Open window warning if forgot to close on cold days

Configuration
1

Hi,

I’ve got some room-thermometer and wanted to be warned, if I forget to close the window after letting fresh air in.
I did not find a plug’n play solution, so this helped.

sensor:
  - platform: statistics
    name: "conf Mittelwert Temperatur Buero"
    unique_id: "conf_mittelwert_temperatur_buero"
    entity_id: sensor.meter_pro_co2_df2f_temperatur
    state_characteristic: mean
    max_age:
      hours: 2


template:
  - sensor:
    - name: "conf_diff Temperatur zu Mittelwert Büro"
      unique_id: "conf_diffTemperaturZuMittelwertBuero"
      unit_of_measurement: '°C'
      device_class: "temperature"
      state: >-
       {{ float(states('sensor.conf_mittelwert_temperatur_buero')) - float(states('sensor.meter_pro_co2_df2f_temperatur')) | round(2) }}

And then you only have to watch if conf_diff_Temp… is over 1 to 1.5