Digital technology is increasingly being singled out as a polluting sector. In particular, the emergence of giant datacentres hosting tens of thousands of servers has raised questions especially when it comes to powering them. However, it will always be more environmentally friendly to host several customers on the same server, into a data center, than each customer has a unique server in their home, as the IEA study shows. Especially since, from a carbon perspective, the impact of digital technology is stronger on the manufacturing and transport phases than on the use phases. In this lecture, we will explain some initiatives aimed at measuring and optimising a datacentre’s power consumption, both hardware and software.