Don’t overfill or underfill
A fridge works best when it’s at least two-thirds full and a freezer when it’s at least three-quarters full. The more empty space you have, then the more energy you’ll use in cooling the air inside.
The reason for this is simple. The cool air spills out when the door is opened and the warm air coming in has to be chilled. This cost can really add up.
Keep refrigerators at least 66% full and freezers at least 75% full to increase efficiency.
In a non-consumer environment, you can reduce this problem by filling up the empty space with airtight bottles filled with water. Cheap airtight plastic food containers filled with water also work well as you can stack them on top of each other.
This will keep your fridge and freezer at an even temperature and it will need less energy to run.
You should also distribute contents evenly for maximum cooling efficiency. Keeping your fridge well organised will also reduce the amount of time you have the door open.
Overfilling your fridge increases energy demand as it inhibits air circulation. Likewise, underfilling a fridge can also increase the energy demand because more cool air is lost when the door opens.