http://www.dingostick.com/2019/07/internet-of-things-air-conditioning.html

ventilation.yaml

- id: '1234'
  alias: ventilate_on
  trigger:
  - payload: 'on'
    platform: mqtt
    topic: ventilate
  condition: []
  action:
  - data:
      entity_id: switch.wind_tunnel
    service: switch.turn_on
  - data:
      entity_id: switch.boys_fan
    service: switch.turn_on
- id: 'ventilate_off'
  alias: ventilate_off
  trigger:
  - payload: 'off'
    platform: mqtt
    topic: ventilate
  condition: []
  action:
  - data:
      entity_id: switch.wind_tunnel
    service: switch.turn_off
  - data:
      entity_id: switch.boys_fan
    service: switch.turn_off