noun
power saving feature; power saver
A feature in devices or software that reduces power consumption. Common in settings menus and technical documentation.
このプリンターには省電力機能がついています。
This printer has a power saving feature.
省電力機能をオンにすると、バッテリーの持ちが良くなります。
Turning on the power saver feature improves battery life.
省エネ is a broader term for energy conservation in general, while 省電力機能 specifically refers to a power-saving feature in electronic devices.
Compound of 省 (save, conserve), 電力 (electric power), and 機能 (function, feature).