Fridges and fridge freezers are evaluated on the amount of energy they use per hour. The lower its kWh consumption, the more efficient it is — and the better its rating.
The old rating system saw the market awash with A rated appliances. Around 10 years ago, more than half of the products on the market were labelled A++ and A+++. Now, with the simplified scale, many of those appliances now fall down the grading system as far as F. This doesn’t mean their energy efficiency is bad; just that the difference between them is so small.
If you’re in the market for a new fridge or fridge freezer, you should try and get one rated D or above.