[Karsten (OP)]

My guess is that the energy consumption is the same for an empty or for a completely filled fridge as long as you keep the doors closed. However, a very full refrigerator should perform better (=less energy consumption) when you occasionally open the doors (as one would to check if everything is still there). Right?

[lyner]

The only significant difference that I could think of would be that a full fridge would have less air convection inside it- effectively insulating the cooling panel from the outside - requiring less energy to maintain its temperature.
One smaller effect could be that a lot of thermal mass (food) inside would slow down temperature variations inside. That could have the effect of reducing the number of times the compressor switches on because it might not be affected by a brief period of warmth in the kitchen (although it would run for longer each time). This could reduce the overall energy consumption because the refrigeration process takes time to 'get going' each time it starts.

[LeeE]

If you're opening the fridge with any regularity, it's better kept full.  With an empty fridge, every time you open and close the door you cycle most of the air in it, replacing the cooled air with warmer air, which has then to be cooled again.  With a full fridge, there's not only less air to be cycled and re-cooled, all the other items that have been cooled stay in the fridge.  The presence of many items in the fridge may also reduce the airflow, as sophiecentaur says, meaning even less air is exchanged each time the door is opened and then closed.

[Karsten (OP)]

Thanks. I figured it would be better to have a full fridge when opening the doors. Makes sense since all the cold air just falls out. There are no commercial designs for a chest fridge, although there is one you can buy parts for rebuilding your chest freezer in Australia. My concern was regarding a fridge that has (currently) the doors most of the time closed.

I think my question was answered. I will fill it to the brim, even if it is just bottles of water. Especially since I will open it sooner of later more often.

Thanks!

[lyner]

Natch, a chest freezer / box would be better in that the cold air wouldn't all dribble out of the bottom like with a 'front loader'.