Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02747876 2011-07-28
TITLE
[0001] System and method for controlling the temperature in a structure
FIELD
[0002] This relates to a system and a method for controlling the temperature
in a
structure.
BACKGROUND
[0003] The most common method of controlling the temperature in a structure is
to
insulate the building and provide a heat or cooling source inside the
insulative envelope. One
example of this type of structure used for cooling can be found in U.S. patent
no. 6,810,945
(Bissevain) entitled "Conditioning the air in a structure utilizing a gravel
heat exchanger
underneath the slab". Another method of controlling the temperature in a
structure is to
provide an air envelope in the walls of a building, such as is described in
U.S. patent no.
6,293,120 (Hashimoto) entitled "Building air conditioning system using
geothermal energy".
Other examples include U.S. patent application publication no. 2010/0198414
(Kroll et al.)
entitled "Systems and methods for controlling interior climates", which
describes a structural
wall panel that includes an embedded fluid conduit, where the circulated fluid
temperature is
higher than the desired room temperature in order to heat the room, and U.S.
patent no.
4,250,957, which describes pumping water from an underground reservoir into
wall panels.
SUMMARY
[0004] There is provided a system for controlling the temperature in a
structure. The
stricture has exterior walls. At least a portion of at least one exterior wall
comprises a cement
core having a layer of insulation on an interior face and an exterior face of
the cement core,
and at least one fluid conduit embedded in the cement core. A source of
temperature-
controlled fluid is connected to the at least one fluid conduit.
[0005] According to another aspect, there may be more than one fluid conduit
in the at
least one exterior wall. The source of temperature-controlled fluid may
circulate temperature-
controlled fluid separately through each fluid conduit.
[0006] According to another aspect, the source of temperature-controlled fluid
may
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comprise a ground-source energy source, a solar energy source, a combustion
energy source,
and/or a refrigeration source. The source of temperature-controlled fluid may
be maintained
at a temperature between 10 and 15 degrees Celsius, and preferably between 10
and 20
degrees Celsius. The R-value of the layers of insulation may be between 10 and
20, and may
be as low as 6 or 7 and may be higher than 20.
[0007] According to an aspect, there is provided a method of controlling the
temperature
in a structure. The method comprises the steps of: embedding a fluid conduit
in a cement
core of at least one exterior wall, the at least one exterior wall comprising
insulation on an
interior face and an exterior face of the cement core; and circulating
temperature-controlled
fluid through the fluid conduit to maintain the cement core within a
predetermined
temperature range.
[0008] According to another aspect, there may be more than one fluid conduit
embedded
in the cement core, and temperature-controlled fluid may be circulated
separately through
each fluid conduit. A controller may control the temperature in each fluid
conduit.
[0009] According to another aspect, one or more fluid conduits may transfer
heat into a
source of temperature-controlled fluid, and one or more fluid conduits may
transfer heat out
of the source of temperature-controlled fluid.
[0010] According to another aspect, the temperature-controlled fluid may be
circulated
through at least one of a ground-source energy source, a solar energy source,
a combustion
energy source and a refrigeration source.
[0011] According to another aspect, the interior of the structure may be
heated, such as
by a heater, to a target temperature, and the temperature-controlled fluid may
be at a
temperature that is less than the target temperature.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] These and other features will become more apparent from the following
description in which reference is made to the appended drawings, the drawings
are for the
purpose of illustration only and are not intended to be in any way limiting,
wherein:
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FIG. 1 is a side elevation view in section of an insulated cement wall with
thermal
loop.
FIG. 2 is a schematic view of an insulated cement wall connected to a ground
loop.
FIG. 3 is a schematic view of an insulated cement wall with a buffer/storage
loop,
ground loop, solar collector loop and an auxiliary heating loop.
FIG. 4 is a side elevation view in section of a structure using the system.
FIG. 5 is a chart showing the ambient air temperature compared to the ground
temperature at various depths in Slave Lake, Alberta.
FIG. 6 is a chart comparing the ambient air temperature to the ground
temperature
at a depth of 300 cm at in Slave Lake, Alberta.
DETAILED DESCRIPTION
[0013] A system for controlling the temperature in a structure, generally
identified by
reference numeral 10, will now be described with reference to FIG. 1 through
6.
[0014] The discussion below assumes that all the entire exterior walls 100 of
a structure
102 (shown in FIG. 4) are made using the teachings described herein. In most
circumstances,
this will provide the best results. However, it will be understood that the
teachings discussed
herein may also be applied to structures where only some of the exterior
walls, or a portion of
the walls, incorporate the teachings below, depending on the preferences of
the user and
demands of the situation.
[0015] FIG. 1 shows a cross section of a wall100 having a cement core 17
sandwiched
between an inner insulating layer 11 and an outer insulating layer 12. It will
be understood
that the term "cement" is intended to be inclusive of different types of
cement that may be
used for structures known to those skilled in the art, and includes concrete
and other cement
composites. The inner and outer insulating layers 11 and 12 preferably have an
R-value of
between 10 and 20, but may be as low as 6 or 7, and may be higher, depending
on the
preferences of the user and the available resources. A fluid-carrying thermal
loop 20, or fluid
conduit, is embedded in the inner wall cement 17.
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[0016] The thermal loss across the inner insulating layer is dependent on the
temperature
difference (AT) between the interior wall finish 13, such as a sheet of
drywall, and the inner
wall cement 17. Likewise, the thermal loss across the outer insulating layer
is dependent on
the AT between the cement 17 in wall 100 and the outside wall finish 14, such
as siding,
stucco, etc. Controlling the temperature of the cement in wall 100 therefore
allows control of
the heat loss and gain of the building interior.
[0017] FIG. 2 shows a primary thermal loop 20 which moves fluid through the
inner wall
cement 17 by using a variable speed circulating pump 21. As depicted, a
microprocessor
pump controller 25 monitors the temperature of the circulating fluid via a
temperature
transmitter 22. Without any heating or cooling systems attached to the primary
loop, the
temperature of the circulating fluid would be equal to the inner wall
temperature. The inner
wall temperature would vary depending on changes in outside and inside
temperatures due to
the thermal energy transfer across the insulating layers. The pump controller
25 can calculate
the thermal energy gain or loss across both insulating layers based on
readings from the
exterior temperature transmitter 23 which is embedded in the outside wall
finish 14, and the
interior temperature transmitter 24 which is embedded in the interior wall
finish 13. In a
preferred embodiment, a thermal ground loop 26 buried underground allows the
controller 25
to transfer thermal energy to and from an area that is generally warmer than
the ambient
temperature in the winter, and cooler than the ambient temperature in summer.
For example,
when ground loop 26 is buried about 10ft underground, the temperature will be
close to a
constant year-round that is close to the annual average above-ground
temperature for a
particular geographical area. In some geographic areas, the temperature may be
maintained at
a temperature of 10 - 15 degrees Celsius, and more preferably closer to 20
degrees Celsius
when supplemented with other energy sources. Should the inner-wall temperature
fall below
the ground loop temperature, the microprocessor will increase the speed of the
ground loop
variable speed pump 21 in order to raise the temperature of the primary loop
20. If the ground
loop 26 is sized properly, the inner wall temperature will be maintained at or
close to the
temperature of the ground loop 26 even during the coldest times of the year.
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[0018] When the pump controller 25 senses that the exterior wall temperature
23 rises
above the primary loop temperature 22, the circulating pump 21 will stop,
allowing thermal
energy to be absorbed through the outer insulating layer 12 into the inner
cement wall. The
pump 21 may start periodically in order to sense the rise in the inner-wall
temperature. Should
5 the inner-wall temperature rise above the temperature setpoint of the
inside, the circulating
pump will start and maintain the inner-wall temperature at setpoint. Thermal
energy will then
be moved into the ground loop. As depicted, temperature sensor 22 is used to
detect the
temperature of the fluid as it exits primary thermal loop 20. In other
embodiments, there may
be other sensors included or used instead, such as sensors that sense the
temperature of the
wall and communicate this information to the pump controller. Furthermore,
there may be
additional temperature sensors positioned inside or outside the structure that
detect changes in
the temperature to allow pump controller 25 to anticipate temperature changes.
[0019] Referring to FIG. 3, in another embodiment, the system may also include
a solar
collector loop 29 that the pump controller 25 can use to add thermal energy to
the primary
loop 20. If the solar loop 29 is of sufficiently high temperature, it may also
be used to directly
heat interior space as shown in FIG. 3, by using radiant heating lines 16.
There may also be
included a thermal storage loop 35, a storage loop temperature transmitter 37
and a storage
loop variable speed circulating pump 36. This can be used to create a buffer
which will allow
the pump controller 25 to better regulate inner wall temperature due to the
increased thermal
mass in the storage loop 35. The difference between the primary loop
temperature transmitter
22 and the storage loop temperature transmitter 37 allows the controller to
calculate if the
storage loop sinks or sources thermal energy. By adjusting the speed of the
storage loop pump
36, the controller 25 can add or remove thermal energy from the primary loop
20 as required
to control the inner-wall temperature. Finally, a conventional heating or
cooling loop could be
used to raise or lower the inner wall and storage loop temperatures. For
example, a batch
process may be used that is nun manually or automatically as required, such as
a wood
gasification burner that delivers a large amount of energy quickly for storage
in the structure
and thermal storage loop. Other types of conventional heating systems may also
be used,
such as a gas furnace, water boiler, etc. to heat. It will be understood that
some or all of the
loops may be closed systems, and that the heat transfer between loops or
between loops and
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fluid storage tanks may occur using heat exchangers. The fluid may be any
suitable heat-
transfer fluid as will be recognized in the industry, such as glycol, water,
etc. Preferably, the
fluid is selected such that it will not freeze the lines should circulation
cease for a certain
period of time.
[0020] In addition to maintaining the inner-wall temperature, the building 102
may be
heated or cooled using known heating or cooling systems. This may be
particularly useful in
geographic areas with extreme temperatures.
[0021] Referring to FIG. 4, additional thermal loops can be included based on
geographical direction or individual room temperature requirements. For
example, a portion
of the structure 102 that receives more solar energy, such as a south-facing
wall, may be on a
separate loop than a portion that receives less solar energy. In addition, the
temperature in the
walls around a cold room may be kept at a lower temperature than the rest of
the structure.
Other separate loops may include the ceiling and basement floor. This allows
the structure to
be completely enclosed by temperature-controlled thermal mass. The ability of
the system to
absorb solar energy and not transfer it to the inside of the building, but
rather store it for future
use allows the south-facing exterior walls to be painted black in order to
maximize solar
energy absorption. A layer of glazing 18 would improve solar gain even more,
for example,
the roof could potentially be completely glass covered as depicted in FIG. 4.
The solar energy
collected by the solar loop can be used to directly heat the building interior
using traditional
radiant heating loops. The overall energy requirement to heat the interior
space is dramatically
reduced, so solar heating would be feasible even in northern climates. The
majority of thermal
energy loss of the building exterior during the coldest times of the year will
be made up of
free ground loop energy, which also is stored solar energy.
[0022] The pump controller 25 is used to control energy absorption and loss
across either
one of insulating layers 11 and 12 by controlling the temperature of the inner
cement core 17.
The building structure is used to actively store thermal energy from different
sources and
additional storage loops can be added as required.
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[0023] There will now be discussed the effect of the present invention in
colder climates.
Referring to FIG. 5, there is shown the above and below ground average daily
temperatures
in Slave Lake, Alberta. The trends shown in FIG. 6 show that half of the year
the ground
temperature at 300 cm is higher than the ambient average air. As can be seen,
the AT across
the wall in January is about 20 C based on average ambient air temperatures.
However, it is
not uncommon to experience temperatures of -50 C or lower when considering
wind chill.
During those days, the AT across the wall would be 55 C. If, however, the
inner wall
temperature is maintained at 5 C, then the heating requirement of the interior
space is
significantly reduced and constant, regardless of outside temperature. An
inner wall
temperature of 5 C will only be effective if there is insulation on both the
inside and outside
of the wall, as it is not "high grade" heat. In the most basic form as shown
in FIG. 2, the
system can be used to reduce heating requirements during the coldest times of
the year
dramatically. Once solar heating, storage, and other systems are added, inner-
wall
temperatures may be increased to 20 C, such that interior space heating
requirements may be
reduced further or even eliminated.
[0024] In this patent document, the word "comprising" is used in its non-
limiting sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
possibility that more than one of the element is present, unless the context
clearly requires that
there be one and only one of the elements.
[0025] The following claims are to be understood to include what is
specifically illustrated
and described above, what is conceptually equivalent, and what can be
obviously substituted.
The scope of the claims should not be limited by the preferred embodiments set
forth in the
examples, but should be given the broadest interpretation consistent with the
description as a
whole.
