Website carbon

As you've probably noticed, I'm displaying carbon emissions on this site. If you want to know why, or what that the numbers mean, read on.

2 minute read

This web page is cleaner than 97% of web pages tested.
0.02 g of CO2 is produced every time someone visits this web page.

Where are these numbers coming from? #

I'm using data from, a carbon calculator built by Wholegrain Digital. You can read more about the calculator there. You'll also find instructions for adding a badge to your own site.

How are these numbers calculated? #

The calculator uses four data points, which it describes as:

  1. Data transfer over the wire
  2. Energy intensity of web data
  3. Energy source used by the data centre
  4. Carbon intensity of electricity
  5. Website traffic

Energy intensity of web data and Website traffic are average values. Energy source used by the data centre and Carbon intensity of electricity can vary depending on whether the website host is considered green. The biggest variable though is Data transfer over the wire, and that's what this calculator is essentially using as a proxy for carbon footprint. You may ask "is data transfer a good proxy?". According to Web Sustainability Consultant Fershad Irani, it "isn’t the best proxy" but right now "it’s the best we’ve got".

Why display these numbers on the site? #

It's easy to overlook how much carbon is emitted by a website, but it's not an inconsequential amount. According to Wholegrain Digital, the internet consumes more electricity in a year than the entire United Kingdom. Testing in public like this keeps my contribution visible, and keeps me in check. I hope this also helps increase awareness of web carbon emissions.

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