Under new rules coming into force in September, manufacturers and importers can no longer sell clear incandescent light bulbs of 100 watts or above in the EU. However, shops may continue to sell bulbs already in stock.

Part of an effort to save energy and fight climate change, the ban will be expanded in September 2011 and 2012 to include lower wattages of clear incandescent bulbs. Frosted bulbs and high-energy halogen lights are also being phased out.

By 2020 the measures will save enough energy to power 23 million households every year, roughly the electricity consumption of Belgium. This will reduce emissions of carbon dioxide by 32 million tons each year, or about one-tenth of the world’s annual emissions of the greenhouse gas.

Introduced 130 years ago, conventional incandescent light bulbs convert only around 5% of the energy they use into light; the rest is given off as heat. They are far more wasteful than newer devices like compact fluorescents and low-energy halogens or emerging products such as light-emitting diodes.

The most efficient lights currently on the European market, fluorescent bulbs use 65-80% less energy than incandescent bulbs. But many consumers have been reluctant to switch to them because of concerns about their cost, health impact and aesthetic quality.

Fluorescent bulbs cost more initially but are cheaper in the end because, besides using less energy, they last much longer. The EU estimates that a household can save at least €50 on electricity bills every year by switching to energy-saving bulbs.

Energy commissioner Andris Piebalgs believes consumers will eventually be won over. “Great ideas are sometimes slow to catch on,” he writes in a recent blog post. He predicts the ban will spur more improvements in lighting.

To help with the transition, the commission explains the changes in 22 languages on its website.

The regulation covers only non-directional light (light emitted equally in all directions). Similar legislation targeting directional lamps like spotlights is expected to be adopted in 2010.