one of the biggest issues for built in refrigeration appliances is heat! usually caused by poor, or no ventilation. manufacturers give conflicting installation instructions for ventilation.
for full height appliances a 200cm² slot in the plinth and top of the built in housing along with a hole beneath the appliance will provide adequate ventilation for any built in refrigeration appliance.
for under counter items, fridge or freezer a slot in the plinth will suffice.
in the absence of manufacturer’s instructions the information provided can be used as a guideline for ventilation.