Zigbee In Air Conditioning

Zigbee is a standard wireless communication protocol which is based on IEEE 802.15.4 specifications that can be used for communication between devices without needing a physical wire connection similar to the WI-FI or Bluetooth technology.

Comparatively, it has the following characteristics suitable for HVAC applications:

  • Simpler
  • Lower data rate
  • Lower power consumption
  • Lower bandwidth 
  • Lower implementation cost
  • MESH topology that enables large network communication
  • Suitable for wireless personal area networks (WPAN)
  • Communication distance of 10m-100m line of sight between each devices.

Many manufacturers have implemented this protocol simply because of the ease of design, lower cost and interoperability with other Zigbee-compliant building management systems. It is also highly secure as the encryption for communication between each devices is using AES 128 bits technology.

On top of that, if designed properly, the batteries of wireless sensors such as thermostats can last for many years.

Take note that your products need to be certified by Zigbee.org before you can use the logo in your products. It is estimated that there will be 8 billion such devices that will be in used by the year 2020.

A Zigbee Thermostat

Zigbee Frequency Assignments

This protocol uses unlicensed frequency bands for its operation. That means that you do not have to pay to use the frequency spectrum unlike mobile phones operators such as 3G or LTE which require approval from the licensing authorities of the countries to operate.

The frequencies being assigned differ from each region of the world. Therefore, when you design or purchase your products, you will have to determine where your products will be marketed. 

Country Frequency
North America
902-928 MHz
868-868.6 MHz
Rest of The World
2.4-2.4835 GHz

HVAC industry has been around for a long time and the prices of equipment have been dropping every year in particular ductless split units and window air conditioners. In the past, many of these units are not equipped to be able to communicate with building management systems or control through smart phones and computers.

However, these are changing and many models of these air conditioners and heat pumps have been equipped with these optional IoT(Internet of Things) devices that enable them to be control through smart phones and tablets. Wireless capability with encryption for secure communication has increasingly being built-in to enable them to take advantage of the advancement in information technology.

Design Consideration

In designing your products to be compliance to this protocol, the best way to do it is to get the chips that have built-in radio transceivers, central processing unit and flash memory. Currently the maximum flash memory size available is 250kB. Besides that, the encryption in the form of AES 128 bits key is necessary.

Here are some examples of chips that are designed with this in mind of which you can consider using in your design.

1) Texas Instruments CC2630 2.4GHz Chip Set

  • 1.8V to 3.8V Operating Voltage
  • 2.4 GHz RF Transceiver
  • 128 KB Flash Memory
  • 8 KB SRAM For Cache
  • AES 128 Bit Encryption
  • 250 kbps Data Rate
  • 48 MHz Clock Speed
  • Sleep Mode Current: 1uA
  • Operating Temperature: -40°C to 85°C
  • ROHS Compliant Packages

2) Microchip/ATMEL ATmega2564RFR2

  • 1.8V to 3.6V Operating Voltage
  • 2.4 GHz RF Transceiver
  • 256 KB Flash Memory
  • 32 KB SRAM 
  • 8192 EEPROM
  • AES 128 Bit Encryption
  • 250kbps to 2Mbps Data Rate
  • Deep Sleep Mode Current: <700 nA at 25°C
  • Operating Temperature: -40°C to 125°C

3) Silicon Lab EFR32MG1P632F256GM32 Mighty Gecko

  • 2.3V to 3.6V Operating Voltage
  • 2.4 GHz RF Transceiver
  • 256 KB Flash Memory
  • 32 KB SRAM 
  • AES 128/256 Bit Encryption
  • 40 MHz Clock Speed
  • Deep Sleep Mode Current: 5.5 uA
  • Operating Temperature: -40°C to 85°C(125°C available)

Get more information from the official Zigbee website.

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