FIELD
This relates to a system and a method for controlling the temperature in a structure.
BACKGROUND
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. Pat. 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. Pat. 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. Pat. No. 4,250,957, which describes pumping water from an underground reservoir into wall panels.
SUMMARY
There is provided a system for controlling the temperature in a structure. The structure 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.
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.
According to another aspect, the source of temperature-controlled fluid may 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.
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.
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.
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.
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.
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
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:
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
A system for controlling the temperature in a structure, generally identified by reference numeral 10, will now be described with reference to FIGS. 1 through 6.
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.
FIG. 1 shows a cross section of a wall 100 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.
The thermal loss across the inner insulating layer is dependent on the temperature difference (ΔT) 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 ΔT 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.
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 10 ft 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.
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 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.
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 run 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 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.
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.
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.
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.
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 ΔT across the wall in January is about 2° 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 ΔT 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.
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.
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.
Patent Application
20130025824
