Using Zigbee entity values in value template calculations

Configuration
1

In my HA system, I was calculating dew points using value templates. My sensors were all MQTT and the calculation seemed straight forward to me. A typical calculation entry in the sensors.yaml looked like this:

  - unique_id: sense34
    platform: mqtt
    state_topic: 'airqual_2'
    name: 'dew_point_airqual_2'
    unit_of_measurement: '°F'
    value_template: '{{ (( ((((value_json.Temp | float) * 1.8 ) + 32) ) - (0.36 * (100 - (value_json.RH | float) ))) | round(2)) }}'

I decided to replace my DIY sensors with SONOFF TH01 sensors, for two reasons; they are battery powered, and their packaging is cleaner looking than anything that I can achieve. The SONOFF sensors are Zigbee sensors and I added them using the ZHA integration.
Now, I have no idea how to implement the dew point calculation using the new entities. Can somebody point me in the right direction?

2

You will have to create template sensors using your new entities:

3

Thank you for the prompt response. I appreciate you taking the time to reply to my question. I apologize for taking so long to acknowledge your answer. It took me until now to figure out how to create the template definitions. All is good!