Ikea, the Swedish retailing behemoth, is installing “Solar Shops” in its U.K. superstores to sell solar panels. It’s a defiant move given that the British government has slashed subsidies for homeowners who sell surplus electricity to the national grid. This suggests that the market is picking up where government aid left off; perhaps Britain will achieve its target of generating 15 percent of its energy from renewable sources by 2020 after all.

Harnessing the sun to meet our energy needs, from portable chargers reviving our mobile phones to sun farms spreading across acres of desert, remains key for reducing carbon emissions. But there’s a much simpler way to help save the planet, in the form of the humble light bulb.

Science is transforming our ability to light buildings and streets more efficiently. An old-style fluorescent light tube, for example, consumes about 58 watts of power. A year ago, LED bulbs typically needed between 25 and 27 watts. Today, that’s down to 22 watts, and will continue to decline. “The technology improves every year,” says Toby Costin, the founder of a London-based company called Social Power Partnerships.

Costin has put together a deal for a London charity called Doddington and Rollo Community Association, which provides business units and community spaces in North Battersea, to replace its existing light bulbs with energy-saving LED devices. The total cost of switching out almost 600 bulbs is about £6,000 ($8,760), with replacing blown bulbs in the coming decade expected to cost about £1,000 per year. But the charity will save some £6,500 on its electricity bills per annum, freeing up much-needed cash for its community activities.

Social Power Partnerships is also working with U.K. housing associations, some of which control hundreds of households, to introduce similar “everyone wins” programs, with tenants paying an upfront fee to their landlord to cover the initial cost of bulb replacement in return for longer-term savings on their fuel bills.

Compact fluorescent lamps — the ones with a thick twirl of glass — started to challenge the dominance of inefficient incandescent bulbs about 10 years ago. Halogen bulbs briefly took the lead at the start of this decade, before light-emitting diodes claimed the top slot.

Switching out light bulbs may become more popular, given recent cutbacks in U.K. government subsidies to solar, which have reduced the amount households can make selling surplus electricity to power companies by about two-thirds.

“Solar is kind of dead as a retail model,” says Costin. As a result, installations of small-scale solar power harvesters have collapsed.

Partly because of the subsidies, U.K. households had been almost three times as enthusiastic as companies in using photovoltaic panels on their roofs to generate power.

But if solar panels were installed on just half of the U.K.’s south-facing commercial roofs, the sun could provide 19 percent of the country’s electricity needs, according to BNEF analysts Lara Hayim and Jenny Chase. That would ensure the country met its renewables target by the end of the decade.

There’s no question that climate change is real, and that we humans are contributing to global warming even if long-term weather trends also play their part. Some experts are already predicting that 2016 will be the warmest year on record; the 21st century has seen 15 of the 16 record temperature years. Some 93 percent of the Great Barrier Reef corals in Australia are now suffering ecosystem-destroying bleaching because of warmer oceans and the El Nino weather system.

IKEA’s Solar Shops and Costin’s light bulb programs are two ways that the market, not government, is helping to address climate change. That is the best hope yet that the global agreements reached in December in Paris will not be just paper targets. Many hands, as they say, make light work.

Mark Gilbert is a Bloomberg View columnist.

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