DESCRIPTION MONITORING SYSTEM FOR AIR CONDITIONER TECHNICAL FIELD 5 The present invention relates to monitoring systems for air conditioners, and more particularly to measures for monitoring energy of the air conditioners. BACKGROUND ART A conventional monitoring system for air conditioners includes, as shown by Patent Document 1, a plurality of air conditioners, local controllers for receiving data 10 output by the air conditioners, and transmitting predetermined operation data, and a host controller for receiving the operation data of the plurality of air conditioners transmitted by the local controllers through communication lines. In the monitoring system, the host controller receives the operation data of the air conditioners, thereby predicting an abnormal event in each of the air 15 conditioners, and outputting a prediction signal. CITATION LIST PATENT DOCUMENT 1: Japanese Patent Publication No. H07-71803 The conventional monitoring system is configured to predict the abnormal event in each of the air conditioners. However, the status of energy utilization 20 efficiency of each of the air conditioners is not checked. Thus, monitoring whether or not power consumption is efficient has not been done.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority 5 date of each claim of this application. Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 10 SUMMARY OF THE INVENTION According to the invention, there is provided an air conditioner monitoring system including: a plurality of air conditioners each including a refrigerant circuit for performing a vapor compression refrigeration cycle; a local controller provided for 15 each of the air conditioners or each of sets of several ones of the air conditioners for receiving data output by the each of the air conditioners or the each of sets of several ones of the air conditioners, and transmitting predetermined operation data; a host controller for receiving the operation data of the plurality of air conditioners transmitted by the local controllers through communication lines; a capability 20 calculator for calculating air conditioning capability of each of the air conditioners in the each of sets of several ones of the air conditioners; an electric power calculator for calculating power consumption of each of the air conditioners in the each of sets of 2 several ones of the air conditioners; and an energy calculator for calculating energy utilization efficiency, which is an air conditioning capability per unit power consumption, of each of the air conditioners based on the air conditioning capability calculated by the capability calculator, and the power consumption calculated by the 5 electric power calculator, wherein the capability calculator is configured to calculate the air conditioning capability of each of the air conditioners based on a saturation temperature Tc corresponding to a condensing pressure in the refrigerant circuit, a saturation temperature Te corresponding to an evaporating pressure in the refrigerant circuit, a refrigerant temperature Ti before pressure decrease in the refrigerant circuit, a 10 refrigerant suction temperature Ts in the compressor in the refrigerant circuit, and characteristics of the compressor in the refrigerant circuit, and the electric power calculator is configured to calculate the power consumption of each of the air conditioners based on a current value sensed by a current sensor provided in the air conditioner, a power factor of the air conditioner, and a power supply voltage of the air 15 conditioner. The energy calculator may be provided in a management controller for managing each of the air conditioners by previously classifying the air conditioners into a plurality of air conditioning blocks according to predetermined relationship, and the energy calculator may be configured to calculate the energy utilization efficiency of 20 each of the air conditioners, and may calculate the energy utilization efficiency of each of the air conditioning blocks. The current sensor may be a control sensor for sensing a current fed to each 3 device in the air conditioner. The capability calculator, the electric power calculator, and the energy calculator may be provided in the host controller. The management controller includes a display means for displaying the 5 energy utilization efficiency of each of the air conditioners, and the energy utilization efficiency of each of the air conditioning blocks calculated by the energy calculator. Thus, according to an embodiment of the invention, the local controllers transmit predetermined operation data from the data output from each of the air conditioners to the host controller through the communication lines. 10 For example, according to an embodiment of the invention, the capability calculator of the host controller calculates the air conditioning capability of the air conditioner. Specifically, according to an embodiment of the invention, the capability calculator calculates the air conditioning capability of the air conditioner based on the saturation temperature Tc corresponding to a condensing pressure in the refrigerant 15 circuit, the saturation temperature Te corresponding to an evaporating pressure in the refrigerant circuit, the refrigerant temperature Ti before pressure decrease in the refrigerant circuit, a refrigerant suction temperature Ts in the compressor, and the characteristics of the compressor. In an embodiment of the invention, the energy calculator calculates the 20 energy utilization efficiency of each of the air conditioners based on the air conditioning capability calculated by the capability calculator, and the power consumption the electric power calculator. According to such an embodiment, the 4 energy calculator calculates the energy utilization efficiency of each of the air conditioning blocks. In an embodiment of the invention, the energy utilization efficiency of each of the air conditioners, and the energy utilization efficiency of each of the air 5 conditioning blocks calculated by the energy calculator are displayed by, for example, the display means. According to an embodiment of the invention, the electric power calculator may calculate the power consumption of the air conditioner based on the current value sensed by the current sensor provided in the air conditioner, the power factor of the air 10 conditioner, and the power supply voltage of the air conditioner. In this case, according to an embodiment of the invention, the current sensor is a control sensor for sensing the current fed to each device of the air conditioner, and the power consumption of the air conditioner is calculated based on the current value sensed by the control sensor. 15 According to an embodiment of the present invention, the energy utilization efficiency of each of the air conditioners is calculated based on the air conditioning capability and the power consumption of each of the air conditioners. This allows for easy determination whether the power consumption is efficient or not. In addition, in an embodiment of the invention, clarification of the energy 20 utilization efficiency of each of the air conditioners allows for clarification of defects of the operation state of each of the air conditioners. In an embodiment of the invention, the calculation of the energy utilization 5 efficiency of each of the air conditioners allows for examination of performance of each of the air conditioners. Further, due to the calculation of the power consumption for calculating the energy utilization efficiency of each of the air conditioners, the amount of CO 2 5 emission from each of the air conditioners can be monitored. According to an embodiment of the invention, the energy utilization efficiency of each of the air conditioning blocks is calculated, and is remote-monitored. Therefore, for example, a full-time keeper is no longer necessary in each building, thereby reducing cost of the management. 10 According to an embodiment of the invention, the air conditioning capability and the power consumption of each of the air conditioners are calculated using the signals from the high pressure sensor, etc., conventionally provided in the refrigerant circuit. This does not involve additional provision of a new sensor, etc., thereby avoiding complexity of the system. 15 According to an embodiment of the invention, the power factor is considered. This allows for more accurate calculation of the power consumption, thereby allowing for more accurate determination whether the power consumption is efficient or not. In particular, according to an embodiment of the invention, the current sensor is comprised of the control sensor. This allows for accurate calculation of the power 20 consumption without increasing the parts count. According to an embodiment of the invention, the electric power calculator, etc., are provided in the host controller. Therefore, the determination whether the 6 power consumption of each of the air conditioners is efficient or not can be performed by a single controller in a centralized manner. In particular, according to an embodiment of the invention, the energy utilization efficiency is displayed, thereby allowing for easy management. 5 BRIEF DESCRIPTION OF THE DRAWINGS [FIG. 1] FIG. I is a block diagram illustrating the structure of an air conditioner monitoring system of a first embodiment. [FIG. 2] FIG. 2 is a circuit diagram illustrating a refrigerant circuit of the air conditioner of the first embodiment. 10 [FIG. 3] FIG. 3 is an enthalpy and pressure (p-h) graph illustrating the operation state of the air conditioner of the first embodiment. [FIG. 4] FIG. 4 is a block diagram illustrating an electrical system of an air conditioner of a second embodiment. [FIG. 5] FIG. 5 is a block diagram illustrating an electrical system of an air 15 conditioner of a third embodiment. [FIG. 6] FIG. 6 is a wiring diagram illustrating how electric power of the air conditioner of the third embodiment is measured when a three-phase power supply is used. [FIG. 7] FIG. 7 is a wiring diagram illustrating how electric power of air 20 conditioner of the third embodiment is measured when a single-phase power supply is used. 7 DESCRIPTION OF EMBODIMENTS Embodiments of the present invention will be described in detail below. [First Embodiment] As shown in FIGS. 1 and 2, a remote monitoring system (IA) of the present 5 embodiment is a monitoring system capable of remote monitoring of a plurality of air conditioners (10). As shown in FIG. 2, each of the air conditioners (10) includes a refrigerant circuit (11) for performing a vapor compression refrigeration cycle, and is configured as a multi-type air conditioner in which a plurality of indoor units (30) are connected to a single outdoor unit 10 (20). In the refrigerant circuit (11), a compressor (21), an oil separator (22), a four way switching valve (23), an outdoor heat exchanger (24) as a heat source side heat exchanger, a motor-operated outdoor expansion valve (25) as an expansion mechanism, a receiver (26), a motor-operated indoor expansion valve (32) as an expansion mechanism, an indoor heat 15 exchanger (31) as a utilization side heat exchanger, and an accumulator (27) are sequentially connected through a refrigeration pipe (40), thereby allowing a refrigerant to flow freely in the circuit. The outdoor unit (20) contains the compressor (21), the oil separator (22), the four way switching valve (23), the outdoor heat exchanger (24), the motor-operated outdoor 20 expansion valve (25), the receiver (26), and the accumulator (27). The indoor units (30) are configured in the same manner, and each of them contains the motor-operated indoor expansion valve (32), and the indoor heat exchanger (31). The outdoor unit (20) and the indoor units (30) are connected through a connection pipe (41) comprised of the refrigerant pipe (40). 25 An operation capacity of the compressor (21) is adjusted by an inverter (2a). The 8 D08-J-157 four way switching valve (23) is switched to the state indicated by a solid line in FIG. 2 in cooling operation, and is switched to the state indicated by a broken line in FIG. 2 in heating operation. The outdoor heat exchanger (24) includes an outdoor fan (2F), and functions as a condenser in the cooling operation, and as an evaporator in the heating operation. The 5 indoor heat exchanger (31) includes an indoor fan (3F), and functions as an evaporator in the cooling operation, and as a condenser in the heating operation. The outdoor unit (20) includes a heating overload controlling bypass path (42), a liquid injection bypass path (43), an oil return pipe (44), an equalizing hot gas bypass path (45), an equalizing path (46), and a suction pipe heat exchanger (2b). 10 The heating overload controlling bypass path (42) is connected in parallel to the outdoor heat exchanger (24) to bypass the outdoor heat exchanger (24). An auxiliary heat exchanger (4a), a capillary tube (4b), and an auxiliary open/close valve (4c) which opens when the refrigerant pressure is high are sequentially connected in series to the heating overload controlling bypass path (42). In the heating overload controlling bypass path (42), 15 the auxiliary open/close valve (4c) is kept opened in the cooling operation, and is opened when the high pressure of the refrigerant excessively increases in the heating operation. This allows a portion of a discharged gas to flow into the heating overload controlling bypass path (42), thereby condensing the portion of the discharged gas in the auxiliary heat exchanger (4a). 20 The liquid injection bypass path (43) adjusts the degree of superheat of a sucked gas by injecting a liquid refrigerant to a suction side of the compressor (21) in the cooling and heating operations. The liquid injection bypass path (43) includes an injection valve (4d) which opens when the temperature of a discharge pipe of the compressor (21) excessively increases, and a capillary tube (4e). 25 The oil return pipe (44) has a capillary tube (4f), and is configured to return a 9 D08-J-l 57 lubricant from the oil separator (22) to the compressor (21). The equalizing hot gas bypass path (45) connects the refrigerant pipe (40) on the discharge side of the compressor (21) and the refrigerant pipe (40) on the suction side of the compressor (21), and includes an equalizing valve (4g) which opens for a predetermined 5 period of time when the compressor (21) stops and before the compressor (21) restarts, and a capillary tube (4h). An end of the equalizing path (46) is connected to an upper end surface of the receiver (26), and the other end is connected to the equalizing hot gas bypass path (45) upstream of the equalizing valve (4g). The equalizing path (46) includes a check valve (4i), 10 and guides a gaseous refrigerant in an upper portion in the receiver (26) to the suction side of the compressor (21) through the equalizing hot gas bypass path (45), with the equalizing valve (4g) kept opened. The suction pipe heat exchanger (2b) allows for heat exchange between the sucked refrigerant in the suction side of the compressor (21) and the liquid refrigerant in the 15 refrigerant pipe (40) to cool the sucked refrigerant, thereby compensating the increase of the degree of superheat of the refrigerant in the connection pipe (41). The air conditioner (10) is provided with multiple sensors. Specifically, the air conditioner (10) includes an indoor air temperature sensor (Thl) for sensing an indoor air temperature TI which is the temperature of air sucked from the inside of the room, an indoor 20 liquid temperature sensor (Th2) for sensing a liquid pipe temperature T2 in the liquid refrigerant pipe (40) connected to the indoor heat exchanger (31), an indoor gas temperature sensor (Th3) for sensing a gas pipe temperature T3 in the gaseous refrigerant pipe (40) connected to the indoor heat exchanger (31), a discharge pipe sensor (Th4) for sensing a discharge pipe temperature T4 of the compressor (21), an outdoor liquid temperature sensor 25 (Th5) for sensing a liquid refrigerant temperature T5 in the outdoor heat exchanger (24), a 10 D08-J-I 57 suction pipe sensor (Th6) for sensing a suction pipe temperature T6 of the compressor (21), an outdoor air temperature sensor (Th7) for sensing an outdoor air temperature T7 which is the temperature of air sucked from the outside of the room, a high pressure sensor (P1) arranged on the discharge side of the compressor (21) for sensing a high pressure HP in the 5 refrigerant circuit (11), a low pressure sensor (P2) arranged on the suction side of the compressor (21) for sensing a low pressure LP in the refrigerant circuit (11), and a high pressure switch (HPS) for protecting the compressor (21) arranged on the discharge side of the compressor (21). The motor-operated expansion valves (25, 32) and the sensors (Thl-Th7, P1, P2), 10 etc., are connected to a control unit (12) through signal lines. The control unit (12) is configured to receive sensed signals from the sensors (Thl-Th7, P1, P2), etc., and to control the opening/closing of the motor-operated expansion valves (25, 32), etc., and the capacity of the compressor (21). The control unit (12) includes an air conditioning control means (13) for controlling 15 air conditioning operation. The control unit (12) is configured to detect a plurality of operation state values, and to output state signals based on the signals from the sensors (Th I Th7, P1, P2), etc., and to control the capacity of the compressor (21). In the air conditioner (10) during the cooling operation, the four way switching valve (23) is switched to the state indicated by the solid line in FIG. 2. Then, the auxiliary 20 open/close valve (4c) of the auxiliary heat exchanger (4a) is kept opened, and the refrigerant compressed in the compressor (21) is condensed in the outdoor heat exchanger (24) and the auxiliary heat exchanger (4a), and is sent to the indoor unit (30) through the connection pipe (41). In this indoor unit (30), the liquid refrigerant decreases in pressure as it passes through the motor-operated indoor expansion valve (32), and evaporates in the indoor heat exchanger 25 (31). After that, the refrigerant in the gaseous state returns to the outdoor unit (20) through I l D08-J-I 57 the connection pipe (41), and is sucked into the compressor (21). That is, the liquid refrigerant evaporates because of heat exchange with the indoor air in the indoor heat exchanger (31), thereby cooling the indoor air. In the heating operation, the four way switching valve (23) is switched to the 5 state indicated by the broken line in FIG. 2. Then, the refrigerant flows in the reverse direction of the flow direction in the cooling operation. Specifically, the refrigerant compressed in the compressor (21) is condensed in the indoor heat exchanger (31), and the refrigerant in the liquid state flows into the outdoor unit (20). The refrigerant decreases in pressure as it passes through the motor-operated outdoor expansion valve 10 (25), evaporates in the outdoor heat exchanger (24), and returns to the compressor (21). That is, the gaseous refrigerant condenses because of heat exchange with the indoor air in the indoor heat exchanger (31), thereby heating the indoor air. The remote monitoring system (IA) monitors the plurality of air conditioners (10) in a centralized manner, and includes a monitoring apparatus (50) as shown in FIG 1. 15 The monitoring apparatus (50) includes a plurality of local controllers (60), and a single host controller (70). Specifically, an interface (51) is connected to each of the control units (12) of the air conditioners (10). The interfaces (51) are connected to the corresponding local controller (60) through an exclusive line (52), and each of the local controllers (60) is connected to the host controller (70) through a communication line 20 (53) such as a telephone line, the Internet, etc. Thus, the plurality of interfaces (51) are connected to each of the local controllers (60). For example, when several air conditioners (10) are provided in one building, the several air conditioners (10) in the one building are monitored by one of the local controllers (60). The several air conditioners (60) monitored by the one local controller (60) correspond to one maintenance client. 12 For example, a plurality of local controllers (60) are connected to the host controller (70), and the host controller (70) performs centralized monitoring of all the air conditioners (10). Each of the local controllers (60) is connected to a personal computer (54), and 5 receives real time data, which is operation data of each of the air conditioners (10), from the air conditioners (10) through the interfaces (51) and the exclusive line (52) every minute. Specifically, the local controller (60) is configured to receive, for example, data such as the suction pipe temperature T6 sensed from the outdoor unit (20) by the sensors (Thl-Th7, P1, P2), etc., and data about an operation mode, i.e., the cooling operation and the heating 10 operation. The host controller (70) is configured to receive predetermined operation data from the local controllers (60) through the communication lines (53). The host controller (70) includes a capability calculator (71), an electric power calculator (72), and a management controller (73). The management controller (73) includes 15 an energy calculator (7a), and a display means (7b). The capability calculator (71) is configured to calculate the air conditioning capability of each of the air conditioners (10) in each of sets of the several air conditioners. Specifically, the capability calculator (71) calculates the air conditioning capability of each of the air conditioners (10) based on a saturation temperature Tc corresponding to a condensing 20 pressure in the refrigerant circuit (11), a saturation temperature Te corresponding to an evaporating pressure in the refrigerant circuit (11), a refrigerant temperature Ti before pressure decrease in the refrigerant circuit (11), a refrigerant suction temperature Ts of the compressor (21), and characteristics of the compressor (21). Specifically, as shown in FIG. 3, the capability calculator (71) calculates the 25 saturation temperature Tc corresponding to a condensing pressure based on the high pressure 13 D08-J-1 57 HP of the refrigerant circuit (11) output by the high pressure sensor (P1), and calculates the saturation temperature Te corresponding to an evaporating pressure based on the low pressure LP of the refrigerant circuit (11) output by the low pressure sensor (P2). The capability calculator (71) calculates the refrigerant temperature Ti before pressure decrease, which is the 5 temperature of the liquid refrigerant in the supercooled state, based on the liquid pipe temperature T2 in the indoor heat exchanger (31) in the cooling operation sensed by the indoor liquid temperature sensor (Th2), or based on the liquid refrigerant temperature T5 in the outdoor heat exchanger (24) in the heating operation sensed by the outdoor liquid temperature sensor (Th5). Further, the capability calculator (71) derives the refrigerant 10 suction temperature Ts in the compressor (21) based on the suction pipe temperature T6 sensed by the suction pipe sensor (Th6). The capability calculator (71) calculates the air conditioning capability of the air conditioner (10) from the characteristics of the compressor (21) based on the saturation temperature Tc corresponding to a condensing pressure, the saturation temperature Te corresponding to an evaporating pressure, the refrigerant 15 temperature Ti before pressure decrease, and the refrigerant suction temperature Ts. The electric power calculator (72) is configured to calculate power consumption of each of the air conditioners (10) in each of sets of several air conditioners (10). Specifically, like the capability calculator (71), the electric power calculator (72) is configured to calculate the power consumption of the air conditioner (10) based on the saturation temperature Tc 20 corresponding to a condensing pressure in the refrigerant circuit (11), and the saturation temperature Te corresponding to an evaporating pressure in the refrigerant circuit (11), the refrigerant temperature Ti before pressure decrease in the refrigerant circuit (11), the refrigerant suction temperature Ts in the compressor (21), and the characteristics of the compressor (21) in the refrigerant circuit (11). 25 Specifically, the electric power calculator (72) calculates the power consumption of 14 D08-J- 157 the air conditioner (10) from the characteristics of the compressor (21) based on the saturation temperature Tc corresponding to a condensing pressure, the saturation temperature Te corresponding to an evaporating pressure, the refrigerant temperature Ti before pressure decrease, and the refrigerant suction temperature Ts of the compressor (21). 5 The management controller (73) is configured to manage each of the plurality of air conditioners (10) by previously classifying the air conditioners (10) into a plurality of air conditioning blocks (1B) according to predetermined relationship. Specifically, as described above, the air conditioners (10) monitored by the single local controller (60) correspond to one maintenance client. Therefore, the air conditioners (10) of the one maintenance client 10 constitute a single air conditioning block (1B). Thus, the management controller (73) manages the air conditioners (10) on the basis of the air conditioning block (IB). The energy calculator (7a) is included in the management controller (73), and calculates an energy utilization efficiency of each of the air conditioners (10) based on the air conditioning capability calculated by the capability calculator (71), and the power 15 consumption calculated by the electric power calculator (72). The energy calculator (7a) calculates the energy utilization efficiency of each of the air conditioning blocks (1 B). Specifically, since the air conditioning capability per unit power consumption is the energy utilization efficiency (air conditioning capability/power consumption), the energy calculator (7a) calculates the instantaneous energy utilization efficiency (air conditioning 20 capability/power consumption), and the energy utilization efficiency for a predetermined period of time (e.g., a year) (Y air conditioning capability/E power consumption) of each of the air conditioners (10) and each of the air conditioning blocks (IB). The display means (7b) is configured to display the energy utilization efficiency of each of the air conditioners (10), and the energy utilization efficiency of each of the air 25 conditioning blocks (IB) calculated by the energy calculator (7a). 15 D08-J- 157 -Operation Mechanism A monitoring mechanism of the monitoring system (lA) of the air conditioners (10) will be described below. First, air conditioning operation of each of the air conditioners (10) is controlled by 5 the control unit (12). Then, data output from the sensors (Thl-Th7, P1, P2), etc., is transmitted from the control unit (12) to the local controller (60). The local controller (60) transmits predetermined operation data from the received data to the host controller (70) through the communication line (53). Then, the capability calculator (71) of the host controller (70) calculates the air 10 conditioning capability of the air conditioner (10) based on the high pressure HP and the low pressure LP of the refrigerant circuit (11), the refrigerant temperature Ti before pressure decrease and the refrigerant suction temperature Ts in the compressor (21) from the liquid pipe temperature T2 in the indoor heat exchanger (31) or the liquid refrigerant temperature T5 in the outdoor heat exchanger (24), and the characteristics of the compressor (21). 15 The electric power calculator (72) of the host controller (70) calculates the power consumption of the air conditioner (10) based on the high pressure HP and the low pressure LP of the refrigerant circuit (11), the refrigerant temperature Ti before the pressure decrease and the refrigerant suction temperature Ts in the compressor (21) from the liquid pipe temperature T2 in the indoor heat exchanger (31) or the liquid refrigerant temperature T5 in 20 the outdoor heat exchanger (24), and the characteristics of the compressor (21). Further, the energy calculator (7a) calculates the energy utilization efficiency of each of air conditioners (10) and each of the air conditioning blocks (IB) based on the air conditioning capability calculated by the capability calculator (71), and the power consumption calculated by the electric power calculator (72). 25 The energy utilization efficiency of each of the air conditioners (10), and the energy 16 D08-J-l 57 utilization efficiency of each of the air conditioning blocks (IB) calculated by the energy calculator (7a) are displayed in the display means energy calculator (7a). Monitoring of the energy utilization efficiency calculated by the energy calculator (7a) allows for monitoring of the power consumption (an amount of CO 2 emission), and 5 allows for management of each of the air conditioners (10) of a plurality of maintenance clients by the host controller (70) in a centralized manner. -Advantages of the Embodiment As described above, according to the present embodiment, the energy utilization efficiency of each of the air conditioners (10) is calculated based on the air conditioning 10 capability and the power consumption of each of the air conditioners (10). This allows for easy determination whether the power consumption is efficient or not. In addition, clarification of the energy utilization efficiency of each of the air conditioners (10) allows for clarification of defects of the operation state of each of the air conditioners (10). 15 The calculation of the energy utilization efficiency of each of the air conditioners (10) allows for examination of performance of each of the air conditioners (10). Further, due to the calculation of the power consumption for calculating the energy utilization efficiency of each of the air conditioners (10), the amount of CO 2 emission from each of the air conditioners (10) can be monitored. 20 The energy utilization efficiency of each of the air conditioning blocks (1B) is calculated, and is remote-monitored. Therefore, for example, a full-time keeper is no longer necessary in each building, thereby reducing cost of the management. The air conditioning capability and the power consumption of each of the air conditioners (10) are calculated using the signals from the high pressure sensor (PI), etc., 25 conventionally provided in the refrigerant circuit (11). This does not involve additional 17 D08-J-1 57 provision of a new sensor, etc., thereby avoiding complexity of the system. Since the electric power calculator (72), etc., are included in the host controller (70), the determination whether the power consumption of each of the air conditioners (10) is efficient or not can be performed in a centralized manner. In particular, the management can 5 easily be done because the energy utilization efficiency is displayed. [Second Embodiment] A second embodiment of the present invention will be described in detail below with reference to the drawings. Unlike the electric power calculator (72) of the first embodiment which calculates 10 the power consumption of the air conditioner (10) based on the characteristics of the compressor (21), etc., the second embodiment is configured to calculate the power consumption of the air conditioner (10) based on a current value sensed by a current sensor (17) provided in the air conditioner (10), a power factor of the air conditioner (10), and a power supply voltage of the air conditioner (10) as shown in FIG. 4. 15 Specifically, in each of the air conditioners (10), electric power is fed from a power supply (15) to the compressor (21), the fans (2F, 3F), and actuators (25, ...) including the other devices such as the electronic expansion valve (25), etc., through an electric power line (16). Current sensors (17) are provided on the electric power line (16) for the compressor (21), the fans (2F, 3F), and the actuators (25, ...), respectively. Each of the current sensors 20 (17) is configured to sense a current value fed to each of the compressor (21), the fans (2F, 3F), and the actuators (25, ... ). In particular, the current sensor (17) is comprised of a control sensor for sensing an overcurrent to control the compressor (21), etc. That is, the control sensor also functions as the current sensor (17) for calculating the electric power. A sensed signal from the current 25 sensor (17) (a current value) is input to the control unit (12). 18 D08-J-I 57 The electric power calculator (72) of the host controller (70) is configured to calculate the power consumption of the air conditioner (10) based on the current value of each device in the air conditioner (10) sensed by the current sensor (17), i.e., the current values of the compressor (21), the fans (2F, 3F), and the actuators (25, ...), a power factor of each of 5 the air conditioners (10), and a power supply voltage of each of the air conditioners (10). In more detail, the electric power calculator (72) includes a power supply storage section for previously storing the power supply voltage of each of the air conditioners (10), and a power factor storage section for previously storing an inherent power factor of each of the compressor (21), the fans (2F, 3F), and the actuators (25, ...), which is the power factor of 10 each of the air conditioners (10). The electric power calculator (72) is configured to calculate the power consumption (current value x power supply voltage x power factor) based on the current value sensed by the current sensor (17), the power factor, and the power supply voltage. Thus, according to the second embodiment, the current sensor (17) senses the 15 current value of each of the devices in each of the air conditioners (10), i.e., the current values of the compressor (21), the fans (2F, 3F), and the actuators (25, ...). The electric power calculator (72) calculates the power consumption of each of the air conditioners (10) based on the current value of each of the air conditioners (10) sensed by the current sensor (17), the previously stored power supply voltage, and the previously stored power factor of each of the 20 actuators (25, ...). Based on the calculated power consumption, and the air conditioning capability calculated by the capability calculator (71), the energy calculator (7a) calculates the energy utilization efficiency of each of the air conditioners (10), and the energy utilization efficiency of each of the air conditioning blocks (IB). As a result, like the first embodiment, the second embodiment allows for easy 25 determination whether the power consumption is efficient or not because the energy power 19 D08-J-1 57 consumption of each of the air conditioners (10) is calculated based on the air conditioning capability and the power consumption of each of the air conditioners (10). In particular, the power consumption is accurately calculated by considering the power factor, thereby allowing for accurate determination whether the power consumption is 5 efficient or not. Further, since the control sensors are used as the current sensors (17), the calculation of the power consumption is accurately performed without increasing the parts count. The structure and advantages of the second embodiment except for the above 10 described features are similar to those of the first embodiment. [Third Embodiment] A third embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 5, the third embodiment is configured to sense the current of each 15 of the air conditioners (10) instead of sensing the current of each of the devices in the second embodiment. Specifically, in each of the air conditioners (10), an electric power extraction section (16a) is provided on the electric power line (16), and an electric power measuring device (18) is connected to the electric power extraction section (16a). As shown in FIG. 6, 20 when a three-phase power supply (15) is used, current sensors (17) are provided for two phases in the electric power extraction section (1 6a), and voltage lines (1 8a) for extracting a voltage between phases are branched from the electric power lines (16). The electric power measuring device (18) is connected to the current sensors (17) through current lines (18b), respectively, and the voltage lines (1 8a) are connected to the electric power measuring device 25 (18). Thus, the electric power measuring device (18) is configured to sense the current value 20 D08-J-l 57 and the power supply voltage, which is an applied voltage, of each of the air conditioners (10), thereby measuring the power consumption of each of the air conditioners (10). The electric power value measured by the electric power measuring device (18) is input from the control unit (12) of each of the air conditioners (10) to the electric power calculator (72) of the host 5 controller (70). The electric power calculator (72) is configured to calculate actual power consumption based on the electric power value measured by the electric power measuring device (18), and the power factor of the devices previously stored in the power factor storage section. 10 Thus, like the second embodiment, the third embodiment allows for accurate calculation of the power consumption because the power factor is considered. This makes it possible to accurately determine whether the power consumption is efficient or not. The structure and advantages of the third embodiment except for the above described features are similar to those of the first and second embodiments. 15 When a single-phase power supply (15) is used as shown in FIG. 7, the electric power extraction section (1 6a) is provided with a single current sensor (17), and voltage lines (1 8a) for extracting a voltage between phases are branched from the electric power lines (16). The current sensor (17) and the voltage lines (18a) are connected to the electric power measuring device (18) to sense the current value and the power supply voltage, which is an 20 applied voltage, of each of the air conditioners (10), thereby measuring the power consumption of each of the air conditioners (10). [Other Embodiments] The above-described embodiments may be modified in the following manner. The electric power calculator (72) of the second and third embodiments is 25 configured to calculate the power consumption of the air conditioner (10) based on the current 21 D08-J-157 value sensed by the current sensor (17), the power supply voltage, and the power factor. However, the power consumption of the air conditioner (10) may be calculated merely based on the current value and the power supply voltage of the air conditioner (10). The refrigerant circuit (11) of the air conditioner (10) is not limited to those 5 described in the embodiments. The air conditioner (10) may be used exclusively for cooling or heating. The capability calculator (71) and the electric power calculator (72) are included in the host controller (70). However, the capability calculator (71) and the electric power calculator (72) may be provided in the local controller (60), or in the personal computer (54). 10 The above embodiments are merely preferred embodiments in nature, and are not intended to limit the scope, applications and use of the disclosed technique. INDUSTRIAL APPLICABILITY As described above, the present invention is useful for a remote monitoring system for a plurality of air conditioners. 15 DESCRIPTION OF REFERENCE CHARACTERS IA Remote monitoring system IB Air conditioning block 10 Air conditioner 15 Power supply 20 16 Electric power line 17 Current sensor 18 Electric power measuring device 50 Remote monitoring apparatus 53 Communication line 25 60 Local controller 22 D08-J-1 57 70 Host controller 71 Capability calculator 72 Electric power calculator 73 Management controller 5 7a Energy calculator 7b Display means 23 D08-J-1 57