Method and sources

Where do the figures come from?

From public data by ADEME, the French Agency for Ecological Transition, published by Impact CO2, which draws on the Base Carbone and Agribalyse databases. The site reads Impact CO2’s public file of equivalents; each action links to its page on impactco2.fr (in French), where its value is explained in detail.

Data: Impact CO2 – ADEME, downloaded on 5 October 2026

Data reused with permission from ADEME’s Impact CO2 team (email of 5 October 2026), free of charge, with the credit “Données : Impact CO2 – ADEME” (in English: “Data: Impact CO2 – ADEME”).

What they count

Each value is an average in kilograms of CO2 equivalent (kg CO2e), which adds up greenhouse gases according to their effect on the climate. We always compare two actions with the same unit:

• Getting around: per kilometre and per person, over the distance you choose;
• Eating: per meal;
• Drinking: per litre;
• Clothes and Digital: per item, for making a new item;
• Deliveries: per purchase, for a 1 kg parcel.

Second-hand. Buying an item that has already been made doesn’t lead to anything new being made: we count 0 kg for manufacturing. This is an assumption, not a measurement. Keeping yours also counts 0 kg.

The parcel. If the second-hand item is delivered, we add sending a parcel to your home, according to Impact CO2: 1 kg for clothing or a smartphone, 2 kg for trainers or a laptop, 15 kg for a television.

Shopping trips. For “Deliveries”, Impact CO2’s values include the trip to collect the parcel: 3.5 km by car for the pickup point, 15 km by car for the shop, and no motorised trip on foot.

What isn’t counted

• the trip to buy second-hand (charity shop, car boot sale, handover in person);
• looking after, washing, repairing or refurbishing an item;
• end of life (resale, donation, waste);
• using appliances (a television’s electricity, for example).

Their limits

These are averages. Your journey, your meal or your clothes may weigh more or less depending on the details.

Counting zero manufacturing for second-hand items favours them: other methods share the manufacturing footprint between an item’s successive lives.

It only shows the choices you note here. It isn’t your carbon footprint, just a record of the differences between the options you compared.

The site doesn’t measure kilos saved or avoided: it counts the gap between the option you choose and the other option you compared, without knowing what you would have done otherwise. That’s why it always says “difference”. A habit noted without a comparison counts no kg (see comparing or keeping up a habit).

Comparing or keeping up a habit

Comparing two actions gives a difference: the gap between the two options, calculated with Impact CO2 data. That difference, and only that, is what your garden adds up.

A habit isn’t compared with anything: if you never eat meat, comparing your meal with a meat dish would give a difference that matches nothing real. So a habit you keep counts no kg and goes into neither the total nor the milestones. It waters your garden: on each day you note at least one, the plants already there move up a step every 3 watered days. It’s a rule of the game, not a measurement.

In winter, the bloom of deciduous trees sleeps: the level reached is kept, but their flowers and fruit only come back in spring.

The garden also follows the seasons of the northern hemisphere (leaves, sky, snow): simple scenery, which doesn’t change any figure.

Seasonal visitors (robin, swallow, cicada, squirrel, wild flowers) and night visitors (owl, fox) drop by on their own: they aren’t unlocked and don’t count anywhere. The sky follows your device’s clock: from 9 pm to 6 am, your garden switches to Ink night. Your plants never die, and an animal that has moved in is never lost: it sleeps, or comes back in its season.

The In season page draws on Impact CO2’s seasonal fruit and vegetables tool: for each product, its months in season and its impact in kg of CO2e per kilo, from lightest to heaviest, with the tool’s categories. Product names are translated; the values are the same.

The data doesn’t say where the produce comes from, except for mangoes, where it separates imports by air from imports by sea. So the site doesn’t compare different origins of the same product.

Data: Impact CO2 – ADEME · Agribalyse 3.2 data (updated 15/01/2025), retrieved on 5 October 2026

“Did you know?”

These little facts are calculated from the same Impact CO2 data as the comparisons, never written by hand: if a value changes, the sentence follows. They are rounded to stay readable and link to the original action’s page.

“Tell us about your day”

You write about your day; Claude Haiku 4.5, a model by Anthropic, spots the actions that are in the site’s catalogue, and nothing else. It doesn’t calculate anything and gives no figures: it only returns the names of the actions, the words that justify them and, for a journey, the distance if you wrote it. An inferred action (“a burger” for a beef meal) is marked “Check this” and isn’t ticked.

The option it’s compared with comes from a table written by hand (the TER regional train is compared with a petrol or diesel car, a vegetarian meal with a chicken meal…), which you can change before adding. The differences are then calculated as everywhere else, from Impact CO2 data. Nothing goes into your journal unless you’ve ticked it.

Each analysis runs an AI model in a data centre: it uses energy and so has a footprint. We don’t show it in grams, because there’s no public source that puts a figure on a single request. That’s why the analysis only runs when you ask, on a short text, with a brief reply.

How this site is made

Designed, illustrated and built by Guillaume (webjuno.com). The code was written with the help of Claude Code, Anthropic’s coding assistant. It’s open: the GitHub repository is public.