The SONOFF AirGuard TH Lite (SNZB-02B) is a Zigbee 3.0 battery-powered temperature and humidity sensor. The device measures ambient air temperature and relative humidity, and also calculates the dew point and Vapor Pressure Deficit (VPD) based on the measured values.
The sensor uses a high-precision Sensirion sensing element, providing ±0.2 °C temperature accuracy and ±2% relative humidity accuracy. Measurement data can be reported to the Zigbee network at intervals as short as 5 seconds. The device is powered by two AAA batteries, offering a battery life of up to 2 years depending on network quality and the configured reporting interval.
Measured values can be displayed as charts in the eWeLink app, exported in CSV format, and used to trigger automations. Displaying dew point and VPD values is especially useful in applications requiring more accurate monitoring of air moisture, such as HVAC systems, humidification control, mold prevention, or plant cultivation environments.
The device uses the Zigbee 3.0 standard and is compatible with SONOFF Zigbee gateways as well as many other Zigbee 3.0-based systems, including Home Assistant (ZHA, Zigbee2MQTT), SmartThings, and Amazon Alexa Zigbee Hub solutions. Thanks to its compact size and battery-powered design, it can be installed without wired power. It can be wall-mounted, placed freely on a flat surface, or hung using the included hanging strap.
About SONOFF
SONOFF manufactures smart home devices, Zigbee sensors, relays, switches, smart controllers, and gateways. Its products are built around the eWeLink platform, while many devices are also compatible with Home Assistant, Zigbee2MQTT, ZHA, SmartThings, and other smart home systems.
Key Product Features
- Temperature measurement: Indoor temperature monitoring with ±0.2 °C accuracy.
- Humidity measurement: Relative humidity measurement with ±2% RH accuracy.
- Dew point calculation: Calculates and displays the dew point based on measured temperature and humidity.
- VPD calculation: Displays the Vapor Pressure Deficit value for plant cultivation and climate control applications.
- Fast data updates: Measurement data can be updated as frequently as every 5 seconds.
- Zigbee 3.0 communication: Low-power wireless communication compatible with Zigbee gateways.
- Battery-powered operation: Powered by 2 × LR03 AAA batteries.
- Data logging: Temperature, humidity, dew point, and VPD history can be viewed in the eWeLink app.
- CSV export: Historical measurement data can be exported in CSV format.
Smart Home Protocols and Platform Compatibility
- Zigbee 3.0: IEEE 802.15.4 wireless communication.
- eWeLink: Full functionality when used with a SONOFF Zigbee gateway.
- Compatible SONOFF gateways: ZBBridge-P, ZBBridge-U, NSPanel Pro, iHost, and supported SONOFF Zigbee USB coordinators.
- Home Assistant: Can be integrated through ZHA or Zigbee2MQTT.
- SmartThings: Compatible when used with the Aeotec SmartThings Hub V3.
- Amazon Alexa: Compatible with Echo devices featuring a built-in Zigbee hub.
- Google Home: Temperature and humidity data are available through the eWeLink cloud integration.
- MQTT: Native MQTT is not supported, but MQTT-based automation is possible via Zigbee2MQTT.
- LAN / Offline operation: Can operate without internet access when used with a local Zigbee system such as Home Assistant with Zigbee2MQTT or ZHA.
- Cloud operation: Remote access is available through eWeLink, SmartThings, or other supported cloud platforms.
Smart Features
- Real-time temperature and humidity monitoring.
- Dew point and VPD monitoring.
- 24-hour hourly charts in the eWeLink app.
- 7-day, monthly, and 6-month trend history.
- Configurable temperature and humidity thresholds.
- Notifications when measured values leave the configured comfort range.
- Temperature and humidity calibration.
- Configurable reporting thresholds and reporting intervals.
- Automation triggers based on temperature or humidity thresholds.
- Delayed event triggering to filter out short-term fluctuations.
- Low battery monitoring with supported gateways.
- CSV export of historical measurement data.
Technical Specifications
- Product name: SONOFF AirGuard TH Lite
- Model: SNZB-02B
- Product type: Zigbee temperature and humidity sensor
- MCU: TLSR8656
- Power supply: 3.0 V, 2 × 1.5 V batteries
- Battery type: 2 × LR03 AAA
- Expected battery life: Approx. 2 years
- Wireless connectivity: Zigbee 3.0, IEEE 802.15.4
- Measured values: Temperature, relative humidity, dew point, VPD
- Temperature accuracy: ±0.2 °C / ±0.4 °F
- Humidity accuracy: ±2% RH
- Operating temperature: -20 °C to +60 °C
- Operating humidity: 5–95% RH, non-condensing
- Dimensions: 66.3 × 27.8 × 20 mm
- Weight: 43 g including batteries
- Enclosure material: PC plastic
- Colour: White
- Installation environment: Indoor
- Certifications: CE, FCC, RoHS
