The public is being given a say on whether to bring in variable electricity tariffs as a means to reduce carbon emissions. The Council for Sustainable Development, a governmentappointed think tank, has launched a four-month public consultation on how to reduce carbon emissions from buildings. Options to be discussed include changing the tariffs, tightening laws governing energy consumption - such as for air conditioning, ventilation and lighting - phasing out energy-inefficient electric appliances and making companies perform carbon audits. Green groups hailed the council's initiative and said tweaking electricity tariffs would not only encourage people to use less electricity but also reduce power bills for many ordinary households. The government currently pays an electricity bill subsidy of up to HK$150 a month, which green groups say encourages waste. Power generation accounts for 60 per cent of the city's carbon dioxide emissions. Variable power tariffs have been successful in reducing consumption overseas. 'A progressive tariff is in place in Taiwan and the United States. The tariff increases if consumption exceeds a set limit,' council chairman Bernard Chan said. Queensland in Australia has a range of charges to reduce power use during peak hours. In some places the tariff in summer, when people use air conditioning a lot, is higher than during winter. Chan said such schemes were workable in Hong Kong, but it would take a lot of time for the two electric companies to make the necessary arrangements. In Hong Kong, progressive electricity tariffs already apply to ordinary households, meaning heavy users pay more. But under a bulk purchase scheme, the opposite applies to heavy commercial users. Greenpeace said a progressive tariff overall would mean most households in the city paid less. 'Currently, ordinary households are in fact paying more than commercial users for each unit of electricity they consume. With the reform, ordinary households using less electricity could pay less while commercial users would need to pay more,' said Koo Wai-muk, a campaigner for Greenpeace. Hahn Chu Hon-keung, Friends of the Earth's environmental affairs manager, welcomed the council's proposals. 'Hong Kong wastes lots of resources in many ways. Energy saving is surely one of the targets that we should look at,' he said. While a progressive electricity tariff would encourage people to use less energy, Chu said more inducements could be offered. 'In the United States, power supply companies will offer rebates or other advantages to customers using energy-efficient appliances,' he said. A CLP Power spokeswoman said: 'We have already implemented a progressive tariff structure to over two million residential customers which amounts to about 86 per cent of our total customers.' 90% The percentage of Hong Kong's electricity consumed in buildings. They are the source of 60 per cent of the city's greenhouse gases.