LED light bulbs are cheap and energy efficient, writes Chris Goodall. A crash programme to replace all the lights in the UK with LEDs would cut electricity bills, reduce carbon emissions and other pollution from coal and diesel generation, and reduce the risk of blackouts. At the peak at about 5.30 on a December evening lighting uses about 15GW (gigawatts / billion watts) out of total UK demand of approximately 52GW. This is an almost unbelievable 29% of our need for electricity, met at the precise moment that future blackouts are most likely. And there’s a simple way to cut that peak electricity demand – making our lighting more efficient by a mass switch to high efficiency LED lightbulbs. If all lights across the country were switched to LEDs my calculations (carried out under a project for Greenpeace UK) suggest that the need for electricity to provide improved lighting would fall by about 8GW, a saving of about 15% of all power consumption. As part of my work for Greenpeace, I located 100 case histories of switches from other types of lights to LEDs in industry, commerce and public sector. On average, replacing less efficient bulbs saved two thirds of the electricity bill. These studies were usually written up by companies with an interest in selling more LED bulbs, but show a very consistent pattern across factories, shops, schools, sports clubs and offices. In most places, lighting quality was improved substantially. In some locations electricity costs were reduced because LEDs produce less waste heat and therefore cut the need for air conditioning in places such as hotels and large office buildings. Even a much more restricted national campaign that just focused on domestic houses would have a dramatic impact. If we switched the lights in the parts of the house that are in use in early evening – essentially the kitchen and living areas – we would reduce home demand by more than 50%. Importantly, these rooms are the places where we now often use halogen downlighter bulbs, the most inefficient lights currently on the market. A standard halogen GU10 bulb uses 50W of power. The LED equivalent does the same job with just 5W.