Abstract
Continuous integration pipelines execute automated tests on ev- ery commit, consuming substantial energy. Batch testing, which groups multiple commits into a single test run, has been shown to reduce test executions in simulation studies, but no prior work has measured whether these reductions translate into actual energy savings. This study measures CPU package energy consumption of CI builds under a baseline run-all approach and two batching strategies (BatchStop4 and linear-4 lwd) across eight open-source Java projects. BatchStop4 achieves energy savings between 57% and 88%, while linear-4 lwd achieves savings between 59% and 94%. Energy savings correlate almost perfectly with time savings (r
0.99), indicating that batching reduces energy primarily by short- ening total execution time. Baseline failure rate strongly predicts achievable savings, while CPU utilisation shows no significant re- lationship. These findings provide empirical evidence that batch testing effectively reduces the environmental footprint of continu- ous integration, particularly for projects with low failure rates.