for example within the respective branch of ductwork to reduce the
air pressure below
outside and inside air pressures, thereby drawing air into the airspace from
the outside
environment and force it onward through the system during heating mode
operation. It will also
be appreciated that in such an arrangement, control over the operation of the
individual fans may
20 be used to control air flow through the respective ducts in instead of
using dampers. Efficient
houseTM1 is a new concept that for the first time introduces air through the
entire envelope, not just
walls but walls and the ceiling, balancing heat losses and gains, thus
improving air quality and
energy efficiency throughout the entire season. This concept is more than an
extension of
previous work in Canada and elsewhere. It is the first system design that is
optimal and, at the
same time, allows for safety if the system should fail (a concern in northern
communities). In
other words, it provides a 'fail-safe mode should mechanical or electronic
failure occur in parts or
the entire system. The fail safe mode may simply be a state in which the
dynamic wall system is
inactive, i.e. air is not drawn dynamically through the exterior facing walls
or ceiling. It is also a
system that, for the first time, balances and takes advantage of typical heat
losses and gains in
each season, and does so in cost effective ways. In heating (winter) season,
heat is recovered
and used to temper incoming ventilation air by drawing in just the right
amount of this air from the
exterior ceiling and each exterior face ¨ north, south, east and west ¨ first
through a permeable
layer and then through the insulation in the exterior walls and ceiling, to a
space behind their
interior finish, collecting and leading this air by ductwork to a heat
exchanger that transfers heat
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from exhaust (e.g., kitchen) air to the incoming air to the furnace, all
controlled by an efficient air
management system. In cooling (summer) season, the system is reversed.
The invention disclosed above is a comprehensive and systematic application of
the three mechanisms of heat loss and gain in houses, meeting requirements for
structure
durability, fresh air supply and optimal heat and cooling transfer through the
exterior envelope of
the building, under varying conditions such as outside wind speed, temperature
and solar
radiation. For example, the system invention takes into account the three main
mechanisms of
heat transfer through the envelope of a building: conduction, convection and
radiation.
Firstly, the disclosed energy conserving approach that is more efficient than
conventional buildings, since it optimally controls all three mechanisms of
heating and cooling
losses, gains and transfers: by including perforated rigid insulation over
exterior studs to minimize
thermal bridging that is common with wood frame construction; by including a
radiant reflecting
material within the wall and ceiling and, potentially the lower floor or
basement slab to reflect heat
in or away from the interior space, as external ambient and internal
conditions demand; by
drawing air across the envelope, differentially from all four directions, to
optimally capture
conductive heat loss or heat gain, and optimally reflect heat towards or away
from the building,
depending on demands of external ambient weather and internal load conditions.
By including a
central collection, distribution and central system to optimally collect,
temper, and filter and
redistribute fresh to where it is needed for efficiency, health and good
practice.
Secondly, the disclosed building also features a more durable structure than
conventional construction since the envelope is of a rain screen type that
guards against and
sheds moisture and is self-drying through passage of relatively dry fresh air
through the envelope,
using a permeable insulation sheathing in combination with exterior fabric
designed to self dry
and allow fresh air across the exterior sheathing, for example using
perforated rigid insulation to
together with the commercially available 'Delta Dry' exterior building
material that allows passage
of fresh air while being self-drying with 70% reflective properties that
assist in the first aspect.
Thirdly, more healthful for building occupants than conventional construction
since
the envelope acts as a giant air to air heat exchanger that draws in fresh air
as well as partially
tempering the incoming air that is further tempered, preferably by a
simplified air to air heat
exchanger that may be fitted with or to an electric coil to add supplementary
heat when required
by the building occupants, all controlled by a central control system that
preferably has monitoring
and communication capability.
In summary, though the idea of heat recovery and fresh air supply through
exterior
walls has been in the public domain for more than 30 years, the efficient
house is the first
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invention that is a total system with uniquely suitable parts. Thus this EH
invention is different in
concept and detail to anything else including these earlier attempts, namely
the experimental
houses constructed in the late 1970s in Sweden and in the early 1980s in
Ontario and Alberta,
Canada where fresh air was drawn through exterior walls by depressurizing the
house, and the
experimental house in Scotland. Differences in key components of and benefits
to the efficient
house system may be summarized as follows:
1. Fresh and tempered air is drawn differentially through exterior
facing walls and ceiling
cavities that are created behind interior finishes. Depressurizing the space
behind the ceiling
and walls is different from earlier attempts to draw air through the exterior
walls alone and by
depressurizing the house. Drawing air from the exterior ceiling increases the
area to meet
fresh air requirements and provides more of the overall heat recovery system.
Robustness of
the system is also improved since uncontrolled air leakage is minimized and is
drawn into
wall/ceiling cavities, such that these remain relatively dry without going to
extraordinary
measures to seal openings, as with Canada's 82000 program.
2. Pre-warmed air passing through the walls and ceiling is collected in
chamber and further
warmed by passing through a simplified air to air heat exchanger that needs no
defrosting in
the heating (winter) season since the incoming air is tempered or pre-heated,
unlike that with
competing devices. Not requiring defrost cycles in the heat exchanger
eliminates a major
reason for most existing heat exchangers failing to operate properly, or at
less than full
efficiency.
3. The fresh and tempered air is carried by air ducts to a fan/heat
coil/furnace/conditioning/filtering system from which it is distributed. This
collection and
distribution is different from, for example, the Timusk house 'dumped' fresh
and somewhat
tempered air directly into the house. The advantages over previous inventions
include
differential supply and further tempering and conditioning of the fresh,
tempered air, as part
of the overall system of the efficient house or building, and reflection of
heat back into the
occupied spaces.
4. A filter in the conditioning system filters out dust and particulate
matter, including any free
fibers before the air is distributed throughout. This filter feature will
allow improvement of
indoor air quality as compared to dynamic wall or other inventions which dump
air directly
into the without filtering.
5. There are techniques to reduce thermal bridging in walls and improve
efficiency and reduce
costs in the collection and distribution of the tempered fresh air. For
example, these
techniques include Delta Dry building wrap combined with polyethylene cladding
with
SUBSTITUTE SHEET (RULE 26)
CA 02841018 2014-01-06
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2. supported and perforated holes to allow air to pass through the
exterior walls, and Delta Dry
building wrap, perforated to allow air flow from the exterior facing ceiling.
Membranes such
a Delta Dry may have reflective properties such that separate reflective
materials within
exterior facing walls and ceiling may not be necessary. These techniques may
lead to
other special assemblies such as combined rain-screen and air permeable
building wraps,
composite assemblies and/or preformed air plenums that might also act as
architectural
valences.
3. There is a control system to optimize the intake of fresh air, depending on
extemal
conditions and sensing devices and inline fan and/or control dampers in the
ducts, so as to
draw air differentially from different locations and/or directions, for
example in different
directions (N, S, E & W). This sensing and control subsystem helps optimize
the entire
system by taking account of certain conditions including wind pressure and/or
solar gains.
The central control and monitoring subsystem is a key differentiating part of
the efficient
house and acts as the "brain" to optimize the "brawn" that is the combination
of the other
parts of the overall system. For example, this central control system picks up
signals from
the sensing devices and sends signals to other devices such as in duct fans
and/or
dampers to control air flow from exterior ceiling and wall areas. The central
system also
incorporates diagnostic logic that may signal local and/or remote panels for
maintenance or
repair.
7. The system can be reversed for cooling, as indicated in Sketch 1B, whereby
air is drawn
into the lower areas (e.g. basement) where air is cooled by running through
tubes in the
ground around the basement walls and then led by the
conditioning/filter/control/ducting
system into the wall and ceiling cavities, thereby reversing the heat flow
into the house in
summer (cooling) season. The advantages of the reversed mode include
elimination of
refrigerated air conditioning, in climates where only moderate cooling is
required. This will
also reduce cooling requirements in hot climates, again saving energy.
References:
Anderlind G. and Johansson B. (1983) "Dynamic Insulation: A Theoritical
Analysis of Thermal Insulation through which a Gas or a Fluid Flows," The
Swedish Council
for Building Research, Stockholm 68 p.
Brown A., lmbabi M., Murphy J., Peacock A. (2008) "The transforming
Technology of the Dynamic Breathing Building", Proceedings, Ecocity World
Summit, San
Francisco, August, 11 p.
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DeProphetis B. (2006) "Roadblocks of Innovation: Commercial Failure of a
Promising Canadian Home Building Technique", M. Mgmt., Lakehead University,
Canada,
174 p.
Forest S. (2004) "How sick is your home? Business Week 9th August, pp. 66-
68.
Goddard L., Guillas and Pang L. (1999) "The Future of Housing Markets in
Canada: with a focus on Thunder Bay," undergraduate report, Lakehead
University, 38 p.
Levon B. (1986) "Experimental Buildings in Scandinavia", The Swedish
Council for Building Research, Stockholm, pp. 158-160.
MacKay V. (1990) "Dynamic Wall Demonstration Project", Innovative Housing
Grants Program, Alberta Municipal Affairs, Edmonton Alberta, 90 p.
McGrew, S. P (2009) ?
Poulin, M. and A.B. Polkki (2008), "The Effect of an Altemate Insulation
Method on Heat Contained in a Building", unpublished report, Winston
Churhchill High
School, December.
Swinton, Brown and Chown (1995) "Controlling the Transfer of Heat, Air and
Moisture through the Building Envelope', in Building Science Insight, IRC-NRC-
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Timusk J. (1987) "Design Construction and Performance of a Dynamic Wall
House", 8th Air Infiltraion Centre Conference, Sept. 24, Uberlingen, FRG, 17
p.
Thoren T. (1982) Dynamic Insulation Controls Flow of Heat Energy,"
Canadian Building, November/December, pp. 45-47.
Walker D. and Poulin B. (2005) "Efficient Housing Business Plan",
unpublished report, Lakehead University, 22 p.
