Website Carbon Calculators are good for awareness about energy consumption of the IT sector, but they currently work based on very rough estimations. Therefore more transparency is needed as well as better tools for developers to create better, more energy efficient code – this is the current conclusion by Roberta Haseleu.
She gave a 15 minute talk at Chaos Communication Camp 2023 about her tests with the existing carbon calculator tools, I recommend it very much:

Website Carbon Calculators mentioned in her talk: https://www.websitecarbon.com/, https://greenpixie.com/, https://ecograder.com/, https://websiteemissions.com/. She also mentioned the startup dedalo.ai, which helped with the test cases. The stage was hosted by Bits & Bäume.
Personally I’m very thankful for this talk and somebody doing some real testing.
Web Sustainability Consultant Fershad Irani also published insightful articles in the past months in regards to the challenge of measuring CO2 of websites:
- Is data transfer the best proxy for website carbon emissions? (May 2023)
- Website carbon: Beyond data transfer (October 2022)
He referred in particular to this talk „The Internet of tomorrow must sleep more and grow old“ by Romain Jacob und Laurent Vanbever, in which I personally learned a lot more about the energy challenge in IT and in regards to server infrastructure.
For an full picture of the current state of the internet and fossil fuel consumption, I can’t recommend this talk enough:
- „Getting to a fossil free internet by 2030“ – Chris Adams, Green Web Foundation (February 2023)
- Slides: https://greentechsouthwest.org/insights/fossil-free-internet/
- Video recording: https://www.crowdcast.io/e/chrisadams
I really hope this conversation will continue!
More resources
A place for following the discussions is the „#greener-webdev“ channel at Climate Action Tech Slack:
Feel free to join, there are local channels like local-germany, local-austria, local-switzerland, etc. etc.
On my blog I also published two articles about Green Web & Energy Consumption in german:
- Der Weg zu einem klimaneutralen Internet (Shout out to the Green Web Foundation!)
- Sustainable Web Design: Mehr Datentransfer = höherer Energieverbrauch?
Article images: Screenshots of talk by Roberta Haseleu, https://media.ccc.de/v/camp2023-57725-fooled_by_the_website_carbon_calculator