25 April 2025
Carbon.txt is a service by the Green Web Foundation which lets you declare your organisation’s sustainability data in way that software can read.
“Carbon.txt is a single, discoverable location on any web domain for public, machine-readable, sustainability data relating to that company.
It’s a web-first, connect not collect style approach, of most benefit to those interested in scraping the structured data companies have to publish according to national laws. Designed to be extended by default, we see carbon.txt becoming essential infrastructure for sustainability data services crunching available numbers and sharing the stories it can tell.”
More about Carbon.txt: background, the syntax, build your own carbon.txt file, validate a carbon.txt file.
OK, sounds cool. Here’s mine: https://www.holdfastprojects.com/_carbon.txt. It seems to validate, so I think I wrote it correctly.
Notes about my carbon.txt file for future me:
- it points at this page, which tbh I need to update. (I also need to resolve my uncertainty about whether to disclose information which I consider relevant, or information which seems closest to the GHG Standard, or just the standard carbon intensity metric which GOV.UK publishes, which is a simplified proxy for the GHG standard. That latter two might make it easier for organisations to understand and compare their own scope 3 emissions etc.)
- my site is managed by Blot, which says its servers are located in a data center that is powered by renewable energy, ie hosted by Amazon
- I posted my carbon.txt file to https://www.holdfastprojects.com/_carbon.txt (the underscore stops Blot trying to publish it as a html file, but perhaps makes the carbon.txt file less discoverable?: the url itself validates ok, but the validator says it can’t file a carbon.txt file on holdfastprojects.com).
- I couldn’t tell whether I should use single or double quotes (“literal” or “basic” strings in TOML’s spec), so I went with double quotes, which seems to validate ok.