How to Build an Environmental Impact Tracking App in FlutterFlow

Before building the UI, seed your emission_factors collection with data. Each document should represent one activity type. The document ID can be a readable slug like 'car-petrol-km'. Fields: category (String: Transport / Home Energy / Food / Shopping / Flights), activityName (String), unit (String: km / kWh / kg / item / flight), co2PerUnit (Number, kg CO2 per unit), country (String: US / UK / EU / Global), source (String: citation), lastUpdated (Timestamp). Create at least 25-30 entries covering: car travel (petrol and electric per km), bus and train per km, short-haul and long-haul flights per km, home electricity by country, natural gas per kWh, beef and chicken per kg, and clothing purchases. This collection becomes the living database your app queries at runtime instead of relying on compiled constants.

Create an AddActivityPage. Add a Dropdown bound to a list of distinct categories fetched from emission_factors (or hardcoded: Transport, Home Energy, Food, Shopping, Flights). When a category is selected, load a second Dropdown with all activityName values for that category from Firestore using a conditional query. Add a TextField for the quantity (with the unit label dynamically set from the selected activity's unit field). Add a DatePicker defaulting to today. Add a notes TextField (optional). When the user taps 'Log Activity', run a Custom Function to calculate CO2: multiply quantity by the co2PerUnit from the selected emission factor document. Save a new document to the user_activities collection with fields: userId, activityId, activityName, category, quantity, unit, co2Kg (calculated), loggedDate, country (from user profile), and notes.

1// Custom Function: calculateCO2
2// Parameters: quantity (double), co2PerUnit (double)
3// Returns: double
4double calculateCO2(double quantity, double co2PerUnit) {
5  return quantity * co2PerUnit;
6}

Create a DashboardPage. Add a month selector (two arrow buttons with a Text showing the current month/year, stored in Page State). Query user_activities for the current user, filtered by loggedDate within the selected month's date range. Sum co2Kg by category using a Custom Function that groups the returned list by the category field. Display a PieChart widget (available in FlutterFlow's chart section) with one slice per category — bind the slices to your grouped data. Below the PieChart, show a summary Row with the total monthly CO2, a comparison chip ('12% below national average' or 'X kg above'), and the user's monthly goal progress bar. The national average is a constant per country — store it in a Firestore document called national_averages/{countryCode} with a field monthlyKgCO2.

Add a LineChart widget below the PieChart on the DashboardPage. Query the user's total monthly CO2 for the last 6 months. To do this efficiently, run a Custom Action that performs 6 Firestore queries (one per month) in parallel using Future.wait, summing co2Kg for each month. Return the results as a list of monthly totals. Bind this list to the LineChart's data series. Add a second line on the chart representing the national monthly average (a flat horizontal line from the national_averages document). This two-line chart immediately shows whether the user is trending toward or away from their goal. Add a simple trendDirection Custom Function that returns 'improving', 'worsening', or 'stable' based on the last three months' slope, and display a corresponding icon and message.

Create a GoalsPage. Display the user's current monthly CO2 target (set by the user via a Slider, stored in their Firestore profile document). Show a progress bar comparing current month total to the target. Add a 'My Top Impact' card that calculates which category contributed the most CO2 this month. Below it, display 2-3 context-sensitive eco tips — fetch tips from a Firestore eco_tips collection where you filter by category. For example, if Transport is the top category, show tips like 'Try combining errands into one trip' or 'Consider an electric vehicle — EVs cut transport emissions by 60-70%'. Fetch 3 random tips per category from eco_tips on page load. Add a monthly achievements system: if the user beats their goal for 3 consecutive months, award a badge stored in their profile.