A scheme by one home appliance retailer to encourage people to switch to energy-efficient models should be backed up at a national level, one expert has suggested. Comet is offering individuals with white goods a chance to trade in their current items and receive a 20 per cent discount on a range of 340 other accessories, something which may benefit those who use a dishwasher instead of a kitchen sink. Green Party member of the London Assembly Darren Johnson said the initiative could work in principle, but that the government must provide support with appropriate legislation. According to Mr Johnson, it is important that there is more flexibility in regards to VAT levels as this is where the more energy-efficient appliances are low-rated or zero-rated and the more gas -cooking appliances attract a much higher level of tax.Comets promotion began on September 10th across 250 stores and will end today (September 14th), although it may be extended.