Electrical appliances such as ovens, dishwashers, dryers and fridges all have to carry an EU Energy Label which indicates how efficient (or inefficient) they are.
Appliances are graded from A to G on their efficiency, with A being the most efficient and G being the least. Fridge freezers have three extra ratings at the top end, A+, A++ and A+++.
The grade is based on how many units of energy they use per hour (their kWh consumption). The lower their kWh consumption is, the more efficient the appliance is.
A sticker on each appliance shows a series of colour co-ordinated bars from A+++ to G.
As you have to leave your fridge and freezer on around the clock, it makes sense to make sure they are as efficient as possible.
Ratings for appliances that keep things cold work a little differently to other white goods, however, as they are rated on how energy efficient they are in relation to their size, rather than their kWh consumption.
Generally speaking, this means the bigger the fridge or freezer's internal volume, the more it will cost to run.