I believe it happened to everyone at least once – you leave your apartment and forget to close a window. It happened to me once when going on a trip and I was looking for a solution to notify me if any window is still open when no one is at home.

I use the following hardware:

Setup

The blog post is divided into four steps:

  1. Door and window sensors
  2. Device tracker
  3. AWS setup
  4. Automation configuration

Door and window sensors

The sensors are connected via ZigBee and are battery-powered. They suppose to last a few years before I have to replace the batteries.

Sensor setup

The ConBee II shows up as an integration in Home Assistant. To add new devices you don’t need any additional plugins. Click on “Configure > Add Device” and put the device in pairing mode. It will show up and you can name it.

ConBee II integration in HA
Adding new ZigBee devices

Device tracker

Next, the device tracker is configured. If no known device is connected I assume nobody is home. Settings are stored in the configuration.yaml file. 

device_tracker:
  - platform: unifi_direct
    host: ip_address_access_point
    username: username_access_point
    password: password_access_point
    new_device_defaults:
      track_new_devices: true

Once the device tracker is configured you assign users their device with the corresponding MAC address. This makes it easier to be included in any automation. Click on “Settings > People” and choose a person. In the menu set the field track device. Now the device is assigned to the user.

AWS setup

The only solution to reach everyone reliably for me seems to be via SMS. So I decided to use Amazon SNS to send out notifications. First, you need an account if don’t have one yet. Second, add the phone number you want to contact. Last, create a topic and add the phone numbers.

As a final step configure the AWS integration in the configuration.yaml file. Choose the region of your choice.

aws:
  credentials:
    - name: project_account
      aws_access_key_id: your_access_key
      aws_secret_access_key: your_secret_key
  notify:
    - service: sns
      region_name: eu-central-1
      name: sns_eu_central_1

Now everything is set up and ready to be used in a home assistant automation.

Automation configuration

The automation is triggered as soon as the device tracker detects a device leaving the network and if a window opens if no one is home. As soon as this happens home assistant checks two things – 1) is no one else still connected and 2) is any window open. If both are true the notification is sent to AWS and as a result to all phones set as recipients.

During the first few nights, we received many notifications because our phones kept disconnecting while sleeping. So I added a timer to only trigger the notifications when a device disconnects if it’s between 6 am and 11 pm.

Here is a simplified configuration I use:

alias: notify everybody if everybody left 
       and window open(s) - day
description: ""
trigger:
  - platform: state
    entity_id:
      - person.person1
      - person.person2
    from: home
  - type: opened
    platform: device
    device_id: device_id
    entity_id: entity_id
    domain: binary_sensor
  [ + other sensors]
condition:
  - condition: or
    conditions:
      - type: is_open
        condition: device
        device_id: device_id
        entity_id: entity_id
        domain: binary_sensor
     [ + other sensors]
  - condition: not
    conditions:
      - condition: state
        entity_id: person.person1
        state: home
      - condition: state
        entity_id: person.person2
        state: home
  - condition: time
    before: "23:00:00"
    after: "06:00:00"
action:
  - service: notify.sns_eu_central_1
    data:
      message: >-
        [WARNING] nobody home and window open 
      target: arn_sns_topic
mode: single

Conclusion

This setup works great for us. It saved us from leaving the apartment while a window is still open a couple of times. I use the device tracker for two additional automations:

  1. turn off my led clock
  2. turn off all running Chromecast audios via media player integration when no one is home. Here is an example action configuration.
action:
  - service: media_player.turn_off
    data: {}
    target:
      device_id:
        - device_id1
        - device_id2

In the future, I plan to install a LED on the way leaving the apartment so you know right away if any window is still open. So far my plan is to use ESPHome to trigger a LED in combination with another automation script.