A star rating system proposed by energy regulator Ofgem will help customers wanting to reduce their carbon footprint compare the environmental credentials of the bewildering diversity of green electricity products on offer. Under its proposals, green power offered to businesses and domestic customers will be awarded one to five stars depending on how much carbon each saves; any additional environmental benefits will also be taken into account. The guidelines could also apply to low carbon technologies such as combined heat and power. Eleven companies in the UK currently offer green products, ranging from some which supply 100% renewable electricity to others where the retailers take action to offset the carbon emissions from the energy sources used. Studies by EnergyWatch and the National Consumers Council reveal confusion and mistrust among consumers over the benefits claimed by green power retailers. A key concern is to ensure that customers opting for a green supply are actually funding additional supplies and not merely paying for the amount of renewables that retailers need to buy to fulfil their legal Renewables Obligations. In its consultation document, Ofgem says that to merit more than one star, retailers should consider retiring renewables obligation certificates, making additional investments in renewables or carbon offsetting.