Officials want to phase out millions of inefficient light bulbs and replace them with fluorescent ones that are up to 70 per cent more energy-efficient and last longer.
But the government has no plan to offer subsidies to help people switch to the greener lights.
In 2009, Chief Executive Donald Tsang Yam-kuen proposed in his policy address handing out HK$100 cash coupons for the public to buy energy-saving bulbs. But the scheme was scrapped when it emerged that one of his in-laws was a major light bulb supplier.
The proposal, now under public consultation for three months, would outlaw the sale and supply of incandescent light bulbs of 25 watts or above if they fail a minimum energy efficiency standard.
Some light bulbs, such as the tungsten halogen lamps widely used for commercial display, will be exempted temporarily as they are deemed relatively more efficient and as yet have no effective substitute - a concession that led an environmental activist to label the proposal half-hearted.
Officials have yet to offer a timetable for the ban, though they have already pledged to provide a 12-month grace period for suppliers to clear existing stocks. Apart from that, bringing in restricted light bulbs from across the border for personal use would still be permitted.
If a law is endorsed, Hong Kong will fall into line with many Western nations in regulating energy-inefficient light bulbs, and will possibly be ahead of the mainland, which has put more focus on restricting the production of such bulbs than on their sale.
Greenpeace campaigner Aloria Chang Wan-ki was unhappy at the exclusion of the tungsten halogen lamps. 'It is just a half-hearted proposal,' Chang said.
The incandescent bulbs are estimated to use 900 million kilowatt hours of electricity a year, or 2 per cent of the power consumed in Hong Kong. In 2008, about 6.8 million were in use, according to a projection by a government consultant. There were 4.2 million tungsten halogen lamps.
The government says that if all the incandescent bulbs were replaced by compact fluorescent lamps, up to HK$390 million in energy bills and 273,000 tonnes of carbon dioxide emissions could be cut a year. The greener bulbs cost HK$20 to HK$30, while less efficient ones are about HK$8. Light-emitting diode bulbs can cost more than HK$100 each.
Acting director of electrical and mechanical services Chan Fan said that while there should be sufficient financial incentives for the switch, a mandatory approach was better than voluntary action or relying on market forces.
'A ban can speed up the replacement, which might take 10 years under market forces or a voluntary approach,' he said.
Asked if lower-income groups might be hit by the sales ban and if subsidies should be provided for switching to energy-saving bulbs, Katherine Choi Man-yee, principal assistant secretary for the environment, said some charity groups had been funded by the Environment and Conservation Fund to distribute free energy-saving light bulbs.
The amount, in HK dollars, that could be saved annually by a family of four replacing up to eight light bulbs with energy-saving ones