Alicia Wise
CLOCKSS is a distributed international archive with physical servers located at 12 institutions in 7 countries. The size of their digital preservation holdings is roughly 250tb and it is estimated that their base line carbon impact is approximately 109,541 kgCO2e/year from the archive and an additional c.11 kgCO2e/year from travel.
CLOCKSS followed the DIMPACT method as this is widely used by publishers and other media organisations. This is also the method that now underpins this toolkit.
It took CLOCKSS about 18 months to gather data at 4 of their 12 hosting sites and estimations could be calculated from here. It was a very useful exercise, but also a heavy lift with a steep learning curve. This experience inspired them to really want to contribute to the development of this toolkit! You can read more about their experiences in this blog post.