Earth Day is a great reminder that small changes in our daily habits can have a meaningful impact over time. For those of us running a smart home, it’s also an opportunity to rethink how we use automation—not just for convenience, but for sustainability.

In this post, I’ll walk through three practical Home Assistant projects that align perfectly with Earth Day:

• Smarter EV charging (not just cheaper—greener)
• Water usage monitoring with ESP32
• A simple “Earth Day” dashboard to visualise your impact

These are all things you can actually use every day—not just nice ideas in theory.

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Why Home Assistant is Perfect for Earth Day

Home Assistant gives you control over your energy and resource usage in a way that most smart home systems don’t. Instead of reacting manually, you can:

• Shift energy usage to better times
• Detect waste automatically
• Track trends over time

And most importantly: you can make it visible.

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1. Smarter EV Charging: Beyond Just Cheap Electricity

Most people (myself included) start with EV charging based on electricity prices. That’s a great start—but it’s only half the story.

The Idea

Instead of charging only when electricity is cheapest, we can combine:

• Low electricity price (kWh)
• Time constraints (calendar)
• Battery state of charge
• Optional: grid conditions or renewable availability

This ensures the car is charged efficiently, but also avoids unnecessary peaks and waste.

Components Used

• EV charger integration (e.g. Easee)
• Battery sensor (e.g. sensor.car_battery_level)
• Nordpool or other electricity price integration
• Calendar entity for planned trips

Example Automation

This example ensures the car charges when electricity is cheap, but is always ready before a scheduled departure.

alias: Smart EV Charging (Earth Day Edition)
description: Charge car when prices are low and ensure it's ready before departure
trigger:
  - platform: time_pattern
    minutes: "/15"

condition:
  - condition: state
    entity_id: device_tracker.car_location
    state: "home"

action:
  - variables:
      current_price: "{{ states('sensor.nordpool_kwh') | float }}"
      battery: "{{ states('sensor.car_battery_level') | float }}"
      target: 80

  - choose:
      - conditions:
          - condition: numeric_state
            entity_id: sensor.nordpool_kwh
            below: 0.80
          - condition: template
            value_template: "{{ battery < target }}"
        sequence:
          - service: switch.turn_on
            target:
              entity_id: switch.ev_charger

      - conditions:
          - condition: numeric_state
            entity_id: sensor.nordpool_kwh
            above: 1.50
        sequence:
          - service: switch.turn_off
            target:
              entity_id: switch.ev_charger

Earth Day Angle

Charging smarter reduces:

• Peak demand
• Grid stress
• Indirect emissions

Even without perfect CO₂ data, simply avoiding high-demand periods is a step in the right direction.

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2. Water Usage Monitoring with ESP32

Energy gets a lot of attention—but water usage is just as important.

If you already run ESPHome, this is a perfect weekend project.

The Idea

Track how much water you use and detect anomalies like:

• Leaks
• Running taps
• Unexpected consumption

Hardware Options

• ESP32
• Ultrasonic sensor (for tanks)
• Pulse sensor (for water meter)
• ESPHome firmware

Example: Daily Water Tracking

Let’s assume you have a sensor like:

sensor.water_usage_today

You can create alerts and insights from this.

Example Automation: Leak Detection

alias: Water Leak Alert
description: Notify if water usage is unusually high
trigger:
  - platform: numeric_state
    entity_id: sensor.water_usage_today
    above: 500

condition: []

action:
  - service: notify.mobile_app_phone
    data:
      message: "Unusually high water usage detected today!"

Optional Enhancement

Track rolling averages:

• Compare today vs last 7 days
• Trigger alerts based on deviation instead of a fixed number

Earth Day Angle

This is where smart homes shine:

• You see your usage
• You react faster
• You waste less

Even a single avoided leak can save hundreds of litres.

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3. Building an “Earth Day Dashboard”

Data is only useful if you can actually understand it.

This is where a custom dashboard comes in.

The Idea

Create a simple view showing:

• Electricity usage (kWh)
• Water usage (litres)
• EV charging status
• “Savings” indicators

Suggested Dashboard Elements

Energy Section

• Daily consumption (kWh)
• Current electricity price
• EV charging status

Water Section

• Today’s usage
• Weekly trend

Sustainability Section

• Estimated saved kWh
• Reduced usage vs yesterday

Example: Template Sensor for “Saved Energy”

template:
  - sensor:
      - name: "Energy Saved Today"
        unit_of_measurement: "kWh"
        state: >
          {% set yesterday = states('sensor.energy_yesterday') | float %}
          {% set today = states('sensor.energy_today') | float %}
          {{ (yesterday - today) | round(2) if yesterday > today else 0 }}

Example: Simple Lovelace Card

type: entities
title: Earth Day Overview
entities:
  - sensor.energy_today
  - sensor.energy_saved_today
  - sensor.water_usage_today
  - sensor.car_battery_level
  - switch.ev_charger

Make It Visual

If you want to take it further:

• Add graphs (24h / 7d)
• Use color thresholds
• Highlight “good” vs “bad” days

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Bringing It All Together

Individually, these projects are useful.

Together, they give you something more powerful:

• Awareness of your consumption
• Control over when and how you use resources
• Automation that actively reduces waste

And importantly: it becomes part of your daily life, not something you think about once a year.

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What You’ll Actually Notice

After running setups like this for a while, you start to see patterns:

• Your car doesn’t need to charge as often as you think
• Water usage spikes are easy to miss without tracking
• Small automations add up over time

It’s not about perfection—it’s about improvement.

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Final Thoughts

Earth Day doesn’t have to mean big, dramatic changes.

In a smart home, it’s about:

• Smarter decisions
• Better timing
• More awareness

Home Assistant gives you the tools—you just need to decide how far you want to take it.