This paper presents a novel approach to convert a conventional house air conditioning

installation into a more ecient system that individually controls the temperature of each zone of

the house through Wi-Fi technology. Each zone regulates the air flow depending on the detected

temperature, providing energy savings and increasing the machine performance. Therefore, the first

step was to examine the communication bus of the air conditioner and obtain the dierent signal codes.

Thus, an alternative Controller module has been designed and developed to control and manage the

requests on the communication bus (Bus–Wi-Fi gateway). A specific circuit has been designed to

adapt the signal of the serial port of the Controller with the communication bus. For the acquisition

of the temperature and humidity data in each zone, a Node module has been developed, which

communicates with the Controller through the Wi-Fi interface using the Message Queuing Telemetry

Transport (MQTT) protocol with Secure Sockets Layer / Transport Layer Security (SSL/TLS) certificates.

It has been equipped with an LCD touch screen as a human-machine interface. The Controller and the

Node modules have been developed with the ultra-low power consumption CC3200 microController

of Texas Instruments and the code has been implemented under the TI-RTOS real-time operating

system. An additional module based on the Raspberry Pi computer has been designed to create the

Wi-Fi network and implement the required network functionalities. The developed system not only

ensures that the temperature in each zone is the desired one, but also controls the fan velocity of the

indoor unit and the opening area of the vent registers, which considerably improves the eciency of

the system. Compared with the single-zone system, the experiments carried out show energy savings

between 75% and 94% when only one of the zones is selected, and 44% when the whole house is

air-conditioned, in addition to considerably improving user comfort.