Optimize Home Watering: A Virtual Rain Sensor That Saves Resources

Sustainable irrigation - In the increasingly intelligent context of home automation, finding ways to make home irrigation more efficient and sustainable is a priority. In this article, we'll explore how Home Assistant and a virtual rain sensor can work together to ensure that your garden watering only occurs when the weather is favorable.

Virtual Rain Sensor: A Barrier against Useless Irrigation

Imagine being able to synchronize your irrigation system with current weather conditions. A virtual rain sensor, created through Home Assistant, becomes the key to ensuring that your garden receives the water it needs only when the skies are clear.Virtual Rain Sensor YAML code:

# Configuration of the Virtual Rain Sensor

sensor:
  - platform: template
    sensors:
      virtual_rain_sensor:
        friendly_name: "Virtual Rain Sensor"
        value_template: >-
          {% if states('sensor.weather_condition') == 'rainy' %}
            True
          {% else %}
            False
          {% endif %}

If you use a recent version of Home Assistant, the correct syntax is this:

templates:
  - sensor:
      - name: "Virtual Rain Sensor"
        unique_id: virtual_rain_sensor
        state: >
          {{ is_state('sensor.weather_condition', 'rainy') }}

Or, if your goal is to have a true binary sensor (best suited for automations and dashboards), it's even better to use abinary_sensor:

templates:
  - binary_sensor:
      - name: "Virtual Rain Sensor"
        unique_id: virtual_rain_sensor
        device_class: moisture
        state: >
          {{ is_state('sensor.weather_condition', 'rainy') }}

Explanation of the code

The virtual rain sensor is created using the engineTemplatesof Home Assistant, which allows you to generate custom entities based on user-defined conditions.

The first example uses the historical syntax (sensor:withplatform: template), still present in many configurations but now considered obsolete in more recent versions of Home Assistant.

In the second example the new syntax is adopted (templates:), introduced to simplify configuration and make it more consistent with the rest of the system. In this case a normal is createdsensor template, whose state takes on the valueTruewhen the sensorsensor.weather_conditionreturnsrainy, AndFalsein all other cases.

The third example represents the recommended solution when the goal is simply to know whether it is raining or not. In this case a is createdbinary_sensor, i.e. a binary sensor that can exclusively assume statesHonAndoff. Thanks todevice_class: moisture, Home Assistant automatically identifies it as a humidity/rain sensor, displaying the correct icon, making it ideal for dashboards, automations, and integrations with other devices.

In all three cases the logic remains the same: the value returned by is checkedsensor.weather_condition; if this matchesrainy, the virtual sensor signals the presence of rain, otherwise it indicates that it is not raining.

Note:for new projects it is advisable to use the syntaxtemplates:and, when you only need to represent a true/false condition such as the presence of rain, prefer abinary_sensor, as it is the most modern, efficient and perfectly integrated solution with Home Assistant.

sustainable irrigation - Practical Use

Imagine you have a garden with an irrigation system. When the virtual rain sensor detects rain conditions (True), it automatically activates a script to temporarily shut down the irrigation system. This prevents you from needlessly watering during rain, thus helping you save water and adopt a more sustainable approach.Irrigation Script YAML code:

# Example of an Irrigation Script script: irrigation_script: sequence: - condition: state entity_id: sensor.virtual_rain_sensor state: "False" - service: notify.notify data: message: "Rain conditions not detected. Starting irrigation system..." - service: switch.turn_on entity_id: switch.irrigation_system - delay: '00:10:00' # Adjust delay based on duration desired for irrigation - service: switch.turn_off entity_id: switch.irrigation_system - service: notify.notify data: message: "Irrigation completed. System turned off."

Code Explanation:

• Before running the irrigation script, the status of the virtual rain sensor is verifiedFalse, indicating that it is not raining.
• A notification is sent to let you know that the irrigation system is about to start only if it is not raining.
• A switch is activated (switch.irrigation_system) to start the irrigation system only if the weather is clear.
• After a 10 minute delay, the switch is turned off, indicating the end of watering.
• Receive a notification that watering is complete and the system is turned off.

The integration of a virtual rain sensor into the Home Assistant sustainable irrigation system represents a step forward in resource management. This solution ensures that your garden only receives the water it needs when the skies are clear, reducing waste and promoting a smarter approach to plant care. The combination of technology and nature in this context demonstrates the positive potential of home automation in our daily lives.