vpd.yaml

sensor:
- platform: template
  id: vpd
  name: "Vapor Pressure Deficit"
  update_interval: 5s
  accuracy_decimals: 2
  unit_of_measurement: 'kPa'
  lambda: |-
    float temperature = (id(mlx90614_temperature_object).state - 32) * 5/9;
    float humidity = id(bme280_humidity).state;
    float vpSaturation = 610.7 * pow(10, (7.5 * temperature / (temperature + 237.3)));
    float vpDeficit = ((100.0 - humidity) / 100.0) * vpSaturation;
    return vpDeficit / 1000;

prometheus:
  relabel:
    vpd:
      id: vpd
      name: "Vapor Pressure Deficit"