Many shoppers find it difficult to determine between different energy efficiency ratings when buying a new appliance, according to an expert.
James Dulley, writing for Tri Valley Central, said that ratings differ depending on the fuel used and the type of product.
He warns that initially consumers should be wary over salespeople playing "loose and fast with the accuracy".
Energy ratings are worked out based on the amount of energy produced and the amount put into the machine, reports the website.
To work out this output should be divided by input, with the output being the usable product, like light, heat or sound.
Some items like electric heaters are 100 per cent efficient, with all the energy produced being used to heat the home.
However, other appliances are not as simple, with consumers having to rely on the yellow energy label provided to make their comparisons.
Mr Dulley's final warning is that the way an appliance is used has a large bearing on its efficiency.
It has also been reported that where an appliance is placed in the home affects it's efficiency.
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