7. A crowded fridge prevents air from circulating. With less air circulation, your fridge is working extra hard to keep cool. And the harder it works, the more electricity it is consuming. Conversely, the fuller your freezer, the more efficiently it works. Avoid putting any warm or hot foods into it straight away. Make sure that liquids are always covered and food is wrapped up, as they might get moist and cause the compressor to work extra hard.