# Energy probes

Modules implementing energy probes (via the EnergyProbe interface) must be positioned in the evowluator/user/probes directory. This last step is only necessary for energy footprint evaluation. Note that evOWLuator comes with two built-in probes that wrap the powermetrics and powertop tools on macOS and GNU/Linux, respectively.

evOWLuator estimates energy consumption by running the reasoner binary and polling the probe until the process exits. The collected samples are then used to compute an energy footprint score as follows:

$score = sampling\_interval * \sum_{i=0}^N sample_i$

This provides a proxy of the energy used by the reasoner during its execution time, which can be leveraged for comparisons among reasoners run on the same device and using the same probe.