Making the windows smart

Having your windows connected to home assistant opens many possibilities. I’ve written down some ideas on what you could do with such information:

  • 🚨 Create an alarm panel, so when a window is being opened while you are away, the siren rings and you get a text message
  • 📱 Be notified which windows are still open before you leave
  • 🌡️ Turn off the heater when someone opens a window
  • ❄️ Ring a bell when the windows are open for too long
  • … and possibly much more

Af the end of this post, your dashboard might look like this:

climate card: heater control and binary sensors for each window in home assistant


magnetic window contact and a nodemcu

How to do this

We will add magnet contacts to every window and wire them all to an ESP8266. There are other possibilities like using wireless contacts, but if you are on a budget or already have sensors pre-wired in your home this is a cheap and reliable way.

Let’s begin with wiring everything together. The magnet contacts close the circuit when the magnet is near them, and is open when not. We will connect one wire of the contact to a digital pin. Not all pins are usable as inputs on the NodeMCU board, so make sure to connect to one of these pins: D0, D1, D2, D5, D6 or D7. You don’t have to use four window contacts as I do but if you want to connect more than six you probably need to use a shift register to get more ports (or use another node).

four window contacts wired to a nodemcu

Writing the program

Using esphomeyaml, flashing the nodemcu becomes a no-brainer. If you already know yaml files from home assistant, it should be easy for you to follow.

Keep in mind to alter the pins to your chosen ones. If you want to add contacts, just copy one of them and make sure all the indents are correct.

  name: window_contacts
  platform: ESP8266
  board: nodemcuv2

  ssid: !secret wifi_ssid
  password: !secret wifi_password

## Enable logging



  - platform: gpio
      number: D1
      mode: INPUT_PULLUP
    name: "Small Window"
    device_class: window

  - platform: gpio
      number: D2
      mode: INPUT_PULLUP
    name: "Balcony Door"
    device_class: window

  - platform: gpio
      number: D6
      mode: INPUT_PULLUP
    name: "Wide Window"
    device_class: window

  - platform: gpio
      number: D7
      mode: INPUT_PULLUP
    name: "Side Window"
    device_class: window

Connect everything and run esphomeyaml window_contacts.yaml run.

To add the entities to your home assistant instance, visit


We connected simple reed switches (window contacts) to a nodemcu (esp8266). We then wrote a simple program using esphomeyaml to report the states to home assistant. After uploading this sketch, everything should be up and running fine.

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