Patent Publication Number: US-2012042672-A1

Title: Air conditioner control apparatus, cooling system, and air conditioner control program

Description:
TECHNICAL FIELD 
     The present invention relates to an air conditioner control apparatus for controlling an air conditioner, as well as a cooling system and an air conditioner control program. 
     BACKGROUND ART 
     Heretofore, for the purpose of cooling the interior of a room, there has widely been used an air conditioner having an indoor unit and an outdoor unit connected with each other through a refrigerant pipe. In case of cooling the interior of a room with the air conditioner, the moisture contained in the indoor air is removed with cooling by the air conditioner. Thus, the air conditioner is used not only for cooling but also for the removal of moisture. Therefore, electric power necessary for the removal of moisture is included in the electric power which is consumed by the air conditioner for cooling the interior of a room. 
     With a view to reducing the electric power which is consumed by the air conditioner for cooling the interior of a room, there has been proposed a method using a desiccant air conditioning system which is provided with a dehumidifying material for the removal of moisture contained in the indoor air (see, for example, Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         [Patent Document 1] Japanese Patent Laid-Open No. 2007-170786 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, the method described in Patent Literature 1 involves the problem that since it is necessary to provide a desiccant air conditioning system separately from the air conditioner, not only the equipment construction becomes complicated, but also the equipment scale becomes large. 
     The present invention has been accomplished in view of the above-mentioned problem and it is an object of the invention to provide an air conditioner control apparatus capable of suppressing electric power which is consumed by an air conditioner for cooling the interior of a room, as well as a cooling system and an air conditioner control program. 
     In one aspect of the present invention for achieving the above-mentioned object, in case of cooling the interior of a room by an air conditioner having an indoor unit and an outdoor unit connected with each other through a refrigerant pipe, a dehumidifying operation for dehumidifying the interior of the room is performed before an indoor cooling operation by controlling the operation of a refrigerant compressor included in the outdoor unit and the operation of a fan included in the indoor unit. 
     In the case where the interior of a room to be cooled by the air conditioner in accordance with the present invention is the interior of a grocery store such as a supermarket, there is the problem that when removing a sensible heat load in the interior of the store in the cooling operation for example in the afternoon of summer, an electric power consumption of the air conditioner increases by an amount corresponding to the amount of a latent heat load processed because latent heat load is removed. 
     Another problem encountered in a grocery store such as a supermarket is that as the absolute humidity in the interior of the store increases for example in summer, the air of such a high humidity is sucked in toward a freezing showcase and a refrigerating showcase (both hereinafter referred to as freezing/refrigerating showcases) installed in the interior of the store, resulting in increase in the amount of frost deposited on a cooler of a refrigerator connected to the freezing/refrigerating showcase. Consequently, the electric power consumption required for operation to remove the frost increases and so does the electric power consumption of the refrigerator. 
     In view of these points, the present invention aims at reducing the electric power consumption of a refrigerator connected to a freezing/refrigerating showcase by removing moisture (removing a latent heat load) in the interior of a store in a time zone of a low sensible heat load, for example, in the morning of summer when the outdoor temperature is low, thereby lowering a peak of electric power consumption of the air conditioner concerned in the daytime and cutting down the heat load on the freezing/refrigerating showcase. 
     In another aspect of the present invention for achieving this object, in an appropriate time zone before opening or after closing of a grocery store such as a supermarket, there is performed a dehumidifying operation in which cold air is blown off into the interior of the store, the cold air being lower in temperature than the cold air blown off into the store interior during cooling operation and the amount of the cold air being smaller than that of the cold air fed during cooling operation. 
     Means for Solving the Problems 
     The air conditioner control apparatus as a characteristic feature of the present invention is for controlling an air conditioner having an indoor unit and an outdoor unit connected with each other through a refrigerant pipe, and according to the gist thereof, it comprises a control unit which performs a dehumidifying operation for removing moisture present in the interior of a room where the indoor unit is installed, prior to a cooling operation for cooling the interior of the room. 
     According to the air conditioner control apparatus which features the present invention, since the dehumidifying operation is performed prior to execution of the cooling operation, it is possible to suppress the necessity of removing moisture simultaneously with the cooling operation. Accordingly, it is possible to save the electric power necessary for dehumidifying in the cooling operation. Consequently, it is possible to suppress the electric power which is consumed by the air conditioner for cooling the interior of the room. 
     The air conditioner control apparatus which features the present invention may comprise a predictive outdoor temperature acquiring unit for acquiring a predictive outdoor temperature in the exterior of the room where the outdoor unit is installed and a time zone setting unit which, on the basis of the predictive outdoor temperature, sets a cooling time zone for execution of the cooling operation and a dehumidifying time zone for execution of the dehumidifying operation, the time zone setting unit setting the dehumidifying time zone to a time zone in which the predictive outdoor temperature is lower than a predetermined threshold value. 
     The air conditioner control apparatus which features the present invention may comprise an indoor temperature acquiring unit for acquiring an indoor temperature and a time zone setting unit which, on the basis of the indoor temperature, sets a cooling time zone for execution of the cooling operation and a dehumidifying time zone for execution of the dehumidifying operation, the time zone setting unit setting the dehumidifying time zone to a time zone in which the indoor temperature alone or a temperature difference between a set temperature for the cooling operation and the indoor temperature is smaller than a predetermined threshold value, prior to the cooling time zone. 
     The air conditioner control apparatus which features the present invention may comprise a predictive heat load acquiring unit for acquiring a predictive heat load in the interior of the room and a time zone setting unit which, on the basis of the predictive heat load, sets a cooling time zone for execution of the cooling operation and a dehumidifying time zone for execution of the dehumidifying operation, the time zone setting unit setting the dehumidifying time zone to a time zone in which the predictive heat load is smaller than a predetermined threshold value. 
     In the air conditioner control apparatus which features the present invention, the indoor unit may have a fan for feeding air to the interior of the room, the outdoor unit may have a compressor for compressing a refrigerant flowing through the refrigerant pipe, and the control unit may make a control such that the air volume of a fan is smaller in the dehumidifying operation than in the cooling operation and a low pressure of the compressor is lower in the dehumidifying operation than in the cooling operation. 
     The cooling system which features the present invention, according to the gist thereof, comprises an air conditioner having an indoor unit and an outdoor unit connected with each other through a refrigerant pipe, a cooler having a showcase installed in the interior of a room where the indoor unit is installed and a refrigerator for supplying a refrigerant to the showcase, and an air conditioner control apparatus for controlling the air conditioner and the cooler, the air conditioner control apparatus comprising a control unit which performs a dehumidifying operation for removing moisture present in the interior of the room prior to execution of a cooling operation for cooling the indoor temperature of the room with the indoor unit installed therein. 
     The air conditioner control program which features the present invention, according to the gist thereof, causes a computer, the computer functioning as an air conditioner control apparatus for controlling an air conditioner having an indoor unit and an outdoor unit connected with each other through a refrigerant pipe, to carry out a process A of executing a dehumidifying operation for removing moisture present in the interior of a room where the indoor unit is installed and a process B of executing a cooling operation for cooling the indoor temperature. 
     There provides the following features in the case where the interior of the room which is cooled by the air conditioner according to the present invention is the interior of a grocery store such as a supermarket. 
     In an air conditioner control apparatus for an air conditioner for a store capable of performing a timer operation such that an air conditioning operation is started at a predetermined operation start time and is stopped at a predetermined operation end time, the present invention is characterized in that a store opening time and a store closing time are set between the operation start time and the operation end time, and when an outdoor temperature is lower than a predetermined temperature in the period from the operation start time until the store opening time and/or in the period from the store closing time until the operation end time, there is performed an operation in which cold air is blown off to the interior of the store, the cold air being designed lower in temperature and smaller in air feed volume than cold air which is blown off to the interior of the store in a cooling operation between the store opening time and the store closing time. 
     Moreover, the present invention is characterized in that the cooling operation has as a refrigerating cycle an annularly connected cycle comprising at least a refrigerant compressor, a condenser, a pressure reducing device and an evaporator through refrigerant pipes and is carried out using a cooling action induced upon evaporation of the refrigerant in the evaporator, the temperature of cold air blown off into the store being obtained by reducing the temperature of the evaporator. 
     Moreover, the present invention is characterized in that the predetermined temperature is a temperature preset on the day preceding the operation start time on the basis of for example past outdoor temperature information or outdoor temperature information available from the exterior. 
     Moreover, the present invention is characterized in that, when the internal temperature of the store has become a temperature of not lower than a preset room temperature, a cooling operation same as the cooling operation performed in the period from the store opening time until the store closing time is performed in the period from the operation start time until the store opening time and/or in the period from the store closing time until the operation end time. 
     Moreover, the present invention is characterized in that an operation start time for starting the air conditioning operation is set subsequent to the operation end time for stopping the air conditioning operation to carry out the air conditioning operation continuously. 
     Further, in an air conditioner control apparatus for an air conditioner for a 24-hour open store of which air conditioner performs a 24-hour cooling operation for the interior of the store, the present invention is characterized in that, when the outdoor temperature is lower than a predetermined temperature in the 24-hour cooling operation, there is performed an operation in which cold air is blown off to the interior of the store, the cold air being designed lower in temperature and smaller in air feed volume than cold air which is blown off to the interior of the store in the cooling operation. 
     Further, the present invention is characterized in that the cooling operation has as a refrigerating cycle an annularly connected cycle comprising at least a refrigerant compressor, a condenser, a pressure reducing device and an evaporator through refrigerating pipes and is carried out using a cooling action induced upon evaporation of the refrigerant in the evaporator, the temperature of cold air blown off into the store being obtained by reducing the temperature of the evaporator. 
     Further, the present invention is characterized in that the predetermined temperature is a temperature preset on the day preceding the business hours of the store on the day concerned on the basis of for example past outdoor temperature information or outdoor temperature information available from the exterior. 
     Further, the present invention is characterized in that, when the internal temperature of the store has become a temperature of not lower than a preset room temperature, there is performed a cooling operation same as the cooling operation performed during business hours of the store. 
     Effect of the Invention 
     According to the present invention, it is possible to provide an air conditioner control apparatus which can suppress electric power consumed by an air conditioner for cooling the interior of a room, as well as a cooling system and an air conditioner control program. 
     According to the present invention, in a grocery store such as a supermarket, by removing moisture (removal of a latent heat load) in the interior of the store by controlling the air volume of a fan (a fan for circulating air chilled by a cooler to the interior of the store) of an indoor unit in an air conditioner for cooling the interior of the store, in an appropriate time zone, for example, in the morning of summer low in outdoor temperature, it is possible to lower a peak of electric power consumed by the air conditioner in the daytime. 
     Further, according to the present invention, as described above, by removing moisture (removal of a latent heat load) in the interior of the store in an appropriate time zone, namely, a time zone of a low sensible heat load, for example, in the morning of summer low in outdoor temperature, the heat load of freezing/refrigerating showcases is cut down and hence it is possible to cut down the electric power consumption of the refrigerator connected to the freezing/refrigerating showcases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an outline of a cooling system  1  according to a first embodiment of the present invention. 
         FIG. 2  is a diagram showing the construction of an air conditioner control apparatus  13  according to the first embodiment. 
         FIG. 3  is a graph showing an example of meteorological information. 
         FIG. 4  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to meteorological information. 
         FIG. 5  is a flow chart showing the operation of the air conditioner control apparatus  13  according to the first embodiment. 
         FIG. 6  is a diagram for explaining effects obtained in the first embodiment. 
         FIG. 7  is a diagram showing the construction of an air conditioner control apparatus  13  according to a second embodiment of the present invention. 
         FIG. 8  is a diagram showing the construction of an air conditioner control apparatus  13  according to a third embodiment of the present invention. 
         FIG. 9  is an example of a graph showing a relation of a dehumidifying time zone and a cooling time zone to a predictive heat load. 
         FIG. 10  is a diagram showing the construction of an air conditioner control apparatus  13  according to a fourth embodiment of the present invention. 
         FIG. 11  is a diagram showing display examples in a display unit  137  according to the fourth embodiment. 
         FIG. 12  is a sectional view showing an example of an open showcase related to the present invention. 
         FIG. 13  is a refrigerant circuit diagram showing the construction of a refrigerator in the open showcase related to the present invention. 
         FIG. 14  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to meteorological information in a sixth embodiment of the present invention. 
         FIG. 15  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to meteorological information in a seventh embodiment of the present invention. 
         FIG. 16  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to an outdoor temperature in an eighth embodiment of the present invention. 
         FIG. 17  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to an outdoor temperature in a ninth embodiment of the present invention. 
         FIG. 18  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to an in-store temperature in a tenth embodiment of the present invention. 
         FIG. 19  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to an in-store temperature in an eleventh embodiment of the present invention. 
         FIG. 20  is a graph showing a case where a dehumidifying operation and a cooling operation are performed in a relation of a dehumidifying time zone and a cooling time zone to an outdoor temperature and an outdoor humidity according to a twelfth embodiment of the present invention. 
         FIG. 21  is a graph showing a case where only the dehumidifying operation is performed in the relation of a dehumidifying time zone and a cooling time zone to an outdoor temperature and an outdoor humidity according to the twelfth embodiment. 
         FIG. 22  is a graph showing a case where the dehumidifying operation is not performed in the relation of a dehumidifying time zone and a cooling time zone to an outdoor temperature and an outdoor humidity according to the twelfth embodiment. 
         FIG. 23  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to an in-store temperature according to a thirteenth embodiment of the present invention. 
         FIG. 24  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to an in-store temperature according to a fourteenth embodiment of the present invention. 
         FIG. 25  is an enlarged diagram of the interior of a dotted-line ellipse shown in  FIG. 24 . 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     Embodiments of the present invention will be described below with reference to the drawings. 
     First, assuming that the interior of a room to be cooled by an air conditioner is the interior of a grocery store such as a supermarket, a description will be given below about in what manner cooling of the store interior is effected by controlling the operation of a refrigerant compressor which is included in an outdoor unit of the air conditioner. 
     In the following description, including the description of the drawings, same or similar portions are identified by the same or similar reference numerals. It should be noted that the drawings are schematic. 
     First Embodiment 
     (Outline of Cooling System) 
     A cooling system according to a first embodiment of the present invention will be outlined below with reference to drawings.  FIG. 1  is a diagram showing an outline of a cooling system  1  according to a first embodiment of the present invention. 
     As shown in  FIG. 1 , the cooling system  1  includes an indoor unit  11 , an outdoor unit  12 , an air conditioner control apparatus  13 , a refrigerator  21  and a showcase  22 . A facility  10  in which the indoor unit  11  and the showcase  22  are installed is a store such as a convenience store or a supermarket. 
     The indoor unit  11  and the outdoor unit  12  constitute an air conditioner for adjusting the temperature and humidity in the interior of the facility  10 . The indoor unit  11  and the outdoor unit  12  are connected with each other through refrigerant pipes P. The indoor unit  11  and the outdoor unit  12  are connected to the air conditioner control apparatus  13  through communication lines Q respectively. 
     The indoor unit  11  is installed in the interior of the facility  10 . The indoor unit  11  has a heat exchanger  111 , a fan  112  and a temperature/humidity sensor  113 . The heat exchanger  111  cools the indoor air with use of a refrigerant flowing through the refrigerant pipes P. The fan  112  feeds the air cooled by the heat exchanger  111  to the interior of the facility. The temperature/humidity sensor  113  detects indoor temperature and humidity in real time. 
     The outdoor unit  12  is installed outside the facility  10 . The outdoor unit  12  includes a heat exchanger  121 , a fan  122 , a compressor  123 , a four-way valve  124  and an expansion valve  125 . The heat exchanger  121  removes the heat of the refrigerant flowing through the refrigerant pipes P to the exterior of the room. The fan  122  feeds air to the heat exchanger  121 . The compressor  123  sucks in the refrigerant of low temperature and low pressure flowing from the indoor unit  11  side and discharges the refrigerant of high temperature and high pressure. The four-way valve  124  is utilized for reversing the refrigerant flow between when cooling and when heating. The expansion valve  125  expands the refrigerant flowing thereto from the heat exchanger  121  and sends it to the indoor unit  11  side. 
     The refrigerator  21  and the showcase  22  constitute a cooler for cooling a cooling space in the showcase  22 . The refrigerator  21  and the showcase  22  are connected with each other through a refrigerant pipe. The refrigerator  21  and the showcase  22  are each connected to the air conditioner control apparatus  13  through a communication line Q. 
     The refrigerator  21  supplies the refrigerant to the showcase  22 . The showcase  22  may be a freezing showcase for freezing commodities or it may be a refrigerating showcase for refrigerating commodities. As examples of the showcase  22 , there are mentioned an open showcase not provided with a door or the like so that customers can take out commodities freely, and a closed showcase provided with a door for enhancing the cooling efficiency. 
     The air conditioner control apparatus  13  controls the air conditioner (the indoor unit  11  and the outdoor unit  12 ) and the cooler (the refrigerator  21  and the showcase  22 ) in an associated manner through communication lines Q. By controlling the air conditioner and the cooler in an associated manner is meant that while taking one state of operation into account, control of the other is executed. The present invention is concerned with controlling the air conditioner by the air conditioner control apparatus  13 . The air conditioner control apparatus  13  controls the air conditioner, thereby performing a cooling operation for cooling the interior of the facility  10  and a dehumidifying operation for removing moisture present in the interior of the facility. More specifically, the air conditioner control apparatus  13  controls for example the feed air volume of the fan  112  and a low pressure of the compressor  123 . Further, the air conditioner control apparatus  13  receives detection results from the temperature/humidity sensor  113  through a communication line Q. 
     (Construction of Air Conditioner Control Apparatus) 
     Now, with reference to drawings, the following description is provided about the construction of the air conditioner control apparatus according to the first embodiment of the present invention.  FIG. 2  is a diagram showing the construction of the air conditioner control apparatus  13  according to the first embodiment. 
     As shown in  FIG. 2 , the air conditioner control apparatus  13  includes a communication unit  131 , a predictive outdoor temperature acquiring unit  132 , a time zone setting unit  133  and a control unit  134 . 
     The communication unit  131  receives detection results of indoor temperature and humidity from the temperature/humidity sensor  113 . The communication unit  131  transmits control signals provided from the control unit  134  to the indoor unit  11  and the outdoor unit  12 . 
     The predictive outdoor temperature acquiring unit  132  acquires meteorological information (e.g., predictive outdoor temperature, predictive outdoor humidity, and weather forecast) near the facility  10  through an external network such as the Internet or on the basis of a data base which stores past meteorological information (e.g., past several years&#39; information near the facility  10 ).  FIG. 3  is a graph showing an example of predictive outdoor temperature and predictive outdoor humidity which the predictive outdoor temperature acquiring unit  132  acquires. As to the coefficient of performance, COP, (a value obtained by dividing the cooling capacity of the air conditioner by energy consumption of the air conditioner) in the cooling operation, the lower the outside temperature, the higher the COP. Usually, as shown in  FIG. 3 , the outdoor temperature becomes high in the daytime, so that the coefficient of performance, COP, of the air conditioner in the cooling operation tends to become higher in the period from night to early morning. 
     On the basis of the predictive outdoor temperature, the time zone setting unit  133  sets a cooling time zone for execution of the cooling operation and a dehumidifying time zone for execution of the dehumidifying operation. As shown in  FIG. 4 , the time zone setting unit  133  sets the dehumidifying time zone prior to the cooling time zone.  FIG. 4  is a graph showing a relation of the dehumidifying time zone and the cooling time zone both set by the time zone setting unit  133  to meteorological information. 
     More specifically, the time zone setting unit  133  sets the dehumidifying time zone to a time zone in which the predictive outdoor temperature is lower than a threshold value α (° C.). The dehumidifying time zone is determined by both a dehumidifying start time and a dehumidifying end time. The dehumidifying start time is set to a set time set by a user or an arbitrary time in the time zone in which the predictive outdoor temperature is lower than the threshold value α (° C.). The dehumidifying end time may be set for example to a real time at which an indoor absolute humidity reaches a target absolute humidity. The target absolute humidity may be set to a value which is the sum of a saturated vapor quantity of the indoor air corresponding to the refrigerant temperature in the heat exchanger  111  and a predetermined vapor quantity. The dehumidifying end time may be defined after a predetermined time which is determined from both the dehumidifying start time and a dehumidifying operation time set by a user. 
     The time zone setting unit  133  sets the cooling time zone to a time zone in which the predictive outdoor temperature is not lower than the threshold value α (° C.). The cooling time zone is determined by both a cooling start time and a cooling end time. The cooling start time may be set to the same as the dehumidifying end time or it may be set to a time after the lapse of a predetermined time from the dehumidifying end time in the time zone in which the predictive outdoor temperature is higher than the threshold value α (° C.). It should be noted that the cooling time zone is preferably close to the dehumidifying time zone. The cooling end time may be set to a time after a predetermined time from the cooling start time. It should be noted that the cooling end time and the dehumidifying start time may be the same time. 
     The control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in the cooling time zone set by the time zone setting unit  133 . More specifically, at the cooling start time the control unit  134  raises the low pressure of the compressor  123  up to a first pressure and controls the air feed volume of the fan  112  to a first air volume in accordance with a temperature difference |ΔT| between both indoor temperature T i  and set temperature T s . The set temperature in the cooling operation may be set arbitrarily. 
     The control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation in the dehumidifying time zone set by the time zone setting unit  133 . More specifically, at the dehumidifying start time the control unit  134  controls the low pressure of the compressor  123  to a second pressure lower than the first pressure in the cooling operation, and further controls the air feed volume of the fan  112  to a second air volume. In this connection, it is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first air volume in the cooling operation. 
     (Operation of Air Conditioner Control Apparatus) 
     Now, with reference to drawings, a description will be given below about the operation of the air conditioner control apparatus according to the first embodiment of the present invention.  FIG. 5  is a flow chart showing the operation of the air conditioner control apparatus  13  according to the first embodiment. 
     As shown in  FIG. 5 , in step S 10 , the air conditioner control apparatus  13  acquires a predictive outdoor temperature of the day concerned to control the indoor unit  11  and the outdoor unit  12 . 
     In step S 11 , the air conditioner control apparatus  13  sets a cooling time zone and a dehumidifying time zone on the basis of the predictive outdoor temperature. The air conditioner control apparatus  13  sets the dehumidifying time zone to a time zone in which the predictive outdoor temperature is lower than the threshold value α (° C.). The dehumidifying end time may be set to a real time at which the indoor humidity reaches a target humidity. 
     In step S 12 , the air conditioner control apparatus  13  determines whether the dehumidifying start time has been reached or not. If the answer is affirmative, execution passes to step S 13 , while if the answer is negative, the processing of step S 12  is repeated. 
     In step S 13 , the air conditioner control apparatus  13  controls the low pressure of the compressor  123  to the second pressure. In this connection, it is to be noted that the second pressure is lower than the first pressure in the cooling operation. 
     In step S 14 , the air conditioner control apparatus  13  controls the air volume of the fan  112  to the second air volume. In this connection, it is to be noted that the second air volume is smaller than a mean value of the first air volume in the cooling operation. 
     In step S 15 , the air conditioner control apparatus  13  determines whether the dehumidifying end time has been reached or not. If the answer is affirmative, execution passes to step S 16 , while if the answer is negative, execution returns to step S 13 . 
     In step S 16 , the air conditioner control apparatus  13  once terminates the control of the compressor  123  and the fan  112 . 
     In step S 17 , the air conditioner control apparatus  13  determines whether the cooling start time has been reached or not. If the answer is affirmative, execution passes to step S 18 , while if the answer is negative, the processing of step S 17  is repeated. 
     In step S 18 , the air conditioner control apparatus  13  controls the low pressure of the compressor  123  to the first pressure. In this connection, it is to be noted that the first pressure is higher than the second pressure in the dehumidifying operation. 
     In step S 19 , the air conditioner control apparatus  13  controls the air volume of the fan  112  to the first air volume. In this connection, it is to be noted that the first air volume is usually larger than the second air volume in the dehumidifying operation. 
     In step S 20 , the air conditioner control apparatus  13  determines whether the cooling end time has been reached or not. If the answer is affirmative, the processing ends, while if the answer is negative, execution returns to step S 18 . 
     (Function and Effect) 
     The air conditioner control apparatus  13  according to the first embodiment performs the dehumidifying operation for removing moisture present in the interior of the room, prior to performing the cooling operation for cooling the interior of the room where the indoor unit  11  is installed. 
     Thus, since the dehumidifying operation is carried out before execution of the cooling operation, it is possible to suppress the necessity of dehumidifying simultaneously with the cooling operation. Consequently, it is possible to save the electric power which is considered necessary for dehumidifying in the cooling operation, thus making it possible to suppress the electric power which is consumed by the air conditioner for cooling the interior of the room. 
     More specifically, as shown in  FIG. 6 , by performing the cooling operation after execution of the dehumidifying operation it is possible to lower a peak of electric power consumption from P1 (kW) to P2 (kW). As a result, if the grocery store concerned makes a demand contract with an electric company, it is possible to cut down the cost of electricity. Moreover, in the summer season in which the electric power consumption increases, it is possible to disperse peak times of electric power consumption. 
     The air conditioner control apparatus  13  according to the first embodiment sets the dehumidifying time zone to a time zone in which the predictive outdoor temperature is lower than the threshold value α (° C.). That is, the air conditioner control apparatus  13  permits efficient dehumidifying for the interior of the room in the time zone in which the coefficient of performance, COP, of the air conditioner in the cooling operation is high. Consequently, it is possible to suppress the electric power which is consumed by the air conditioner for dehumidifying the interior of the room. 
     More specifically, as shown in  FIG. 6 , in case of performing the dehumidifying operation simultaneously with the cooling operation, electric energy A is necessary for the dehumidifying operation, while in case of performing the dehumidifying operation before the cooling operation, electric energy B (&lt;electric energy A) is necessary for the dehumidifying operation. Thus, it is possible to decrease the total quantity of electric energy required for indoor cooling. 
     Second Embodiment 
     A second embodiment of the present invention will be described below with reference to drawings. The following description will be directed mainly to different points between the first and the second embodiments. 
     More specifically, in the above first embodiment, the time zone setting unit  133  sets both cooling time zone and dehumidifying time zone on the basis of the predictive outdoor temperature. On the other hand, in this second embodiment, the time zone setting unit  133  sets both cooling time zone and dehumidifying time zone on the basis of a temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s  in the cooling operation. 
     (Construction of Air Conditioner Control Apparatus) 
     The construction of an air conditioner control apparatus according to the second embodiment of the present invention will be described below with reference to drawings.  FIG. 7  is a diagram showing the construction of an air conditioner control apparatus  13  according to the second embodiment. 
     As shown in  FIG. 7 , the air conditioner control apparatus  13  has an indoor temperature acquiring unit  135 . The indoor temperature acquiring unit  135  acquires an indoor temperature T i  in real time from the temperature/humidity sensor  113  through a communication line Q. 
     The time zone setting unit  133  acquires a set temperature T s  in the cooling operation through a communication line Q. The time zone setting unit  133  sets both cooling time zone and dehumidifying time zone on the basis of a temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s  in the cooling operation. The time zone setting unit  133  sets the dehumidifying time zone before the cooling time zone. 
     More specifically, the time zone setting unit  133  calculates the temperature difference |ΔT| in real time and sets the dehumidifying time zone to a time zone in which the temperature difference |ΔT| is smaller than a threshold value β (° C.). For example, the threshold value β (° C.) may be set to 1˜2 (° C.) or so. The dehumidifying start time is set, for example, to a time at which the temperature difference |ΔT| has become not larger than the threshold value β (° C.), or an arbitrary time in the time zone in which the temperature difference |ΔT| is not larger than the threshold value β (° C.), or a set time set by a user. The dehumidifying end time is set, for example, to a time at which the temperature difference |ΔT| has become higher than the threshold value β (° C.), or an arbitrary time in the time zone in which the temperature difference |ΔT| is not larger than the threshold value β (° C.), or a set time determined from both the dehumidifying start time and a dehumidifying operation time set by a user. In the time zone setting unit  133  according to this embodiment, the time at which the temperature difference |ΔT| is smaller than the threshold value β (° C.) is set as the dehumidifying start time and the time at which the temperature difference |ΔT| has become not smaller than the threshold value β (° C.) is set as the dehumidifying end time. 
     The time zone setting unit  133  sets the cooling time zone to a time zone in which the temperature difference |ΔT| is not smaller than the threshold value β (° C.). In this connection, the cooling start time may be set to the same time as the dehumidifying end time, or it may be set to a time after the lapse of a predetermined time from the dehumidifying end time in the time zone in which the temperature difference |ΔT| is larger than the threshold value β (° C.). It should be noted that the cooling time zone is preferably close to the dehumidifying time zone. Further, the cooling end time may be defined to a time after a predetermined time from the cooling start time. The cooling end time and the dehumidifying start time may be the same time. 
     The control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in the cooling time zone. Further, in the dehumidifying time zone, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation. 
     (Function and Effect) 
     The air conditioner control apparatus  13  according to this second embodiment sets the dehumidifying time zone to a time zone in which the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s  in the cooling operation is smaller than the threshold value β (° C.). Therefore, the air conditioner control apparatus  13  can dehumidify the interior of the room efficiently in the time zone in which the temperature difference |ΔT| is smaller than the threshold value β (° C.), namely, in the time zone in which the outside temperature is low and the coefficient of performance, COP, of the air conditioner in the cooling operation is high. Consequently, it is possible to suppress the electric power which is consumed by the air conditioner for indoor dehumidification. 
     Third Embodiment 
     A third embodiment of the present invention will be described below with reference to drawings. In the following description, reference will be made mainly to different points from the previous first embodiment. 
     More specifically, in the first embodiment described previously, the time zone setting unit  133  sets the cooling time zone and the dehumidifying time zone on the basis of the predictive outdoor temperature. On the other hand, in this third embodiment, the time zone setting unit  133  sets the cooling time zone and the dehumidifying time zone on the basis of an indoor predictive heat load Q [kW]. By the indoor predictive heat load Q is meant heat which enters the interior of the room per unit time. 
     (Construction of Air Conditioner Control Apparatus) 
     The construction of an air conditioner control apparatus according to a third embodiment of the present invention will be described below with reference to drawings.  FIG. 8  is a diagram showing the construction of an air conditioner control apparatus  13  according to the third embodiment. 
     As shown in  FIG. 8 , the air conditioner control apparatus  13  has a predictive heat load acquiring unit  136 . The predictive heat load acquiring unit  136  acquires predictive meteorological information (e.g., predictive outdoor temperature, predictive outdoor humidity, weather forecast) of the day concerned neat the facility  10  through an external network such as the Internet or from a data base which stores past meteorological information (e.g., information of the past several years). Further, the predictive heat load acquiring unit  136  acquires predictive indoor temperature and predictive indoor humidity of the day concerned from a data base which stores them. 
     From a predetermined data base, the predictive heat load acquiring unit  136  acquires various information pieces necessary for calculating a predictive heat load Q. As examples of such information pieces are mentioned indoor volume [m 3 ], roof area [m 2 ], exterior wall area [m 2 ], glass window area [m 2 ], overall heat transfer coefficient [kW/m 2 /° C.], total rated electric power consumption of indoor lighting [kW], total rated electric power consumption of indoor equipments [kW], the number of times of ventilation [times/h], the number of persons present in the room [persons], generation heat from human body [kW/person], air density [kg/m 3 ], outdoor air enthalpy [kJ/kg′], indoor air enthalpy [kJ/kg′], and the number of showcases [cases] installed in the interior of the room. 
     Using the above various information pieces, the predictive heat load acquiring unit  136  calculates a predictive heat load Q. More specifically, the predictive heat load acquiring unit  136  calculates the predictive heat load Q by subtracting a heat loss due to cold air leak from showcase Q9 from the sum of solar radiant heat Q1, exterior wall conductive heat Q2, glass window conductive heat Q3, roof conductive heat Q4, generation heat from human body Q5, heat from lighting Q6, heat from electrical equipment Q7 and outdoor air heat (ventilation-related heat, obtained by a ventilation frequency method) Q8. That is, the predictive heat load Q is obtained by the following equation (1): 
         Q  [kW]= Q 1 +Q 2 +Q 3 +Q 4 +Q 5 +Q 6 +Q 7 +Q 8 −Q 9  (1)
 
     Next, a detailed description will be given below with respect to each of the heats Q1 to Q9. 
     First, the solar radiant heat Q1 is obtained by the following equation (2): 
         Q 1=(glass window area)×(standard solar heat acquired from glass window)×(shade factor)  (2)
 
     The exterior wall conductive heat Q2 is obtained by the following equation (3): 
         Q 2=(exterior wall area)×(overall heat transfer coefficient)×(indoor/outdoor temperature difference)  (3)
 
     The glass window conductive heat Q3 is obtained by the following equation (4): 
         Q 3=(glass window area)×(overall heat transfer coefficient)×(indoor/outdoor temperature difference)  (4)
 
     The roof conductive heat Q4 is obtained by the following equation (5): 
         Q 4=(roof area)×(overall heat transfer coefficient)×(indoor/outdoor temperature difference)  (5)
 
     The generation heat from human body Q5 is obtained by the following equation (6): 
         Q 5=(number of persons present in the room)×(generation heat from human body)  (6)
 
     The heat from lighting Q6 is obtained by the following equation (7): 
         Q 6=(total rated electric power consumption of indoor lighting)  (7)
 
     The heat from electrical equipment Q7 is obtained by the following equation (8): 
         Q 7=(total rated electric power consumption of indoor equipments)  (8)
 
     The indoor equipments indicate equipments which generate heat in the interior of the room such as personal computer, copying machine and microwave oven. 
     The outdoor air heat Q8 is obtained by the following equation (9): 
         Q 8=(the number of times of ventilation)×(indoor volume/3600)×(air density)×(outdoor air enthalpy−indoor air enthalpy)  (9)
 
     The heat loss due to cold air leak from showcase Q9 is obtained by the following equation (10). In the equation (10), it is assumed that r1 stands for a heat loss factor due to cold air leak from showcase, r2 stands for required refrigerating capacity hour of the showcase [kW], r3 stands for enthalpy of the air inside showcase [kJ/kg], and r4 stands for enthalpy of the air around the showcase (required refrigerating capacity hour) [kJ/kg]. 
         Q 9=(number of showcase)× r 1× r 2×(indoor air enthalpy− r 3)/( r 4− r 3)  (10)
 
     The time zone setting unit  133  acquires the above predictive heat load Q. The time zone setting unit  133  sets both cooling time zone and dehumidifying time zone on the basis of the predictive heat load Q. As shown in  FIG. 9 , the time zone setting unit  133  sets the dehumidifying time zone before the cooling time zone.  FIG. 9  is an example of a graph showing a relation of the dehumidifying time zone and the cooling time zone both set by the time zone setting unit  133  to the predictive heat load Q. 
     More specifically, the time zone setting unit  133  sets the dehumidifying time zone to a time zone in which the predictive heat load Q is lower than a threshold value γ [kW]. A dehumidifying start time is set to a set time set by a user or an arbitrary time in the time zone in which the predictive heat load Q is lower than the threshold value γ [kW]. A dehumidifying end time is set, for example, to a time at which the predictive heat load Q has become not lower than the threshold value γ [kW], or an arbitrary time in the time zone in which the predictive heat load Q is lower than the threshold value γ [kW], or a set time which is determined from both the dehumidifying start time and a dehumidifying operation time set by a user. 
     Further, the time zone setting unit  133  sets the cooling time zone to a time zone in which the predictive heat load Q is not lower than the threshold value γ [kW]. The cooling time zone is determined by both cooling start time and cooling end time. The cooling start time may be set to the same time as the dehumidifying end time or it may be set after the lapse of a predetermined time from the dehumidifying end time in the time zone in which the predictive heat load Q is not lower than the threshold value γ [kW]. The cooling end time may be set to a time after a predetermined time from the cooling start time. 
     The control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in the cooling time zone set by the time setting unit  133 . 
     (Function and Effect) 
     The air conditioner control apparatus  13  according to the third embodiment sets the dehumidifying time zone to a time zone in which the predictive heat load Q is lower than the threshold value γ [kW]. Therefore, the interior of the room can be dehumidified efficiently in the time zone in which the predictive heat load Q (° C.) in the interior of the room is lower than the threshold value γ [kW], namely, in the time zone in which the outdoor temperature is low and the coefficient of performance, COP, of the air conditioner in the cooling operation is high. Consequently, it is possible to suppress the electric power which is consumed by the air conditioner for dehumidifying the interior of the room. 
     Fourth Embodiment 
     A fourth embodiment of the present invention will be described below with reference to drawings. In the following description, reference will be made mainly to different points from the previous first embodiment. 
     (Construction of Air Conditioner Control Apparatus) 
     The construction of an air conditioner control apparatus according to a fourth embodiment of the present invention will be described below with reference to drawings.  FIG. 10  is a diagram showing the construction of an air conditioner control apparatus  13  according to the fourth embodiment. 
     As shown in  FIG. 10 , the air conditioner control apparatus  13  according to the fourth embodiment has a display unit  137 . For example, the display unit  137  is a display of a personal computer. On the display unit  137  is displayed for example in what state the air conditioner is controlled by the control unit  134 .  FIG. 11  is a diagram showing display examples of the display unit  137 . 
     More specifically, as shown in  FIG. 11(   a ), an initial display is provided on the display unit  137 . In the initial display, it is possible to select either an energy saving operation mode or a normal operation mode. The energy saving operation mode is a mode in which a dehumidifying time zone is set before a cooling time zone. The normal operation mode is a mode in which a dehumidifying time zone is not set before a cooling time zone. 
     If a user selects the normal operation mode, a normal operation mode display is provided on the display unit  137 , as shown in  FIG. 11(   b ). For example, a set temperature in the cooling operation and the state of operation (“ON” or “OFF”) are displayed on the normal operation mode display. 
     If the user selects the energy saving operation mode, an energy saving operation mode display is provided on the display unit  137 , as shown in  FIG. 11(   c ). For example, a set temperature in the cooling operation, indoor humidity, the type of operation (“Cooling Operation” or “Dehumidifying Operation”) and a setting button are displayed on the energy saving operation mode display. 
     If the user depresses the setting button on the energy saving operation mode display, a setting display is provided on the display unit  137 , as shown in  FIG. 11(   d ). On the setting display the user can confirm and set the dehumidifying start time and end time, target humidity and store type. 
     Fifth Embodiment 
     Although the present invention has been described above by way of embodiments thereof, it is not to be understood that the statements and drawings constituting a part of the above disclosure limit the present invention. From the above disclosure, various alternative embodiments, examples and application techniques will become apparent to those skilled in the art. 
     For example, the cooling time zone need not always be set although no particular reference is made to this point in the above embodiments. More particularly, when the predictive outdoor temperature is lower than the set temperature T s , or when the weather is rainy or cloudy, or when the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s  is smaller than a predetermined value, the air conditioner control apparatus  13  does not set the cooling time zone. In the case of the air conditioner control apparatus  13  installed for example in an office building, the air conditioner control apparatus  13  need not always set the dehumidifying time zone if the cooling time zone is not set. On the other hand, in the case of the air conditioner control apparatus  13  installed for example in a store having a showcase, the dehumidifying time zone may be set even if the cooling time zone is not set. In the case where the cooling system  1  is provided with the showcase  22 , the heat load on the showcase  22  can be reduced by performing the dehumidifying operation, thus making it possible to reduce the electric power consumption of the refrigerator. 
     Although in the above embodiments the predictive outdoor temperature, the predictive heat load, or the real time temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s  in the cooling operation, is used as an index for setting the dehumidifying time zone to a time zone in which the coefficient of performance, COP, of the air conditioner in the cooling operation is high and the necessity of indoor cooling is small, no limitation is made thereto. For example, in order to detect the time zone in which the coefficient of performance, COP, of the air conditioner in the cooling operation is high and the necessity of indoor cooling is small, there may be used a real time indoor temperature T i , a real time outdoor temperature, and a temperature difference between the real time outdoor temperature and the real time indoor temperature. 
     Although in the above embodiments the dehumidifying time zone and the cooling time zone are set in a continuous manner, both need not always be continuous. More specifically, a time not affecting the indoor humidity may be provided between the dehumidifying time zone and the cooling time zone. 
     Although in the above embodiments the cooling time zone and the dehumidifying time zone are set in a discontinuous manner, both may be continuous. Particularly, in the case where the facility  10  is a 24-hour open store, the whole time zone other than the dehumidifying time zone is set as the cooling time zone. 
     Although in the above embodiments the cooling time zone is set in the daytime, the cooling time zone may be set late at night or early in the morning depending on the business condition of the facility  10  and if it is after the dehumidifying time zone. The present invention does not limit the time zone to which the cooling time zone is to be set in a day. 
     Although in the above second embodiment the time zone setting unit  133  sets the cooling time zone and the dehumidifying time zone on the basis of the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s  in the cooling operation, both time zones may be set on the basis of only the indoor temperature T i . More specifically, the time zone setting unit  133  acquires the indoor temperature T i  in real time and sets the dehumidifying time zone to a time zone in which the indoor temperature T i  is lower than a threshold value δ (° C.). The threshold value δ (° C.) may be set, for example, at about 20-22 (° C.). In this case, the air conditioner control apparatus  13  permits efficient dehumidification of the room interior in a time zone in which the indoor temperature T i  is lower than the threshold value δ (° C.), namely, a time zone in which the outdoor temperature is low and the coefficient of performance, COP, of the air conditioner in the cooling operation is high. Therefore, it is possible to suppress the electric power which is consumed by the air conditioner for dehumidifying the room interior. 
     The threshold values α, β, γ and δ are obtained from past measured data or experiments although no particularly reference is made to this point in the above embodiments. 
     The hardware configuration of the air conditioner control apparatus  13  described above can be implemented as a program module. Therefore, the above processing carried out in the air conditioner control apparatus  13  may be carried out for example by a general-purpose computer having the function of the air conditioner control apparatus  13 . 
     Now, the following description is provided about the case where the interior of the facility  10  cooled by the air conditioner according to the present invention is the interior of a grocery store such as a supermarket. 
     As one method for cooling the interior of the grocery store such as a supermarket, a dehumidifying operation is performed in an appropriate time zone before opening and/or after closing of the store, in which dehumidifying operation cold air is blown off into the store, the cold air being lower in temperature and smaller in air feed volume than the cold air which is blown off into the store in the cooling operation. 
     Sixth Embodiment 
     A sixth embodiment of the present invention will now be described with reference to  FIG. 14 . A description will be given about a control method which utilizes a predictive outdoor temperature (or a calculated predictive heat load value) in a non-24-hour open store. This store is, for example, a supermarket or a convenience store. A freezing showcase and a refrigerating showcase (hereinafter referred to as the freezing/refrigerating showcases) for the storage of foods for sale are installed in the interior of the store. The interior of the store is cooled by an air conditioner. In the present invention, by the interior of the room is meant the interior of the store. 
     According to this control method, a schedule of both dehumidifying operation and cooling operation for the whole of the following day (starting at twelve midnight) is determined on the preceding day. Since the store related to  FIG. 14  is a non-24-hour open store (a store which opens in a predetermined time zone out of 24 hours), the air conditioning time zone of the store by operation of the air conditioner is not 24 hours. 
     In the store, the outdoor temperature is assumed to be unpredictable and a predictive outdoor temperature of the following day is acquired by utilizing the Internet from a meteorological information offering company or the like. How to acquire the predictive outdoor temperature, etc. is the same as in the first embodiment. 
     In this case, the construction of the air conditioner control apparatus  13  according to this embodiment is as shown in  FIG. 8 . How to obtain the calculated predictive heat load value is the same as in the third embodiment. 
     In  FIG. 8 , as noted previously, the air conditioner control apparatus  13  has the predictive heat load acquiring unit  136 . Through an external network such as the Internet or from a data base which stores past meteorological information (e.g., information of the past several years), the predictive heat load acquiring unit  136  acquires predictive meteorological information (e.g., predictive outdoor temperature, predictive outdoor humidity, weather forecast) of the day concerned near the facility  10 . The predictive heat load acquiring unit  136  acquires both predictive indoor temperature and predictive indoor humidity of the day concerned from a data base which stores them. Calculation of the predictive heat load Q is performed while making reference to the foregoing equation (1) of the predictive heat load Q. 
     Referring to  FIG. 14 , in connection with the time zone of dehumidifying operation, the threshold value α is determined to be an outdoor temperature of 30° C. for example, and in the time zone (0˜9 o&#39;clock a.m. in  FIG. 14 ) in which the predictive outdoor temperature is presumed to become lower than the threshold value α, a time close to an air conditioning start time (e.g., 5 o&#39;clock a.m.) of the store is set as a dehumidifying operation start time. In  FIG. 14 , 5 o&#39;clock a.m. is the dehumidifying operation start time. A dehumidifying operation end time is the time at which the predictive outdoor temperature is presumed to become a temperature of not lower than the threshold value α. In  FIG. 14 , the dehumidifying operation end time is 9 o&#39;clock a.m. It should be noted that, in the case where the indoor temperature becomes a temperature of not lower than a set value (e.g., 25° C. or higher) in the dehumidifying operation, the dehumidifying operation is stopped and a shift is made to the cooling operation mode. 
     Referring to  FIG. 14 , in the air conditioning time zone of the store, the whole time zone other than the dehumidifying operation is made a cooling operation time zone. Whether the cooling operation is to be actually performed or not depends on both room temperature and set temperature for the air conditioner and is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 , as described in the first embodiment. 
     Since the store is a non-24-hour open store, the air conditioning time zone of the store is the time zone from a preparation start time to a clearing work end time in the store or the time zone from an opening time to a closing time of the store. It is a time zone set beforehand by the store manager. In  FIG. 14 , it is the time zone from 5 a.m. to 11 p.m. (5 o&#39;clock to 23 o&#39;clock). 
     In this case, the cooling operation is the same as in the first embodiment. For permitting a timer operation so as to start an air conditioning operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to perform the cooling operation in a cooling time zone set by the time zone setting unit  133 . More specifically, at the cooling start time, the control unit  134  raises the low pressure of the compressor  123  up to the first pressure and controls the air feed volume of the fan  112  to the first air volume in accordance with the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s . The cooling operation temperature can be set to an arbitrary temperature. 
     In this case, the dehumidifying operation is the same as in the first embodiment. For permitting a timer operation so as to start the dehumidifying operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation in a dehumidifying time zone set by the time zone setting unit  133 . More specifically, at the dehumidifying start time, the control unit  134  not only controls the low pressure of the compressor  123  to the second pressure lower than the first pressure in the cooling operation but also controls the air feed volume of the fan  112  to the second air volume. In this connection, it is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first air volume in the cooling operation. 
     By such a control, in the air conditioner control apparatus to control the air conditioner for the store, which permits a timer operation involving starting the air conditioning operation at a predetermined operation start time and stopping it at an operation end time, a store opening time and a store closing time are set between the operation start time and the operation end time of the air conditioner, and in the case where the outdoor temperature is lower than the predetermined temperature (threshold value α) in the period from such an operation start time until the store opening time, there is performed an operation in which cold air is blown off into the store, the cold air being designed lower in temperature and smaller in air feed volume than the cold air which is blown off into the store in the cooling operation carried out in the period from the store opening time until the store closing time. 
     If the control of the cooling operation described above is such that the operation of the compressor  123  and that of the fan  112  are inverter-controlled (frequency-controlled so that the closer to the air conditioner-set temperature with drop in room temperature, the lower the number of revolutions of the motor of the compressor  123  and that of the motor of the fan  112 ) by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , it is possible in the dehumidifying operation to make control so that the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     If the control of the cooling operation described above is such that the operation of the compressor  123  and that of the fan  112  are controlled by the air conditioner control apparatus  13  so as to change stepwise (for example a three-step changing control in which when the room temperature is higher than the air conditioner-set temperature, the number of revolutions of the motor of the compressor  123  and that of the motor of the fan  112  are high, which state is “Strong Cooling,” and as the room temperature drops and approaches the air conditioner-set temperature, the number of revolutions of the motor of the compressor  123  and that of the motor of the fan  112  drop, causing a change from “Medium Cooling” to “Weak Cooling”) on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , it is possible in the dehumidifying operation to make control so that the compressor  123  and the fan  112  are operated in a minimum cooling condition corresponding to “Weak Cooling.” 
     Seventh Embodiment 
     A seventh embodiment of the present invention will now be described with reference to  FIG. 15 . A description will be given about a control method utilizing a predictive outdoor temperature (or a calculated predictive heat load value) in a 24-hour open store. This store is like a supermarket or a convenience store in which there are installed a freezing showcase and a refrigerating showcase (hereinafter referred to as the freezing/refrigerating showcases) for the storage of foods for sale. The interior of the store is cooled by an air conditioner. In the present invention, the interior of the room means the interior of the store. 
     In this control method, a schedule of a dehumidifying operation and a cooling operation for the whole of the following day (starting at twelve midnight) is determined on the preceding day. Since the store related to  FIG. 15  is a 24-hour open store (a store which opens 24 hours), the air conditioning time zone of the store by operation of the air conditioner is 24 hours. 
     In this case, in the store it is assumed that the outdoor temperature is unpredictable, and the predictive outdoor temperature of the following day is acquired by utilizing the Internet from a meteorological information offering company or the like. 
     In this case, the construction of the air conditioner control apparatus  13  is as shown in  FIG. 8 , and how to obtain the calculated predictive heat load value is the same as in the third embodiment. 
     In  FIG. 8 , as described previously, the air conditioner control apparatus  13  has the predictive heat load acquiring unit  136 . The predictive heat load acquiring unit  136  acquires predictive meteorological information (e.g., predictive outdoor temperature, predictive outdoor humidity, weather forecast) of the day concerned near the facility  10  through an external network such as the Internet or from a data base which stores past meteorological information (e.g., information of the past several years). Moreover, the predictive heat load acquiring unit  136  acquires both predictive indoor temperature and predictive indoor humidity of the day concerned from a data base which stores them. Calculation of the predictive heat load Q is performed while making reference to the foregoing equation (1) of the predictive heat load Q. 
     Referring to  FIG. 15 , in connection with the time zone of dehumidifying operation, the threshold value α is determined to be an outdoor temperature of 30° C. for example and the earliest time (twelve midnight in  FIG. 15 ) is made a dehumidifying operation start time in the time zone (0 to 9 a.m. in  FIG. 15 ) in which the predictive outdoor temperature is presumed to become lower than the threshold value α. In  FIG. 15 , twelve midnight is the dehumidifying operation start time. A dehumidifying operation end time is a time at which the predictive outdoor temperature is presumed to become a temperature of not lower than the threshold value α. In  FIG. 15 , 9 o&#39;clock a.m. is the dehumidifying operation end time. It should be noted that, in the case where the indoor temperature becomes not lower than a set value, (e.g., 25° C. or higher) in the dehumidifying operation, the same operation is stopped and a shift is made to the cooling operation mode. If the predictive outdoor temperature drops in the evening or thereafter, there can be a case where the second dehumidifying operation is performed on the same day. In  FIG. 15 , the dehumidifying operation is performed in the period from 19 o&#39;clock to 24 o&#39;clock. 
     Referring to  FIG. 15 , in the air conditioning time zone of the store, the whole time zone other than the dehumidifying operation is made a cooling operation time zone. Whether the cooling operation is to be actually performed or not depends on both room temperature and air conditioner-set temperature and is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 , as described in the first embodiment. 
     In the air conditioning time zone of the store, since the store is a 24-hour open store, the business hours of the store are from 0 o&#39;clock to 24 o&#39;clock, but the store manager can set actual business hours in advance. 
     In this case, the cooling operation is the same as in the first embodiment, and for permitting a timer operation so as to start an air conditioning operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in the cooling time zone set by the time zone setting unit  133 . More specifically, at the cooling start time, the control unit  134  raises the low pressure of the compressor  123  up to the first pressure and controls the air feed volume of the fan  112  to the first air volume in accordance with the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s . The set temperature for the cooling operation can be set arbitrarily. 
     In this case, moreover, the dehumidifying operation is the same as in the first embodiment, and for permitting a timer operation so as to start the dehumidifying operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation in the dehumidifying time zone set by the time zone setting unit  133 . More specifically, at the dehumidifying start time, the control unit  134  controls the low pressure of the compressor  123  to the second pressure lower than the first pressure in the cooling operation and controls the air feed volume of the fan  112  to the second air volume. In this connection, it is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first air volume in the cooling operation. 
     By such a control, in the air conditioner control apparatus to control the air conditioner for the store, which permits a timer operation involving starting the air conditioning operation at a predetermined operation start time and stopping it at an operation end time, a store opening time and a store closing time are set between the operation start time and the operation end time of the air conditioner. When the outdoor temperature is lower than the predetermined temperature (threshold value α) in the period from the operation start time until the store opening time and/or from the store closing time until the operation end time, there is performed an operation in which cold air is blown off into the store, the cold air being designed to be lower in temperature and smaller in air feed volume than the cold air which is blown off into the store in the cooling operation in the period from the store opening time until the store closing time. 
     If the control of the cooling operation described above is such that the operation of the compressor  123  and that of the fan  112  are inverter-controlled by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are switched stepwise by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated in a minimum cooling state corresponding to “Weak Cooling.” 
     Eighth Embodiment 
     An eighth embodiment of the present invention will now be described with reference to  FIG. 16 . A description will be given about a control method utilizing a measured outdoor temperature in a non-24-hour open store. This store is like a supermarket or a convenience store. A freezing showcase and a refrigerating showcase (hereinafter referred to as freezing/refrigerating showcases) for the storage of foods for sale are installed in the interior of the store. The interior of the store is cooled by an air conditioner. In the present invention, the interior of the room means the interior of the store. 
     In this control method, a schedule of both dehumidifying operation and cooling operation for the day concerned is determined in real time on the day concerned. Since the store related to  FIG. 16  is a non-24-hour open store (a store which opens in a predetermined time zone out of 24 hours), the air conditioning time zone of the store by operation of the air conditioner is not 24 hours. In this case, measurement of the outdoor temperature can be made in the store. 
     Referring to  FIG. 16 , in connection with the time zone of the dehumidifying operation, the threshold value α is determined to be an outdoor temperature of 30° C. for example, and if the outdoor temperature is lower than the threshold value α at the air conditioning start time (5 a.m. in  FIG. 16 ) in the store, the air conditioning start time is set as the dehumidifying operation start time. In  FIG. 16 , 5 o&#39;clock a.m. is the dehumidifying operation start time. The dehumidifying operation end time is set to the time at which the outdoor temperature has become a temperature of not lower than the threshold value α or the time at which the indoor temperature (in-store temperature) has becomes a temperature of not lower than a set value, (e.g., 25° C. or higher), (9 o&#39;clock in  FIG. 16 ). At this time, the dehumidifying operation is stopped and a shift is made to the cooling operation mode. 
     Referring to  FIG. 16 , as to the time zone of the cooling operation, the whole time zone other than the dehumidifying operation in the store air conditioning time zone is the cooling operation time zone. Whether the cooling operation is actually performed or not depends on both room temperature and air conditioner-set temperature and is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 , as described in the first embodiment. 
     Since the store is a non-24-hour open store, the air conditioning time zone of the store is a time zone from a preparation start time until a clearing work end time of the store or from an opening time until a closing time of the store and it is a time zone set by the store manager beforehand. In  FIG. 16 , the air conditioning time zone is from 5 a.m. to 11 p.m. (5 o&#39;clock to 23 o&#39;clock). 
     In this case, the cooling operation is the same as in the first embodiment. For permitting a timer operation so as to start the air conditioning operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in a cooling time zone set by the time zone setting unit  133 . More specifically, at the cooling start time, the control unit  134  raises the low pressure of the compressor  123  up to the first pressure and controls the air feed volume of the fan  112  to the first air volume in accordance with the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s . The set temperature for the cooling operation can be set arbitrarily. 
     In this case, the dehumidifying operation is the same as in the first embodiment. For permitting a timer operation involving starting the dehumidifying operation at a predetermined operation start time and stopping it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation in a dehumidifying time zone set by the time zone setting unit  133 . More specifically, at the dehumidifying start time, the control unit  134  controls the low pressure of the compressor  123  to the second pressure which is lower than the first pressure in the cooling operation and controls the air feed volume of the fan  112  to the second air volume. It is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first volume in the cooling operation. 
     By such a control, in the air conditioner control apparatus to control the air conditioner for the store, which permits a timer operation involving starting the air conditioning operation at a predetermined operation start time and stopping it at an operation end time, both store opening time and store closing time are set between the operation start time and the operation end time of the air conditioner. If the outdoor temperature is lower than the predetermined temperature (threshold value α) in the period from the operation start time until the store opening time, there is performed an operation in which cold air is blown off into the store, the cold air being designed lower in temperature and smaller in air feed volume than the cold air which is blown off into the store in the cooling operation carried out in the period from the store opening time until the store closing time. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are inverter-controlled by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are switched stepwise by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated in a minimum cooling condition corresponding to “Weak Cooling.” 
     Ninth Embodiment 
     A ninth embodiment will now be described with reference to  FIG. 17 . A description will be given about a control method utilizing a measured outdoor temperature in a 24-hour open store. This store is like a supermarket or a convenience store. A freezing showcase and a refrigerating showcase (hereinafter referred to as the freezing/refrigerating showcases) for the storage of foods for sale are installed in the interior of the store. The interior of the store is cooled by an air conditioner. In the present invention, the interior of the room means the interior of the store. 
     According to this control method, a schedule of both dehumidifying operation and cooling operation for the day concerned is determined in real time on the day concerned. Since the store related to  FIG. 17  is a 24-hour open store (a store which opens 24 hours), the air conditioning time zone in the store by operation of the air conditioner is 24 hours. In the store, it is made possible to measure the outdoor temperature. 
     Referring to  FIG. 17 , in connection with the time zone of the dehumidifying operation, the threshold value α is determined to be an outdoor temperature of 30° C. for example, and since the air conditioning time zone in the store is 24 hours, if the outdoor temperature is lower than the threshold value α, the time concerned is determined to be the dehumidifying operation start time. In  FIG. 17 , twelve midnight is the dehumidifying operation start time. The dehumidifying operation end time is set to the time at which the outdoor temperature has become a temperature of not lower than the threshold value α or the time at which the indoor temperature (in-store temperature) has become a temperature of not lower than a set value, (e.g., 25° C. or higher), (9 o&#39;clock in  FIG. 17 ). At this dehumidifying end time, the dehumidifying operation is stopped and a shift is made to the cooling operation mode. When the outdoor temperature has become a temperature of lower than the threshold value α, there is a case where a second dehumidifying operation is performed on the same day. In  FIG. 17 , the dehumidifying operation is performed in the period from 19 o&#39;clock to 24 o&#39;clock. 
     Referring to  FIG. 17 , in the air conditioning time zone of the store, the whole time zone other than the dehumidifying operation is the cooling time zone. Whether the cooling operation is actually performed or not depends on both room temperature and air conditioner-set temperature and is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 , as described in the first embodiment. 
     Since the store is a 24-hour open store, the air conditioning time zone of the store is from 0 o&#39;clock to 24 o&#39;clock as business hours, but the actual business hours can be set by the store manager in advance. 
     In this case, the cooling operation is the same as in the first embodiment, and for permitting a timer operation so as to start the air conditioning operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in a cooling time zone set by the time zone setting unit  133 . More specifically, at the cooling start time, the control unit  134  raises the low pressure of the compressor  123  up to the first pressure and controls the air feed volume of the fan  112  to the first air volume in accordance with the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s . The set temperature for the cooling operation can be set arbitrarily. 
     In this case, the dehumidifying operation is the same as in the first embodiment. For permitting timer operation involving starting the dehumidifying operation at a predetermined operation start time and stopping it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation in a dehumidifying time zone set by the time zone setting unit  133 . More specifically, at the dehumidifying start time, the control unit  134  controls the low pressure of the compressor  123  to the second pressure which is lower than the first pressure in the cooling operation and controls the air feed volume of the fan  112  to the second air volume. In this connection, it is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first air volume in the cooling operation. 
     By such a control, in the air conditioner control apparatus to control the air conditioner for the store, which permits a timer operation involving starting the air conditioning operation at a predetermined operation start time and stopping it at an operation end time, a store opening time and a store closing time are set between the operation start time and the operation end time of the air conditioner. If the outdoor temperature is lower than the predetermined temperature (threshold value α) in the period from the operation start time until the store opening time and/or from the store closing time until the operation end time, there is performed an operation in which cold air is blown off into the store, the cold air being designed lower in temperature and smaller in air feed volume than the cold air which is blown off into the store in the cooling operation performed in the period from the store opening time until the store closing time. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are inverter-controlled by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are switched stepwise by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated in a minimum cooling condition corresponding to “Weak Cooling.” 
     Tenth Embodiment 
     A tenth embodiment of the present invention will now be described with reference to  FIG. 18 . A description will be given about a control method utilizing a measured indoor temperature (in-store temperature) in a non-24-hour open store. This store is like a supermarket or a convenience store, in the interior of which are installed a freezing showcase and a refrigerating showcase (hereinafter referred to as the freezing/refrigerating showcases) for the storage of foods for sale. The interior of the store is cooled by an air conditioner. In the present invention, the interior of the room means the interior of the store. 
     According to this control method, a schedule of both dehumidifying operation and cooling operation for the day concerned is determined in real time on the day concerned. Since the store related to  FIG. 18  is a non-24-hour open store (a store which opens in a predetermined time zone out of 24 hours), the air conditioning time zone of the store by operation of the air conditioner is not 24 hours. In this case, in the store it is made possible to measure an in-store temperature. 
     Referring to  FIG. 18 , in connection with the time zone of the dehumidifying operation, the threshold value α is determined to be an in-store temperature of 25° C. for example, and if the in-store temperature is lower than the threshold value α at the air conditioning start time (5 a.m. in  FIG. 18 ) of the store, the time in question is set as the dehumidifying operation start time. In  FIG. 18 , 5 o&#39;clock a.m. is the dehumidifying operation start time. As to the dehumidifying operation end time, at the time (9 o&#39;clock in  FIG. 18 ) at which the in-store temperature has become a temperature of not lower than the threshold value α, the dehumidifying operation is stopped and a shift is made to the cooling operation mode. 
     Referring to  FIG. 18 , as to the time zone of the cooling operation, the whole air conditioning time zone of the store other than the dehumidifying operation is the cooling operation time zone. Whether the cooling operation is actually performed or not depends on both room temperature and air conditioner-set temperature and is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 . 
     Since the store is a non-24-hour open store, the air conditioning time zone in the store is from a store preparation start time until a clearing work end time or from the store opening time until the store closing time. It is a time zone set beforehand by the store manager. In  FIG. 18 , the air conditioning time zone is a time zone from 5 a.m. to 11 p.m. (5 o&#39;clock to 23 o&#39;clock). 
     In this case, the cooling operation is the same as in the first embodiment. For permitting a timer operation so as to start the air conditioning operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in a cooling time zone set by the time zone setting unit  133 . More specifically, the control unit  134  raises the low pressure of the compressor  123  up to the first pressure and controls the air feed volume of the fan  112  to the first air volume in accordance with the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s . The set temperature for the cooling operation can be set arbitrarily. 
     In this case, the dehumidifying operation is the same as in the first embodiment. For permitting a timer operation so as to start the dehumidifying operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation in a dehumidifying time zone set by the time zone setting unit  133 . More specifically, at the dehumidifying start time, the control unit  134  controls the low pressure of the compressor  123  to the second pressure which is lower than the first pressure in the cooling operation and controls the air feed volume of the fan  112  to the second air volume. In this connection, it is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first air volume in the cooling operation. 
     By such a control, in the air conditioner control apparatus to control the air conditioner for the store, which permits a timer operation involving starting the air conditioning operation at a predetermined operation start time and stopping it at an operation end time, a store opening time and a store closing time are set between the operation start time and the operation end time of the air conditioner. If the in-store temperature is lower than the predetermined temperature (threshold value α) in the period from the operation start time until the store opening time, there is performed an operation in which cold air is blown off into the store, the cold air being designed lower in temperature and smaller in air feed volume than the cold air which is blown off into the store in the cooling operation performed in the period from the store opening time until the store closing time. 
     If the control of the cooling operation described above is a control such that the compressor  123  and the fan  112  are inverter-controlled by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are switched stepwise by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated in a minimum cooling condition corresponding to “Weak Cooling.” 
     Eleventh Embodiment 
     An eleventh embodiment of the present invention will now be described with reference to  FIG. 19 . A description will be given about a control method utilizing a measured indoor temperature (in-store temperature) in a 24-hour open store. This store is like a supermarket or a convenience store, in the interior of which are installed a freezing showcase and a refrigerating showcase (hereinafter referred to as the freezing/refrigerating showcases) for the storage of foods for sale. The interior of the store is cooled by an air conditioner. In the present invention, the interior of the room means the interior of the store. 
     According to this control method, a schedule of both dehumidifying operation and cooling operation for the day concerned is determined in real time. Since the store related to  FIG. 19  is a 24-hour open store (a store which opens 24 hours), the air conditioning time zone of the store by operation of the air conditioner is 24 hours. In this case, measurement of an in-store temperature is made possible. 
     Referring to  FIG. 19 , in connection with the time zone of the dehumidifying operation, the threshold value α is determined to be an in-store temperature of 25° C. for example, and since the air conditioning time zone of the store is 24 hours, if the in-store temperature is lower than the threshold value α, the time in question is set as the dehumidifying operation start time. In  FIG. 19 , twelve midnight is the dehumidifying operation start time. As to the dehumidifying operation end time, the dehumidifying operation is stopped at the time (9 o&#39;clock in  FIG. 19 ) at which the in-store temperature has become a temperature of not lower than the threshold value α and a shift is made to the cooling operation mode. If the in-store temperature has become lower than the threshold value α, there also is a case where the second dehumidifying operation is performed on the same day. In  FIG. 19 , the dehumidifying operation is performed in the period from 19 o&#39;clock to 24 o&#39;clock. 
     Referring to  FIG. 19 , as to the cooling operation time zone, the whole air conditioning time zone in the store other than the dehumidifying operation is the cooling operation time zone. As noted above, whether the cooling operation is actually performed or not depends on both room temperature and air conditioner-set temperature and is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 . 
     As to the air conditioning time zone in the store, since the store is a 24-hour open store, 0 o&#39;clock to 24 o&#39;clock are business hours, but the store manager can set actual business hours in advance. 
     In this case, the cooling operation is the same as in the first embodiment. For permitting a timer operation so as to start the air conditioning operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in a cooling time zone set by the time zone setting unit  133 . More specifically, at the cooling operation start time, the control unit  134  raises the low pressure of the compressor  123  up to the first pressure and controls the air feed volume of the fan  112  to the first air volume in accordance with the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s . The set temperature for the cooling operation can be set arbitrarily. 
     In this case, the dehumidifying operation is the same as in the first embodiment. For permitting a timer operation so as to start the dehumidifying operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation. More specifically, at the dehumidifying start time, the control unit  134  controls the low pressure of the compressor  123  to the second pressure which is lower than the first pressure in the cooling operation and controls the air feed volume of the fan  112  to the second air volume. In this connection, it is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first air volume in the cooling operation. 
     By such a control, in the air conditioner control apparatus to control the air conditioner for the store, which permits a timer operation involving starting the air conditioning operation at a predetermined operation start time and stopping it at an operation end time, a store opening time and a store closing time are set between the operation start time and the operation end time of the air conditioner. If the in-store temperature is lower than the predetermined temperature (threshold value α) in the period from the operation start time until the store opening time and/or in the period from the store closing time until the operation end time, there is performed an operation in which cold air is blown off into the store, the cold air being designed lower in temperature and smaller in air feed volume than the cola air which is blown off into the store in the cooling operation performed in the period from the store opening time until the store closing time. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are inverter-controlled by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are switched stepwise on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set by the air conditioner control apparatus  13 , the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated in a lowest cooling condition corresponding to “Weak Cooling.” 
     Although in the eleventh embodiment the dehumidifying operation and the cooling operation are switched from one to the other on the basis of only the measured in-store temperature, there may be adopted, as an alternative method, a method wherein the time zone, in which the difference between the in-store temperature and the air conditioner-set temperature is not larger than the threshold value α (in this case it is not 25° C., but takes another value), is set as the dehumidifying operation time zone. 
     Twelfth Embodiment 
     A twelfth embodiment of the present invention will now be described with reference to  FIGS. 20 to 22 . A description will be given about a control method utilizing measured outdoor temperature and outdoor humidity in a non-24-hour open store. This store is like a supermarket or a convenience store. A freezing showcase and a refrigerating showcase (hereinafter referred to as the freezing/refrigerating showcases) for the storage of foods for sale are installed in the interior of the store, which interior is cooled by an air conditioner. In the present invention, the interior of the room means the interior of the store. 
     According to this control method, a schedule of both dehumidifying operation and cooling operation for the day concerned is determined in real time on the day concerned while taking both outdoor temperature and outdoor humidity into account. In this case, when both outdoor temperature and outdoor humidity are high, the dehumidifying operation is performed because the in-store humidity also becomes high. 
       FIG. 20  is a graph showing a case where both dehumidifying operation and cooling operation are performed in the relation of both dehumidifying time zone and cooling time zone to both outdoor temperature and outdoor humidity.  FIG. 21  is a graph showing a case where only the dehumidifying operation is performed in the relation of both dehumidifying time zone and cooling time zone to both outdoor temperature and outdoor humidity.  FIG. 22  is a graph showing a case where the dehumidifying operation is not performed in the relation of both dehumidifying time zone and cooling time zone to both outdoor temperature and outdoor humidity. 
     Since this store is a non-24-hour open store (a store which opens in a predetermined time zone out of 24 hours), the store air conditioning time zone by operation of the air conditioner is not 24 hours, but, for example, 5 a.m. to 11 p.m. (5 o&#39;clock to 23 o&#39;clock). In this case, in the store, both measurement of the outdoor temperature and measurement of the outdoor humidity are made possible. 
     In connection with the time zone of the dehumidifying operation, the dehumidifying operation is performed when the outdoor humidity is not lower than the threshold value β and the outdoor temperature is lower than the threshold value α. In the illustrated case, the dehumidifying operation time zone is 5 o&#39;clock to 9 o&#39;clock in  FIG. 20 , while in  FIG. 21  it is 5 o&#39;clock to 23 o&#39;clock. However, when the outdoor humidity is lower than the threshold value β, as shown in  FIG. 22 , the dehumidifying operation is not performed. When the indoor temperature (in-store temperature) has become a temperature of not lower than a set value, (e.g., 25° C. or higher), in the dehumidifying operation, the dehumidifying operation is stopped and a shift is made to the cooling operation mode. 
     As to the time zone of the cooling operation, when the outdoor temperature is not lower than the threshold value α, a shift is made to the cooling operation mode irrespective of the outdoor humidity. When the outdoor temperature is lower than the threshold value α and the outside humidity is lower than the threshold value β, the operation mode becomes the cooling operation mode. In this case, since the outdoor temperature is low, the indoor temperature (in-store temperature) is also apt to become low, so that the cooling operation is stopped by the control unit  134  when the indoor temperature (in-store temperature) has dropped to a level of not higher than a set value, (e.g., 25° C. or lower), as a result of the cooling operation. 
     As described in the first embodiment, whether the cooling operation is actually performed or not depends on both room temperature and air conditioner-set temperature and it is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 . 
     Since the store is a non-24-hour open store, the air conditioning time zone of the store is from a store preparation start time until a clearing work end time or from the store opening time until the store closing time and it is a time zone which is set beforehand by the store manager. As shown in  FIGS. 20 to 22 , the air conditioning time zone of the store is 5 a.m. to 11 p.m. (5 o&#39;clock to 23 o&#39;clock). 
     In this case, the cooling operation is the same as in the first embodiment. For permitting a timer operation so as to start the air conditioning operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the cooling operation in a cooling time zone set by the time zone setting unit  133 . More specifically, the control unit  134  raises the low pressure of the compressor  123  up to the first pressure and controls the air feed volume of the fan  112  to the first air volume in accordance with the temperature difference |ΔT| between the indoor temperature T i  and the set temperature T s . The set temperature in the cooling operation can be set arbitrarily 
     In this case, the dehumidifying operation is the same as in the first embodiment. For permitting a timer operation so as to start the dehumidifying operation at a predetermined operation start time and stop it at an operation end time, the control unit  134  causes the indoor unit  11  and the outdoor unit  12  to carry out the dehumidifying operation in a dehumidifying time zone set by the time zone setting unit  133 . More specifically, at the dehumidifying start time, the control unit  134  controls the low pressure of the compressor  123  to the second pressure which is lower than the first pressure in the cooling operation and controls the air feed volume of the fan  112  to the second air volume. In this connection, it is to be noted that the second air volume in the dehumidifying operation is smaller than a mean value of the first air volume in the cooling operation. 
     If the control of the cooling operation described above is a control such that the operation of the compressor  123  and that of the fan  112  are inverter-controlled by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     If the control of the cooling operation described above is a control in which the operation of the compressor  123  and that of the fan  112  are switched stepwise by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set in the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated in a lowest cooling condition corresponding to “Weak Cooling.” 
     Thirteenth Embodiment 
     A thirteenth embodiment of the present invention will be described below with reference to  FIG. 23 . 
     In the sixth embodiment (shown in  FIG. 14 ) to the twelfth embodiment (shown in  FIGS. 20 to 22 ) described above the dehumidifying operation end time is determined on the basis of whether the indoor and/or outdoor temperature(s) and/or humidity (ties) exceed(s) a threshold value(s) or not, but in this thirteenth embodiment an in-store temperature rising speed is detected and a dehumidifying operation end time is determined on the basis of the result of the detection. 
     If the dehumidifying operation end time is set to a time at which the in-store temperature exceeds the threshold value, there may occur a case where the in-store environment becomes worse (the in-store temperature becomes too high) upon sudden change of the in-store environment, e.g., upon entry of a large number of customers into the store. To avoid such an inconvenience, a rising speed of the in-store temperature, (e.g., how the in-store temperature changes in one minute), is checked and when it is larger than a predetermined value, the dehumidifying operation is stopped before exceeding the set threshold value α and a shift is made to the cooling operation mode. In this way it is possible to prevent the in-store temperature from becoming too high. 
     As described in the first embodiment, whether the cooling operation is actually performed or not depends on both room temperature and air conditioner-set temperature and is determined by the air conditioner control apparatus  13  while receiving detection results from the temperature/humidity sensor  113 . In this case, in the dehumidifying operation mode, if a determining unit provided in the air conditioner control apparatus  13  determines that the in-store temperature rising speed detected by the temperature/humidity sensor  113  is larger than a predetermined value in the state before exceeding the set threshold value α, a control is made so as to stop the dehumidifying operation and make a shift to the cooling operation mode. 
     In this case, if the control of the cooling operation is a control such that the operation of the compressor  123  and that of the fan  112  are inverter-controlled by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set by the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated at low speed and at a lowest frequency. 
     In this case, if the control of the cooling operation is a control such that the operation of the compressor  123  and that of the fan  112  are switched stepwise by the air conditioner control apparatus  13  on the basis of the relation between the room temperature detected by the temperature/humidity sensor  113  and the air conditioner-set temperature set by the air conditioner control apparatus  13 , as described in the sixth embodiment, the dehumidifying operation can be brought to a state in which the compressor  123  and the fan  112  are operated in a lowest cooling condition corresponding to “Weak Cooling.” 
     Fourteenth Embodiment 
     A fourteenth embodiment of the present invention will now be described with reference to  FIGS. 24 and 25 .  FIG. 24  is a graph showing a relation of a dehumidifying time zone and a cooling time zone to an in-store temperature according to the fourth embodiment and  FIG. 25  is an enlarged diagram of the interior of a dotted-line ellipse in  FIG. 24 . 
     In the above first to fifth embodiments, as a method of operation of the air conditioner in the dehumidifying operation, the low pressure of the compressor is set to the first pressure and the air feed volume of the fan  112  is set to the first air feed volume both in the cooling operation, while in the dehumidifying operation, for lowering the refrigerant evaporating temperature, the low pressure of the compressor is set to the second pressure lower than the first pressure and the air feed volume of the fan  112  is set to the second air feed volume smaller than the first air feed volume. But in this fourteenth embodiment, the low pressure of the compressor is not so changed in both cooling operation and dehumidifying operation, but there is made a control such that the air feed volume of the fan  112  is set in the cooling operation to the first air feed volume which is a large volume, while in the dehumidifying operation it is set to the second air feed volume which is smaller than the first air feed volume, thereby attaining simplification of the control. 
     Generally, for the open showcase  22  there is adopted a method wherein when the business hours of the facility (store)  10  are over (closed), a front opening of a commodity storage chamber  202  is covered with a night cover to diminish leakage of chilled air from the chamber  202 , thereby suppressing a rise in temperature of the room. An example of this construction will be described below. 
     As shown in  FIG. 12 , an open showcase  200  as an example of the showcase  22  is formed with a commodity storage chamber  202  defined by a heat insulating wall  201  and having a front opening. Behind the commodity storage chamber  202  are formed a chilled air passage  204  partitioned by a partition plate  203  and a protective air passage  206  partitioned by a partition plate  205 . A cooler  207  which constitutes the refrigerator  21  and a chilled air circulating fan  208  are disposed in the chilled air passage  204 , while a fan  209  is disposed in the protective air passage  206 . 
     In the refrigerator  21 , as shown in  FIG. 13 , a compressor  210  for compressing a refrigerant, a condenser  211  for condensing the refrigerant, a pressure reducing device  212  such as an expansion valve, and the cooler  207  wherein the refrigerant evaporates, are connected in order through refrigerant pipes to constitute a refrigerant circulation circuit. A fan  213  for improving the refrigerant condensing action is provided in the condenser  211 . In the store such as a supermarket, a plurality of open showcases  200  are installed, so there is known a method (called a built-in type) wherein the refrigerator  21  is provided for each of the open showcases  200  and there also is known a method (called a separately installed type) wherein common compressor  210  and condenser  211 , (called a conditioning unit), are installed outside the store and a pressure reducing device  212  and a cooler  207 , which are provided for each open showcase  200 , are connected to the conditioning unit through refrigerant pipes. The latter method is illustrated in  FIG. 13 . Each open showcase  200  is cooled by either of the methods. 
     With operation of the refrigerator  21 , the refrigerant compressed by the compressor  210  is condensed by the condenser  211  and is reduced in pressure by the pressure reducing device  212 , then is evaporated in the cooler  207 . Further, with operation of the fan  208 , the air chilled in the cooler  207  passes through the chilled air passage  204  and is blown off from a blow-off port  214  formed in a front upper portion of the commodity storage chamber  202  toward a suction port  215  formed in a front lower portion of the chamber  202 , forming a chilled air curtain  216  in the front opening of the commodity storage chamber  202 . At the same time, with operation of the fan  208 , the air from the protective air passage  206  is blown off from a blow-off port  217  formed in a front upper portion of the commodity storage chamber  202  toward a suction part  218  formed in a front lower portion of the chamber  202 , forming a protective air curtain  219  outside the chilled air curtain  216 . 
     With the chilled air curtain  216  and the protective air curtain  219  thus formed, a portion of the chilled air which constitutes the chilled air curtain  216  circulates into the commodity storage chamber  202  to cool foods placed on shelves  220  in the chamber  202 . If the open showcases  200  are cold storage open showcases, the foods are cooled to the cold storage temperature, while if the open showcases  200  are refrigerating open showcases, the foods are cooled to the refrigerating temperature. 
     The open showcases  200  are each provided with a night cover for covering the front opening of the commodity storage chamber  202  selectively. The night cover  221  is supported so as to be wound up to an upper portion  222  automatically. In the business time zone of the store  10  (from opening to closing of the store) the night cover  221  is kept wound up to the upper portion, while in the non-business time zone (from closing to opening of the store) the night cover  221  is drawn out and brought into engagement with a lower retaining portion  223 , thereby covering the front opening of the commodity storage chamber  202 , as shown in  FIG. 13 . 
     When the business hours of the facility  10  are over, the operation mode of the refrigerator  21  is switched to the energy saving operation mode so that the temperature in the commodity storage chamber  202  is in a higher allowable temperature range than the temperature in the business time zone. In this case, by drawing out the night cover  221  and covering the front opening of the commodity storage chamber  202  with the night cover, as shown in  FIG. 13 , it is possible to diminish the leakage of chilled air from the chamber  202  and hence it is possible to suppress a rise in temperature of the chamber  202 . Consequently, the operation efficiency of the refrigerator  21  in the energy saving operation mode is improved. 
     In such a non-business time zone of the store  10  (from closing to opening of the store) as shown in the above sixth, eighth, and/or tenth to thirteenth embodiments, the front opening of the commodity storage chamber  202  is covered with the night cover  221 , as shown in  FIG. 13 . In the time zone of the dehumidifying operation which is performed in the non-business time zone of the store  10  (from closing to opening of the store), as shown in  FIGS. 24 and 25 , there is made a timer control by the air conditioner control apparatus  13  so that in the first half time zone the fan  112  is operated in the first air feed volume which is a large volume, while in the latter half time zone the fan is operated in the second air feed volume smaller than the first volume. 
     That is, in such a non-24-hour open store as shown in the above sixth, eighth, and/or tenth to thirteenth embodiments, the night cover  221  covers the front opening of the commodity storage chamber  202  until the showcase preparation start time. In this state, as shown in  FIGS. 24 and 25 , if the dehumidifying operation is to be performed in the time zone of a high in-store humidity, for example, until opening of the night cover  221  of the open showcase  200 , the fan  112  is operated in the first half time zone in the first air feed volume which is a large volume so as to increase the amount of moisture removed. As a result, the amount of moisture removed becomes larger because the amount of air fed by the fan  112  is large, although the absolute temperature difference between the air blown off into the store by the fan  112  after being chilled in the heat exchanger  111  of the air conditioner and the air sucked into the heat exchanger  111  of the air conditioner by the fan  112  may be small. 
     In each open showcase  200 , a portion of the in-store air is sucked into the cooler  207  from the front opening of the open showcase with operation of the chilled air circulating fan  208 . Consequently, when the humidity of the in-store air is high, the amount of frost deposited on the cooler  207  becomes larger, resulting in deterioration of the cooling effect in the interior of the showcase and increase in the time required for defrosting in the defrosting process. Thus, the so-called heat load of the open showcase increases. However, while the night cover  221  is closed, the suction of the in-store air into the cooler  207  is suppressed and so is the amount of frost deposited on the cooler  207 . Therefore, as described above, by performing the dehumidifying operation during closure of the night cover  221 , it becomes possible to cut down the heat load of the open showcase  200 . Further, since the in-store humidity becomes lower in the first half time zone, the dehumidifying operation in the latter half time zone is performed in the second air feed volume which is smaller than the first air feed volume. 
     According to this method, in the non-business, or closed, time zone of the store  10 , the front opening of the commodity storage chamber  102  is covered with the night cover  221 , so that by thus controlling the operation of the fan  112  in two steps involving the first and second air feed volumes, it becomes possible to carry out the dehumidifying operation effectively and hence possible to attain the simplification of the control. 
     In such a 24-hour open store as shown in the seventh and ninth embodiments, the night cover  221  of the open showcase  200  is not closed and the front opening of the open showcase  200  is open. Therefore, when the in-store humidity is higher than the threshold value β in the dehumidifying operation time zone, there is made a timer control such that by controlling the operation of the fan  112  in the same manner as above the fan  112  is operated, in the first half time zone, in the first air feed volume which is a large volume so as to increase the amount of moisture removed, while in the latter half time zone the fan  112  is operated in the second air feed volume smaller than the first air feed volume. 
     Thus, in the case where the store  10  is a 24-hour open store, the operation of the fan  112  is controlled in two steps involving the first and second air feed volumes, although the night cover  221  is kept open, whereby the dehumidifying operation can be done effectively and it is possible to simplify the control. 
     INDUSTRIAL APPLICABILITY 
     The air conditioner control apparatus according to the present invention is not limited to the constructions described in the above embodiments, but is applicable to various modes, and various modes are included in the technical scope of the present invention. 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
           1  . . . cooling system 
           10  . . . facility 
           11  . . . indoor unit 
           12  . . . outdoor unit 
           13  . . . air conditioner control apparatus 
           21  . . . refrigerator 
           22  . . . showcase 
           111  . . . heat exchanger 
           112  . . . fan 
           113  . . . temperature/humidity sensor 
           121  . . . heat exchanger 
           122  . . . fan 
           123  . . . compressor 
           124  . . . four-way valve 
           125  . . . expansion valve 
           131  . . . communication unit 
           132  . . . predictive outdoor temperature acquiring unit 
           133  . . . time zone setting unit 
           134  . . . control unit 
           135  . . . indoor temperature acquiring unit 
           136  . . . predictive heat load acquiring unit 
           137  . . . display unit 
           200  . . . open showcase 
           201  . . . heat insulating wall 
           202  . . . commodity storage chamber 
           207  . . . cooler 
           208  . . . chilled air circulating fan 
           209  . . . fan 
           210  . . . compressor 
           211  . . . condenser 
           212  . . . pressure reducing device 
           221  . . . night cover