Carbon footprint calculator

This is a simple project to help me learn web development with Svelte.

Motivation

Lots of people are willing to make lifestyle changes to reduce their carbon footprint, but can't easily quantify the impact these changes. I believe this leads to well-meaning people worrying about largely inconsequential changes (e.g. turning lights off obsessively), and/or attempting a large number of lifestyle changes, which is stressful difficult to maintain.

Secondly, the most important lesson from a carbon footprint calculator is what you can change to make a difference. Most calculators I've tried do not allow you to see how different changes affect your footprint; you usually need to re-take the full test.

We should be encouraging people to make the changes with the highest impact-to-effort ratio. A single change is much easier to manage, and in many cases can have a dramatic impact.

Contributing

Running locally

To run locally, first clone the repo, then:

cd carbon-footprint
npm install
npm run dev

To deploy, locally run ./deploy.sh (you'll need to be on main and stash any changes first).

Editing the calculator

If you think there's an error or significant inaccuracy in this calculator, you can make an issue, make PR to fix it, or make a fork with your own values. All content and variables for this calculator are stored in src/content.yaml. It should hopefully be pretty clear how editing this file affects the built web app, but here's a quick overview of how it works:

• This carbon calculator app is built from a bunch of smaller calculators (e.g. travel, diet), each in its own panel. Each calculator is an entry under calculators, and you can add more entries to create more panels.

• Calculators contain variables that the user can change. Each variable has a kgco2pu value, which is the kg of CO2 produced per 'unit'. The unit used for this value should be:

  • km for distance,
  • years for time,
  • grams for mass,
  • kWh for energy.

  We have some special syntax that creates a dropdown box where users can change the input units, (e.g. [ km | miles ]). If the software recognizes a unit, it'll multiply the result by the conversion factor to correct for the change in units. E.g. if the user selects miles (~1.61km), the calculator would return value * kgco2pu * 1.61. You can use an @ symbol to override the built-in conversion unit, which allows you to mix different types of units. For example, we assume planes move at ~800km/hr, so we let the user select 'hours' as one of the units. The label for this variable is [ hours @ 800 | km | miles ], which means our calculator returns value * kgco2pu * 800.

  Each variable has a minmax value. When the variable input is in slider mode, the minmax value is the smallest slider range allowed (i.e. the minimum maximum value). This should generally be set to 1.3 * the UK average for that value.

• Each calculator also includes 'about' info, that we use to explain our sources, methods and assumptions to the user. Make sure to edit this when you edit the values.

• We summarize all other emission factors to be ~ 1 tonne CO2eq / year. This value is set under baseEmissions.