THERMAL ENERGY UNIT FOR QUASI-AUTONOMOUS CLIMATE CONTROL

Abstract

A system includes: a housing; a hot water tank arranged within the housing and configured to store a first volume of water; a cold water tank arranged within the housing and configured to store a second volume of water; an exterior heat exchanger arranged on the housing and defining a set of fluid channels extending vertically along an exterior wall of the housing; and an interior heat exchanger thermally coupled to an interior volume of a building. The system also includes a set of valves configured to: during daytime, route the first volume between the hot water tank and the exterior heat exchanger and route the second volume between the cold water tank and the interior heat exchanger; and, during nighttime, route the first volume between the hot water tank and the interior heat exchanger and route the second volume between the cold water tank and the exterior heat exchanger.

Description

TECHNICAL FIELD

This invention relates generally to the field of heating, ventilation, and air conditioning (or “HVAC”) and, more specifically, to an HVAC thermal energy storage system in the field of HVAC.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic representation of a thermal energy unit;

FIG. 2 is a schematic representation of one variation of the thermal energy unit;

FIG. 3 is a schematic representation of one variation of the thermal energy unit;

FIG. 4A is a flowchart representation of a method;

FIG. 4B is a flowchart representation of one variation of the method;

FIG. 5 is a schematic representation of one variation of the thermal energy unit;

FIG. 6 is a flowchart representation of one variation of the method;

FIG. 7 is a flowchart representation of one variation of the method;

FIG. 8 is a flowchart representation of one variation of the method;

FIG. 9A is a schematic representation of one variation of the thermal energy unit;

FIG. 9B is a schematic representation of one variation of the thermal energy unit; and

FIG. 9C is a schematic representation of one variation of the thermal energy unit.

DESCRIPTION OF THE EMBODIMENTS

The following description of embodiments of the invention is not intended to limit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention. Variations, configurations, implementations, example implementations, and examples described herein are optional and are not exclusive to the variations, configurations, implementations, example implementations, and examples they describe. The invention described herein can include any and all permutations of these variations, configurations, implementations, example implementations, and examples.

1. System

As shown in FIGS. 1-3, 5, and 9A-9C, a thermal energy unit 100 includes: a housing 110; a hot water tank 120 arranged within the housing no and configured to store a first volume of water; a cold water tank 130 arranged within the housing no and configured to store a second volume of water; an exterior heat exchanger 140 arranged on the housing 110 and defining a set of fluid channels extending vertically along an exterior wall of the housing 110; and an interior heat exchanger 150 thermally coupled to an interior volume of a building. For example, the interior volume of the building can include volumes of bedroom(s), kitchen(s), hallway(s), living space(s), and any other room(s) of the building. The thermal energy unit 100 also includes a set of valves 160 configured to: during a daytime period, route the first volume of water between the hot water tank 120 and the exterior heat exchanger 140 and route the second volume of water between the cold water tank 130 and the interior heat exchanger 150; and, during a nighttime period, route the first volume of water between the hot water tank 120 and the interior heat exchanger 150 and route the second volume of water between the cold water tank 130 and the exterior heat exchanger 140.

1.1 Variation: Thermal Energy Unit+Controller+Heat Pump

In one variation, the thermal energy unit 100 includes: a housing 110 positioned on a side (e.g., south-facing side) of a building; a set of sensors 170; and a controller 180.

In this variation, the thermal energy unit 100 also includes: a hot water tank 120 that stores hot water; a cold water tank 130 that stores cold water; a heat pump 190 configured to transfer thermal energy (e.g., heat) from the cold water tank 130 to the hot water tank 120; and an exterior heat exchanger 140 configured to receive hot water from the hot water tank 120 and transfer thermal energy from outdoor environment to the hot water and to receive cold water from the cold water tank 130 and to transfer thermal energy from the cold water to outdoor environment. The thermal energy unit 100 also includes (or couples to) an interior heat exchanger 150: coupled to a heating, ventilation, and air conditioning system in the building; configured to receive hot water from the hot water tank 120 and transfer thermal energy from the hot water to air circulated within the building; and configured to receive cold water from the cold water tank 130 and transfer thermal energy from air circulated within the building into the cold water. The thermal energy unit 100 also includes a set of valves 160 configured to selectively: fluidly couple the hot water tank 120 to the exterior heat exchanger 140 during a daytime period to heat water in the hot water tank 120; fluidly couple the hot water tank 120 to the heat exchanger during a daytime period to transfer heat from the hot water tank 120 into the building; fluidly couple the cold water tank 130 to the exterior heat exchanger 140 during a nighttime period to cool water in the hot water tank 120; and fluidly couple the cold water tank 130 to the heat exchanger during the daytime period to transfer heat from the building into the cold water tank 130.

In this variation, the set of sensors 170 are configured to output signals corresponding to: temperatures of water in the hot water tank 120; temperatures of water in the cold water tank 130; temperature gradient across the exterior heat exchanger 140; ambient temperature (e.g., outdoor air temperature, surface temperature of the exterior heat exchanger 140); interior air (or floor) temperature; interior air humidity, outdoor air humidity; interior/outdoor carbon dioxide levels; and/or atmospheric irradiance; etc.

In this variation, the controller 180 is configured to: monitor temperatures within the thermal energy unit 100 and/or temperatures within the building based on signals received from the set of sensors 170; access a target indoor temperature set for the building (e.g., via a thermostat in the building); and set states of the set of valves 160 based on temperatures within the thermal energy unit 100, temperatures within the building, and the target indoor temperature.

In this variation, the thermal energy unit 100 further includes a photovoltaic solar panel 195: arranged on the thermal energy unit 100; and configured to power the heat pump 190 (e.g., via a battery) to transfer thermal energy from the cold water tank 130 to the hot water tank 120.

In this variation, the thermal energy unit 100 further includes: a fluid pump configured to actively pump water through the thermal energy unit 100; and/or a photovoltaic solar panel 195 configured to power the fluid pump.

2. Method

As shown in FIGS. 4A-4B and 6-8, a method S100 includes, at a first time during a daytime period: accessing a first hot tank temperature of a first volume of water occupying a hot water tank 120 in Block S102; accessing a first heat exchanger temperature of an exterior heat exchanger 140 in Block S104; and, in response to the first heat exchanger temperature exceeding the first hot tank temperature, triggering a set of valves 160 to route the first volume of water between the hot water tank 120 and the exterior heat exchanger 140 in Block Silo. The method S100 also includes, at a second time during the daytime period, triggering the set of valves 160 to route a second volume of water between a cold water tank 130 and an interior heat exchanger 150 thermally coupled to an interior volume of a building in Block S130. The method S100 also includes, at a third time during a nighttime period: triggering the set of valves 160 to route the first volume of water between the hot water tank 120 and the interior heat exchanger 150 in Block S170. The method S100 also includes, at a fourth time during the nighttime period: accessing a second cold tank temperature of the second volume of water in the cold water tank 130 in Block S142; accessing a second heat exchanger temperature of the exterior heat exchanger 140 in Block S144; and, in response to the second cold tank temperature exceeding the second heat exchanger temperature, triggering the set of valves 160 to route the second volume of water between the cold water tank 130 and the exterior heat exchanger 140 in Block S150.

2.1 Variation: 24-Hour Interior Cooling Cycle

In one variation, the method S100 includes, at a first time during a nighttime period: accessing a first cold tank temperature of a first volume of water in a cold water tank 130 in Block S142; accessing a first heat exchanger temperature of an exterior heat exchanger 140 in Block S144; and, in response to the first cold tank temperature exceeding the first heat exchanger temperature, triggering a set of valves 160 to route the first volume of water between the cold water tank 130 and the exterior heat exchanger 140 in Block S150. The method S100 also includes, at a second time succeeding the first time: accessing a second cold tank temperature of the first volume of water in the cold water tank 130 in Block S152; accessing a second heat exchanger temperature of the exterior heat exchanger 140 in Block 154; and, in response to the second heat exchanger temperature exceeding the second cold tank temperature, triggering the set of valves 160 to disable flow of the first volume of water between the cold water tank 130 and the exterior heat exchanger 140 in Block S160. The method S100 further includes, at a third time during a daytime period: accessing a first signal representing a first request to cool an interior volume of a building in Block S122; and, in response to receiving the first request, triggering the set of valves 160 to route the first volume of water between the cold water tank 130 and an interior heat exchanger 150 thermally coupled to the interior volume of the building in Block S130. The method S100 further includes, at a fourth time succeeding the third time: accessing a second signal representing a second request to maintain a current temperature of the interior volume of the building in Block S32; and, in response to receiving the second request, triggering the set of valves 160 to disable flow of the first volume of water from the cold water tank 130 to the interior heat exchanger 150 in Block S140.

2.3 Variation: 24-Hour Cooling and Heating Cycle

In one variation, the method S100 includes, during a daytime period: in response to a hot tank temperature falling below a heat exchanger temperature of an exterior heat exchanger 140 in a thermal energy unit 100, triggering a first set of valves 160 connecting the hot water tank 120 and the exterior heat exchanger 140 to open in Block Silo; and, in response to the hot tank temperature exceeding the heat exchanger temperature of the exterior heat exchanger 140, triggering the first set of valves 160 connecting the hot water tank 120 and the exterior heat exchanger 140 to close in Block S120.

The method S100 also includes, during the daytime period: in response to a cold tank temperature falling below a target indoor temperature, and in response to a current building temperature exceeding the target indoor temperature, triggering a second set of valves 160 connecting the cold water tank 130 and an interior heat exchanger 150 in the building to open in Block S130; in response to the cold tank temperature exceeding the target indoor temperature, triggering the second set of valves 160 connecting the cold water tank 130 and the interior heat exchanger 150 to close; and, in response to the current building temperature falling below the target indoor temperature, triggering the second set of valves 160 connecting the cold water tank 130 and the interior heat exchanger 150 to close in Block S140.

The method S100 further includes, during a nighttime period (e.g., thermal energy dissipation period): in response to the cold tank temperature exceeding a heat exchanger temperature of the exterior heat exchanger 140, triggering a third set of valves 160 connecting the cold water tank 130 and the exterior heat exchanger 140 to open in Block S150; and, in response to the cold tank temperature falling below the heat exchanger temperature of the exterior heat exchanger 140, triggering the third set of valves 160 connecting the cold water tank 130 and the exterior heat exchanger 140 to close in Block S160.

The method S100 also includes, during the nighttime period: in response to the hot tank temperature exceeding a target indoor temperature, and in response to the current building temperature falling below the target indoor temperature, triggering a fourth set of valves 160 connecting the hot water tank 120 and the interior heat exchanger 150 in the building to open in Block S170; in response to the hot tank temperature falling below the target indoor temperature, triggering the fourth set of valves 160 connecting the hot water tank 120 and the interior heat exchanger 150 to close; and, in response to the current building temperature exceeding the target indoor temperature, triggering the fourth set of valves 160 connecting the hot water tank 120 and the interior heat exchanger 150 to close in Block S180.

2.4 Variation: Maximum Temperature-Based Exterior Heating and Cooling

In one variation, the method S100 includes, at a first time during the daytime period: accessing a heat exchanger temperature of an exterior heat exchanger 140 in Block S104 and a first hot water temperature in the hot water tank 120 in a thermal energy unit 100 in Block S102; transforming the heat exchanger temperature to maximum hot water temperature of the water in the hot water tank 120 in Block S106; and, in response to the maximum hot water temperature exceeding the hot tank temperature, triggering the first set of valves 160 connecting the hot water tank 120 and the exterior heat exchanger 140 to open in Block 110. At a second time during the daytime period, the method also includes: accessing a second hot water temperature in the hot water tank 120 in Block S102; and, in response to the maximum hot water temperature exceeding the second hot water temperature in the hot water tank 120 by less than a threshold difference, trigger the first set of valves 160 connecting the hot water tank 120 and the exterior heat exchanger 140 to close in Block S120.

The method S100 also includes, at a first time during the nighttime period: accessing a heat exchanger temperature of an exterior heat exchanger 140 in Block S144 and a first cold water temperature in the cold water tank 130 in a thermal energy unit 100 in Block S142; transforming the heat exchanger temperature to minimum cold water temperature of the water in the cold water tank 130; in response to the first cold water temperature in the cold water tank 130 exceeding the minimum cold water temperature, triggering the second set of valves 160 connecting the cold water tank 130 and the exterior heat exchanger 140 to open in Block S150. At a second time during the nighttime period: accessing a second cold water temperature in the cold water tank 130 in Block S142; and, in response to the second cold water temperature in the cold water tank 130 exceeding the minimum cold water temperature by less than a threshold difference, trigger the second set of valves 160 connecting the cold water tank 130 and the exterior heat exchanger 140 to close in Block S160.

2.3 Variation: Threshold-Based Thermal Storage Regulation

In one variation, the method S100 includes, at a first time during the daytime period: accessing a first hot water temperature in the hot water tank 120 in a thermal energy unit 100 in Block S102; and triggering the first set of valves 160 connecting the hot water tank 120 and the exterior heat exchanger 140 to open in Block Silo. At a second time during the daytime period: accessing a second hot water temperature in the hot water tank 120 in Block S102; and, in response to the second hot water temperature exceeding the first hot water temperature by more than a threshold difference, maintaining the first set of valves 160 connecting the hot water tank 120 and the exterior heat exchanger 140 in an open state in Block Silo. At a third time during the daytime period: accessing a third hot water temperature in the hot water tank 120 in a thermal energy unit 100 in Block S102; and, in response to the third hot water temperature exceeding the second hot water temperature by less than the threshold difference, triggering the first set of valves 160 connecting the hot water tank 120 and the exterior heat exchanger 140 to close in Block S120.

The method also includes, at a first time during the nighttime period: accessing a first cold water temperature in the cold water tank 130 in a thermal energy unit 100 in Block S142; and triggering the first set of valves 160 connecting the cold water tank 130 and the exterior heat exchanger 140 to open in Block S150. At a second time during the nighttime period, the method also includes: accessing a second cold water temperature in the cold water tank 130 in Block S142; and, in response to the first cold water temperature exceeding the second cold water temperature by over a threshold difference, maintaining the first set of valves 160 connecting the cold water tank 130 and the exterior heat exchanger 140 in an open state in Block S150. At a third time during the nighttime period, the method also includes: accessing a third cold water temperature in the cold water tank 130 in Block S142; and, in response to the second cold water temperature exceeding the third cold water temperature by less than the threshold difference, triggering the second set of valves 160 connecting the cold water tank 130 and the exterior heat exchanger 140 to close in Block S160.

2.4 Variation: Thermal Energy Transfer Between Thermal Storage Tanks

One variation of the method further includes: charging an electrical battery 197 in the thermal energy unit 100 via a photovoltaic solar panel 195 in Block S190; and, in response to a temperature difference between water in the hot water tank 120 and water in the cold water tank 130 falling below a threshold difference, supplying energy from the electrical battery 197 to a heat pump 190 to transfer thermal energy from the cold water tank 130 to the hot water tank 120 in Block S192. One variation of the method further includes: in response to a temperature decrease in the hot water tank 120 exceeding a threshold temperature change, activating a heat pump 190 to transfer thermal energy from the cold water tank 130, the interior volume of the building, or the outdoor environment into the hot tank in Block S194; and, in response to a temperature increase in the cold water tank 130 exceeding a threshold temperature change, activating the heat pump 190 at to transfer thermal energy from the cold water tank 130 to the hot water tank 120, the interior volume of the building, or the outdoor environment in Block S196.

3. Applications

Generally, the thermal energy unit 100 defines an indoor climate regulation system configured: to collect and store thermal radiation and ambient heat in a hot water tank 120 (e.g., hot-side thermal energy storage) during daytime periods and/or periods in which the outdoor ambient temperature exceeds the temperature of water in the hot water tank 120 by more than a threshold temperature difference; and to circulate hot water from the hot water tank 120 into a building—such as via a radiant floor heating circuit, a wall radiator, or an interior heat exchanger 150 coupled to a forced-air heating, ventilation, and air conditioning (herein also referred to as “HVAC”) system within the building—to heat the interior of the building during nighttime periods and/or periods in which an indoor temperature in the building is less than a set target indoor temperature for the building and less than the temperature of water in the hot water tank 120.

The thermal energy unit 100 further: radiates thermal energy from water stored in a cold water tank 130 (e.g., cold-side thermal energy storage) into the outdoor environment during nighttime periods and/or periods in which the outdoor ambient temperature exceeds the temperature of water in the cold water tank 130 by more than a threshold temperature difference; and circulates cold water from the cold water tank 130 into the building to cool (i.e., decrease the temperature of) the interior of the building during daytime periods and/or periods in which the indoor temperature in the building is greater than the target indoor temperature set for the building and greater than the temperature of water in the cold water tank 130.

More specifically, the thermal energy unit 100 includes: a housing 110 configured to be installed on an exterior of a building; a set of sensors 170; and a controller 180. The thermal energy unit 100 includes: an exterior heat exchanger 140 defining a vertical array of fluid channels and forming an exterior wall and/or roof surface of the housing 110; a hot water tank 120 arranged behind the exterior heat exchanger 140; a cold water tank 130 arranged behind the exterior heat exchanger 140; a water supply configured to couple to an inlet of an interior heat exchanger 150 arranged in the building; and a water return configured to couple to an outlet of the interior heat exchanger 150. The thermal energy unit 100 also includes a set of valves 160 operable in a set of valve configurations: to selectively fluidly couple the hot water tank 120 or the cold water tank 130 (or neither) to the exterior heat exchanger 140; and to selectively fluidly couple the hot water tank 120 or the cold water tank 130 (or neither) to the interior heat exchanger 150.

The controller 180 is configured to transition the valves between these valve configurations based on hot tank temperatures and cold tank temperatures, indoor temperatures, exterior heat exchanger temperatures (or ambient temperatures, surface temperatures), and target indoor temperatures in order to: passively redistribute thermal energy between the interior of the building and the thermal energy unit 100; reduce temperature differences between actual and target indoor temperatures; and thus replace or reduce thermal load on active HVAC systems within the building.

In particular, the thermal energy unit 100 can enable a passive flow of hot water from a bottom of the hot water tank 120, up the exterior heat exchanger 140, and back into the hot water tank 120. To enable the passive flow of hot water through the exterior heat exchanger 140 during daytime periods, the exterior heat exchanger 140 can absorb solar radiation and ambient heat during daytime periods and conduct thermal energy into water in vertical fluid channels, which creates a thermal gradient that induces passive upward flow of water. In addition, the thermal energy unit 100 can enable passive flow from a top of the cold water tank 130, down the exterior heat exchanger 140, and back into the cold water tank 130. In particular, the exterior heat exchanger 140 can include black surfaces that radiate black body radiation that radiate thermal energy from water in the fluid channels into the outdoor environment and into the atmosphere (i.e., night sky radiant cooling), thereby creating a thermal gradient that induces passive downward flow.

During daytime periods, the thermal energy unit 100 can increase the temperature of the hot water by circulating the hot water through the exterior heat exchanger 140 by opening the set of valves 160 connecting the hot water tank 120 to the exterior heat exchanger 140. The thermal energy unit 100 can further, during nighttime periods, decrease the temperature of the cold water by circulating the cold water through the exterior heat exchanger 140. Therefore, the thermal energy unit 100 can heat the water in the hot water tank 120 and cool the water in the cold water tank 130 without drawing electricity from the electrical grid. Further, the thermal energy unit 100 can heat and cool the interior air in the building without drawing electricity from the electrical grid.

For example, the thermal energy unit 100 can: access a target indoor temperature of the building; and access a current indoor temperature of the building. Then, in response to the target indoor temperature exceeding the current indoor temperature, the thermal energy unit 100 can: trigger valves connecting the hot water tank 120 to the interior heat exchanger 150 to open; activate a pump connected to the interior heat exchanger 150 to circulate water between the hot water tank 120 and the interior heat exchanger 150; and/or activate a blower (e.g., fan) to circulate air within the building through the interior heat exchanger 150, thereby heating this air.

Conversely, in response to the current indoor temperature exceeding the target indoor temperature, the thermal energy unit 100 can: trigger valves connecting the cold water tank 130 to the interior heat exchanger 150 to open; activate the pump connected to the interior heat exchanger 150 to circulate water between the cold water tank 130 and the interior heat exchanger 150; and/or activate a blower (e.g., fan) to circulate air within the building through the interior heat exchanger 150, thereby cooling this air. Thus, the thermal energy unit 100 can selectively distribute hot water and cold water from thermal batteries in the thermal energy unit 100 into the building to reduce temperature differences between actual and target indoor temperatures within the building with no or limited electrical energy consumption.

In one implementation, the thermal energy unit 100 functions as a passive thermal energy storage unit that augments daytime cooling and nighttime heating of a HVAC system in the building, thereby reducing electrical energy and/or gas consumed by the HVAC system to maintain indoor temperatures within the building. For example, the thermal energy unit 100 can: pump hot water from the hot water tank 120 into an interior heat exchanger 150 in the building to pre-heat interior air entering the HVAC system during nighttime periods; and pump cold water from the cold water tank 130 into the interior heat exchanger to pre-cool interior air entering the HVAC system during daytime periods.

Generally, the thermal energy unit 100 can function as a “thermal capacitor” within a climate-regulation system of a building. More specifically, the thermal energy unit 100 can be: “charged” by absorbing thermal energy from the outdoor environment and storing the thermal energy in the hot water tank 120 or by releasing thermal energy from the cold water tank 130 into the outdoor environment to temporarily create a thermal gradient (e.g., difference in thermal energy concentration, temperature) between the cold water tank 130 and the hot water tank 120; and “discharged” by releasing thermal energy from the hot water tank 120 into the indoor environment or by absorbing the thermal energy from the indoor environment and storing the thermal energy in the cold water tank 130. For example, by absorbing thermal energy from the outdoor environment or releasing the thermal energy into the outdoor environment, the thermal energy unit 100 can create a thermal energy source in the hot water tank 120 and a thermal energy sink in the cold water tank 130, thereby “charging” the thermal energy unit 100, over time durations ranging from several hours to several days. The thermal energy unit 100 can then “discharge” thermal energy by releasing thermal energy on-demand, such as in response to an indoor temperature within the building exceeding or falling below a target interior temperature. For example, the thermal energy unit 100 can release thermal energy from the hot water tank 120 into the indoor environment to heat the indoor environment or absorb the thermal energy from the indoor environment into the cold water tank 130 to cool the indoor environment.

Generally, the thermal energy unit 100 is described herein as passively storing “hot” and “cold” water in water tanks and passively transferring heat between water in these water tanks, the indoor environment, and the outdoor environment to maintain a target indoor temperature inside a building. However, the thermal energy unit 100 additionally or alternatively operates semi-passively, such as by drawing energy from an electrical grid to operate a heat pump 190 to transfer thermal energy between the indoor environment or the outdoor environment, the hot water tank 120, and/or the cold water tank 130.

Herein, “daytime” is an example of a time period during which the outdoor environment is expected to be hot and/or sunny, which is conducive to heating of the water via the exterior heat exchanger 140. However, the thermal energy unit 100 is not limited to heating the water during the daytime period. Similarly, “nighttime” is an example of a time period during which the outdoor environment is expected to be cool, which is conducive to cooling of the water via the exterior heat exchanger 140. However, the thermal energy unit 100 is not limited to cooling the water during the nighttime. Furthermore, while the charging of the electrical battery 197 is expected to occur during the daytime period when sunlight is available, electrical energy can be supplied to the heat pump 190 via the electrical battery 197 anytime prior to the next charging of the electrical battery 197. For example, the thermal energy unit 100 can activate the heat pump 190 during the nighttime period.

4. Thermal Energy Unit

Generally, the thermal energy unit 100 includes: a housing 110; a hot water tank 120 arranged within the housing no and configured to store a first volume of water; a cold water tank 130 arranged within the housing 110 and configured to store a second volume of water; an exterior heat exchanger 140 arranged on the housing 110 and defining a set of fluid channels extending vertically along an exterior wall of the housing 110; and an interior heat exchanger thermally coupled to an interior volume of a building. The thermal energy unit 100 also includes a set of valves 160 configured to selectively route the first volume of water between the hot water tank 120 and the exterior heat exchanger 140 and route the second volume of water between the cold water tank 130 and the interior heat exchanger during a daytime period. The set of valves 160 can also route the first volume of water between the hot water tank 120 and the interior heat exchanger and route the second volume of water between the cold water tank 130 and the exterior heat exchanger 140 during a nighttime period.

4.1 Building Integration of Thermal Energy Unit

The thermal energy unit 100 can include: the hot water tank 120, the cold water tank 130, the heat pump 190, the interior heat exchanger, the exterior heat exchanger 140, and a photovoltaic solar panel 195 positioned on the top surface and/or the side surface of the thermal energy unit 100. The thermal energy unit 100 can be configured to connect to the HVAC system of the building to supply heating and/or cooling of the interior air of the building. Furthermore, the thermal energy unit 100 can be deployed alongside additional thermal energy units 100. For example, the several thermal energy units 100 can be stacked one on top of another to supply heating and/or cooling for a multi-story building, effectively becoming an operative element of the facade, or several thermal energy units 100 can be arranged in a row to supply heating and/or cooling for a large building such as a warehouse. Further, in a thermal energy unit 100 that includes several thermal energy units 100 that are working together to heat or cool the building, one thermal energy unit 100 can be replaced or removed without replacement or removal of the other thermal energy units 100.

In one implementation, one or multiple thermal energy units 100 can be configured for integration into a building, such as a single-family residential building, a multi-family residential building, a single-floor commercial building, and/or a multi-floor commercial building. In one example: one thermal energy unit 100 can be installed on a single-family home; four thermal energy units 100 can be installed on a multi-family building; ten thermal energy units 100 can be installed on a single-floor commercial building; and 100 thermal energy units 100 can be stacked in pairs on a fifty-story building. In one example, a set of thermal energy units 100 can be configured for integration into a building including a set of climate zones. In this example, each thermal energy unit 100, in the set of thermal energy units 100, can correspond to and affect the interior temperature within a climate zone in the set of climate zones.

Furthermore, a thermal energy unit 100 can be configured with select components based on local weather conditions. For example, a first thermal energy unit 100—installed in a first geographic location characterized by an abundance of daytime sunlight—can include a photovoltaic solar panel 195 that supplies electricity to an electrical battery 197, which powers a heat pump 190 configured to transfer thermal energy from the cold water tank 130 to the hot water tank 120. In this example, a second thermal energy unit 100—installed in a second geographic location characterized by reduced amounts of daytime sunlight—can exclude the photovoltaic solar panel 195 and instead include a wired connection to the electrical grid that can supply electricity to the heat pump 190. In another example, a first thermal energy unit 100—installed in a first geographic location characterized by low ambient temperatures—can include a single hot water tank 120 and no cold water tank 130.

In addition, the first thermal energy unit 100 can include heat pump 190 powered by a photovoltaic solar panel 195 and configured to transfer thermal energy from the outdoor environment to the hot water tank 120. In the first geographic location, temperature of the air inside a building can be low (due to low temperature of the outdoor environment). Therefore, the first thermal energy unit 100 with a single hot water tank 120 can be configured to heat the air inside building. However, in a geographic location where the temperature of the outdoor environment fluctuates between hot and cold, a thermal energy unit 100 can be configured to both heat and cool the air inside a building. In particular, a second thermal energy unit 100—installed in a second geographic location characterized by high daytime temperatures and low nighttime temperatures—can include both a hot water tank 120 and a cold water tank 130. In this example, the hot water tank 120 of the first thermal energy unit 100 can define twice the volume of the hot water tank 120 of the second thermal energy unit 100. Therefore, the first thermal energy unit 100 can heat the air inside the building for a longer time duration and/or produce a larger temperature increase of the indoor air than the second thermal energy unit 100. a third thermal energy unit 100—installed in a third geographic location characterized by hot ambient temperatures—can include a single cold water tank 130 configured to supply cold water for cooling of air inside a building, a heat pump 190 configured to transfer thermal energy from the cold water tank 130 (e.g., to the outdoor environment), and no hot water tank 120. And a fourth thermal energy unit 100—installed in a fourth geographic location characterized by seasonal fluctuations in temperature (e.g., hot summers and cold winters)—can include two water tanks that can both store hot water in winter and cold water in summer.

4.2 Hot Water Tank

The hot water tank 120 can act as a high thermal energy reservoir by storing hot water. The hot water tank 120 can store hot water with temperature higher than room temperature and lower than the boiling point temperature of water. When the temperature of the outdoor environment is high (e.g., when it is hot, sunny, dry outside), the hot water tank 120 can supply the hot water to the exterior heat exchanger 140 for heating. In addition, the hot water tank 120 can receive thermal energy from the heat pump 190 and supply hot water to the interior heat exchanger in the building to heat the interior of the building. In one variation, the hot water tank 120 also supplies hot water to an interior heat exchanger 150 fluidly coupled to a domestic hot water supply, such as to augment or replace a hot water boiler in the building.

4.3 Cold Water Tank

The cold water tank 130 can act as a low thermal energy reservoir by storing cold water. For example, the cold water tank 130 can store water with temperature above the freezing temperature of water and below the room temperature. When the temperature of the outdoor environment is low (e.g., it is cold, windy, raining outside), the cold water tank 130 can supply the cold water to the exterior heat exchanger 140 for cooling. In addition, the cold water tank 130 can supply thermal energy to the heat pump 190, and supply the cold water to the interior heat exchanger 150 to cool the interior air of the building.

4.4 Heat Pump

The heat pump 190 can be configured to transfer thermal energy (e.g., heat) from the cold water in the cold water tank 130 to the hot water in the hot water tank 120. The heat pump 190 can include a compressor, an expansion valve, a condenser that exchanges thermal energy with the hot water tank 120, and an evaporator that exchanges thermal energy with the cold water tank 130. The heat pump 190 can also include natural refrigerant, such as propane, that cycles through the heat pump 190. In one implementation, the compressor of the heat pump 190 can be powered by an electrical battery 197, which is charged by a photovoltaic solar panel 195. Therefore, the heat pump 190 may operate during daytime when the sky is overcast or during nighttime, powered by electricity supplied to the electrical battery 197.

In one implementation, the thermal energy unit 100 includes: a heat pump 190 configured to transfer thermal energy from the cold water tank 130 to the hot water tank 120; and a photovoltaic solar panel 195 arranged on the housing 110 of the thermal energy unit 100 and configured to supply electrical energy to the heat pump 190. Therefore, during the daytime period, the photovoltaic solar panel 195 can directly supply electrical energy to the heat pump 190 to power the heat pump 190. In an alternative implementation, the photovoltaic solar panel 195 can charge an electrical battery 197 during the daytime period. Then, the controller 180 can supply the electrical energy from the electrical battery 197 to the heat pump 190 to power the heat pump at any time. For example, the controller 180 can supply the electrical energy from the electrical battery 197 to the heat pump 190 during the nighttime, when there is no solar irradiance.

In one implementation, the controller 180 selectively supplies electrical energy from an electrical grid or from the electrical battery 197—such as arranged within the housing no and charged by a photovoltaic solar panel 195 arranged on a wall or roof surface of the housing 100—to the heat pump 190 to transfer thermal energy: between the cold water tank 130 to the hot water tank 120; between the hot water tank 120 and the outdoor heat exchanger; between the hot water tank 120 and the indoor heat exchanger; between the cold water tank 130 and the outdoor heat exchanger; and/or between the cold water tank 130 and the indoor heat exchanger.

Generally, the controller 180 can activate the heat pump 190 to transfer thermal energy to/from the cold water tank 130 and/or the hot water tank 120 in order to increase a thermal capacity of the thermal energy unit 100. In addition, the controller 180 can supply electrical energy from the electrical grid to power the heat pump 190 during periods of low electricity demand, such as during the nighttime, to reduce the load on the electrical grid.

4.5 Exterior Heat Exchanger

The exterior heat exchanger 140 can be configured to heat the water passing through the exterior heat exchanger 140 by transferring thermal energy from the outdoor environment to the water when the thermal energy in the outdoor environment is abundant (e.g., it is hot, sunny outside). Generally, this may occur during daytime when high amounts of thermal energy are imparted to the exterior heat exchanger 140 from the sunlight. The exterior heat exchanger 140 can also be configured to cool the water passing through the exterior heat exchanger 140 by transferring the thermal energy from the water to the outdoor environment when the thermal energy in the outdoor environment is scarce (e.g., it is cold outside). Generally, this may occur during nighttime when the exterior heat exchanger 140 may radiate thermal energy out into the outdoor environment. In one implementation, the exterior heat exchanger 140 can be reversible such that it may alternate between heating hot water and cooling cold water. In an alternative implementation, the thermal energy unit 100 may include one exterior heat exchanger 140 for heating of water, and another solar “collector”/emitter for cooling of water.

In one implementation, the exterior heat exchanger 140 can include a solar collector configured to: accumulate thermal energy from sunlight during the daytime period; and radiate thermal energy into the outdoor environment during the nighttime period. The solar collector can also include an array of channels: fluidly coupled to the hot water tank 120 and the cold water tank 130; and configured to exchange thermal energy with the exterior heat exchanger 140.

More specifically, the exterior heat exchanger 140 can include an array of channels positioned between a transparent plate and an absorptive surface that can trap or emit thermal energy. During heating or cooling, the water enters the exterior heat exchanger 140 through an inlet/pipe and is distributed via a manifold to the array of channels. As the water passes through the channels, it gains or loses thermal energy depending on the environmental conditions. Then, the water passes into a second manifold and exits through a pipe. In one implementation, the channels of the exterior heat exchanger 140 can define a radius that facilitates thermodynamic movement of the water through the channels. Generally, hot water, which is less dense, rises to the top of a tank and cold water, which is more dense, falls to the bottom of the tank. The channels can act as a siphon by allowing water that is heated to rise through the channels (e.g., from the bottom of the hot water tank 120 or cold water tank 130 to the top) and the water that is cooled to fall through the channels (e.g., from the top of the hot water tank 120 or cold water tank 130 to the bottom). During heating of the hot water: the channels can facilitate the movement of hot water from the bottom of the hot water tank 120 into the exterior heat exchanger 140 (e.g., where the hot water is heated) and the movement of hot water from the exterior heat exchanger 140 to the top of the hot water tank 120. During cooling of the cold water: the channels can facilitate the movement of cold water from the top of the cold water tank 130 into the exterior heat exchanger 140 (e.g., where the cold where it is cooled) and the movement of the cooled cold water from the exterior heat exchanger 140 to the bottom of the cold water tank 130.

In one implementation, the exterior heat exchanger 140 can be positioned on the surface of the thermal energy unit 100 and angled (e.g., with respect to the horizontal) to increase thermal energy absorption during the daytime and thermal energy emission during the nighttime. For example, one portion of the exterior heat exchanger 140 can be arranged on the south-facing side of the thermal energy unit 100 at a go-degree angle to the horizon, while another portion of the exterior heat exchanger 140 can be arranged on the top of the thermal energy unit 100 at a 10 degree angle to the horizon. The portion of the exterior heat exchanger 140 at the top surface of the thermal energy unit 100 can increase the dissipation of the thermal energy at nighttime and the portion of the exterior heat exchanger 140 at the south-facing side can increase the absorption of the thermal energy during the daytime.

In one implementation, the exterior heat exchanger 140 can include a photovoltaic surface and/or photovoltaic cells (i.e., photovoltaic-thermal collector). In this implementation, the exterior heat exchanger 140 can simultaneously convert light into electricity and transfer thermal energy to or from water.

4.6 Interior Heat Exchanger

The interior heat exchanger 150 can transfer thermal energy from hot water to interior air in order to heat the building or transfer thermal energy from interior air to cold water in order to cool the building. In one implementation, the interior heat exchanger 150 can include a shell filled with a first fluid (e.g., water) and a ribbed tube or a series of channels inside the shell through which a second fluid (e.g., interior air) can pass. In one implementation, the interior heat exchanger 150 can facilitate exchange of thermal energy between the water and another fluid such as oil, which is circulated through piping and radiators throughout the building. In one implementation, the interior heat exchanger 150 can include channels of water in the floor of the building that heat or cool the floor of the building. In one implementation, the interior heat exchanger 150 may work together with an HVAC system of the building to control the interior air temperature. In this case, the interior heat exchanger 150 can adjust the temperature of the interior air prior to heating or cooling by the HVAC system. For example, the interior heat exchanger 150 can pre-heat or pre-cool the interior air before the interior air is heated or cooled by the HVAC system.

In one example, the interior heat exchanger 150 can include a set of channels configured to: receive the first volume of water from the hot water tank 120 or the second volume of water from the second water tank; and exchange thermal energy with air circulated within the building by the air handling unit (e.g., HVAC system). In this implementation, the interior heat exchanger 150 can also include a fan configured to circulate air within the building proximal the set of channels to facilitate the thermal energy exchange.

Generally, the interior heat exchanger 150 includes thermal distribution elements, such as radiators, floor heating panels, and forced air HVAC systems, configured to heat, or cool the interior volume of the building. In one implementation, the interior heat exchanger 150 can include a radiator (e.g., convective radiator, radiant heater) arranged within the building. In another implementation, the interior heat exchanger 150 is arranged within a forced air HVAC system located within the building. Additionally, or alternatively, the interior heat exchanger 150 can also include floor heating, ceiling heating, or wall heating. Therefore, the interior heat exchanger 150 can be arranged within the building, can be arranged within the walls, ceiling, or floors of the buildings, or can be fluidly coupled to a forced air HVAC system of the building.

4.7 Valves

The thermal energy unit 100 can include a set of valves 160 that regulate the flow of water between the hot water tank 120, the cold water tank 130, the interior heat exchanger 150, and the exterior heat exchanger 140. In one implementation, the thermal energy unit 100 can include four tri-state (e.g., three-way) valves: an upper cold water valve, a lower cold water valve, an upper hot water valve, and a lower hot water valve. In one implementation, the thermal energy unit 100 can be configured to regulate the flow of water between its various components (e.g., hot water tank 120, cold water tank 130, interior heat exchanger 150, exterior heat exchanger 140) via manifolds.

In one implementation, the set of valves 160 includes a first valve (e.g., tri-state valve) arranged proximal a top of the hot water tank 120 and operable: in a first state, to route the first volume of water from the first top of the hot water tank 120 to the interior heat exchanger 150; and, in a second state, to route the first volume of water from the exterior heat exchanger 140 to the first top of the hot water tank 120. The set of valves 160 also includes a second valve arranged proximal a bottom of the hot water tank 120 and operable: in a first state, to route the first volume of water from the first bottom of the hot water tank 120 to the exterior heat exchanger 140; and, in a second state, to route the first volume of water from the interior heat exchanger 150 to the first bottom of the hot water tank 120. The set of valves 160 also includes a third valve arranged proximal a second top of the cold water tank 130 and operable: in a first state, to route the second volume of water from the second top of the cold water tank 130 to the exterior heat exchanger 140; and, in a second state, to route the second volume of water from the interior heat exchanger 150 to the second top of the cold water tank 130. The set of valves 160 also includes a fourth valve arranged proximal a second bottom of the cold water tank 130 and operable: in a first state, to route the second volume of water from the second bottom of the cold water tank 130 to the interior heat exchanger 150; and, in an eighth state to route the second volume of water from the exterior heat exchanger 140 to the second bottom of the cold water tank 130.

In one example, the set of valves include: electromechanical solenoid valves; rotary valves; ball valves; check valves; gate valves; stop valves; butterfly valves; etc.

4.7.1 Upper Cold Water Valve

The upper cold water valve can regulate the flow of water between the top of the cold water tank 130 and the exterior heat exchanger 140 and between the top of the cold water tank 130 and the interior heat exchanger 150. In a first state, the upper cold water valve can allow the cold water to flow from the top of the cold water tank 130 to the exterior heat exchanger 140. In a second state, the upper cold water valve can allow the cold water to flow from the interior heat exchanger 150 to the top of the cold water tank 130. In a third state, the upper cold water valve can block the water from flowing between the top of the cold water tank 130 and the exterior heat exchanger 140 and between the top of the cold water tank 130 and the interior heat exchanger 150.

4.7.2 Lower Cold Water Valve

The lower cold water valve can regulate the flow of water between the bottom of the cold water tank 130 and the exterior heat exchanger 140 and between the bottom of the cold water tank 130 and the interior heat exchanger 150. In a first state, the lower cold water valve can allow the cold water to flow from the exterior heat exchanger 140 to the bottom of the cold water tank 130. In a second state, the lower cold water valve can allow the water to flow from the bottom of the cold water tank 130 to the interior heat exchanger 150. In a third state, the lower cold water valve can block the water from flowing between the bottom of the cold water tank 130 and the exterior heat exchanger 140 and between the bottom of the cold water tank 130 and the interior heat exchanger 150.

4.7.3 Upper Hot Water Valve

The upper hot water valve can regulate the flow of water between the top of the hot water tank 120 and the exterior heat exchanger 140 and between the top of the hot water tank 120 and the interior heat exchanger 150. In a first state, the upper hot water valve can allow the hot water to flow from the exterior heat exchanger 140 to the top of the hot water tank 120. In a second state, the upper hot water valve can allow the hot water to flow from the top of the hot water tank 120 to the interior heat exchanger 150. In a third state, the upper hot water valve can block the hot water from flowing between the top of the hot water tank 120 and the exterior heat exchanger 140 and between the top of the hot water tank 120 and the interior heat exchanger 150.

4.7.4 Lower Hot Water Valve

The lower hot water valve can regulate the flow of water between the bottom of the hot water tank 120 and the exterior heat exchanger 140 and between the bottom of the hot water tank 120 and the interior heat exchanger 150. In a first state, the lower hot water valve can allow hot water to flow from the bottom of the hot water tank 120 to the exterior heat exchanger 140. In a second state, the lower hot water valve can allow the hot water to flow from the interior heat exchanger 150 to the bottom of the hot water tank 120. In a third state, the lower hot water valve can block the hot water from flowing between the bottom of the hot water tank 120 and the exterior heat exchanger 140 and between the bottom of the hot water tank 120 and the interior heat exchanger 150

4.7.5 Combination Valves

In one variation, the upper cold water valve and the upper hot water valve form a unitary, multi-state upper combination valve configured to control flow of water between the hot and cold water tank 130s, the interior heat exchanger 150, and the exterior heat exchanger 140. For Example, the upper cold water valve and the upper hot water valve can be arranged in a single valve housing.

Similarly, in this variation, the lower cold water valve and the lower hot water valve can form a unitary, multi-state lower combination valve configured to control flow of water between the hot and cold water tank 130s, the interior heat exchanger 150, and the exterior heat exchanger 140.

4.8 Sensors and Controller

The thermal energy unit 100 can include various sensors that collect temperature data. In particular, the sensors can include: an indoor temperature sensor that measures the temperature of the interior of the building, a cold water temperature sensor that measures temperature of the water in the cold water tank 130, a hot water temperature sensor that measures temperature of the water in the hot water tank 120, an environmental temperature sensor that measures the temperature of the outdoor environment, and the exterior heat exchanger temperature sensor that measures the temperature of the exterior heat exchanger 140. In one implementation, the thermal energy unit 100 can include additional types of sensors such as interior air humidity sensor, outdoor air humidity sensor, carbon dioxide sensor, and/or atmospheric irradiance sensor (e.g., pyranometer).

Generally, the thermal energy unit 100 can include controller 180 configured to control various components of the thermal energy unit 100 to increase the hot tank temperature, decrease the cold tank temperature, as well as heat and cool the interior air within the building. In particular, the controller 180 can: receive the target indoor temperature from the thermostat of the building, access the hot tank temperature, access the cold tank temperature, access the temperature of the outdoor environment, and access the temperature of the exterior heat exchanger 140. Then, based on these temperature measurements, the controller 180 can: supply water from the tank to the exterior heat exchanger 140 for water heating or cooling; or supply water to the interior heat exchanger 150 for heating or cooling of the interior air.

4.8.1 Sensors

In one variation, the thermal energy unit 100 can include a set of sensors 170, such as a set of interior building sensors, arranged within the building, communicatively coupled to the controller 180, and configured to output signals representing indoor temperature and indoor building humidity of the air within the building. In this variation, the thermal energy unit 100 can also include a user interface configured to receive user input representing target indoor temperature.

Additionally, or alternatively, the thermal energy unit 100 can access the target indoor temperature from an external temperature regulator. For example, the thermal energy unit 100 can include a first temperature sensor arranged within the building and configured to output: a first signal representing a first cold tank temperature of the second volume of water within the cold water tank 130 at a first time; and a second signal representing a first cold tank temperature of the second volume of water within the cold water tank 130 at a second time. The thermal energy unit 100 can also include a second temperature sensor configured to output: a third signal representing a first indoor temperature of the interior volume of the building at the first time; and a fourth signal representing a second indoor temperature of an interior volume of the building at the second time. In this example, at the first time during the daytime period, the controller 180 can: access the first cold tank temperature from the first temperature sensor; access the first indoor temperature from the second temperature sensor; access the target indoor temperature; and, in response to the target indoor temperature exceeding the first indoor temperature and in response to first indoor temperature exceeding the first cold tank temperature, trigger the set of valves 160 route the second volume of water between the cold water tank 130 and the interior heat exchanger 150. In this example, at a second time during the daytime period, the thermal energy unit 100 can: access the second cold tank temperature from the first temperature sensor; access the second indoor temperature from the second temperature sensor; and, in response to the second cold tank temperature exceeding the second indoor temperature, trigger the set of valves 160 to disable flow of the second volume of water between the cold water tank 130 and the interior heat exchanger 150.

4.8.2 Temperature Regulator

In one variation, the thermal energy unit 100 can be communicatively coupled to an exterior temperature regulator, such as a thermostat, configured to output signals representing requests to heat the building, cool the building, and/or maintain current indoor temperature within the building. In one example, the controller 180 can access a signal from the temperature regulator, the signal representing a request to decrease the indoor temperature to a target indoor temperature. In this example, the controller 180 can route the second volume of water from the cold water tank 130 to the interior heat exchanger 150 until the target indoor temperature is reached. In another example, the controller 180 can access a signal from the temperature regulator, the signal representing a request to decrease the indoor temperature for a fixed time period. In this example, the controller 180 can route the second volume of water from the cold water tank 130 to the interior heat exchanger 150 until it the fixed time period expires.

In one example, the thermal energy unit 100 can include a first temperature sensor configured to output a first signal representing a first cold tank temperature of the second volume of water within the cold water tank 130. In this implementation, at a first time during the daytime period, the controller 180 can receive a first request to decrease the temperature of the interior volume of the building to a target indoor temperature and, in response to receiving the first request: access the first cold tank temperature from the first temperature sensor; and, in response to the target indoor temperature exceeding the first cold tank temperature, trigger the set of valves 160 route the second volume of water between the cold water tank 130 and the interior heat exchanger 150. In this implementation, at a second time during the daytime period, the controller 180 can access a second request to terminate decreasing the temperature of the interior volume of the building and, in response to receiving the second request: trigger the set of valves 160 to disable flow of the second volume of water between the cold water tank 130 and the interior heat exchanger 150.

However, in this example, the controller 180 can also disable the flow of the second volume of water to the interior heat exchanger 150 in response to the cold tank temperature exceeding a target indoor temperature. In this implementation, the first temperature can output a second signal representing a second cold tank temperature of the second volume of water within the cold water tank 130. The controller 180 can then: access the second cold tank temperature from the first temperature sensor; and, in response to the second cold tank temperature exceeding the target indoor temperature, trigger the set of valves 160 to disable flow of the second volume of water between the cold water tank 130 and the interior heat exchanger 150.

5. Controls

Generally, the controller 180 can: at a first time during the daytime period: access a first hot tank temperature of the first volume of water occupying the hot water tank 120; access a first heat exchanger temperature of the exterior heat exchanger 140; and, in response to the first heat exchanger temperature exceeding the first hot tank temperature, trigger the set of valves 160 to route the first volume of water between the hot water tank 120 and the exterior heat exchanger 140. At a second time during the daytime period, the controller 180 can trigger the set of valves 160 to route the second volume of water between the cold water tank 130 and the interior heat exchanger 150 thermally coupled to the interior volume of the building. At a third time during the nighttime period, the controller 180 can, trigger the set of valves 160 to route the first volume of water between the hot water tank 120 and the interior heat exchanger 150. At a fourth time during the nighttime period, the controller 180 can: access a second cold tank temperature of the second volume of water in the cold water tank 130; access a second heat exchanger temperature of the exterior heat exchanger 140; and, in response to the second cold tank temperature exceeding the second heat exchanger temperature, trigger the set of valves 160 to route the second volume of water between the cold water tank 130 and the exterior heat exchanger 140.

Further, the controller 180 can, at a fifth time succeeding the first time during the daytime period: access a third hot tank temperature of the first volume of water in the hot water tank 120; access a third heat exchanger temperature of the exterior heat exchanger 140; and, in response to the third hot tank temperature exceeding the third heat exchanger temperature, trigger the set of valves 160 to disable flow of the first volume of water between the hot water tank 120 and the exterior heat exchanger 140. At a sixth time succeeding the second time during the daytime period, the controller 180 can trigger the set of valves 160 disable flow of the second volume of water from the cold water tank 130 to the interior heat exchanger 150. At a seventh time succeeding the third time during the nighttime period, trigger the set of valves 160 disable flow of the second volume of water between the hot water tank 120 and the interior heat exchanger 150. At an eighth time succeeding the fourth time during the nighttime period, the controller 180 can: access a fourth cold tank temperature of the second volume of water in the cold water tank 130; access a fourth heat exchanger temperature of the exterior heat exchanger 140; and, in response to the fourth heat exchanger temperature exceeding the fourth cold tank temperature, trigger the set of valves 160 to disable flow of the second volume of water between the cold water tank 130 and the exterior heat exchanger 140.

5.1 Cooling Cold Water Tank Via Exterior Heat Exchanger

In one implementation, the controller 180 can enable cooling of the cold water via the exterior heat exchanger 140 based on the cold tank temperature and/or the temperature of the exterior heat exchanger 140 (e.g., average temperature of the exterior heat exchanger 140). For example, the controller 180 can compare the temperature of the exterior heat exchanger 140 to the cold tank temperature. The controller 180 can change the state of the upper cold water valve from the third state to the first state to let water into the exterior heat exchanger 140 for cooling in response to the cold tank temperature exceeding the temperature of the exterior heat exchanger 140. Concurrently, the controller 180 can change the state of the lower cold water valve from the third state to the first state to allow the cooled cold water from the exterior heat exchanger 140 to flow back into the cold water tank 130. However, in one implementation, the controller 180 can also maintain the cold water valves (e.g., upper cold water valve and lower cold water valve) in the third state in response to the temperature of the exterior heat exchanger 140 falling below a threshold temperature (e.g., below the freezing point of water). In an additional or an alternative implementation, in response to the temperature of the exterior heat exchanger 140 falling below the freezing point of water, but above a threshold minimum temperature, the controller 180 can activate a pump to pump the cold water through the exterior heat exchanger 140, which may allow the water to move through the exterior heat exchanger 140 without freezing.

5.2 Heating Hot Water Tank Via Exterior Heat Exchanger

In response to the hot tank temperature falling below the temperature of the exterior heat exchanger 140, the controller 180 can change the state of the lower hot water valve from the third state to the first state to allow the hot water to flow into the exterior heat exchanger 140 for heating. Concurrently, the controller 180 can change the state of the upper hot water valve from the third state to the first state to allow the hot water from the exterior heat exchanger 140 to flow back into the hot tank. However, in one implementation, the controller 180 can maintain the hot water valves (e.g., upper hot water valve and the lower hot water valve) in the third state in response to the temperature of the hot water exceeding a threshold maximum temperature (e.g., boiling point of water).

5.3 Indoor Air Cooling Via Interior Heat Exchanger

In one implementation, the controller 180 can supply water to the interior heat exchanger 150 to heat or cool the interior air based on the target indoor temperature, current interior air temperature, and the temperature of the water. For example, in response to the current indoor temperature exceeding the target indoor temperature, the controller 180 can compare the current indoor temperature to the cold water temperature. In response to the cold water temperature falling below the current interior air temperature, the controller 180 can change the state of the lower cold water valve from the third state to the first state to pass the cold water from the cold water tank 130 to the interior heat exchanger 150. Concurrently, the controller 180 can change the state of the lower cold water valve from the third state to the first state to allow the cold water to flow back into the cold tank.

5.4 Indoor Air Cooling Via Interior Heat Exchanger

In response to the current indoor temperature falling below the target indoor temperature (e.g., interior air needs heating), the controller 180 can compare the current interior air temperature to the hot water temperature. In response to the hot water temperature exceeding the current interior air temperature, the controller 180 can change the state of the lower hot water valve from the third state to the first state to pass the hot water from the hot water tank 120 to the interior heat exchanger 150 where the water will give off thermal energy to the interior air. Concurrently, the controller 180 can change the state of the lower hot water valve from the third state to the first state to allow the hot water to flow back into the hot water tank 120. In one implementation, when the water is thus directed to the interior heat exchanger 150, the controller 180 can send a signal to the HVAC system of the building instructing the HVAC system to supply interior air to the interior heat exchanger 150.

5.5 Interior Air Temperature Maintenance

The controller 180 can maintain the hot water valves (e.g., upper hot water valve and lower hot water valve) in the third state in response to: the current indoor temperature matching the target indoor temperature; and/or the target indoor temperature exceeding the hot water temperature in the hot water tank 120. Similarly, the controller 180 can maintain the cold water valves (e.g., upper cold water valve and lower cold water valve) in the third state in response to: the current indoor temperature matching the target indoor temperature; and/or in response to the cold tank temperature exceeding the target indoor temperature.

5.6 Example: Heat Pump Controls

In one implementation, the controller 180 can activate or deactivate the heat pump 190 based on state of charge (i.e., level of charge of the electrical battery 197 relative to battery capacity) of the electrical battery 197 and the temperature of the first volume of water and the second volume of water. For example, the controller 180 can activate the heat pump 190 in response to receiving a signal indicating that the electrical battery 197 is fully charged and the photovoltaic solar panel 195 continues to generate electricity. Additionally, or alternatively, the controller 180 can deactivate the heat pump 190 in response to an indication that the temperature difference between the hot water tank 120 and the cold water tank 130 exceeds a threshold difference. In addition, the controller 180 can deactivate the heat pump 190 in response to receiving an indication that the cold water temperature in the cold water tank 130 has reached a target minimum temperature (e.g., 0 degrees Celsius) or in response to receiving an indication that the hot water temperature in the hot water tank 120 has reached a target maximum temperature (e.g., 100 degrees Celsius).

Generally, the controller can activate the heat pump to transfer thermal energy between thermal energy storage (i.e., cold water tank 130 and hot water tank 120) and/or the heat exchangers (i.e., exterior heat exchanger 140 and interior heat exchanger 150) to: increase the thermal energy efficiency of the thermal energy unit 100; and decrease, over a time period (e.g., days, weeks), the amount of grid electricity (e.g., electrical energy received from the electrical grid) consumed by the thermal energy unit 100 and sum a target indoor temperature within the building.

For example, the controller 180 can activate the heat pump 190 to cool the second volume of water in the cold water tank 130 by transferring thermal energy from the cold water tank 130 to the hot water tank 120, and then cool the interior volume of the building by supplying the second volume of water from the cold water tank 130 to the interior heat exchanger 150. More specifically, during the daytime period, the controller 180 can charge an electrical battery 197 via a photovoltaic solar panel 195. In this implementation, at a first time during the daytime period, the controller 180 can: access a first hot tank temperature of the first volume of water; access a first cold tank temperature of the second volume of water; and, in response to a temperature difference between the first hot tank temperature and the first cold tank temperature falling below a threshold difference, supply electrical energy from the electrical battery 197 to the heat pump 190 to transfer thermal energy from the cold water tank 130 to the hot water tank 120. The controller 180 than can, in response to receiving a signal representing a request to cool the interior volume of the building, trigger the set of valves 160 to route the second volume of water between the cold water tank 130 and the interior heat exchanger 150.

Therefore, the controller 180 can power the heat pump 190 with electrical energy collected by the photovoltaic solar panel 195 to transfer thermal energy from the cold water tank 130 to the hot water tank 120, thereby heating the hot water tank 120 and cooling the cold water tank 130, in order to cool the interior volume of the building by supplying the second volume of water from the cold water tank 130 to the interior heat exchanger 150.

In another example, to achieve efficient cooling of the building, the controller 180 can activate the heat pump 190 to transfer thermal energy from the interior volume of the building to the cold water tank 130. More specifically, during the daytime period, the controller 180 can: access a target indoor temperature; access a first indoor temperature of the indoor environment within the building; access a first cold tank temperature of the second volume of water within the cold water tank 130; and, in response to a difference between the target indoor temperature and the first indoor temperature exceeding a threshold difference and in response to the first cold tank temperature exceeding the first indoor temperature, supply electrical energy to the heat pump 190 to transfer thermal energy from the interior heat exchanger 150 to the hot water tank 120 and/or the cold water tank 130. During the nighttime period, the controller 180 can: trigger the set of valves 160 to route the second volume of water between the cold water tank 130 and the exterior heat exchanger 140; and trigger the set of valves 160 to route the first volume of water between the hot water tank 120 and the exterior heat exchanger 140. Therefore, if temperature of the second volume of water within the cold water tank 130 is insufficiently low to cool the interior volume of the building (e.g., on a hot day), the controller 180 can activate the heat pump 190 to transfer thermal energy from the interior volume of the building to either or both of the thermal storage tanks in order to decrease the indoor temperature of the internal volume of the building. Then, during the nighttime period, the controller 180 can supply the first volume of water and the second volume of water to the exterior heat exchanger 140 in order to dissipate the excess thermal energy stored in the storage tanks.

5.6 Example: Thermal and Electrical Load Shifting

In one implementation, in order to reduce load on the electrical grid during times of peak electrical energy demand, the controller 180 can power the heat pump 190 with electrical energy from the electrical grid only during periods of low electrical energy demand. For example, the controller 180 can supply electrical energy to the heat pump 190 to transfer thermal energy to the hot water tank 120 during the nighttime period when electrical energy demand is generally low.

In one implementation, the controller 180 can activate the heat pump 190 to transfer thermal energy to or from the cold water tank 130 or the hot water tank 120 in anticipation of a heating event, such as a time period during which the indoor temperature exceeds the target indoor temperature, or a cooling event, such as a time period during which the indoor temperature falls below the target indoor temperature. For example, the controller 180 can: access weather information from a weather station; based on the weather information, predict a heating event (e.g., indoor temperature within the building exceeding a target indoor temperature of the building) occurring at a first time during the daytime period and persisting over a four hour duration; based on the weather information, predict a cold tank temperature of the second volume of water within the cold water tank 130 exceeding the indoor temperature after one hour of cooling; and activate the heat pump 190 to cool the second volume of water within the cold water tank 130 in order to increase a time period during which the indoor temperature exceeds the cold tank temperature.

In one implementation, the controller 180 can: predict a cooling event based on historic indoor temperature data (or past or future weather data); predict a period of low electricity demand based on historic electricity demand data; activate the heat pump during the period of low electricity demand in order to cool the second volume of water in the cold water tank 130; and, during the cooling event, supply the second volume of water to the interior heat exchanger 140 to cool the building. More specifically, the controller 180 can: access a series of historical indoor temperatures; access a target indoor temperature; and, based on the series of historical indoor temperatures, predict an indoor temperature exceeding the target indoor temperature by temperature difference at a second time during the daytime period. Then, in response to the temperature difference exceeding a threshold difference, the controller 180 can: access a series of historical electricity demand levels; and, based on the series of historical electricity demand levels, predict a period of low electricity demand at a first time preceding the second time. At the first time, the controller 180 can: supply electrical energy from the electrical grid to the heat pump 190 in order to decrease a cold tank temperature of the second volume of water in the cold water tank 130. Then, at the second time, the controller 180 can trigger the set of valves 160 to route the second volume of water from the cold water tank 130 to the interior heat exchanger 150.

Therefore, the computer system can: based on historical electricity demand data, predict the period of low electricity demand; based on historical indoor temperature data, predict a cooling event (or a heating event) succeeding the period of low electricity demand; during the period of low electricity demand, activate the heat pump 190 to transfer thermal energy from the cold water tank 130 (or to the hot water tank 120); and, during the cooling event, supply the second volume of water from the cold water tank 130 to the interior heat exchanger 150 to cool the interior volume of the building.

5.6 Example: Indoor Temperature Control Based on Heat & Cool Requests

In one implementation, the controller 180 can accesses from an external controller, such as a thermostat installed in the building, requests to heat, cool, or maintain the indoor temperature within the building. In particular, the external controller can: access a current indoor temperature from a temperature sensor arranged within the building; access a target indoor temperature from a user interface configured to receive user input; and, in response to the current indoor temperature exceeding the target indoor temperature, transmit a cooling request to the controller 180, the cooling request prompting the controller 180 to decrease the indoor temperature of the internal volume of the building; or, in response to the current indoor temperature falling below the target indoor temperature, transmit a heating request to the controller 180; or in response to a difference between the current indoor temperature and the target indoor temperature falling below a threshold difference, transmit a request to maintain the indoor temperature. Then, in response to receiving the heating request, the controller 180 can supply the first volume of water from the hot water tank 120 to the interior heat exchanger 150. Or, in response to receiving the cooling request, the controller can supply the second volume of water from the cold water tank 130 to the interior heat exchanger.

For example, at a first time during the daytime period, the controller 180 can: access a first signal representing a first request to cool the interior volume of the building; and, in response to receiving the first request, trigger the set of valves 160 to route the second volume of water from the cold water tank 130 to the interior heat exchanger 150. In this implementation, the controller 180 can also, at a second time during the nighttime period: access a second signal representing a second request to heat the interior volume of the building; and, in response to receiving the second request, trigger the set of valves 160 to route the first volume of water from the hot water tank 120 to the interior heat exchanger 150.

In this example, the controller 180 can further, during at a third time succeeding the first time: access a third signal representing a request to maintain the current indoor temperature of the internal volume of the building; and, in response to receiving the third signal, trigger the set of valves 160 to disable flow of the second volume of water from the cold water tank 130 to the interior heat exchanger 150. In this implementation, the controller 180 can further, at a fourth time succeeding the second time: access a fourth signal representing the request to maintain the temperature of the internal volume of the building; and, in response to receiving the fourth signal, trigger the set of valves 160 to disable flow of the second volume of water between the hot water tank 120 and the interior heat exchanger 150. Therefore, the controller 180 can: access, from an external controller, such as a thermostat of the building, a set of signals representing a request to heat the interior volume of the building, cool the interior volume of the building, or maintain current temperature of the interior volume of the building; and, based on these signals, enable or disable the flow of the first volume of water or the second volume of water to the interior heat exchanger 150.

5.7 Example: Indoor Temperature Controls Based on Sensor Data

In one implementation, the controller 180 can: directly access the indoor temperature from a temperature sensor communicatively coupled to the controller 180 and arranged within the building; and directly access the target indoor temperature from a user interface communicatively coupled to the controller 180 and arranged within the building. In particular, the controller 180 can: access the current indoor temperature from the temperature sensor; access the target indoor temperature; and, in response to the current indoor temperature exceeding the target indoor temperature, route the second volume of water from the cold water tank 130 to the interior heat exchanger 150 to cool interior volume of the building; or, in response to the current indoor temperature falling below the target indoor temperature, route the first volume of water from the hot water tank 120 to the interior heat exchanger 150 to heat the interior volume of the building; or in response to a difference between the current indoor temperature and the target indoor temperature falling below a threshold difference, close the set of valves 190 to disable heating or cooling of the interior volume of the building.

In one example, the controller 180 can, at a first time during the daytime period: access a first cold tank temperature of the second volume of water occupying the cold water tank 130; access a first indoor temperature and a target indoor temperature; and, in response to the first indoor temperature exceeding the target indoor temperature and in response to the first indoor temperature exceeding the first cold tank temperature, trigger the set of valves 160 to route the second volume of water between the cold water tank 130 and the interior heat exchanger 150.

In this example, the controller 180 can further, at a second time during the nighttime period: access a second hot tank temperature of the first volume of water in the hot water tank 120; access a second indoor temperature; and, in response to the target indoor temperature exceeding the second indoor temperature and in response to the second hot tank temperature exceeding the second indoor temperature, trigger the set of valves 160 to route the first volume of water between the hot water tank 120 and the interior heat exchanger 150.

In this example, the controller 180 can, at a third time during the daytime period: access a third cold tank temperature of the second volume of water in the cold water tank 130; access a first indoor temperature and a target indoor temperature; and, in response to the first indoor temperature falling below the target indoor temperature or in response to the second cold tank temperature exceeding the target indoor temperature, trigger the set of valves 160 to disable flow of the second volume of water from the cold water tank 130 to the interior heat exchanger 150.

Therefore, the controller 180 can: directly access indoor temperatures of the internal volume of the building from temperature sensors arranged within the building; and, based on the indoor temperatures of the internal volume of the building, enable, or disable flow of the first volume of water or the second volume of water to the interior heat exchanger 150.

5.8 Example: Controls in Based on Outdoor Environment Conditions

Generally, conditions of the outdoor environment, such as solar irradiance, air humidity, air temperature, solar azimuth, wind speed, can influence whether the exterior heat exchanger 140 can heat the first volume of water within the hot water tank 120. In one implementation, the controller 180 can calculate a maximum water temperature that can be achieved by passing the first volume of water from the hot water tank 120 through the exterior heat exchanger 140 based on the current conditions of the outdoor environment, such as solar irradiance, air humidity, air temperature, solar azimuth, wind speed. Based on the maximum water temperature exceeding the hot water temperature of the first volume of water within the hot water tank 120, the controller 180 can trigger the set of valves 160 to route the first volume of water to the exterior heat exchanger 140 to heat the first volume of water.

For example, at the first time during the daytime period, the controller 180 can: access a first hot tank temperature of the first volume of water within the hot water tank 120 from a first tank temperature sensor arranged within the hot water tank 120; access a first heat exchanger temperature of an exterior heat exchanger 140 from a first temperature sensor arranged on the exterior heat exchanger 140; access a first exterior temperature of the outdoor environment from a second temperature sensor arranged on the housing 110 of the thermal energy unit 100; access a first solar irradiance level from a pyranometer arranged on the housing 110; access a first ambient humidity level from a humidity sensor arranged on the housing 110; access a first wind speed from an anemometer arranged on the housing no; based on the first heat exchanger temperature, the first exterior temperature, the first solar irradiance level, the first wind speed, and the first ambient humidity level, calculate a first maximum water temperature of the first volume of water routed through the exterior heat exchanger 140; and, in response to the first maximum water temperature exceeding the hot tank temperature, trigger the set of valves 160 to route the first volume of water from the hot water tank 120 to the exterior heat exchanger 140.

In this example, at the second time during the daytime period, the controller 180 can: access a second hot tank temperature of the first volume of water within the hot water tank 120 from the first tank temperature sensor; access a second heat exchanger temperature of the exterior heat exchanger 140 from the first temperature sensor; access a second exterior temperature of the outdoor environment from the second temperature sensor; access a second solar irradiance level from the pyranometer; access a second wind speed from the anemometer; access a second ambient humidity level from the humidity sensor; based on the second heat exchanger temperature, the second exterior temperature, the second solar irradiance level, the second wind speed, and the second ambient humidity level, calculate a second maximum water temperature of the second volume of water routed through the exterior heat exchanger 140; and, in response to the second maximum water temperature falling below the second hot tank temperature, trigger the set of valves 160 disable flow of the first volume of water between the hot water tank 120 and the exterior heat exchanger 140.

Therefore, the controller 180 can calculate a maximum water temperature that can be reached by passing the first volume of water through the exterior heat exchanger 140 during the daytime period based on the daytime heat exchanger temperature, outdoor environment temperature, ambient humidity level, and solar irradiance level, and/or wind speed. Then, based on the maximum water temperature and the hot tank temperature, the controller 180 can trigger the set of valves 160 to enable or disable the flow of the first volume of water between the hot water tank 120 and the exterior heat exchanger 140. Similarly, the controller 180 can calculate a minimum water temperature that can be reached by passing the second volume of water through the exterior heat exchanger 140 during the nighttime period based on the nighttime: heat exchanger temperature, outdoor environment temperature, ambient humidity level, and solar irradiance level, and/or wind speed. Then, based on the minimum water temperature and the cold tank temperature of the second volume of water within the cold water tank 130, the controller 180 can trigger the set of valves 160 to enable or disable the flow of the second volume of water between the cold water tank 130 and the exterior heat exchanger 140.

5.9 Example: 24-Hour Indoor Cooling Cycle

Generally, to cool an interior of the building during daytime, the controller 180 can route the first volume of water between a cold water tank 130, the exterior heat exchanger 140, and the interior heat exchanger 150 over a 24-hour period.

For example, at a first time during a nighttime period, the controller 180 can: access a first cold tank temperature of a first volume of water in a cold water tank 130; access a first heat exchanger temperature of an exterior heat exchanger 140; and, in response to the first cold tank temperature exceeding the first heat exchanger temperature, trigger a set of valves 160 to route the first volume of water between the cold water tank 130 and the exterior heat exchanger 140. Therefore, during the nighttime period, the controller 180 can route the first volume of water from the cold water tank 130 to the exterior heat exchanger 140 to cool the first volume of water.

In this example, at a second time succeeding the first time, the controller 180 can: access a second cold tank temperature of the first volume of water in the cold water tank 130; access a second heat exchanger temperature of the exterior heat exchanger 140; and, in response to the second heat exchanger temperature exceeding the second cold tank temperature, trigger the set of valves 160 to disable flow of the first volume of water between the cold water tank 130 and the exterior heat exchanger 140. Therefore, after the controller 180 routes the first volume of water from the cold water tank 130 to the exterior heat exchanger 140, the controller 180 can block the flow of the first volume of water from the cold water tank 130 to the exterior heat exchanger 140. For example, the controller 180 can block the flow of the first volume of water to the exterior heat exchanger 140 in the morning when the exterior heat exchanger 140 cannot cool the first volume of water due to the temperature of the exterior heat exchanger 140 increasing.

In this example, at a third time during a daytime period, the controller 180 can: access a first signal representing a first request to cool an interior volume of the building; and, in response to accessing the first request, trigger the set of valves 160 to route the first volume of water between the cold water tank 130 and an interior heat exchanger 150 thermally coupled to the interior volume of the building. Therefore, during daytime period, the controller 180 can route the first volume of water from the cold water tank 130 to the interior heat exchanger 150 to cool the interior volume of the building.

In this example, at a fourth time succeeding the third time, the controller 180 can: access a second signal representing a second request to maintain a current temperature of the interior volume of the building; and, in response to accessing the second request, trigger the set of valves 160 to disable flow of the first volume of water from the cold water tank 130 to the interior heat exchanger 150. Therefore, after the controller 180 routes the first volume of water from the cold water tank 130 to the interior heat exchanger 150, the controller 180 can disable the flow of the first volume of water from the cold water tank 130 to the interior heat exchanger 150. For example, the controller 180 can block the flow of the first volume of water to the exterior heat exchanger 140 in the evening when the indoor temperature of the internal volume of the building may decrease due to the decreasing temperature of the outdoor environment.

5.10 Example: Threshold-Based Thermal Storage Regulation

In one implementation, when routing the first volume of water from the cold water tank 130 to the exterior heat exchanger 140, the controller 180 can continue routing the first volume of water to the exterior heat exchanger 140 in response to a difference between a current temperature of the first volume of water within the cold water tank 130 and a previous temperature of the first volume of water exceeding a threshold difference, which may indicate that the exterior heat exchanger 140 decreased the temperature of the first volume of water. Alternatively, the controller 180 can stop routing the first volume of water to the exterior heat exchanger 140 in response to a difference between the current temperature of the first volume of water within the cold water tank 130 and the previous temperature of the first volume of water falling below a threshold difference, which may indicate that the exterior heat exchanger 140 cannot decrease the temperature of the first volume of water.

For example, at a first time during a nighttime period, the controller 180 can: access a first cold tank temperature of a first volume of water in a cold water tank 130 from a first temperature sensor arranged within the cold water tank 130; access a first heat exchanger temperature of an exterior heat exchanger 140 from a second temperature sensor arranged on the exterior heat exchanger 140; and, in response to the first cold tank temperature exceeding the first heat exchanger temperature, trigger a set of valves 160 to route the first volume of water between the cold water tank 130 and the exterior heat exchanger 140. In this example, at a second time succeeding the first time during the nighttime period, the controller 180 can: access a second cold tank temperature of the first volume of water in the cold water tank 130 from the first temperature sensor; and, in response to a first difference between the first cold tank temperature and the second cold tank temperature exceeding a threshold difference, maintain a current state of the set of valves 160 to continue routing the first volume of water between the cold water tank 130 and the exterior heat exchanger 140. In this example, at a third time succeeding the second time during the nighttime period, the controller 180 can: access a third cold tank temperature of the first volume of water in the cold water tank 130 from the first temperature sensor; and, in response to a second difference between the second cold tank temperature and the third cold tank temperature falling below the threshold difference, trigger the set of valves 160 to disable flow of the first volume of water between the cold water tank 130 and the exterior heat exchanger 140.

Therefore, the controller 180 can continue routing the first volume of water to the exterior heat exchanger 140 by maintaining the current state of the valves 160 in response to a difference between the temperature of the exterior heat exchanger 140 and the temperature of the first volume of water within the cold water tank 130 exceeding a threshold difference, which may indicate that the exterior heat exchanger 140 can further decrease the temperature of the first volume of water. Alternatively, the controller 180 can stop routing the first volume of water to the exterior heat exchanger 140 by changing the state of valves (e.g., closing the valves) in response to a difference between the temperature of the exterior heat exchanger 140 and the temperature of the first volume of water within the cold water tank 130 falling below a threshold difference, which may indicate that the exterior heat exchanger 140 cannot decrease the temperature of the first volume of water.

The systems and methods described herein can be embodied and/or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions can be executed by computer-executable components integrated with the application, applet, host, server, network, website, communication service, communication interface, hardware/firmware/software elements of a user computer or mobile device, wristband, smartphone, or any suitable combination thereof. Other systems and methods of the embodiment can be embodied and/or implemented at least in part as a machine configured to receive a computer-readable medium storing computer-readable instructions. The instructions can be executed by computer-executable components integrated by computer-executable components integrated with apparatuses and networks of the type described above. The computer-readable medium can be stored on any suitable computer readable media such as RAMs, ROMs, flash memory, EEPROMs, optical devices (CD or DVD), hard drives, floppy drives, or any suitable device. The computer-executable component can be a processor but any suitable dedicated hardware device can (alternatively or additionally) execute the instructions.

As a person skilled in the art will recognize from the previous detailed description and from the figures and claims, modifications and changes can be made to the embodiments of the invention without departing from the scope of this invention as defined in the following claims.

Claims

1. A thermal energy unit comprising: a housing;a hot water tank: arranged within the housing; andconfigured to store a first volume of water;a cold water tank: arranged within the housing; andconfigured to store a second volume of water;an exterior heat exchanger: arranged on the housing; anddefining a set of fluid channels extending vertically along an exterior wall of the housing;an interior heat exchanger: thermally coupled to an interior volume of a building; anda set of valves: configured to selectively: during a daytime period: route the first volume of water between the hot water tank and the exterior heat exchanger; androute the second volume of water between the cold water tank and the interior heat exchanger; andduring a nighttime period: route the first volume of water between the hot water tank and the interior heat exchanger; androute the second volume of water between the cold water tank and the exterior heat exchanger.

2. The thermal energy unit of claim 1, wherein the set of valves comprises: a first valve: arranged proximal a first top of the hot water tank; andoperable in: a first state to route the first volume of water from the first top of the hot water tank to the interior heat exchanger; anda second state to route the first volume of water from the exterior heat exchanger to the first top of the hot water tank;second valve: arranged proximal a first bottom of the hot water tank; andoperable in: a third state to route the first volume of water from the first bottom of the hot water tank to the exterior heat exchanger; anda fourth state route the first volume of water from the interior heat exchanger to the first bottom of the hot water tank;third valve: arranged proximal a second top of the cold water tank; andoperable in: a fifth state to route the second volume of water from the second top of the cold water tank to the exterior heat exchanger; anda sixth state to route the second volume of water from the interior heat exchanger to the second top of the cold water tank; anda fourth valve: arranged proximal a second bottom of the cold water tank; andoperable in: a seventh state to route the second volume of water from the second bottom of the cold water tank to the interior heat exchanger; andan eighth state to route the second volume of water from the exterior heat exchanger to the second bottom of the cold water tank.

3. The thermal energy unit of claim 1, further comprising: a first temperature sensor configured to output: a first signal representing a first cold tank temperature of the second volume of water within the cold water tank at a first time; anda second signal representing a second cold tank temperature of the second volume of water within the cold water tank at a second time;a second temperature sensor configured to output: a third signal representing a first indoor temperature of the interior volume of building at the first time; anda fourth signal representing a second indoor temperature of the interior volume of building at the second time; anda controller configured to: at the first time during the daytime period: access the first cold tank temperature from the first temperature sensor;access the first indoor temperature from the second temperature sensor;access a target indoor temperature; andin response to the target indoor temperature exceeding the first indoor temperature and in response to the first indoor temperature exceeding the first cold tank temperature, trigger the set of valves route the second volume of water between the cold water tank and the interior heat exchanger; andat the second time during the daytime period: access the second cold tank temperature from the first temperature sensor;access the second indoor temperature from the second temperature sensor; andin response to the second cold tank temperature exceeding the second indoor temperature, trigger the set of valves to disable flow of the second volume of water between the cold water tank and the interior heat exchanger.

4. The thermal energy unit of claim 1, further comprising: a first temperature sensor configured to output a first signal representing a first cold tank temperature of the second volume of water within the cold water tank; anda controller configured to: at a first time during the daytime period: receive a first request to cool the interior volume of the building to a target indoor temperature; andin response to receiving the first request: access the first cold tank temperature from the first temperature sensor; andin response to the target indoor temperature exceeding the first cold tank temperature, trigger the set of valves route the second volume of water between the cold water tank and the interior heat exchanger; andat a second time during the daytime period: access a second request to terminate cooling the interior volume of the building; andin response to receiving the second request, triggering the set of valves to disable flow of the second volume of water between the cold water tank and the interior heat exchanger.

5. The thermal energy unit of claim 4: wherein the first temperature sensor is further configured to output a second signal representing a second cold tank temperature of the second volume of water within the cold water tank; andwherein the controller is further configured to: at a third time subsequent the first time and prior to the second time: access the second cold tank temperature from the first temperature sensor; andin response to the second cold tank temperature exceeding the target indoor temperature, trigger the set of valves to disable flow of the second volume of water between the cold water tank and the interior heat exchanger.

6. The thermal energy unit of claim 1, further comprising: a heat pump configured to transfer thermal energy from the cold water tank to the hot water tank; anda photovoltaic solar panel: arranged on the housing; andconfigured to supply electrical energy to the heat pump.

7. The thermal energy unit of claim 1, wherein the interior heat exchanger comprises a radiator arranged in the building.

8. The thermal energy unit of claim 1, wherein the interior heat exchanger is arranged within a forced air heating, ventilation, and air conditioning system within the building.

9. The thermal energy unit of claim 1, wherein the exterior heat exchanger: is configured to: during the daytime period, accumulate thermal energy from sunlight; andduring the nighttime period, radiate thermal energy into an outdoor environment; andcomprises a set of channels: fluidly coupled to the hot water tank and the cold water tank; andconfigured exchange thermal energy with the exterior heat exchanger.

10. A method comprising: during a daytime period: at a first time: accessing a first hot tank temperature of a first volume of water occupying a hot water tank;accessing a first heat exchanger temperature of an exterior heat exchanger; andin response to the first heat exchanger temperature exceeding the first hot tank temperature, triggering a set of valves to route the first volume of water between the hot water tank and the exterior heat exchanger; andat a second time: triggering the set of valves to route a second volume of water between a cold water tank and an interior heat exchanger thermally coupled to an interior volume of a building; andduring a nighttime period: at a third time: triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger; andat a fourth time: accessing a second cold tank temperature of the second volume of water in the cold water tank;accessing a second heat exchanger temperature of the exterior heat exchanger; andin response to the second cold tank temperature exceeding the second heat exchanger temperature, triggering the set of valves to route the second volume of water between the cold water tank and the exterior heat exchanger.

11. The method of claim 10: wherein triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger comprises: accessing a first cold tank temperature of the second volume of water occupying the cold water tank;accessing a first indoor temperature and a target indoor temperature; andin response to the first indoor temperature exceeding the target indoor temperature and in response to the first indoor temperature exceeding the first cold tank temperature, triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger; andwherein triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger comprises: accessing a second hot tank temperature of the first volume of water in the hot water tank;accessing a second indoor temperature; andin response to the target indoor temperature exceeding the second indoor temperature and in response to the second hot tank temperature exceeding the second indoor temperature, triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger.

12. The method of claim 10, further comprising: during the daytime period: at a fifth time succeeding the first time: accessing a third hot tank temperature of the first volume of water in the hot water tank;accessing a third heat exchanger temperature of the exterior heat exchanger; andin response to the third hot tank temperature exceeding the third heat exchanger temperature, triggering the set of valves to disable flow of the first volume of water between the hot water tank and the exterior heat exchanger; andat a sixth time succeeding the second time: accessing a third cold tank temperature of the second volume of water in the cold water tank;accessing a first indoor temperature and a target indoor temperature; andin response to the first indoor temperature falling below the target indoor temperature or in response to the second cold tank temperature exceeding the target indoor temperature, triggering the set of valves disable flow of the second volume of water from the cold water tank to the interior heat exchanger; andduring the nighttime period: at a seventh time succeeding the third time: accessing a fourth hot tank temperature;accessing a second indoor temperature; andin response to the target indoor temperature exceeding the fourth hot tank temperature or in response to the second indoor temperature exceeding the target indoor temperature, triggering the set of valves disable flow of the second volume of water between the hot water tank and the interior heat exchanger; andat an eighth time succeeding the fourth time: accessing a fourth cold tank temperature of the second volume of water in the cold water tank;accessing a fourth heat exchanger temperature of the exterior heat exchanger; andin response to the fourth heat exchanger temperature exceeding the fourth cold tank temperature, triggering the set of valves to disable flow of the second volume of water between the cold water tank and the exterior heat exchanger.

13. The method of claim 10: wherein triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger comprises: accessing a first signal representing a first request to cool the interior volume of the building; andin response to receiving the first request, triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger; andwherein triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger comprises: accessing a second signal representing a second request to heat the interior volume of the building; andin response to receiving the second request, triggering the set of valves to route the first volume of water between the hot water tank and the interior heat exchanger.

14. The method of claim 10, further comprising: during the daytime period: at a sixth time succeeding the second time: accessing a third signal representing a request to disable cooling of the interior volume of the building; andin response to receiving the third signal, triggering the set of valves disable flow of the second volume of water from the cold water tank to the interior heat exchanger; andduring the nighttime period: at a seventh time succeeding the third time: accessing a fourth signal representing the request to disable heating of the interior volume of the building; andin response to receiving the fourth signal, triggering the set of valves disable flow of the second volume of water between the hot water tank and the interior heat exchanger.

15. The method of claim 10: further comprising: at the first time: accessing a first solar irradiance level from a pyranometer arranged on the exterior heat exchanger;accessing a first ambient humidity level from a humidity sensor arranged proximal the exterior heat exchanger; andbased on the first solar irradiance level, the first ambient humidity, and the first heat exchanger temperature, calculating a first maximum water temperature of the first volume of water; andat a fifth time succeeding the first time: accessing a second hot tank temperature of the first volume of water occupying the hot water tank;accessing a second solar irradiance level from the pyranometer;accessing a second ambient humidity level from the humidity sensor;based on the second solar irradiance level, the second ambient humidity, and the second heat exchanger temperature, calculating a second maximum water temperature of the first volume of water; andin response to the second maximum water temperature falling below the second hot tank temperature, triggering the set of valves disable flow of the first volume of water between the hot water tank and the exterior heat exchanger; andwherein routing the first volume of water between the hot water tank and the exterior heat exchanger comprises: in response to the first maximum water temperature exceeding the first hot tank temperature, routing the first volume of water between the hot water tank and the exterior heat exchanger.

16. The method of claim 10, further comprising: during the daytime period, charging an electrical battery via a photovoltaic solar panel; andat a fifth time during the daytime period: accessing a third hot tank temperature of the first volume of water;accessing a third cold tank temperature of the second volume of water;in response to a temperature difference between the third hot tank temperature and the third cold tank temperature falling below a threshold difference, supplying electrical energy from the electrical battery to a heat pump to transfer thermal energy from the cold water tank to the hot water tank; andin response to receiving a signal representing a request to cool the interior volume of the building, triggering the set of valves to route the second volume of water between the cold water tank and the interior heat exchanger.

17. The method of claim 10, further comprising: accessing a series of historical indoor temperatures;accessing a target indoor temperature;based on the series of historical indoor temperatures, predicting an indoor temperature exceeding the target indoor temperature by temperature difference at a sixth time during the daytime period;in response to the temperature difference exceeding a threshold difference: accessing a series of historical electricity demand levels; andbased on the series of historical electricity demand levels, predicting a period of low electricity demand at a fifth time preceding the sixth time;at the fifth time, supplying electrical energy from an electrical grid to a heat pump to decrease a third cold tank temperature of the second volume of water within the cold water tank; andat the sixth time, triggering the set of valves to route the second volume of water from the cold water tank to the interior heat exchanger.

18. A method comprising: during a nighttime period: at a first time: accessing a first cold tank temperature of a first volume of water in a cold water tank;accessing a first heat exchanger temperature of an exterior heat exchanger; andin response to the first cold tank temperature exceeding the first heat exchanger temperature, triggering a set of valves to route the first volume of water between the cold water tank and the exterior heat exchanger; andat a second time succeeding the first time: accessing a second cold tank temperature of the first volume of water in the cold water tank;accessing a second heat exchanger temperature of the exterior heat exchanger; andin response to the second heat exchanger temperature exceeding the second cold tank temperature, triggering the set of valves to disable flow of the first volume of water between the cold water tank and the exterior heat exchanger; andduring a daytime period: at a third time: accessing a first signal representing a first request to cool an interior volume of a building; andin response to receiving the first request, triggering the set of valves to route the first volume of water between the cold water tank and an interior heat exchanger thermally coupled to the interior volume of the building; andat a fourth time succeeding the third time: accessing a second signal representing a second request to maintain current temperature of the interior volume on the building; andin response to receiving the second request, triggering the set of valves disable flow of the first volume of water from the cold water tank to the interior heat exchanger.

19. The method of claim 18, further comprising: at a fifth time during the nighttime period: accessing a third cold tank temperature of the first volume of water in the cold water tank; andin response to the first cold tank temperature exceeding the third cold tank temperature by over a threshold difference, maintaining a current state of the set of valves to continue routing the first volume of water between the cold water tank and the exterior heat exchanger.

20. The method of claim 18, further comprising: during the daytime period: charging an electrical battery via a photovoltaic solar panel;accessing a set of weather data from a weather station; andbased on the set of weather data, predicting a cooling event for cooling the interior volume of the building at a fifth time during the daytime period;at a sixth time preceding the fifth time during the daytime period, supplying electrical energy from the electrical battery to a heat pump to transfer thermal energy from the cold water tank to a hot water tank; andat the fifth time during the daytime period, triggering the set of valves to route the first volume of water between the cold water tank and the interior heat exchanger.