The Electricity Commission says more than two-thirds of 850 people surveyed were not able to tell the difference between eco-friendly bulbs and traditional lightbulbs.

Shoppers in Auckland and Christchurch took part in the experiment in which they were shown two identical booths lit by the two types of lightbulbs.

Despite most of the shoppers being confident they could pick the eco-bulb before the experiment, 68 per cent either incorrectly identified which room was lit by the efficient bulb or said they could not spot any difference.