Sustainability in HEP Computing

The European energy crisis during 2022 prompted many computing facilities to take urgent electricity saving measures. In part voluntary, in response to EU and national appeals, but also to keep within a flat energy budget, as the electricity price rose. We review some of these measures and, as the situation normalizes, take a longer view on how the flexibility of high throughput computing can best contribute to the net-zero energy transition. We discuss carbon intensity estimation of workloads, automatically powering down nodes during low-demand periods, CPU frequency modulation to track variable electricity tariffs or renewable generation throughout the day and potential spin-down disk storage solutions.