In November 2015, I judged that it was time to change from the CFLs to LEDs, so bought them in batches to confirm the light output (in lumens) and the beam angle (in degrees) were both acceptable. In the event, I found that eight of the 13 CFLs could be replaced with LEDs of lower nominal light output because they came on at full brightness. The other five CFLs were replaced with LEDs of equal or lesser output because they proved sufficient. Thus the power saving for all 13 lamps was 56%. As the change from incandescent to CFL lamps had saved about 80%, the change to LEDs increased the saving to about 90%.
'Light emitting diode (LED) lighting technology has taken the world by storm in recent years, but nowhere like in Japan. LEDs have, in fact, become so pervasive that the country may soon face a saturation point. High reliability, low power consumption, long life, low pollution, and falling production costs have enabled LED use to spread rapidly. By 2015, global market penetration was expected to reach 31%, according to industry news source LED Inside.(See: 'Japan First to Hit LED Saturation Point?', 2016-04-14).
In Japan, where LED industry policies began with the "21st Century Lighting Project" in 1998, the buildout has been even more dramatic, with penetration soon hitting 50%. That figure is seen at 70% by 2020; the government targets near 100% adoption by 2030. "The 2011 Tohoku earthquake and tsunami (in Japan's northeast) provided a big emotional kick to national energy policy, after the government asked the general population to cut household energy consumption by double-digits when all the nuclear plants were switched off," says Eiji Fujiwara, senior sales executive at industrial LED-maker DNL Lighting. Faced with rolling brownouts in Tokyo and other big cities, this goal was accomplished almost overnight, he notes, as people rushed to replace fluorescent bulbs with LEDs. LEDs typically last four to five times longer than fluorescents (40-50 times longer than incandescents) and consume 40% to 80% less electricity, respectively'.
'Improvements in luminosity and efficiency are constant. Recently, over 300 lm/W (lumens per watt) were measured for the most advanced white LEDs, compared with just 16 lm/W for traditional light bulbs and 70 lm/W for fluorescent lamps. Average LED lifespans approaching 100,000 hours are also within reach'.
Before Fukushima, nuclear power plants had been producing 30% of Japan's electricity. Five years later, having cut electricity consumption by such measures as LEDs, almost all are still shut down.
My table shows the declared luminous efficacy of my LED bulbs ranges from 85 to 118 lm/W. So with the most advanced LED lamps already at 300 lm/W, best practice should be capable of about 200 lm/W - offering a further saving of 50%.
'At the peak at about 5.30 on a December evening lighting uses about 15 gigawatts out of total UK demand of approximately 52 gigawatts. This is an almost unbelievable 29% of our need for electricity, met at the precise moment that future blackouts are most likely. Although LEDs are growing in importance, the number installed is still a small fraction of the total stock of lightbulbs. If all lights across the country were switched to LEDs my calculations suggest that the need for electricity to provide improved lighting would fall by about 8 gigawatts, a saving of about 15% of all power consumption'.(See: 'Shaving the peak in electricity demand: the urgent need for an LED installation programme.', 2016-05-27).
So compared with the lighting load of 15 GW, the saving of 8 GW would be over 50%. As such a changeover could be effected in say five years, this should be the first choice for 'keeping the lights on'.