Where to start with sensors

Hi guys, I’m a total newbie on home assistant and hass.io and I’m trying to figure out what to buy and how to setup it.
I’d like to have smart sensors around home (gas, smoke, temperature…) and a central hub to manage them all and get push notifications on my smartphone.
Then I’d like to turn all lights into smart lights and so on.
Could you give me some suggestions?
Thanks in advance

DIY or off the shelf?

I could evaluate both options

I have no off the shelf suggestions but you can make pretty much any sort of multisensor you want with a yaml file an ESP board and Esphome. It does all the hard coding work for you.

It has an addon for Hassio.
It has an API that talks to home assistant.
It integrates seamlessly with home assistant discovery.
It supports over the air programming (once Esphome is loaded using a serial connection).

Have a look at the available sensors in the link above and their configuration options.

Here’s a simple file for my lux meter:

  name: lux_sensor
  platform: ESP8266
  board: d1_mini

  ssid: 'WAPLO'
  password: !secret wifi_pwd

  password: !secret api_password

  level: WARN

  password: !secret esp_pwd

  - platform: status
    name: "Lux Sensor Status"

  sda: 4
  scl: 5
  scan: False

  - platform: wifi_signal
    name: "Outside Light Level WiFi Signal"
    update_interval: 15s
      - sliding_window_moving_average:
          window_size: 15
          send_every: 15
          send_first_at: 15

  - platform: bh1750
    name: "Outside Light Level"
    address: 0x23
    update_interval: 4s
      - sliding_window_moving_average:
          window_size: 15
          send_every: 15
          send_first_at: 15

This is complied by Esphome and uploaded to the ESP board.

This has become my favourite ESP32 module:

Also using an ESP32 board as a Bluetooth gateway you can use these as temperature and humidity sensors if you want local (eink) display:


Well, that’s Home Assistant, and there are lots of notification options.

You’ve got a wide range of choices, Z-Wave, Zigbee, DIY, and so on. Zigbee tends to be cheap but you have to check that your chosen Zigbee integration (zha, deconz, zigbee2mqtt) supports thd device you want. Z-Wave costs more, but any Z-Wave Plus device will work. DIY takes more effort, may not look as pretty, but gives you exactly what you want.

You can of course use a combination. I have a mix of Zigbee and Z-Wave sensors.

The simplest way of doing that is to make your light switches smart. Again you’ve got choices of Zigbee, Z-Wave, WiFi, and even semi-DIY.

I’d suggest that you split these into separate questions, include which country you’re in (since some choices are regional or specific to certain countries), what your budget is (eg you’ve got €200 for 25 sensors), and anything else relevant. It’ll be much easier for people to answer specific questions than yet another where do I begin question that touches on everything.