Abstract: Internal control devices (41A to 41D) included respectively in air conditioners (10A to 10D) in an air conditioning system (1) are communicably connected one by one correspondingly to external control devices (42A to 42D). Each of the external control devices (42A to 42D) is configured to execute command generating operation of generating an operation command to a corresponding one of the air conditioners (10A to 10D). The external control devices (42A to 42D) constitute an external control system (50). In the external control system (50), one of the external control devices (42A) functions as a master control device configured to execute the command generating operation whereas remaining ones of the external control devices (42A to 42D) other than the external control device (42A) functioning as the master control device function as sub control devices configured not to execute the command generating operation.

Abstract: The humidity control unit includes: an air passage through which a first space which is a target space and a second space communicate with each other; a moisture absorber arranged in the air passage and configured to absorb moisture from air and desorb the moisture to the air; a heat source arranged in the air passage and configured to at least cool or heat the moisture absorber; an air transport mechanism configured to allow the air in the air passage to flow in reverse directions; and a controller configured to control the heat source and the air transport mechanism.

Abstract: Internal control devices (41A to 41D) included respectively in air conditioners (10A to 10D) in an air conditioning system (1) are communicably connected one by one correspondingly to external control devices (42A to 42D). Each of the external control devices (42A to 42D) is configured to execute command generating operation of generating an operation command to a corresponding one of the air conditioners (10A to 10D). The external control devices (42A to 42D) constitute an external control system (50). In the external control system (50), one of the external control devices (42A) functions as a master control device configured to execute the command generating operation whereas remaining ones of the external control devices (42A to 42D) other than the external control device (42A) functioning as the master control device function as sub control devices configured not to execute the command generating operation.

Abstract: A total heat exchanger exchanges heat between air flowing through an air supply passage and air flowing through an air exhaust passage. An air supply fan transfers air from the outside of a room into the room through the air supply passage. If the temperature of outdoor air (OA) is below a lower temperature threshold (Tth), a controller intermittently stops the air supply fan in response to an index of the moisture content in room air (RA) such that as the stage of the index of the moisture content depending on the moisture content in the room air (RA) shifts toward higher stages, the period of time during which the air supply fan is at rest in an intermittent operating cycle increases.

Abstract: A total heat exchanger exchanges heat between air flowing through an air supply passage and air flowing through an air exhaust passage. An air supply fan transfers air from the outside of a room into the room through the air supply passage. If the temperature of outdoor air (OA) is below a lower temperature threshold (Tth), a controller intermittently stops the air supply fan in response to an index of the moisture content in room air (RA) such that as the stage of the index of the moisture content depending on the moisture content in the room air (RA) shifts toward higher stages, the period of time during which the air supply fan is at rest in an intermittent operating cycle increases.