Patent Publication Number: US-2021164708-A1

Title: System, an arrangement and method for heating and cooling

Description:
FIELD OF THE INVENTION 
     The present invention relates to a heating and cooling system and more particularly to a heating and cooling system and more particularly according to the preamble of claim  1 . The present invention also relates to an arrangement for heating and cooling of several building spaces or buildings, and more particularly to an arrangement according to the preamble of claim  10 . The present invention further relates to a method heating and cooling of several building spaces or buildings, and more particularly to a method according to the preamble of claim  18 . 
     BACKGROUND OF THE INVENTION 
     District heating and cooling, or centralized heating and cooling, are commonly known systems in which heat energy or cooling energy is produced in a centralized plant or source and distributed via a pipe network to several buildings. The source of heat energy in centralized heating systems is an energy plant or an industrial plant which can produce heat energy for the distribution to all buildings. Conventionally all the buildings receive heat energy in similar manner and may utilize or consume the heat energy according to needs of the building. The source of cooling energy in centralized cooling systems is normally a large water reservoir or a lake or a sea from which cool water is distributed to all buildings. Conventionally all the buildings receive cooling energy in similar manner and may utilize or consume the cooing energy according to needs of the building. The buildings have a heat exchanger in which the heat energy or the cooling energy of a secondary working fluid flow of the centralized heating system and the pipe network thereof is transferred to primary working fluid of the building for heating or cooling the building. The primary working fluid may be for example heating or cooling air supplied to the building or water flowing in the building heating system. 
     The disadvantage of prior art centralized heating or cooling systems is that they are complex and do not take into account individual needs of different buildings. This means, that when centralized heating is carried out, all the buildings receive heat energy via the pipe network and each building may only decide how much heat energy it will utilize. Similarly, when centralized cooling is carried out, all the buildings receive cooling energy via the pipe network and each building may only decide how much cooling energy it will utilize. Accordingly, the buildings cannot decide between the heating and cooling. Furthermore, often the heating and cooling sources are different and also the heating and cooling networks may be different. This makes the prior art systems even more complex. 
     BRIEF DESCRIPTION OF THE INVENTION 
     An object of the present invention is to provide a heating and cooling system, and an arrangement and method for heating and cooling of several building spaces or buildings so as to solve or at least alleviate the prior art disadvantages. The objects of the invention are achieved by a heating and cooling system which is characterized by what is stated in the independent claim  1 . The objects of the present invention are also achieved with an arrangement for heating and cooling of several building spaces or buildings which is characterized by what is stated in the independent claim  10 . The objects of the present invention are further achieved with a method for heating and cooling of several building spaces or buildings which is characterized by what is stated in the independent claim  18 . 
     The preferred embodiments of the invention are disclosed in the dependent claims. 
     The invention is based on the idea of providing a heating and cooling system for conditioning several building spaces. 
     The heating and cooling system comprises:
         a secondary thermal network for circulating secondary working fluid, the secondary thermal network comprising a supply line for circulating high-temperature secondary working fluid and a return line for circulating low-temperature secondary working fluid;   two or more connection lines provided to the secondary thermal network, each connection line extending between the supply line and the return line and arranged to connect the supply line and the return line to each other;   two or more primary heat exchangers arranged to the two or more connection lines and arranged to provide primary heat exchange connection between the secondary thermal network and the building space; and   a geothermal heat exchanger arranged in connection with the secondary thermal network.       

     According to the present invention, the geothermal heat exchanger comprises a geothermal network having a rise pipe and a drain pipe. The rise pipe is arranged inside the drain pipe, and the rise pipe of the geothermal heat exchanger is provided with a first thermal insulation surrounding the rise pipe and extending along at least part of the length of the rise pipe from the ground surface. 
     The coaxial structure of the geothermal heat exchanger together with the thermal insulation in the rise pipe enables utilizing deep geothermal energy higher geothermal temperatures in connection with the secondary thermal network. Further, this allows utilizing the geothermal heat exchanger and the ground hole in which it is installed both as a heat source or heat sink depending on the need of the secondary thermal network. 
     According to the above mentioned, the present invention provides a heating and cooling system in which two or more building spaces or buildings may be arranged parallel to each other in the secondary thermal network. This allows the two or more building spaces or buildings to be provided in heat exchange connection with each other via the secondary thermal network. Further, the building spaces or buildings are additionally in heat exchange connection with geothermal heat exchanger arranged in connection with the secondary thermal network. 
     The geothermal heat exchanger may comprise a rise pipe and a drain pipe and the supply line of the secondary thermal network is connected to the rise pipe and arranged in fluid communication with the rise pipe for allowing secondary working fluid flow between the rise pipe and the supply line. Further, the return line of the secondary thermal network may be connected to the drain pipe and arranged in fluid communication with the drain pipe for allowing secondary working fluid flow between the drain pipe and the return line. 
     The rise pipe is directly connected to the supply line such that the secondary working fluid may flow along the rise pipe and the supply line. Further, the drain pipe is directly connected to the return line such that the secondary working fluid may flow along the drain pipe and the return line. 
     Alternatively, the geothermal heat exchanger may comprise a rise pipe and a drain pipe arranged to provide a geothermal network for circulating geothermal working fluid along the rise pipe and the drain pipe, and the heating and cooling system may further comprise a secondary heat exchanger arranged between the secondary thermal network and the geothermal network, the secondary heat exchanger may be arranged to provide secondary heat exchange connection between the secondary working fluid and the geothermal working fluid. 
     Therefore, there is no direct connection between the secondary thermal network and the geothermal network, or the rise pipe and the supply line and the drain pipe and the return line. However, the geothermal network and the secondary thermal network are in heat exchange connection. Thus, there may be geothermal working fluid flowing in the geothermal network and the secondary working fluid in the secondary thermal network. The geothermal working fluid and the secondary working fluid may be in heat exchange connection via the secondary heat exchanger. 
     In one embodiment, the secondary heat exchanger is a secondary heat pump arranged between the secondary thermal network) and the geothermal network. The secondary heat pump is arranged to provide secondary heat exchange connection between the secondary working fluid the geothermal working fluid. 
     Therefore, the building spaces or buildings are additionally in heat exchange connection with geothermal heat exchanger arranged in connection with the secondary thermal network via the secondary heat pump. Thus, the geothermal network and the secondary thermal network are separate networks which are provided in the secondary heat exchange connection via the secondary heat pump. The secondary heat pump enables utilizing different temperatures and different working fluids in the geothermal network and in the secondary thermal network. Thus, low temperatures in the ground may be efficiently utilized in the secondary thermal network. 
     In one embodiment, the geothermal network is arranged in heat exchange connection with the secondary heat exchanger and the secondary thermal network is arranged in heat exchange connection with the secondary heat exchanger for providing the secondary heat exchange connection between the secondary working fluid and the geothermal working fluid. Thus, the secondary heat pump or the secondary heat exchanger provides heat exchange between the geothermal network and the secondary thermal network and between geothermal working fluid and the secondary working fluid. 
     The secondary thermal network may comprise a first secondary thermal sub-network, a second secondary thermal sub-network and a sub-network heat exchanger provided between the first secondary thermal sub-network and the second secondary thermal sub-network and arranged to provide sub-network heat exchange between the first secondary thermal sub-network and the second secondary thermal sub-network. 
     Accordingly, the secondary thermal network may be divided to two or more sub-networks connected to each other with sub-network heat exchangers. Each of the secondary thermal sub-networks comprise the supply line and the return line. The supply lines of the two or more secondary thermal sub-networks form the supply line of the overall secondary thermal network and the return lines of the two or more secondary thermal sub-networks form the return line of the overall secondary thermal network. Further, at least two of the secondary thermal sub-networks comprise one or more connection lines extending between the supply line and the return line and arranged to connect the supply line and the return line of the secondary thermal sub-network to each other, and one or more primary heat exchangers arranged to the two or more connection lines. 
     Alternatively, the secondary thermal network may comprise a first secondary thermal sub-network, a second secondary thermal sub-network and a sub-network heat pump provided between the first secondary thermal sub-network and the second secondary thermal sub-network and arranged to provide sub-network heat exchange between the first secondary thermal sub-network and the second secondary thermal sub-network. 
     The heat pump between the first and second secondary thermal sub-network allows the adjusting the temperature of the secondary working fluid in between the first and second secondary thermal sub-networks, or between the respective supply lines or return lines of the first and second secondary thermal sub-networks. 
     The system may comprise a first pump arranged to operate the geothermal heat exchanger in a heat extraction mode in which the secondary working fluid is circulated downwards in the drain pipe and upwards in the rise pipe, and a second pump arranged to operate the geothermal heat exchanger in a heat charging mode in which the secondary working fluid is circulated downwards in the rise pipe and upwards in the drain pipe. 
     Alternatively, the system may comprise a first pump which may be a reversible pump arranged to selectively operate the geothermal heat exchanger in a heat extraction mode in which the secondary working fluid is circulated downwards in the drain pipe and upwards in the rise pipe in a heat charging mode in which the secondary working fluid is circulated downwards in the rise pipe and upwards in the drain pipe. 
     Therefore, the geothermal heat exchanger may be used for supplying heat energy to the secondary thermal network, or to the supply line thereof, and for receiving heat energy from the secondary thermal network, or from the supply line thereof, to the geothermal heat exchanger. Therefore, the net or overall thermal energy need of the secondary thermal network or the buildings or buildings spaces may be taken into account in the utilization of the geothermal heat exchanger. 
     The rise pipe of the geothermal heat exchanger may be provided with a first thermal insulation surrounding the rise pipe extending along at least part of the length of the rise pipe from the ground surface. 
     Alternatively, the rise pipe of the geothermal heat exchanger may be an evacuated tube comprising a vacuum layer surrounding a flow channel of the rise pipe. The vacuum layer may be arranged to form a first thermal insulation extending along at least part of the length of the rise pipe. 
     Further alternatively, the rise pipe of the geothermal heat exchanger may comprise an insulation material layer on outer surface or on an inner surface of the rise pipe. The insulation material layer being arranged to form a first thermal insulation extending along at least part of the length of the rise pipe 
     Further, the rise pipe of the geothermal heat exchanger may comprise an inner pipe wall, an outer pipe wall and an insulation material layer provided between the inner pipe wall and the outer pipe wall of the rise pipe. The insulation material layer arranged to form the first thermal insulation surrounding the rise pipe and extending along at least part of the length of the rise pipe. 
     The first thermal insulation prevents heat transfer from the rise pipe to the ground along the rise pipe, preferably from the ground surface along the rise pipe towards the lower end of the rise and the lower end of the ground hole. Accordingly, the geothermal working fluid or the secondary working fluid may be transported from the lower end of the rise pipe to the ground surface such that the heat transfer is restricted and the temperature of the geothermal working fluid or the secondary working fluid may be kept high. Further, the geothermal working fluid or the secondary working fluid may be transported from the ground surface towards the lower end of the rise pipe such that the heat transfer is restricted and the temperature of the geothermal working fluid or the secondary working fluid may be kept high. 
     The two or more connection lines may be provided with a connection pump arranged to circulate the secondary working fluid between the supply line and the return line. 
     Further, at least one of the two or more connection lines may be provided with a first connection pump arranged to circulate the secondary working fluid in a direction from the supply line to the return line, and with a second connection pump arranged to circulate the secondary working fluid in a direction from the return line to the return line. 
     Alternatively, at least one of the two or more connection lines may be provided with a first connection pump which may be a reversible pump arranged to selectively circulate the secondary working fluid in a direction from the supply line to the return line and in a direction from the return line to the return line. 
     Accordingly, each of the parallel connection lines provided between the supply line and the return line may circulate the secondary working fluid from the supply line to the return line, or from the return line to the supply line, or from the supply line to the return line and from the return line to the supply line based on the operating mode of the primary heat exchanger. This may allow the connection lines to be in fluid communication with each other via the supply line and the return line and/or in heat exchange connection with each other via the supply line and he return line. 
     The primary heat exchanger may be a heat pump, or a heat pump arranged to circulate a heat pump working fluid in the heat pump and comprising a compressor and an evaporation device. The heat pump may enable utilizing low-temperature secondary working fluid for heating the building space or the building or providing high-temperature water for the building. 
     The primary heat exchanger may be a heat pump, and the heating and cooling system may comprise the solar energy apparatus provided in connection with the building or the building space and connected to the heat pump for supplying solar energy to the heat pump and for operating the heat pump. 
     This allows solar energy to be utilized in the heating and cooling and further to enhance energy efficiency of the system towards energy self-sufficiency. 
     The present invention further relates to an arrangement for heating and cooling of several building spaces or buildings. 
     The arrangement may comprise two or more building spaces or buildings and a secondary thermal network for circulating secondary working fluid. The secondary thermal network may comprise a supply line for circulating high-temperature secondary working fluid and a return line for circulating low-temperature secondary working fluid. The arrangement further comprises two or more building connections arranged parallel to each other and between the supply line and the return line of the secondary thermal network. The two or more building connections may comprise a primary heat exchanger provided in connection with the two or more building spaces or buildings. The arrangement may further comprise a ground hole provided into the ground and extending from the ground surface and a geothermal heat exchanger provided to the ground hole and arranged in connection with the secondary thermal network. 
     According to the present invention, the depth of the ground hole is at least 300, and that the arrangement comprises the geothermal heat exchanger provided to the ground hole having the depth of at least 300 m an arranged in connection with the secondary thermal network. 
     Therefore, the arrangement provides two or more parallel building connections which are connected to each other and the geothermal heat exchanger in the ground hole via the to the secondary thermal network. Thus, the arrangement enables the buildings or building spaces to exchange thermal energy with each other and with the geothermal heat exchanger. 
     Further, the deep ground hole of at least 300 meters enables access to higher temperatures in the ground. The temperature in the ground increases as function of the depth. Access to higher temperatures provides more efficient secondary thermal network as the temperature changes needs to be smaller within the arrangement. Further, the deep ground hole enables efficient storing of the excessive thermal energy from the buildings or building spaces without the thermal energy escaping from the ground hole. 
     The primary heat exchangers of the two or more building connections may be arranged in connection with different building spaces of a building. 
     The primary heat exchangers of the two or more building connections may be connected to building space thermal networks of different building spaces. The building space thermal networks may be arranged to circulate the primary working fluid of the building space. 
     Alternatively, two or more primary heat exchangers of the two or more building connections may be arranged in connection with different buildings. 
     Two or more primary heat exchangers of the two or more building connections may be connected to building thermal networks of different buildings. The building space thermal networks arranged to circulate the primary working fluid of the building. 
     Accordingly, in the arrangement the building connections may be provided in connection with different building spaces or different buildings or different building spaces and different buildings. This allows flexible and most efficient manner for utilizing thermal energy between the buildings and building spaces. 
     The geothermal heat exchanger may be connected to the secondary thermal network and the geothermal heat exchanger and the secondary thermal network may be arranged in fluid communication with each other for circulating the secondary working fluid in the geothermal heat exchanger. 
     Thus, the secondary working fluid may flow in the secondary thermal network and also in the geothermal heat exchanger. 
     Alternatively, the geothermal heat exchanger may be arranged in heat exchange connection with the secondary thermal network, and a secondary heat exchanger may be provided between the geothermal heat exchanger and the secondary thermal network for providing heat exchange between secondary thermal network and the geothermal heat exchanger. 
     Therefore, geothermal working fluid may be separate circulated in the geothermal heat exchanger and the secondary working fluid may be separately circulated in the secondary thermal network. Heat exchange between the geothermal working fluid and the secondary working fluid is carried out with the secondary heat exchanger. 
     In one embodiment, the secondary heat exchanger is a secondary heat pump arranged between the secondary thermal network and the geothermal network. The secondary heat pump is arranged to provide secondary heat exchange connection between the secondary working fluid the geothermal working fluid. The secondary heat pump enables utilizing different temperatures and different working fluids in the geothermal network and in the secondary thermal network. Thus, low temperatures in the ground may be efficiently utilized in the secondary thermal network. 
     In one embodiment, the geothermal network is arranged in heat exchange connection with the secondary heat exchanger and the secondary thermal network is arranged in heat exchange connection with the secondary heat exchanger or providing the secondary heat exchange connection between the secondary working fluid and the geothermal working fluid. Thus, the secondary heat pump or secondary heat exchanger provides heat exchange between the geothermal network and the secondary thermal network and between geothermal working fluid and the secondary working fluid. 
     Thus, the pipes or channels of the geothermal network and the pipes or channels of the secondary thermal network are not arranged in fluid connection with each other, but are separate from each other. This allows the geothermal network and the secondary thermal network to be operated in different temperatures and the geothermal working fluid and the secondary working fluid may be separate working fluids, if desired. Therefore, geothermal working fluid may be separately circulated in the geothermal heat exchanger and the secondary working fluid may be separately circulated in the secondary thermal network. Heat exchange between the geothermal working fluid and the secondary working fluid is carried out with the secondary heat pump. 
     The secondary thermal network may comprise two or more secondary thermal sub-networks arranged in heat exchange connection with each other. 
     Alternatively, the secondary thermal network may comprise two or more secondary thermal sub-networks. A sub-network heat exchanger may be arranged between the two or more secondary thermal sub-networks for providing heat exchange between the two or more secondary thermal sub-networks. 
     Further alternatively, the secondary thermal network may comprise two or more secondary thermal sub-networks. A sub-network heat exchanger or sub-network heat pump may be arranged between the two or more secondary thermal sub-networks for providing heat exchange between the two or more secondary thermal sub-networks. 
     Accordingly, the secondary thermal network may be divided into two or more secondary thermal sub-network which are provided in heat exchange connection with each other 
     The two or more parallel building connections may be connected to the each other via the supply line and the return line of the two or more secondary thermal sub-networks and arranged in heat transfer connection with each other via the supply line and the return line. 
     Alternatively, the secondary thermal network may comprise two or more secondary thermal sub-networks. One or more sub-network heat pumps may be arranged between the two or more secondary thermal sub-networks for providing heat exchange connection between the two or more secondary thermal sub-networks. At least two of the two or more secondary thermal sub-networks may comprise one or more building connections. The building connections may be connected to the each other via the two or more secondary thermal sub-networks and the one or more sub-network heat pumps and may be arranged in heat transfer connection with each other via the two or more secondary thermal sub-networks and the one or more sub-network heat pumps. 
     The sub-network heat pump(s) may allow adjusting, raising or lowering, temperature of the secondary working fluid flowing in connected secondary thermal sub-networks. 
     The arrangement of the present invention may comprise a heating and cooling system according to described above. 
     The present invention further relates to a method for heating and cooling of several building spaces or buildings. 
     The method may comprise:
         circulating secondary working fluid in a secondary thermal network   performing two or more first heat exchange steps parallel in the secondary thermal network between the secondary working fluid and a primary working fluid of the building space or building in connection with two or more different building spaces or buildings;   performing a second heat exchange step between the secondary working fluid circulated in the secondary thermal network and ground with a geothermal heat exchanger arranged in a ground hole and arranged in connection with the secondary thermal network.       

     According to the present invention, the method comprises performing the second heat exchange step between the secondary working fluid circulated in the secondary thermal network ground with the geothermal heat exchanger in the ground hole. The ground hole has a depth of at least 300 m. 
     Further, the deep ground hole of at least 300 meters enables performing the second heat exchange step at higher temperatures in the ground. The temperature in the ground increases as function of the depth. Access to higher temperatures provides more efficient method as the temperature changes needs to be smaller within the method. Further, the deep ground hole enables efficient storing of the excessive thermal energy from the buildings or building spaces without the thermal energy escaping from the ground hole. 
     The parallel first exchange steps enable combining the heat exchange of the parallel first exchange steps to each other and to the second heat exchange step. 
     The second heat exchange step may comprise circulating the secondary working fluid in the geothermal heat exchanger and performing heat exchange between the secondary working fluid and the ground in the ground hole. 
     Thus, the secondary working fluid may be utilized in the first and second heat exchange steps. 
     Alternatively, the second heat exchange step may comprise circulating geothermal working fluid in the geothermal heat exchanger, performing heat exchange between the secondary working fluid circulated in the secondary thermal network and the geothermal working fluid circulated in the geothermal heat exchanger and performing heat exchange between the geothermal working fluid and the ground in the ground hole. 
     Accordingly, the geothermal working fluid and the secondary working fluid may circulated separate and arranged in heat exchange connection with each other. 
     In one embodiment, the second heat exchange step comprises circulating the geothermal working fluid in a geothermal network provided to the geothermal heat exchanger in the ground, performing the second heat exchange step with a secondary heat exchanger or a secondary heat pump between the secondary working fluid circulated in the secondary thermal network and the geothermal working fluid circulated in the geothermal network, and performing a geothermal heat exchange step between the geothermal working fluid and the ground with the geothermal heat exchanger arranged in the ground hole. 
     Accordingly, the geothermal working fluid and the secondary working fluid may circulated separately and arranged in heat exchange connection with each other with the secondary heat pump or the secondary heat exchanger. 
     Therefore, the building spaces or buildings are additionally in heat exchange connection with geothermal heat exchanger arranged in connection with the secondary thermal network via the secondary heat pump. Thus, the geothermal network and the secondary thermal network are separate networks which are provided in the secondary heat exchange connection via the secondary heat pump or the secondary heat exchanger. The secondary heat pump enables utilizing different temperatures and different working fluids in the geothermal network and in the secondary thermal network. Thus, low temperatures in the ground may be efficiently utilized in the secondary thermal network. 
     The method may further comprise operating the geothermal heat exchanger in a heat extraction mode in which the second heat exchange step comprises transferring heat energy from the ground to the secondary working fluid or to the geothermal working fluid in the geothermal heat exchanger. 
     Alternatively, the method may comprise operating the geothermal heat exchanger in a heat charging mode in which the second heat exchange step comprises transferring heat energy from the secondary working fluid or from the geothermal working fluid to the ground in the geothermal heat exchanger. 
     Therefore, the geothermal heat exchanger may be used in the extraction mode or in charging based on the net heat energy need or excess of the parallel first heat exchange steps. 
     The method may also comprise performing at least one of the two or more parallel first heat exchange steps in a heating mode in which heat energy in transferred from the secondary working fluid to the primary working fluid of the building space or the building. 
     Alternatively or additionally, the method may comprise performing at least one of the two or more parallel first heat exchange steps in a cooling mode in which heat energy in transferred from the primary working fluid of the building space or the building to the secondary working fluid. 
     Further alternatively, the method may comprise performing at least one of the two or more parallel first heat exchange steps in a heating mode in which heat energy in transferred from the secondary working fluid to the primary working fluid of the building space or the building, and performing at least one of the two or more first primary heat exchange steps in a cooling mode in which heat energy in transferred from the primary working fluid of the building space or the building to the secondary working fluid. 
     Thus, each of the first heat exchange steps may be carried out in heating or in cooling mode independently of the other first heat exchange steps. 
     The method may comprise carrying out the two or more parallel first heat exchange steps with two or more parallel primary heat exchangers provided in connection with two or more different building spaces, operating at least one of the two or more the primary heat exchanges in the heating mode in which heat energy in transferred from the secondary working fluid to the primary working fluid of the building space or the building, and operating at least one of the two or more the primary heat exchangers in the cooling mode in which heat energy in transferred from the primary working fluid of the building space or the building to the secondary working fluid. The method may further comprise carrying out district thermal exchange between the at least one of the two or more the primary heat exchanges operated in the heating mode and the at least one of the two or more the primary heat exchangers operated in the cooling mode via the secondary thermal network. 
     The method may further comprise circulating high-temperature secondary working fluid in a supply line of the secondary thermal network and low-temperature secondary working fluid in a return line of the secondary thermal network, and increasing the temperature of the high-temperature secondary working fluid circulated in supply line of the secondary thermal network and lowering the temperature of the low-temperature secondary working fluid circulated in return line of the secondary thermal network by utilizing a heat pump arranged to the secondary thermal network between the supply line and the return line. 
     An advantage of the invention is that the system, arrangement and method combines district and local heating as well as heating and cooling. The invention allows different buildings and building spaces to be heated and cooled individually and further to exchange thermal energy with each other. Therefore, the different buildings or building spaces may utilize thermal energy of each other and only the net or overall thermal energy needed or in excess may be extracted or supplied to or from, respectively, the geothermal heat exchanger which is connected to the buildings or building spaces. Further, the geothermal heat exchanger may be used in the heat extraction mode when net thermal energy need of the buildings or building spaces is negative, and in heat charging mode when net thermal energy need of the buildings or building spaces is positive. In the heat extraction mode heat energy is supplied from the ground to the geothermal heat exchanger and further to the secondary thermal network. In the heat charging mode heat energy is supplied from the secondary thermal network to the geothermal heat exchanger and further to the ground. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in detail by means of specific embodiments with reference to the enclosed drawings, in which 
         FIG. 1  shows schematically a geothermal heat exchanger in extraction mode; 
         FIG. 2  shows schematically a geothermal heat exchanger in charging mode; 
         FIG. 3  shows schematically principle of a heating and cooling system according to the present invention; 
         FIG. 4  shows a modification of the system of  FIG. 3  with a secondary heat exchanger; 
         FIG. 5  shows schematically a heat pump utilized in the heating and cooling system; 
         FIG. 6  shows schematically a secondary heat pump utilized in the present invention; 
         FIG. 7  shows schematically one embodiment of a heating and cooling system according to the present invention; 
         FIG. 8  shows a modification of the system of  FIG. 3  with a secondary heat exchanger; 
         FIG. 9  shows schematically another embodiment of a heating and cooling system according to the present invention; 
         FIGS. 10, 11, 12 and 13  show schematically alternative embodiments of the heating and cooling system according to the present invention; 
         FIG. 14  shows one embodiment of a geothermal heat exchanger; and 
         FIG. 15  shows another embodiment of a geothermal heat exchanger. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a geothermal heating apparatus. The geothermal heating apparatus comprises a ground hole  2  or bore hole provided to the ground and extending downwards into the ground from the ground surface  1 . The ground hole  2  may be formed by drilling or some other excavating method. 
     In the context of the present application the depth of the ground hole  2  from the ground surface  1  may be at least 300 m, or at least 500 m, or between 300 m and 3000 m, or between 500 m and 2500 m. Alternatively or additionally, the ground hole  2  extends into the ground to a depth in which the temperature is at least 15° C., or approximately 20° C., or at least 20° C. 
     The ground hole  2  may extend to a depth under the water table in the ground, meaning through the water table. Alternatively, the ground hole  2  may extend to a depth above the water table in the ground. 
     It should be noted that in the figures similar structural part and structures are denoted with same reference numerals and their description is not repeated in relation to every figure. 
     It should be noted that according to the present invention the geothermal heat exchanger may be used in heat extraction mode or in heat charging mode. 
     Further, in the present application the ground hole  2  may be any kind of hole extending into the ground it may be vertical hole, straight vertical or otherwise straight hole extending into the ground in an angle to the ground surface  1  or to the vertical direction. Furthermore, the ground hole  2  may be may have one or more bends and the direction of the ground hole may change one or more times along the length of the ground towards the lower end or bottom of the ground hole  2 . Additionally, it should be noted that shape or form a rise pipe and a drain pipe may of a geothermal heat exchanger preferably conform the shape or form of the ground hole  2 , at least substantially, in order to provide proper installation of the rise pipe and the drain pipe into the ground hole  2 . Preferably, the ground hole  2  extends to a depth as mentioned above, but it may one or more bends along the length or it may be straight. 
     The ground material at the lower end  4  of the ground hole  2  is usually rock material. Accordingly, the ground or the rock material of the ground may form surface of the ground hole  2  or inner surface of a rise pipe or a drain pipe of a geothermal heat exchanger along at least part of the length of the rise pipe or the drain pipe of the geothermal heat exchanger. 
     There is a geothermal heat exchanger  55  arranged in connection with the ground hole  2 . The geothermal heat exchanger  55  comprises a piping arrangement in which a working fluid is circulated. The piping arrangement usually comprises a closed loop piping arranged to provide closed circulation of the working fluid. The working fluid is usually a liquid, such as water or methanol or ethanol based working fluid. The piping arrangement comprises a rise pipe  11  and a drain pipe  21  arranged into the ground hole  2  such that they extend from the ground surface  1  towards a bottom  4  of the ground hole  2 . The rise pipe  11  and the drain pipe  21  are in fluid communication with each other at the lower ends of the rise pipe  11  and the drain pipe  21  or at the lower end  4  of the ground hole  2  for circulating the working fluid in ground hole  2  between the rise pipe  11  and the drain pipe  21 . There may be one or more rise pipes  11  and drain pipe  21  arranged into the same or different ground holes  2 . 
     In the embodiment of  FIG. 1 , there is no separate drain pipe  21 , but the ground hole  2  is arranged to form the drain pipe  21 . This enables efficient heat transfer between the geothermal working fluid and the ground. In this embodiment, the ground may be formed from rock enabling using the ground as the drain pipe  21 . In this embodiment, the rise pipe  11  is arranged inside the drain pipe  21 . The rise pipe  11  and the drain pipe  21  may be arranged inside each other or coaxially and/or parallel to each other and within each other. However, it should be noted that similarly the drain pipe  21  could be arranged inside the rise pipe  11 . 
     The heat pump  30  and the rise pipe  11  may be connected to each other with a first connection pipe  3  and the heat pump  30  and the drain pipe  21  may be connected to each other with a second connection pipe  5 . The first connection pipe  3  may form part of the rise pipe  11  and the second connection pipe  5  may form part of the drain pipe  5 . 
     The geothermal heat exchanger  55  of  FIG. 1  comprises a first pump  8  arranged to the piping arrangement for circulating the working fluid in the piping arrangement in the heat charging mode of the geothermal heat exchanger  55  in which the working fluid is circulated in the direction towards the lower end  17  of the rise pipe  11  or downwards in the rise pipe  11  and upwards the drain pipe  21 , as shown with arrows  22  and  12 . The first pump  8  may be any kind of known pump capable of circulating the working fluid. The geothermal heat exchanger  55  further comprises a second pump  9  arranged to circulate the working fluid in a direction downwards the drain pipe  21  and upwards the rise pipe  11 , when the geothermal heat exchanger and the geothermal heat arrangement are in heat extraction mode. The second pump  9  may be any kind of known pump capable of circulating the working fluid. Accordingly, the first pump  8  is arranged to operate in the heat charging mode and the second pump  9  in the heat extraction mode. 
     The first pump  8  may be arranged to or in connection with the first connection pipe  3  or the to the rise pipe  11 . The second pump  9  may be arranged to or in connection with the second connection pipe  5  or the to the drain pipe  21 . 
       FIG. 1  shows the geothermal heat exchanger  55  in heat extraction mode in which the working fluid receives heat energy from the ground in the ground hole  2  and circulates the heated working fluid upwards in the rise pipe  11 , as shown with arrow  22 . The working fluid releases the heat energy in the heat pump  30 , for example to a building space. Thus, a cool working fluid flow  54  receives heat energy in the heat pump  30  and becomes as heated working fluid flow  52 . At the same time the temperature of the working fluid flow circulating the geothermal heat exchanger  55  decreases and the cooled working fluid returns to the ground hole  2  along the drain pipe  21 , and again receives thermal energy from the ground as indicated with arrows C. Thus, when the geothermal heat exchanger operates in heat extraction mode, the heat pump  30  operates in the heating mode in which the working fluid receives heat energy from the geothermal heat exchanger  55 . 
       FIG. 2  shows the geothermal heat exchanger  55  in heat charging mode in which the working fluid releases heat energy to the ground in the ground hole  2  and circulates the cooled working fluid upwards in the drain pipe  21 , as shown with arrow  12 . The working fluid receives the heat energy in the heat pump  30 , for example from a building space. Thus, a heated primary working fluid flow  51  releases heat energy in the heat pump  30  and becomes as cooled primary working fluid flow  53 . At the same time the temperature of the working fluid flow circulating the geothermal heat exchanger  55  increases and the heated working fluid returns to the ground hole  2  along the rise pipe  11 , and again releases thermal energy to the ground as indicated with arrows C. Thus, when the geothermal heat exchanger operates in heat charging mode, the heat pump  30  operates in the cooling mode in which the primary working fluid releases heat energy to the geothermal heat exchanger  55 . 
     In the embodiment of  FIG. 2 , there is only the first pump  8 . The first pump  8  may a reversible pump arranged to pump the working fluid in a direction downwards the rise pipe  10  and upwards the drain pipe  20 , or alternatively in direction downwards the drain pipe  20  and upwards the rise pipe  10 . The first one is the charging mode in which thermal energy is charged to the ground and the second is a reverse mode, meaning extraction, mode in which charged thermal energy is extracted from the ground. 
     As shown in  FIGS. 1 and 2 , a first thermal insulation  25  extends from the ground surface  1  to the lower end  17  of the rise pipe  11  along the rise pipe  11 . Thus, the first thermal insulation  25  may extend along the entire length of the rise pipe  11 , at least inside the ground hole  2  or the drain pipe  21 . The first thermal insulation  25  may also extend along the entire length of the rise pipe  11 . In these embodiments, the rise pipe  11  may be an evacuated tube comprising a vacuum layer surrounding the flow channel of the rise pipe  11 . Thus, the vacuum layer is arranged to form the first thermal insulation  25 . It may also be provided with any other insulating material. The rise pipe  11  may comprise an inner pipe wall, an outer pipe wall and an insulation material layer  25  provided between the inner pipe wall and the outer pipe wall of the rise pipe  11 . 
     The thermal insulation layer or the first thermal insulation  25  may be formed any suitable material preventing or decreasing heat exchange of the working fluid. The thermal insulation means material capable insulating against transmission of heat, or material of relatively low heat conductivity used to shield the fluid against loss or entrance of heat by radiation, convection, or conduction. Several different thermal insulation materials or vacuum may be used. 
     The first thermal insulation  25  decreases or minimizes heat transfer to and from the working fluid flow  22  in the rise pipe  11  such that the working fluid may be transported in heated form or in elevated temperature to the lower end  17  of the first pipe  11  and the lower end  4  of the ground hole  2  in the heat charging mode. Accordingly, the working fluid releases thermal energy C at elevated temperature to the ground surrounding the ground hole  2  at the lower end  4  of the ground hole  2  and thus charges thermal energy to the ground for later use, as shown in  FIG. 2 . This applies to all embodiment in which the first thermal insulation  25  is used. Furthermore, first thermal insulation  25  decreases or minimizes heat transfer to and from the working fluid flow  22  in the rise pipe  11  such that the working fluid may be transported in heated form or in elevated temperature from the lower end  17  of the first pipe  11  and the lower end  4  of the ground hole  2  in the heat extraction mode, to the ground surface  1 . Accordingly, the working fluid receives thermal energy C at elevated temperature from the ground surrounding the ground hole  2  at the lower end  4  of the ground hole  2  and thus extracts thermal energy from the ground to be transported to the heat pump  30 . This applies to all embodiment in which the first thermal insulation  25  is used 
     It should be noted, that also the drain pipe  21  may be provided with a second thermal insulation extending from the ground surface towards the lower end  4  of the ground hole  2  in similar manner as the first thermal insulation  25 . 
       FIG. 3  shows one embodiment of the present invention. The present invention provides a heating and cooling system for conditioning several building spaces. The system comprises a secondary thermal network  3 ,  5  for circulating secondary working fluid. The secondary thermal network comprises a supply line  3  in which high-temperature secondary working fluid is circulated and return line  5  in which low-temperature secondary working fluid is circulated. In the secondary thermal network the supply line  3  and the return line  5  are connected to each other with two or more connection lines or pipes  60 ,  61 ,  62 ,  63 . The two or more connection lines or pipes  60 ,  61 ,  62 ,  63  arranged between the supply line  3  and the return line  5  and arranged to connect the supply line  3  and the return line  5  to each other such that the secondary thermal working fluid may flow between the supply line  3  and the return line  5  via the two or more connection lines  60 ,  61 ,  62 ,  63 . Accordingly, the connection lines  60 ,  61 ,  62 ,  63  are arranged parallel to each other to the secondary thermal network and between the supply line  3  and the return line  5 . 
     Two or more of the connection lines  60 ,  61 ,  62 ,  63  is provided with a primary heat exchanger  30 ,  31 ,  32 ,  33 . The primary heat exchangers  30 ,  31 ,  32 ,  33  are arranged to provide a primary heat exchange connection between the secondary thermal network and a building space or building. Thus, the primary heat exchangers  30 ,  31 ,  32 ,  33  are provided in connection with buildings or building spaces. Thus, the parallel primary heat exchangers  30 ,  31 ,  32 ,  33  may utilize the secondary working fluid circulating in the supply line  3  and the return line  5  for the primary heat exchange for the buildings or building spaces. 
     The system further comprises at least one geothermal heat exchanger  55  arranged in connection with the secondary thermal network. The geothermal heat exchanger  55  is provided with a geothermal network  92  for circulating geothermal working fluid in the geothermal heat exchanger  55  and in the ground hole  2 . 
     The rise pipe  10 ,  11  and the drain pipe  20 ,  21  may form the geothermal network  92 . 
     The geothermal heat exchanger  55  is preferably connected between the supply line  3  and the return line  5  directly or in heat exchange connection such that that the geothermal heat exchanger  55  may receive and release heat energy to and from the secondary thermal network. 
     In  FIG. 3 , the geothermal heat exchanger  55  comprises the rise pipe  10 ,  11  and the drain pipe  20 ,  21  and the geothermal heat exchanger is directly connected to the secondary thermal network. Thus, the supply line  3  of the secondary thermal network is connected to the rise pipe  10 ,  11  and arranged in fluid communication with the rise pipe  10 ,  11  for allowing secondary working fluid flow between the rise pipe  10 ,  11  and the supply line  3 . Similarly, the return line  5  of the secondary thermal network is connected to the drain pipe  20 ,  21  and arranged in fluid communication with the drain pipe  20 ,  21  for allowing secondary working fluid flow between the drain pipe  20 ,  21  and the return line  5 . 
     Accordingly, in this embodiment the geothermal heat exchanger  55  is connected to the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63 , and the geothermal heat exchanger  55  and the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  are arranged in fluid communication with each other for circulating the secondary working fluid in the geothermal heat exchanger  55   
     The connection lines  60 ,  61 ,  62 ,  63  are provided with a connection pump  70 ,  71 ,  72 ,  73  arranged to circulate the secondary working fluid between the supply line  3  and the return line  5 . Thus, at least one of the two or more connection lines  60 ,  61 ,  62 ,  63  is provided with a first connection pump  70 ,  71 ,  72 ,  73  arranged to circulate the secondary working fluid in a direction from the supply line  3  to the return line  5 , and with a second connection pump  74  arranged to circulate the secondary working fluid in a direction from the return line  5  to the return line  3 . Alternatively, at least one of the two or more connection lines  60 ,  61 ,  62 ,  63  is provided with a first connection pump  70 ,  71 ,  72 ,  73  which is a reversible pump arranged to selectively circulate the secondary working fluid in a direction from the supply line  3  to the return line  5  and in a direction from the return line  5  to the return line  3 . 
     In the heating mode of the primary heat exchanger  30 ,  31 ,  33 , the secondary working fluid releases heat energy to the building or building space, as shown in  FIG. 3  with arrows  52 . Then the secondary working fluid is circulated from the supply line  3  via the connection lines  60 ,  61 ,  63  and the primary heat exchangers  30 ,  31 ,  33  to the return line  5 . In the cooling mode of the primary heat exchanger  32 , the secondary working fluid receives heat energy from the building or building space, as shown in  FIG. 3  with arrow  54 . Then the secondary working fluid is circulated from the return line  5  via the connection line  62  and the primary heat exchanger  32  to the supply line  3 . 
     It should be noted, that each of the primary heat exchangers  30 ,  31 ,  32 ,  33  may be operated in the cooling mode or in the heating mode. Therefore, the parallel primary heat exchangers  30 ,  31 ,  32 ,  33  are arranged in heat exchange connection with each other via the secondary thermal network and the supply line  3  and the return line  5 . Thus, the primary heat exchangers(s)  32  operated in cooling mode may supply heat energy to the supply line  3  and this heat energy may be utilized by the primary heat exchangers  30 ,  31 ,  33  in the heating mode. 
     The geothermal heat exchanger  55  may be operated in the heat extraction mode or in the heat charging mode based on a net or overall heat energy demand of the parallel primary heat exchangers  30 ,  31 ,  32 ,  33 . When the primary heat exchangers  30 ,  31 ,  33  operated in the heating mode need more heat energy from the secondary thermal network than the primary heat exchanger(s)  32  operated in the cooling mode supplies to the secondary thermal network, then the geothermal heat exchanger  55  may be operated in heat extraction mode. Alternatively, when the primary heat exchangers  30 ,  31 ,  33  operated in the heating mode less heat energy from the secondary thermal network than the primary heat exchanger(s)  32  operated in the cooling mode supplies to the secondary thermal network, then the geothermal heat exchanger  55  may be operated in heat charging mode. 
     The system may comprise the first pump  8 , the first pump being a reversible pump arranged to selectively operate the geothermal heat exchanger  55  in a heat extraction mode in which the secondary working fluid is circulated downwards in the drain pipe  21  and upwards in the rise pipe  11  in a heat charging mode in which the secondary working fluid is circulated downwards in the rise pipe  11  and upwards in the drain pipe  21 . The first pump  8  may be provided to the supply line  3 , or return line  5 , or rise pipe  11  or drain pipe  21 . 
     Alternatively, in the embodiment of  FIG. 3 , in which the secondary working fluid is also circulated in the geothermal heat exchanger  55 , the first connection pumps  70 ,  71 ,  72 ,  73  provided to the connection lines  60 ,  61 ,  62 ,  63  or in connection with the primary heat exchangers  30 ,  31 ,  32 ,  33  may be arranged to circulate the secondary working fluid in the geothermal heat exchanger  55  and the first pump  8  may be omitted. This may be advantageous, as the system and the use of the geothermal heat exchanger  55  becomes automated based on the net heat energy demand of the primary heat exchangers  55 . 
     The primary heat exchanger  30 ,  31 ,  32 ,  33  may be a heat pump or any other known type of heat exchanger. 
       FIG. 4  shows an alternative embodiment of  FIG. 3 . In this embodiment, the heating and cooling system or arrangement further comprises a secondary heat pump  90  arranged between the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  and the geothermal network  11 ,  21 ,  92 . The secondary heat pump  90  is arranged to provide secondary heat exchange connection between the secondary working fluid and the geothermal working fluid, and between the geothermal network  92  and the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63 . Accordingly, the circulation of the secondary working fluid and the geothermal working fluid, as well as the geothermal network (or the geothermal heat exchanger  55 ) and the secondary thermal network are separated from each other with the secondary heat pump  90 . Therefore, the geothermal heat exchanger  55 , or the geothermal network  92 , is arranged in secondary heat exchange connection with the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63 , and the secondary heat pump  90  is provided between the geothermal heat exchanger  55 , or the geothermal network  92 , and the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  for providing heat exchange between secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  and the geothermal heat exchanger  55 . Thus, the geothermal network  92  is connected to the secondary heat pump  90  and the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  is also connected to the secondary heat pump  90  for providing the secondary heat exchange connection and for carrying out heat transfer between the geothermal network  92  and the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63 , and the geothermal working fluid and the secondary working fluid. 
     Therefore, in the heat extraction mode of the geothermal heat exchanger  55  heat energy is transferred from the geothermal network  92  and the geothermal working fluid to the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  and the secondary working fluid in the secondary heat pump  90 . Similarly, in the heat charging mode of the geothermal heat exchanger  55  heat energy is transferred from the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  and the secondary working fluid to the geothermal network  92  and the geothermal working fluid in the secondary heat pump  90 . 
     The secondary heat pump  90  enables the geothermal network  92  and the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  to be operated in different temperatures. Further, the secondary heat pump  90  enables utilizing also small temperature differences and small thermal energy amounts together with the geothermal heat exchanger  55 . 
     The secondary heat pump  90  may be replaced with a secondary heat exchanger. 
     The geothermal heat exchanger  55  of  FIG. 4  comprises a first pump  8  arranged to the piping arrangement for circulating the working fluid in the piping arrangement in the heat charging mode of the geothermal heat exchanger  55  in which the working fluid is circulated in the direction towards the lower end  17  of the rise pipe  11  or downwards in the rise pipe  11  and upwards the drain pipe  21 , as shown with arrows  22  and  12 . The first pump  8  may be any kind of known pump capable of circulating the working fluid. The geothermal heat exchanger  55  further comprises a second pump  8 ′ arranged to circulate the working fluid in a direction downwards the drain pipe  21  and upwards the rise pipe  11 , when the geothermal heat exchanger and the geothermal heat arrangement are in heat extraction mode. The second pump  8 ′ may be any kind of known pump capable of circulating the working fluid. Accordingly, the first pump  8  is arranged to operate in the heat charging mode and the second pump  8 ′ in the heat extraction mode. 
     Thus, the geothermal network is provided with the first pump  8  and the second pump  8 ′. Further, the first pump  8  may be reversible pump and the second pump  8 ′ may be omitted. 
       FIG. 5  shows schematically one embodiment of the primary heat pump  30  arranged to the connection line  60  and between the supply line  3  and the return line  5 . 
     In the heating mode of the heat pump  30  and in heat extraction mode of the geothermal heat exchange, in the heat pump  30  the secondary working fluid releases thermal energy to the heat pump working fluid. The heat pump working fluid receives thermal energy from the secondary working fluid in a secondary heat exchange connection  104  of the heat pump  30 . The heat pump working fluid may be any suitable fluid such as refrigerant. The heat pump  30  may comprise a pump  35  provided to the heat pump  30  for circulating the heat pump working fluid in the heat pump  30 . 
     The secondary heat exchange connection  104  may be an evaporator and the liquid heat pump working fluid receives or absorbs thermal energy from the secondary working fluid in the evaporator  104  and the heat pump working fluid is turned into gas or becomes gas. Then the gaseous heat pump working fluid flows or is circulated into a compressor  101  arranged to raise the pressure and increase the temperature of the gaseous heat pump working fluid. 
     Then the gaseous heat pump working fluid releases thermal energy to a primary working fluid of the building space or building in a primary heat exchange connection  103  of the heat pump  30 . The primary working fluid receives thermal energy from the heat pump working fluid in the primary heat transfer connection  103 . 
     The primary heat exchange connection  103  may be a condenser and the gaseous heat pump working fluid may condense back to liquid as it releases thermal energy to the primary working fluid. Then the liquid heat pump working fluid flows or is circulated to an expansion device  102  in which the pressure of the liquid heat pump working fluid is reduced and the temperature decreased. 
     In the heating mode of the heat pump  30  cold primary working fluid flow  54  is received into the heat pump  30  from the building or the building space and it receives thermal energy in the primary heat exchange connection  103  such that the temperature of the primary working fluid increases. Then the heated primary working fluid flow  52  is supplied to the building or the building space. 
     Then heat pump working fluid flows or is circulated back to the secondary heat transfer connection  104  and the cycle is repeated. 
     The secondary working fluid releases thermal energy in the heat pump  30 , or in the secondary heat transfer connection  104  of the heat pump  30 . The thermal energy is released and received to the heat pump working fluid. Therefore, the temperature of the secondary working fluid decreases in the heat pump  30  or as it flows through the heat pump  30  or the secondary heat exchange connection  104 . The secondary working fluid is circulated from the supply line  3  to the heat pump  30  and further to the return line  5 , and it releases heat energy in the heat pump  30  and the temperature of the secondary working fluid is decreased. 
     When the heat pump  30  is operated in the cooling mode, the heat pump  30  receives or absorbs heat energy from the primary working fluid of the building or the building space. In the cooling mode the primary heat exchange connection  103  is arranged to transfer thermal energy from the heat pump working fluid to the primary working fluid such that the temperature of the primary working fluid decreases and the temperature of the heat pump working fluid increases. 
     Liquid heat pump working fluid receives or absorbs thermal energy from the primary working fluid of the building space or building in the primary heat exchange connection  103  of the heat pump  30 . Thus, a warm or hot flow of primary working fluid releases thermal energy to the liquid heat pump working fluid in the primary heat transfer connection  103 . The primary working fluid cools down or the temperature of the primary working fluid decreases. The cool primary working fluid flow flows back from the heat pump  30  to the building or the building space. 
     The primary heat exchange connection  103  may be now an evaporator. The liquid heat pump working fluid receives or absorbs thermal energy from the primary working fluid in the evaporator and evaporates to gas forming gaseous heat pump working fluid. 
     The gaseous heat pump working fluid flows or is circulated to the compressor  101 . The compressor  101  is arranged to raise the pressure and to increase the temperature of the gaseous working fluid. From the compressor  101  the gaseous heat pump working fluid flows or is circulated to the secondary heat exchange connection  104 . In the secondary heat exchange connection  104  high-temperature heat pump working fluid releases heat energy to the secondary working fluid in the secondary heat exchange connection  104 . Therefore, the temperature of the heat pump working fluid decreases and the heat pump working fluid returns to liquid state. 
     The secondary heat exchange connection  104  may be now the condenser. The gaseous heat pump working fluid releases thermal energy to the secondary working fluid in the condenser and turns into liquid forming liquid heat pump working fluid. 
     It should be noted, that in the context of the present invention the heat pump  30  may comprise only the primary and secondary heat transfer connections  103 ,  104 . Furthermore, the primary and secondary heat transfer connections  103 ,  104  may comprise any know kind of heat exchangers. Accordingly, the present invention is not limited to any particular kind of heat pump  30 . The heat pump  30  may be liquid-to-liquid heat pump in which both the geothermal working fluid and the primary working fluid are liquids, or liquid-to-gas (or liquid-to-air) heat pump in which the geothermal working fluid is liquid and the primary working fluid is gas, such as air. 
     Further, in some embodiments the heat pump  30  may be replaced or it may be a heat exchanger in which the thermal energy is transferred directly between the secondary working fluid and the primary working fluid of the building space or the building. The flow of the secondary working fluid in the connection lines  60 ,  61 ,  62 ,  63  is carried out based on the heating and cooling modes. Alternatively, the heat pump  30  may be replaced or it may be any known kind of heat exchange connection provided between the primary working fluid and the secondary working fluid. 
     Additionally it should be noted, that the heat pump working fluid could also be omitted and the primary working fluid or the secondary working fluid could be circulated in the heat pump  30  via the compressor  101 , the expansion device  102  and the primary and secondary heat exchange connections  103 ,  104 . 
       FIG. 6  shows schematically one embodiment of the secondary heat pump  90  arranged between the geothermal network  92  and the secondary thermal network  3 ,  5 . 
     In heat extraction mode of the geothermal heat exchanger  55  the geothermal working fluid flowing in the geothermal network  92  releases thermal energy in the secondary heat pump  90  to the heat pump working fluid. The heat pump working fluid receives thermal energy from the geothermal working fluid in a secondary heat exchange connection  204  of the secondary heat pump  90 . The heat pump working fluid may be any suitable fluid such as refrigerant. The secondary heat pump  90  may comprise a pump  205  provided to the secondary heat pump  90  for circulating the heat pump working fluid in the secondary heat pump  90 . The geothermal working fluid is circulated in the geothermal network upwards the rise pipe  11  to the secondary heat pump  90 . 
     The secondary heat exchange connection  204  may be an evaporator and the liquid heat pump working fluid receives or absorbs thermal energy from the geothermal working fluid in the evaporator  204  and the heat pump working fluid is turned into gas or becomes gas. Then the gaseous heat pump working fluid flows or is circulated into a compressor  201  arranged to raise the pressure and increase the temperature of the gaseous heat pump working fluid. 
     Then the gaseous heat pump working fluid releases thermal energy to a secondary working fluid flowing in the secondary thermal network  3 ,  5  in a primary heat exchange connection  203  of the secondary heat pump  90 . The secondary working fluid receives thermal energy from the heat pump working fluid in the primary heat transfer connection  203 . The secondary working fluid flows to the secondary heat pump  90  from the return line  5  and back to the supply line  3  via the primary heat exchange connection  203  in elevated temperature. 
     The primary heat exchange connection  203  may be a condenser and the gaseous heat pump working fluid may condense back to liquid as it releases thermal energy to the primary working fluid. Then the liquid heat pump working fluid flows or is circulated to an expansion device  202  in which the pressure of the liquid heat pump working fluid is reduced and the temperature decreased. 
     In the heat charging mode of the geothermal heat exchanger  55  the geothermal working fluid flowing in the geothermal network  92  receives thermal energy in the secondary heat pump  90  from the heat pump working fluid. The heat pump working fluid releases thermal energy to the geothermal working fluid in the secondary heat exchange connection  204  of the secondary heat pump  90 . The heated geothermal working fluid is circulated in the geothermal network downwards the rise pipe  11  from the secondary heat pump  90 . 
     In secondary heat pump  90  heated secondary working fluid flow is received into the secondary heat pump  90  from secondary thermal network  3 ,  5 , or the supply line  3 , and it releases thermal energy in the primary heat exchange connection  203  such that the temperature of the secondary working fluid decreases. Then the secondary working fluid flows to the return line  5 . 
     Then heat pump working fluid flows or is circulated back to the secondary heat transfer connection  204  and the cycle is repeated. 
     The secondary working fluid releases thermal energy in the secondary heat pump  90 , or in the secondary heat transfer connection  204  of the secondary heat pump  90 . The thermal energy is released and received to the heat pump working fluid. Therefore, the temperature of the secondary working fluid decreases in the secondary heat pump  90  or as it flows through the secondary heat pump  90  or the secondary heat exchange connection  204 . The secondary working fluid is circulated from the supply line  3  to the secondary heat pump  50  and further to the return line  5 , and it releases heat energy in the secondary heat pump  90  and the temperature of the secondary working fluid is decreased. 
     When the geothermal heat exchanger  55  is operated in the heat charging mode, the secondary heat pump  90  receives or absorbs heat energy from the secondary working fluid in the secondary thermal network  3 ,  5 . The primary heat exchange connection  203  is arranged to transfer thermal energy from secondary working fluid to the heat pump working fluid such that the temperature of the secondary working fluid decreases and the temperature of the heat pump working fluid increases. 
     Liquid heat pump working fluid receives or absorbs thermal energy from the secondary working fluid of the secondary thermal network in the primary heat exchange connection  203  of the secondary heat pump  90 . Thus, a warm or hot flow of secondary working fluid releases thermal energy to the liquid heat pump working fluid in the primary heat transfer connection  203 . The secondary working fluid cools down or the temperature of the secondary working fluid decreases. The cool secondary working fluid flow flows back from the secondary heat pump  30  to the return line  5 . 
     The primary heat exchange connection  203  may be now an evaporator. The liquid heat pump working fluid receives or absorbs thermal energy from the primary working fluid in the evaporator and evaporates to gas forming gaseous heat pump working fluid. 
     The gaseous heat pump working fluid flows or is circulated to the compressor  201 . The compressor  201  is arranged to raise the pressure and to increase the temperature of the gaseous working fluid. From the compressor  201  the gaseous heat pump working fluid flows or is circulated to the secondary heat exchange connection  204 . In the secondary heat exchange connection  204  high-temperature heat pump working fluid releases heat energy to the geothermal working fluid in the secondary heat exchange connection  204 . Therefore, the temperature of the heat pump working fluid decreases and the heat pump working fluid returns to liquid state. 
     The secondary heat exchange connection  204  may be now the condenser. The gaseous heat pump working fluid releases thermal energy to the geothermal working fluid in the condenser and turns into liquid forming liquid heat pump working fluid. 
     It should be noted, that in the context of the present invention the secondary heat pump  90  may comprise only the primary and secondary heat transfer connections  203 ,  204 . Furthermore, the primary and secondary heat transfer connections  203 ,  204  may comprise any know kind of heat exchangers. Accordingly, the present invention is not limited to any particular kind of secondary heat pump  90 . The secondary heat pump  90  may be liquid-to-liquid heat pump in which both the geothermal working fluid and the primary working fluid are liquids, or liquid-to-gas (or liquid-to-air) heat pump in which the geothermal working fluid is liquid and the primary working fluid is gas, such as air. 
     As shown in  FIGS. 3 and 4 , the system may further comprise solar electricity apparatus  110  provided in connection with the building or the building space and connected to the primary heat pump  33  for supplying electricity to the primary heat pump  33  and for operating the primary heat pump  33 . There may also or alternatively a solar electricity apparatus  110  may also be connected to the secondary heat pump  90  in the embodiment of  FIG. 4 . 
     As shown in  FIGS. 3 and 4 , the present invention provides an arrangement for heating and cooling of two or more buildings or building spaces. 
     The arrangement comprises two or more building spaces  80 ,  81 ,  82 ,  83  or buildings  50 , as shown for example in  FIGS. 7 and 9 . The arrangement further comprises the secondary thermal network for circulating secondary working fluid. The secondary thermal network comprises the supply line  3  for circulating high-temperature secondary working fluid and the return line  5  for circulating low-temperature secondary working fluid. The arrangement further comprises two or more building connections  100  shown with dotted lines in  FIGS. 3 and 4 . The two or more building connections  100  are arranged parallel to each other and between the supply line  3  and the return line  5  of the secondary thermal network. The two or more building connections  100  comprise the primary heat exchangers  30 ,  31 ,  32 ,  33  provided in connection with the two or more building spaces  80 ,  81 ,  82 ,  83  or buildings  50 . Thus, the two or more buildings  50  or building spaces  80 ,  81 ,  82 ,  83  are connected, or in heat exchange connection with each other via the building connections  100  and the supply line  3  and the return line  5 . 
     The building connections  100  may comprises the connection lines  60 ,  616 ,  62 ,  63  and the connection pumps  70 ,  71 ,  72 ,  73 ,  74 , as disclosed above. 
     The building connection  100  may be further provided control devices  40 ,  41 ,  42 ,  43  connected with control lines  44 ,  45 ,  46 ,  47  to the primary heat exchangers  30 ,  31 ,  32 ,  33  and/or to the connection pumps  70 ,  71 ,  72 ,  73 , respectively. The control device  40 ,  41 ,  42 ,  43  may be arranged to operate the primary heat exchangers  30 ,  31 ,  32 ,  33  selectively in the cooling and heating modes. 
     The arrangement further comprises the ground hole  2  provided into the ground and extending from the ground surface  1  and the geothermal heat exchanger  55  provided to the ground hole  2  and arranged in connection with the secondary thermal network, as described above. 
     The building connection  100  or the primary heat exchangers  30 ,  31 ,  32 ,  33  of the two or more building connections  100  may be arranged in connection with different building spaces  80 ,  81 ,  82 ,  83  of one building  50 , as shown in  FIG. 7 . Accordingly, the supply line  3  and the return line  5  continue in the building  50  and the building connection  100  or the primary heat exchangers  30 ,  31 ,  32 ,  33  are arranged parallel between the supply line  3  and the return line  5  and in connection with different building spaces  80 ,  81 ,  82 ,  83 . Thus, the building spaces  80 ,  81 ,  82 ,  83  may be heated and/or cooled independently of each other and at the same time providing heat exchange connection between the building spaces  80 ,  81 ,  82 ,  83 . 
     In  FIG. 7 , the system and arrangement comprises the geothermal heat exchanger  5  connected supply line  3  and the return line  5 . In this embodiment, the system comprises a first pump  8  arranged to operate the geothermal heat exchanger  55  in a heat extraction mode in which the secondary working fluid is circulated downwards in the drain pipe  21  and upwards in the rise pipe  11 , and a second pump  9  arranged to operate the geothermal heat exchanger  55  in a heat charging mode in which the secondary working fluid is circulated downwards in the rise pipe  11  and upwards in the drain pipe  21 . 
     The building  50  or the building spaces  80 ,  81 ,  82 ,  83  may comprise a building thermal network  52 ,  54  for heating the building spaces  80 ,  81 ,  82 ,  83 . The buildings thermal network  52 ,  54  may be a ventilation system, liquid circulation heating system or the like arranged to circulate the primary working fluid of the building space  80 ,  81 ,  82 ,  83 . The primary heat exchangers  30 ,  31 ,  32 ,  33  of the two or more building connections  100  may be connected to building space thermal networks  52 ,  54  of different building spaces  80 ,  81 ,  82 ,  83 . 
     In  FIG. 8 , the system and arrangement comprises the geothermal heat exchanger  55  with a geothermal network  92 . The secondary heat pump  90  is arranged between the geothermal network  92  and the secondary thermal network  3 ,  5  comprising the supply line  3  and the return line  5 . In this embodiment, the system comprises a first pump  9  arranged to circulate the secondary working fluid in the heat charging mode of the geothermal heat exchanger  55  in which the secondary working fluid flows from the supply line  3  to the secondary heat pump  90 . The system comprises also a first pump  9 ′ arranged to circulate the secondary working fluid in the heat extraction mode of the geothermal heat exchanger  55  in which the secondary working fluid flows from the return line  5  to the secondary heat pump  90 . 
     Embodiment of  FIG. 8  is a modification of the embodiment of  FIG. 7  with the secondary heat pump  90  or the secondary heat exchanger  90 . 
       FIG. 9  shows an alternative embodiment, in which the building connection  100  or the primary heat exchangers  30 ,  31 ,  32 ,  33  of the two or more building connections  100  may be arranged in connection with different building s  50 . Accordingly, the supply line  3  and the return line  5  continue between the different buildings and the building connection  100  or the primary heat exchangers  30 ,  31 ,  32 ,  33  are arranged parallel between the supply line  3  and the return line  5  and in connection with different buildings. Thus, the buildings  50  may be heated and/or cooled independently of each other and at the same time providing heat exchange connection between the buildings  50 . 
     In  FIG. 9 , the system and arrangement comprises the geothermal heat exchanger  55  connected supply line  3  and the return line  5  with the secondary heat pump  90 . The geothermal heat exchanger  55  comprises the rise pipe  11  and the drain pipe  21  arranged to provide the geothermal network  92  for circulating geothermal working fluid along the rise pipe  11  and the drain pipe  21 . The heating and cooling system or arrangement further comprises the secondary heat pump  90  arranged between the secondary thermal network  3 ,  5  and the geothermal network  92 . The secondary heat pump  90  is arranged to provide secondary heat exchange connection between the secondary working fluid and the geothermal working fluid, and between the geothermal network  92  and the secondary thermal network  3 ,  5 . Accordingly, the circulation of the secondary working fluid and the geothermal working fluid, as well as the geothermal network (or the geothermal heat exchanger  55 ) and the secondary thermal network  3 ,  5  are separated from each other with the secondary heat pump  90 . Therefore, the geothermal heat exchanger  55  is arranged in heat exchange connection with the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  and the secondary heat pump  90  is provided between the geothermal heat exchanger  55  and the secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  for providing heat exchange between secondary thermal network  3 ,  5 ,  60 ,  61 ,  62 ,  63  and the geothermal heat exchanger  55 . 
     The buildings  50  may comprise a building thermal network  52 ,  54  for heating the buildings  50 . The building thermal network  52 ,  54  may be a ventilation system, liquid circulation heating system or the like arranged to circulate the primary working fluid of the buildings  50 . The primary heat exchangers  30 ,  31 ,  32 ,  33  of the two or more building connections  100  may be connected to building thermal networks  52 ,  54  of different buildings  50 . 
     Thus, in  FIG. 9  the two or more two or more building connections  100  or the primary heat exchangers  30 ,  31 ,  32 ,  33  of the two or more building connections  100  are arranged in connection with different buildings  50 . 
       FIG. 10  shows an embodiment in which the secondary thermal network  3 ,  3 ′,  5 ,  5 ′ comprises two secondary thermal sub-networks  3 ,  5  and  3 ′,  5 ′ arranged in heat exchange connection with each other. In  FIG. 10  there is a first secondary thermal sub-network  3 ,  5  and a second secondary thermal sub-network  3 ′,  5 ′. However, there may be two or more secondary thermal sub-networks. In the embodiment of  FIG. 10 , the secondary thermal sub-networks  3 , 5  and  3 ′,  5 ′ are arranged in fluid communication with each other such that the same secondary working fluid may flow in both secondary thermal sub-networks  3 , 5  and  3 ′,  5 ′. Accordingly, the supply line  3  of the first secondary thermal sub-network is connected and in fluid communication with the supply line  3 ′ of the second secondary thermal sub-network. Similarly, the return line  5  of the first secondary thermal sub-network is connected and in fluid communication with the return line  5 ′ of the second secondary thermal sub-network. 
     In  FIG. 10 , the sub-network heat exchanger  95  divides the secondary thermal network to the first secondary thermal sub-network  3 ,  5  and to the second secondary thermal sub-network  3 ′,  5 ′. The sub-network heat exchanger  95  may be sub-network heat pump  95  arranged between the supply line  3 , ‘ 3 ’ and the return line  5 ,  5 ′ allowing heat exchange between the supply line  3 ,  3 ′ and the return line  5 ,  5 ′. The sub-network heat pump  95  comprise sub-network heat exchanger fluid circuit  98 ,  99  and a first sub-network heat exchange connection  96  and a second sub-network heat exchange connection  97  such that heat energy may be exchanged between the supply line  3 ,  3 ′ and the return line  5 ,  5 ′. Thus, the sub-network heat exchanger  95  divides the secondary thermal network to secondary thermal sub-networks and allows adjusting the temperature of the secondary working fluid. Accordingly, the sub-network heat exchanger  95  may raise the temperature of the secondary working fluid flowing the from the supply line  3  of the first secondary thermal sub-network to the supply line  3 ′ of the second secondary thermal sub-network, and lower the temperature of the secondary working fluid flowing the from the return line  5 ′ of the second secondary thermal sub-network to the return line  5  of the first secondary thermal sub-network. 
     Accordingly, this allows circulating high-temperature secondary working fluid in a supply line  3 ,  3 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and low-temperature secondary working fluid in a return line  5 ,  5 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63 . Further, increasing the temperature of the high-temperature secondary working fluid circulated in supply line  3 ,  3 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and lowering the temperature of the low-temperature secondary working fluid circulated in return line  5 ,  5 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  by utilizing a heat pump arranged to the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  between the supply line  3 ,  3 ′ and the return line  5 ,  5 ′. 
       FIG. 11  shows a modification of embodiment of  FIG. 10 . In  FIG. 11 , the sub-network heat exchanger  95  divides the secondary thermal network to the first secondary thermal sub-network  3 ,  5  and to the second secondary thermal sub-network  3 ′,  5 ′. The sub-network heat exchanger  95  may be sub-network heat pump  95  arranged between the supply line  3 , ‘ 3 ’ and the return line  5 ,  5 ′ allowing heat exchange between the supply line  3 ,  3 ′ and the return line  5 ,  5 ′. The sub-network heat pump  95  comprise sub-network heat exchanger fluid circuit  98 ,  99  and a first sub-network heat exchange connection  96  and a second sub-network heat exchange connection  97  such that heat energy may be exchanged between the supply line  3 ,  3 ′ and the return line  5 ,  5 ′. Thus, the sub-network heat exchanger  95  divides the secondary thermal network to secondary thermal sub-networks and allows adjusting the temperature of the secondary working fluid. Accordingly, the sub-network heat exchanger  95  may raise the temperature of the secondary working fluid flowing the from the supply line  3  of the first secondary thermal sub-network to the supply line  3 ′ of the second secondary thermal sub-network, and lower the temperature of the secondary working fluid flowing the from the return line  5 ′ of the second secondary thermal sub-network to the return line  5  of the first secondary thermal sub-network. 
     Accordingly, this allows circulating high-temperature secondary working fluid in a supply line  3 ,  3 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and low-temperature secondary working fluid in a return line  5 ,  5 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63 . Further, increasing the temperature of the high-temperature secondary working fluid circulated in supply line  3 ,  3 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and lowering the temperature of the low-temperature secondary working fluid circulated in return line  5 ,  5 ′ of the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  by utilizing a heat pump arranged to the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  between the supply line  3 ,  3 ′ and the return line  5 ,  5 ′. 
     The embodiment of  FIG. 11  further comprises the secondary heat pump or heat exchanger  90  arranged between the first secondary thermal sub-network  3 ,  5  and the geothermal network  92 . The secondary heat pump  90  is arranged to provide secondary heat exchange connection between the secondary working fluid and the geothermal working fluid, and between the geothermal network  92  and the first secondary thermal network  3 ,  5 . Accordingly, the circulation of the secondary working fluid and the geothermal working fluid, as well as the geothermal network (or the geothermal heat exchanger  55 ) and the first secondary thermal network  3 ,  5  are separated from each other with the secondary heat pump  90 . Therefore, the geothermal heat exchanger  55  is arranged in heat exchange connection with the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and the secondary heat pump  90  is provided between the geothermal heat exchanger  55  and the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  or the first secondary thermal network  3 ,  5  for providing heat exchange between secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  or the first secondary thermal network  3 ,  5  and the geothermal heat exchanger  55 . 
       FIG. 12  shows an alternative embodiment in which the sub-network heat exchanger or heat pump  95  provided between the first secondary thermal sub-network  3 ,  5  and the second secondary thermal sub-network  3 ′,  5 ′ and arranged to provide sub-network heat exchange between the first secondary thermal sub-network  3 ,  5  and the second secondary thermal sub-network  3 ′,  5 ′. Thus, in this embodiment, the sub-network heat exchanger or sub-network heat pump  95  is arranged between the two or more secondary thermal sub-networks  3 ,  5 ,  60 ;  3 ′,  5 ′,  61 ,  62 ,  63  for providing heat exchange between the two or more secondary thermal sub-networks  3 ,  5 ,  60 ;  3 ′,  5 ′,  61 ,  62 ,  63  and the two or more secondary thermal sub-networks are separate from each other with the sub-network heat exchanger or sub-network heat pump  95 . Accordingly, the first secondary thermal sub-network provides a first secondary working fluid circulation and the second secondary thermal sub-network provides a second secondary working fluid circulation. The first and second secondary thermal sub-networks are not in fluid communication with each other but separate secondary working fluid are circulated in the first and second secondary thermal sub-networks. However, the system and arrangement of  FIG. 12  may be operated in similar manner as the system and arrangement of  FIG. 10  for raising and lowering temperature. 
       FIG. 13  shows a modification of the embodiment of  FIG. 12 .  FIG. 13  shows an alternative embodiment in which the sub-network heat exchanger or heat pump  95  provided between the first secondary thermal sub-network  3 ,  5  and the second secondary thermal sub-network  3 ′,  5 ′ and arranged to provide sub-network heat exchange between the first secondary thermal sub-network  3 ,  5  and the second secondary thermal sub-network  3 ′,  5 ′. Thus, in this embodiment, the sub-network heat exchanger or sub-network heat pump  95  is arranged between the two or more secondary thermal sub-networks  3 ,  5 ,  60 ;  3 ′,  5 ′,  61 ,  62 ,  63  for providing heat exchange between the two or more secondary thermal sub-networks  3 ,  5 ,  60 ;  3 ′,  5 ′,  61 ,  62 ,  63  and the two or more secondary thermal sub-networks are separate from each other with the sub-network heat exchanger or sub-network heat pump  95 . Accordingly, the first secondary thermal sub-network provides a first secondary working fluid circulation and the second secondary thermal sub-network provides a second secondary working fluid circulation. The first and second secondary thermal sub-networks are not in fluid communication with each other but separate secondary working fluid are circulated in the first and second secondary thermal sub-networks. However, the system and arrangement of  FIG. 13  may be operated in similar manner as the system and arrangement of  FIG. 11  for raising and lowering temperature. 
     The embodiment of  FIG. 13  further comprises the secondary heat pump or heat exchanger  90  arranged between the first secondary thermal sub-network  3 ,  5  and the geothermal network  92 . The secondary heat pump  90  is arranged to provide secondary heat exchange connection between the secondary working fluid and the geothermal working fluid, and between the geothermal network  92  and the first secondary thermal network  3 ,  5 . Accordingly, the circulation of the secondary working fluid and the geothermal working fluid, as well as the geothermal network (or the geothermal heat exchanger  55 ) and the first secondary thermal network  3 ,  5  are separated from each other with the secondary heat pump  90 . Therefore, the geothermal heat exchanger  55  is arranged in heat exchange connection with the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and the secondary heat pump  90  is provided between the geothermal heat exchanger  55  and the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  or the first secondary thermal network  3 ,  5  for providing heat exchange between secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  or the first secondary thermal network  3 ,  5  and the geothermal heat exchanger  55 . 
     According to  FIGS. 10, 11, 12 and 13 , two or more parallel building connections  100  may be connected to the each other via the supply line  3 ,  3 ′ and the return line  5 ,  5 ′ of the two or more secondary thermal sub-networks  3 ,  5 ,  60 ;  3 ′,  5 ′,  61 ,  62 ,  63  and arranged in heat transfer connection with each other via the supply line  3 ,  3 ′ and the return line  5 ,  5 ′. 
     Further, at least two of the two or more secondary thermal sub-networks comprises one or more building connections  100  or one or more primary heat exchangers  30 ,  31 ,  32 ,  33 . Additionally, the building connections  100  are connected to the each other via the two or more secondary thermal sub-networks and the one or more sub-network heat pumps  95  and arranged in heat transfer connection with each other via the two or more secondary thermal sub-networks and the one or more sub-network heat pumps  95 . 
     According to the above mentioned, when the secondary thermal network comprises two or more secondary thermal sub-networks, the building connections  100  and the primary heat exchangers  30 ,  31 ,  32 ,  33  of different secondary thermal sub-networks are in heat exchange connection with each other via the supply lines  3 ,  3 ′ and return lines  5 ,  5 ′ of different secondary thermal sub-networks and via the one or more sub-network heat pumps or heat exchangers  95 . 
       FIGS. 14 and 14  shows different embodiment of the geothermal heat exchanger  55 . 
       FIG. 14  shows another embodiment in which the rise pipe  11  is arranged inside the drain pipe  21 . In this embodiment, the rise pipe  11  and the drain pipe  21  are arranged nested within each other or they may be arranged coaxially within each other such that the rise pipe  11  is inside the drain pipe  21 , as in  FIG. 1 . The rise pipe  11  comprises the first thermal insulation  25 . The first thermal insulation  25  decreases or minimizes heat transfer between the rise pipe  11  and the drain pipe  21  and between the working fluid flow  22  and the working fluid flow  12 . 
     As shown in  FIG. 14 , the thermal insulation  25  extends to a distance from the lower end  17  of the rise pipe  11  along the rise pipe  11 . 
     In the embodiment of  FIG. 10 , the drain pipe  21  is a pipe having a closed lower end  13  and extending inside the ground hole  2  to the lower end  4  of the ground hole in the vicinity thereof. Accordingly, the rise pipe  11  is entirely inside the drain pipe  21  in the ground hole  2  and the geothermal working fluid does not come in direct contact with the ground. 
     It should be noted, that the ground hole  2  may form the drain pipe  21  and the separate drain pipe may be omitted, as in  FIGS. 1 and 2 . Alternatively, the separate drain pipe  21  extends a pre-determined distance from the ground surface  1  with an open lower end, and the ground hole  2  forms at least part of the drain pipe. 
     In the embodiment of  FIG. 15 , the rise pipe  10  and the drain pipe  20  are arranged at a distance from each other and connected to each other with a connection pipe part  18 , or bend, at the lower ends of the rise pipe  10  and the drain pipe  20 . In other words, the rise pipe  10  and the drain pipe  20  form a U-shaped pipe structure. However, it should be noted that the present invention is not limited to any particular pipe structure of the rise pipe  10  and the drain pipe  20  or any number of rise pipes  10  and drain pipe  20 . 
     In the embodiment of  FIG. 15 , the first thermal insulation  25  extends along the rise pipe  10  to distance from the lower end of the rise pipe  10  or the connection pipe part  18  or the bend. 
     The first thermal insulation may be provided don the inner surface and/or outer surface of the rise pipe  10 ,  11 . 
     The present invention provides a method for heating and cooling of several building spaces  80 ,  81 ,  82 ,  83  or buildings  50  by utilizing the system and arrangement as described above in connection with  FIGS. 1 to 15 . 
     The method comprises circulating secondary working fluid in the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and performing two or more first heat exchange steps parallel in the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  between the secondary working fluid and the primary working fluid of the building space  80 ,  81 ,  82 ,  83  or buildings  50  in connection with two or more different building spaces  80 ,  81 ,  82 ,  83  or buildings  5 . The method further comprises performing a second heat exchange step between the secondary working fluid circulated in the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and ground with a geothermal heat exchanger  55  arranged in a ground hole  2  and arranged in connection with the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63 . Accordingly, the method may comprise heat exchange between building space  80 ,  81 ,  82 ,  83  or buildings  50  and between the geothermal heat exchanger  55  and the building space  80 ,  81 ,  82 ,  83  or buildings  50 . 
     In the method, at least one of the two or more parallel first heat exchange steps may be performed in a heating mode in which heat energy in transferred from the secondary working fluid to the primary working fluid of the building space  80 ,  81 ,  82 ,  83  or the building  50 , and at least one of the two or more first primary heat exchange steps may be performed in a cooling mode in which heat energy in transferred from the primary working fluid of the building space  80 ,  81 ,  82 ,  83  or the building  50  to the secondary working fluid. 
     Therefore, the method may comprise carrying out the two or more parallel first heat exchange steps with two or more parallel primary heat exchangers  30 ,  31 ,  32 ,  33  or the building connections  100  provided in connection with two or more different building spaces  80 ,  81 ,  82 ,  83  or buildings  5 . Then, operating at least one of the two or more the primary heat exchanges  30 ,  31 ,  32 ,  33 in the heating mode in which heat energy in transferred from the secondary working fluid to the primary working fluid of the building space  80 ,  81 ,  82 ,  83  or the building  50 , and operating at least one of the two or more the primary heat exchangers  30 ,  31 ,  32 ,  33  in the cooling mode in which heat energy in transferred from the primary working fluid of the building space  80 ,  81 ,  82 ,  83  or the building  50  to the secondary working fluid. The method may thus further comprise carrying out district thermal exchange between the at least one of the two or more the primary heat exchanges  30 ,  31 ,  32 ,  33  operated in the heating mode and the at least one of the two or more the primary heat exchangers  30 ,  31 ,  32 ,  33  operated in the cooling mode via the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63 . 
     Accordingly, in the method the geothermal heat exchanger  55  in a heat extraction mode in which the second heat exchange step comprises transferring heat energy from the ground to the secondary working fluid or to the geothermal working fluid in the geothermal heat exchanger  55 , or in a heat charging mode in which the second heat exchange step comprises transferring heat energy from the secondary working fluid or from the geothermal working fluid to the ground in the geothermal heat exchanger  55  based on the overall or net thermal energy demand of the parallel building connections  100  or the primary heat exchanges  30 ,  31 ,  32 ,  33 . 
     The second heat exchange step may comprise circulating the secondary working fluid in the geothermal heat exchanger  55  and performing heat exchange between the secondary working fluid and the ground in the ground hole  2 . 
     Alternatively, the second heat exchange step may comprise circulating geothermal working fluid in the geothermal heat exchanger  55 , performing heat exchange between the secondary working fluid circulated in the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and the geothermal working fluid circulated in the geothermal heat exchanger  55  and performing heat exchange between the geothermal working fluid and the ground in the ground hole  2 . 
     Alternatively, the method may further comprise operating the geothermal heat exchanger  55  in a heat extraction mode in which the second heat exchange step comprises transferring heat energy from the geothermal working fluid in the geothermal heat exchanger  55  to the secondary working fluid in the secondary heat pump  90 , or in a heat charging mode in which the second heat exchange step comprises transferring heat energy from the secondary working fluid to the geothermal working fluid in the secondary heat pump  90  based on the overall or net thermal energy demand of the parallel building connections  100  or the primary heat exchanges  30 ,  31 ,  32 ,  33 . 
     The second heat exchange step is performed between the secondary working fluid circulated in the secondary thermal network  3 ,  3 ′,  5 ,  5 ′,  60 ,  61 ,  62 ,  63  and ground with the geothermal heat exchanger  55  in the ground hole  2 . The ground hole has a depth of at least 300 m, or at least 500 m, or between 300 m and 3000 m, or between 500 m and 2500 m. Alternatively or additionally, the ground hole  2  extends into the ground to a depth in which the temperature is at least 15° C., or approximately 20° C., or at least 20° C. 
     The invention has been described above with reference to the examples shown in the figures. However, the invention is in no way restricted to the above examples but may vary within the scope of the claims.