Emission factors

[skeydan]

Gathering adequate emission factors is quite a challenge.

Air travel: distance-based (preferred way)

too much information needed:

• ICAO method

relatively coarse-grained:

• DEFRA Problem: little detail outside the UK

even more condensed:

• EPA - based on DEFRA, but more detailed re US flights
• World Resources Institute is publishing yearly inventories (such as https://www.wri.org/sustainability-wri/dashboard/methodology#category-6) - based on DEFRA

Additional links

• WIOD

[skeydan]

By now I'm at a point where I think that for air travel, the package should not offer spend-based calculation at all.

DEFRA say

There are no confirmed industry benchmarks that provide accurate CO2e/£ spend data for air travel. We recommend that organisations improve their data collection processes so that they can report on distance (for which CO2e/km figures are available). Alternatively, organisations may, over a number of years, collect their own data and generate their own benchmarks.

I do see that we could create our own "benchmark" from existing data, but we wouldn't know how well this generalizes to other companies, and we wouldn't want to be held responsible for any inadequacies...

I'm gonna create a PR using EPA distance-based factors only... we can always revert to including spend if we want to...

[skeydan]

Changing opinion again...sometimes, people may be in real trouble obtaining travel distances ... So some conversion logic between price and distance is needed.

We could start with package defaults and see where that gets us ... I was going to suggest offering users an option to provide their own conversion formula, but not sure this makes sense - if someone has a specific formula they want to use, it's pretty likely they do have access to distance data...

Collecting default conversion factors here:

• air travel: price = $50 +(distance*$.11)

[skeydan]

Finally we decided NOT to provide spend-based calculation for air travel, will remove again.