Patent Description:
In order to improve indoor air quality, ventilation is required. For example, Patent Literature <NUM> discloses an air conditioner in which an area to be air-conditioned is divided into a plurality of areas by a plurality of human body detection sensors, and a ventilation fan provided in an indoor unit is operated when it is detected that there is no person in all the areas.

<CIT> discloses an air conditioner and an air quality based ventilation system wherein a a user is alerted when ventilation is desired upon user specific air quality thresholds and measured indoor and outdoor air quality parameters. A user may be prompted to open a window.

<CIT> discloses the combination of an air conditioner and a ventilator, wherein the ventilator is activated when the air conditioner is in a maintenance operation.

<CIT> discloses a window ventilation control device which detects opening of a window and determines an instance for closing the window upon indoor temperature data measured in the vicinity of the window. The user is prompted by an alarm to close the window for saving energy.

Sufficient ventilation is required when a person is in a room in order to suppress a decrease in indoor air quality due to a person's activity in the room. In particular, in order to prevent a spread of the novel coronavirus (COVID-<NUM>) infection, the Ministry of Health, Labour and Welfare has proposed ventilation twice or more per hour.

However, Patent Literature <NUM> does not disclose how to perform ventilation when a person is in a room.

An object of the present invention is to promote sufficient ventilation when a person is in a room.

When the variation of the load in the room is within the predetermined range in the first time period, there is a possibility that a ventilation amount in the room is insufficient. By notifying the user that ventilation is necessary when the load condition is satisfied, it is possible to prompt the user to perform ventilation.

(<NUM>) The detection unit preferably includes a temperature sensor configured to detect a temperature in the room, and the load condition is preferably that time during which the temperature in the room detected by the temperature sensor deviates from a specified range determined by a reference temperature does not continue for a second time period or more entirely during the first time period, the second time period being shorter than the first time period. The preceding term "for a second time period or more entirely during the first time period" is to be understood as "for a second time period or more in the first time period as a whole".

Such a configuration allows the load in the room to be detected as a room temperature. Since the air-conditioned room temperature changes when ventilation is performed, it is possible to determine whether the ventilation amount is sufficient on the basis of the variation in the room temperature. When the time during which the room temperature deviates from the specified range from the reference temperature does not continue for the second time period or more in the first time period as a whole, there is a possibility that the ventilation amount in the room is insufficient. It is possible to eliminate the insufficiency of the ventilation amount by notifying the user that ventilation is necessary.

(<NUM>) A display configured to display information is preferably provided, and the control unit preferably causes the display to display that ventilation is necessary when the load condition is satisfied.

Such a configuration allows the user to know that ventilation is necessary by checking what is displayed on the display.

(<NUM>) Preferably a room comprising the aforementioned air conditioner is not provided with a ventilation function.

The configuration of the present invention can prompt the user to perform ventilation by opening a window or a door in a room not provided with a ventilation function.

Hereinafter, embodiments of an air conditioner will be described in detail with reference to the accompanying drawings.

<FIG> is a schematic diagram of an example of a configuration of an air conditioner according to Embodiment <NUM>.

An air conditioner <NUM> adjusts a temperature of air in a room, which is a target space for air conditioning, to a predetermined target temperature. The air conditioner <NUM> according to the present embodiment performs at least one of a heating operation for raising an indoor temperature or a cooling operation for lowering the indoor temperature.

The air conditioner <NUM> includes indoor units 100A and 100B an outdoor unit <NUM>. The air conditioner <NUM> according to the present embodiment is a multi-type air conditioner <NUM> in which the plurality of indoor units 100A and 100B is connected in parallel to the outdoor unit <NUM>, and is applied to a building having multiple rooms, for example. In an example shown in <FIG>, the two indoor units 100A and 100B are connected to one outdoor unit <NUM>. However, the number of the outdoor units <NUM> and the number of the indoor units <NUM> are not limited. Hereinafter, the indoor units 100A and 100B are also collectively referred to as the indoor unit <NUM>. The components of the indoor units 100A and 100B may be collectively referred to in a similar manner.

The air conditioner <NUM> includes a refrigerant circuit <NUM>. The refrigerant circuit <NUM> circulates a refrigerant between the indoor units <NUM> and the outdoor unit <NUM>. The refrigerant circuit <NUM> includes a compressor <NUM>, an outdoor heat exchanger (heat source heat exchanger) <NUM>, the indoor heat exchangers (utilization heat exchangers) 110A and 110B, and a refrigerant pipe <NUM> connecting all of the above. The refrigerant circuit <NUM> includes valves (not shown) such as an expansion valve, a liquid shutoff valve, a gas shutoff valve, and a four-way switching valve, but details thereof are omitted.

Each of the indoor units 100A and 100B is installed in a separate room. The indoor unit 100A performs air conditioning in one room, and the indoor unit 100B performs air conditioning in another room.

The indoor unit <NUM> includes an indoor heat exchanger <NUM> included in the refrigerant circuit <NUM>. The indoor heat exchanger <NUM> is a cross fin tube type or microchannel type heat exchanger, and is used for exchanging heat with indoor air.

The indoor unit <NUM> further includes an indoor fan <NUM>. The indoor fan <NUM> is configured to take indoor air into the indoor unit <NUM>, cause the indoor heat exchanger <NUM> to exchange heat with the air taken in, and then blow the air into the room. The indoor fan <NUM> includes a motor of which number of revolutions is adjustable by inverter control.

The indoor unit <NUM> further includes a temperature sensor <NUM>, a notification unit <NUM>, and a control unit <NUM>. The temperature sensor <NUM> detects an indoor temperature. The indoor temperature is an example of an indoor load.

The notification unit <NUM> can notify a user that ventilation is necessary. The notification unit <NUM> includes an LED <NUM> and a buzzer <NUM>. The LED <NUM> notifies the user that ventilation is necessary by emitting light, and the buzzer <NUM> notifies the user that ventilation is necessary by emitting a sound.

The control unit <NUM> can control components of the indoor unit <NUM>. <FIG> is a block diagram showing an example of a configuration of the control unit. The control unit <NUM> includes a processor <NUM>, a non-volatile memory <NUM>, a volatile memory <NUM>, and an input-output interface <NUM>.

The volatile memory <NUM> is, for example, a static random access memory (SRAM), a dynamic random access memory (DRAM), or the like. The non-volatile memory <NUM> is, for example, a flash memory, a hard disk, a read only memory (ROM), or the like. The non-volatile memory <NUM> stores a control program <NUM> that is a computer program and data used for executing the control program <NUM>. Each function of the indoor unit <NUM> is exerted by the control program <NUM> executed by the processor <NUM>. The control program <NUM> can be stored in a recording medium such as a flash memory, a ROM, or a CD-ROM.

The processor <NUM> is, for example, a central processing unit (CPU). However, the processor <NUM> is not limited to the CPU. The processor <NUM> may be a graphics processing unit (GPU). The processor <NUM> may be, for example, an application specific integrated circuit (ASIC) or a programmable logistic device such as a gate array and a field programmable gate array (FPGA). In this case, the ASIC or the programmable logic device is configured to be able to execute processing similar to the processing of the control program <NUM>.

The input-output interface <NUM> is used to input and output data between the control unit <NUM> and the components of the indoor unit <NUM>. The input-output interface <NUM> is connected to the temperature sensor <NUM>, the LED <NUM>, and the buzzer <NUM>. Furthermore, the input-output interface <NUM> is connected to a communication unit (not shown), and can transmit a signal to a remote controller <NUM> via the communication unit and receive a signal from the remote controller <NUM>.

The remote controller <NUM> includes a display <NUM> and an operation unit <NUM>. The display <NUM> includes, for example, a liquid crystal panel, and displays information such as a set operating mode (cooling mode, heating mode, and the like) and a set temperature. The operation unit <NUM> includes, for example, a plurality of button switches, and can receive an operation from the user. The user can designate the operating mode and the set temperature by operating the operation unit <NUM>. The remote controller <NUM> includes a communication unit (not shown), and can transmit command values of the operating mode and the set temperature received from the user to the control unit <NUM>. The control unit <NUM> controls each part of the components of the indoor unit <NUM> in accordance with the received command values of the operating mode and the set temperature.

The display <NUM> can display notification information to the user. When an event requiring notification of information to the user occurs, the control unit <NUM> transmits display command for a notification information to the remote controller <NUM>. When receiving the command, the remote controller <NUM> causes the display <NUM> to display the notification information.

The outdoor unit <NUM> includes the compressor <NUM> and the outdoor heat exchanger <NUM> included in the refrigerant circuit <NUM>.

The compressor <NUM> sucks a low-pressure gas refrigerant and discharges a high-pressure gas refrigerant. The compressor <NUM> includes a motor of which number of revolutions is adjustable by inverter control and compresses the gas refrigerant by the motor. The outdoor heat exchanger <NUM> is, for example, a cross fin tube type or microchannel type heat exchanger, and is used for exchanging heat with a refrigerant by using air as a heat source.

The outdoor unit <NUM> further includes an outdoor fan <NUM>. The outdoor fan <NUM> includes a motor of which number of revolutions is adjustable by inverter control. The outdoor fan <NUM> is configured to take outdoor air into the outdoor unit <NUM>, cause the outdoor heat exchanger <NUM> to exchange heat with the air taken in, and then blow the air out of the outdoor unit <NUM>.

When the air conditioner <NUM> having the above configuration performs the cooling operation or the heating operation, the liquid or gaseous refrigerant circulates through the refrigerant pipe <NUM>, heat is exchanged between the refrigerant and the outdoor air by the outdoor heat exchanger <NUM>, and heat is exchanged between the refrigerant and the indoor air by the indoor heat exchanger <NUM>. The outdoor air heated or cooled by the outdoor heat exchanger <NUM> is discharged to outside of the outdoor unit <NUM> by the outdoor fan <NUM>. The indoor air cooled or heated by the indoor heat exchanger <NUM> is released from the indoor unit <NUM> into the room by the indoor fan <NUM>.

The Ministry of Health, Labour and Welfare has proposed ventilation two or more times per hour to prevent a spread of COVID-<NUM> infection. The air conditioner <NUM> according to the present embodiment determines whether ventilation has been performed for sufficient time during a certain period. When determining that ventilation has not been performed for sufficient time, the air conditioner notifies the user that ventilation is necessary. A load condition is used to determine whether ventilation has been performed for sufficient time during a certain period. The load condition is a condition indicating that a variation of the load in the room is within a predetermined range in a first time period. The air conditioner <NUM> according to the present embodiment determines whether ventilation has been performed for sufficient time (a second time period P<NUM> or more) once or more in a first time period P<NUM> in accordance with the proposal of the Ministry of Health, Labour and Welfare described above, for example. In the present embodiment, the load condition is that time during which the indoor temperature detected by the temperature sensor <NUM> deviates from a specified range determined by a reference temperature T<NUM> does not continue for the second time period P<NUM> or more entirely during the first time period P<NUM>, the second time period P<NUM> being shorter than the first time period P<NUM>. The first time period P<NUM> is, for example, <NUM> minutes, and the second time period P<NUM> is, for example, <NUM> minutes.

<FIG> is a flowchart showing an example of a procedure of operating the air conditioner <NUM> according to the present embodiment. When the processor <NUM> activates the control program <NUM>, the processor <NUM> executes the following processing.

The processor <NUM> sets a first timer (step S101) and sets a second timer (step S102). The first timer and the second timer are different timers, and can start clocking at different timings.

The temperature sensor <NUM> detects an indoor temperature at a predetermined cycle and outputs a detected indoor temperature. The processor <NUM> receives the detected indoor temperature output from the temperature sensor <NUM> (step S103).

Next, the processor <NUM> determines whether the detected indoor temperature deviates from a specified range determined by the reference temperature (step S104). The indoor temperature deviates from the outdoor temperature due to heating or cooling, and is close to the set temperature. For example, when ventilation of the room is performed by operating a ventilator or opening a door and a window, the indoor load varies. As a specific example of the variation of the load, the indoor temperature changes to approach the outdoor temperature. Thus, the detected indoor temperature deviates from the specified range. On the other hand, when ventilation is not performed, the indoor temperature maintains a value close to the set temperature. Thus, the detected indoor temperature falls within the specified range. In this manner, in step S104, it is determined whether ventilation is performed on the basis of the variation of the load.

In the present embodiment, the reference temperature is a set temperature (a set temperature for the cooling operation or the heating operation) designated by the user. The specified range is a preset temperature range. For example, the specified range is a range that has an upper limit of a temperature T<NUM> + S which is higher than the reference temperature T<NUM> by a set value S and a lower limit of a temperature T<NUM> - S which is lower than the reference temperature T<NUM> by the set value S. The set value S is set by a service engineer, for example, when the indoor unit <NUM> is installed in the room. The set value S can be determined in accordance with cooling and heating performance of the air conditioner <NUM>, a size of the room, and the like. The specified range only has to be a temperature range including the reference temperature, and may be a range different from the above.

When the detected indoor temperature does not deviate from the specified range determined by the reference temperature (NO in step S104), it can be determined that ventilation is not performed. In this case, the processor <NUM> determines whether a value of the first timer exceeds the first time period P<NUM> (step S105). The first time period P<NUM> is a time for determining insufficient ventilation, and is set in advance. The first time period P<NUM> is set, for example, when the air conditioner <NUM> is shipped from a factory.

When the value of the first timer does not exceed the first time period P<NUM> (NO in step S105), the processor <NUM> returns to step S102. As a result, the second timer is reset.

When the value of the first timer exceeds the first time period P<NUM> (YES in step S105), the processor <NUM> proceeds to step S108. Step S108 will be described later.

When the detected indoor temperature deviates from the specified range determined by the reference temperature (YES in step S104), it can be determined that ventilation is performed. In this case, the processor <NUM> determines whether a value of the second timer exceeds the second time period P<NUM> (step S106). The second time period P<NUM> is a time for determining whether sufficient ventilation is performed, and is set in advance. The second time period P<NUM> is shorter than the first time period P<NUM>. The second time period P<NUM> is set, for example, when the air conditioner <NUM> is shipped from the factory.

When the value of the second timer does not exceed the second time period P<NUM> (NO in step S106), the processor <NUM> determines whether the value of the first timer exceeds the first time period P<NUM> (step S107). When the value of the first timer does not exceed the first time period P<NUM> (NO in step S107), the processor <NUM> returns to step S103.

<FIG> is a graph showing an example of a temporal change in the indoor temperature when ventilation is sufficiently performed. <FIG> is a graph showing an example of a temporal change in the indoor temperature when ventilation is not sufficiently performed. <FIG> show changes in the indoor temperature in a room where cooling is performed. An air-conditioned indoor temperature T takes a value close to the reference temperature T<NUM> which is a set temperature. When ventilation is not performed, the indoor temperature T maintains a value around the reference temperature T<NUM>. When ventilation is performed, the indoor temperature T changes and exceeds the upper limit T<NUM> + S of the specified range.

In the present embodiment, when the time during which the indoor temperature T deviates from the specified range exceeds the second time period P<NUM>, it is determined that sufficient ventilation is performed. In the example of <FIG>, a time period Pex during which the indoor temperature T deviates from the specified range determined by the reference temperature T<NUM> exceeds the second time period P<NUM>. Therefore, in the example of <FIG>, sufficient ventilation is performed.

In the present embodiment, when the time during which the indoor temperature T deviates from the specified range does not exceed the second time period P<NUM>, it is determined that sufficient ventilation is not performed. Note that even when the indoor temperature T is within the specified range, it is naturally determined that sufficient ventilation is not performed. In the example of <FIG>, the time period Pex during which the indoor temperature T deviates from the specified range determined by the reference temperature T<NUM> does not exceed the second time period P<NUM>. Therefore, in the example of <FIG>, sufficient ventilation is not performed.

<FIG> is referred to again. If NO in step S107, step S103 and subsequent steps are executed without resetting the second timer, and the value of the second timer is added. Therefore, when a state in which the indoor temperature T deviates from the specified range is maintained, steps S103, S104, S106, and S107 are repeated while the value of the second timer does not exceed the second time period P<NUM>.

In step S106, when the value of the second timer exceeds the second time period P<NUM> (YES in step S106), it can be determined that ventilation has been performed for sufficient time. In this case, the processor <NUM> ends the processing.

In step S107, when the value of the first timer exceeds the first time period P<NUM> (YES in step S107), the value of the first timer exceeds the first time period P<NUM> while the value of the second timer does not exceed the second time period P<NUM>. Therefore, it can be determined that sufficient ventilation is not performed entirely during the first time period P<NUM>. In this case, the processor <NUM> notifies the user that ventilation is necessary (insufficient ventilation) (step S108). In a case where a ventilation function is not provided in the room, the user who knows that ventilation is necessary can open the window and the door, for example. In a case where a ventilator is provided in the room but is stopped, the user who knows that ventilation is necessary can operate the ventilator.

If YES in step S105, the value of the second timer does not exceed the second time period P<NUM> even once, and the value of the first timer exceeds the first time period P<NUM>. In this case, the processor <NUM> also proceeds to step S108.

Specifically, in step S108, the processor <NUM> controls the LED <NUM> to emit light, controls the buzzer <NUM> to sound, and outputs a command to display the notification information on the display <NUM>. As a result, the user is notified of insufficient ventilation by the light emission of the LED <NUM>, the sounding of the server <NUM>, and the display by the display <NUM>. The notification information displayed on the display <NUM> includes, for example, text information such as "Ventilation is insufficient. Please perform ventilation.

The notification of insufficient ventilation as described above is performed for each of the indoor units 100A and 100B. When insufficient ventilation occurs in a room in which the indoor unit 100A is installed and insufficient ventilation does not occur in a room in which the indoor unit 100B is installed, the indoor unit 100A notifies insufficient ventilation, and the indoor unit 100B does not notify insufficient ventilation. When insufficient ventilation does not occur in the room in which the indoor unit 100A is installed and insufficient ventilation occurs in the room in which the indoor unit 100B is installed, the indoor unit 100A does not notify insufficient ventilation, and the indoor unit 100B notifies insufficient ventilation. When insufficient ventilation is notified by an LED 141A, a buzzer 142A, and a display 161A in the room in which the indoor unit 100A is installed, the user in the room performs ventilation in the room. When insufficient ventilation is notified by an LED 141B, a buzzer 142B, and a display 161B in the room in which the indoor unit 100B is installed, the user in the room performs ventilation in the room.

In the present embodiment, as a result of air conditioning, the reference temperature is set to the converged indoor temperature. <FIG> is a flowchart showing an example of a procedure of setting the reference temperature of an air conditioner <NUM> according to the present embodiment.

The temperature sensor <NUM> repeatedly outputs a detected indoor temperature at a predetermined cycle. The processor <NUM> repeatedly receives the detected indoor temperature from the temperature sensor <NUM> (step S201). In this way, the processor <NUM> acquires the time-series detected indoor temperature for a certain period. Next, the processor <NUM> determines whether the detected indoor temperature is unchanged continuously for a certain period (step S202). When the detected indoor temperature is continuously within a certain allowable range in step S202, it can be determined that the detected indoor temperature is unchanged.

When the detected indoor temperature is not unchanged continuously for a certain period (NO in step S202), the processor <NUM> returns to step S201.

When the detected indoor temperature is unchanged continuously for a certain period (YES in step S202), it can be determined that the indoor temperature has converged to a certain value. In this case, the processor <NUM> sets the reference temperature as the detected indoor temperature (step S203). The setting of the reference temperature ends here.

The reference temperature set as described above is used for determining whether ventilation described in Embodiment <NUM> is necessary.

In the present embodiment, variation of power consumption in the indoor unit <NUM> is used as the variation of the load in the room.

<FIG> is a schematic diagram of an example of a configuration of an indoor unit of an air conditioner according to the present embodiment. The indoor unit <NUM> according to the present embodiment includes a current sensor <NUM> and a voltage sensor <NUM>. AC power supplied from a commercial power source to the indoor unit <NUM> is converted into DC power by a power converter (not shown) incorporated in the indoor unit <NUM>. The DC power is supplied to the components of the indoor unit <NUM>, such as the indoor fan <NUM> and various valves. The current sensor <NUM> detects an output current of the DC power converter. The voltage sensor <NUM> detects an output voltage of the DC power converter.

Each of the current sensor <NUM> and the voltage sensor <NUM> is connected to the input-output interface <NUM> (see <FIG>) of the control unit <NUM>. A detected current value of the current sensor <NUM> and a detected voltage value of the voltage sensor <NUM> are provided to the processor <NUM> via the input-output interface <NUM>. The processor <NUM> can calculate the power consumption of the indoor unit <NUM> by using the detected current value and the detected voltage value.

Since other configurations of the indoor unit <NUM> according to the present embodiment are similar to those of the indoor unit <NUM> described in Embodiment <NUM>, the same components are denoted by the same reference signs, and description thereof will be omitted.

<FIG> is a flowchart showing an example of a procedure of operating the air conditioner <NUM> according to the present embodiment. The processor <NUM> sets the first timer (step S301) and sets the second timer (step S302).

The current sensor <NUM> and the voltage sensor <NUM> detect a current value and a voltage value, respectively, at a predetermined cycle, and outputs a detected current value and a detected voltage value, respectively. The processor <NUM> receives the detected current value and the detected voltage value output from the current sensor <NUM> and the voltage sensor <NUM>, respectively (step S303).

Next, the processor <NUM> calculates the power consumption by using the detected current value and the detected voltage value having been received (step S304). The processor <NUM> determines whether the power consumption deviates from a specified range determined by a reference power (step S305). The indoor temperature deviates from the outdoor temperature due to heating or cooling, and is close to the set temperature. For example, when ventilation of the room is performed by operating a ventilator or opening a door and a window, the indoor temperature changes to approach the outdoor temperature. When the indoor temperature rises and deviates from the set temperature, the indoor fan <NUM> and the refrigerant circuit <NUM> operate with high power consumption to bring the indoor temperature close to the set temperature. Therefore, the power consumption of the indoor unit <NUM> increases and deviates from the specified range. On the other hand, when ventilation is not performed, the indoor temperature maintains a value close to the set temperature. Therefore, the indoor fan <NUM> and the refrigerant circuit <NUM> operate with low power consumption, and the power consumption of the indoor unit <NUM> falls within the specified range. In this manner, in step S305, it is determined whether ventilation is performed on the basis of the variation of the load.

In the present embodiment, the reference power is power consumption when the indoor unit <NUM> operates near the set temperature. The specified range is a preset power range.

When the power consumption does not deviate from the specified range determined by the reference power (NO in step S305), it can be determined that ventilation is not performed. In this case, the processor <NUM> determines whether the value of the first timer exceeds the first time period P<NUM> (step S306).

When the value of the first timer does not exceed the first time period P<NUM> (NO in step S306), the processor <NUM> returns to step S302. As a result, the second timer is reset.

When the value of the first timer exceeds the first time period P<NUM> (YES in step S306), the processor <NUM> proceeds to step S309.

When the power consumption deviates from the specified range determined by the reference power (YES in step S305), it can be determined that ventilation is performed. In this case, the processor <NUM> determines whether the value of the second timer exceeds the second time period P<NUM> (step S307).

When the value of the second timer does not exceed the second time period P<NUM> (NO in step S307), the processor <NUM> determines whether the value of the first timer exceeds the first time period P<NUM> (step S308). When the value of the first timer does not exceed the first time period P<NUM> (NO in step S308), the processor <NUM> returns to step S303.

If NO in step S308, step S303 and subsequent steps are executed without resetting the second timer, and the value of the second timer is added. Therefore, when a state in which the power consumption deviates from the specified range is maintained, steps S303, S304, S305, S307, and S308 are repeated while the value of the second timer does not exceed the second time period P<NUM>.

In step S307, when the value of the second timer exceeds the second time period P<NUM> (YES in step S307), it can be determined that ventilation has been performed for sufficient time. In this case, the processor <NUM> ends the processing.

In step S308, when the value of the first timer exceeds the first time period P<NUM> (YES in step S308), the value of the first timer exceeds the first time period P<NUM> while the value of the second timer does not exceed the second time period P<NUM>. Therefore, it can be determined that sufficient ventilation is not performed entirely during the first time period P<NUM>. In this case, the processor <NUM> notifies the user that ventilation is necessary (insufficient ventilation) (step S309).

If YES in step S306, the value of the second timer does not exceed the second time period P<NUM> even once, and the value of the first timer exceeds the first time period P<NUM>. In this case, the processor <NUM> also proceeds to step S309.

When the variation of the load in the room is within the predetermined range in the first time period P<NUM>, there is a possibility that the ventilation amount in the room is insufficient. By notifying the user that ventilation is necessary when the load condition is satisfied, it is possible to prompt the user to perform ventilation.

(<NUM>) The detection unit may include the temperature sensor <NUM> that detects the temperature in the room. The load condition can be that time during which the indoor temperature detected by the temperature sensor <NUM> deviates from a specified range determined by a reference temperature T<NUM> does not continue for the second time period P<NUM> or more entirely during the first time period P<NUM>, the second time period P<NUM> being shorter than the first time period P<NUM>.

Such a configuration allows the load in the room to be detected as a room temperature. Since the air-conditioned room temperature changes when ventilation is performed, it is possible to determine whether the ventilation amount is sufficient on the basis of the variation in the room temperature. When the time during which the room temperature deviates from the specified range from the reference temperature T<NUM> does not continue for the second time period P<NUM> or more entirely during the first time period P<NUM>, there is a possibility that the ventilation amount in the room is insufficient. It is possible to eliminate the insufficiency of the ventilation amount by notifying the user that ventilation is necessary.

(<NUM>) The air conditioner <NUM> includes the display <NUM> that displays information. When the load condition is satisfied, the control unit <NUM> causes the display <NUM> to display that ventilation is necessary.

Such a configuration allows the user to know that ventilation is necessary by checking what is displayed on the display <NUM>.

(<NUM>) The ventilation function need not be provided in the room in which the air conditioner <NUM> is installed.

It is possible to prompt the user to perform ventilation by opening a window or a door in the room not provided with the ventilation function.

Claim 1:
An air conditioner (<NUM>) for performing air conditioning in a room, the air conditioner comprising:
a detection unit (<NUM>, <NUM>, <NUM>) configured to detect a load in the room;
a notification unit (<NUM>) configured to notify a user of information; and
a control unit (<NUM>), wherein
the control unit (<NUM>) is configured to cause the notification unit (<NUM>) to notify the user that ventilation is necessary when a load condition indicating that a variation of the load detected by the detection unit (<NUM>, <NUM>, <NUM>) is within a predetermined range in a first time period (P<NUM>) is satisfied.