Earth Hour 2013: Does it really save energy?

Earth Hour 2013 commences Saturday at 8:30 p.m., regardless of where in the world you live. For the duration of an hour, Earth Hour participants will shut off their lights in a global action against climate change. 

The six-year-old tradition is largely symbolic. It's intent is to spur on environmental awareness that lasts well beyond the hour of candlelit reflection, organizers say. Still, some view it as counterproductive because it accomplishes little in the way of reducing carbon emissions. 

Earth Hour's "vain symbolism reveals exactly what is wrong with today’s feel-good environmentalism," writes Bjørn Lomborg in an opinion piece in Slate. "[T]he cozy candles that many participants will light, which seem so natural and environmentally friendly, are still fossil fuels – and almost 100 times less efficient than incandescent light bulbs." 

In 2009, the Monitor posed the candle versus light bulb debate to Zeke Hausfather, then an executive with an online carbon measurement and reduction utility. On Friday, we got back in touch with Mr. Hausfather, now with the Berkeley Earth Surface Temperature Project, for an update. Here's what he told us via e-mail:

Mr. "Lomborg is taking a grain of truth and stretching it much further than warranted. While he is roughly correct in stating that a candle is much less efficient in creating light than an incandescent bulb, and lighting enough candles to provide the same lumen output as a single 100 watt bulb would produce much more carbon, that's not really the question at hand. Indeed, if everyone lit enough candles during [E]arth [H]our to replace the light coming from their bulbs, it would rather defeat the purpose, as none of the buildings would be dark! A comparison that more accurately reflects the behavior of folks would be lighting 1 candle for each bulb turned off." 

A lighted paraffin candle releases an average 10 grams or so of carbon dioxide in an hour, Hausfather calculates. If an incandescent bulb is turned off during that time, the reduction in CO2 ranges from 14.5 grams to 89.3 grams, depending on whether the light bulb is 60-watt or 100-watt and whether it's located in low-emission California or high-emission Kansas.

Replace incandescents with their equivalent (and much more efficient) compact fluorescent light bulbs (CFLs) and things start to get interesting. If they're located in Kansas, the candles still win. If the CFLs are aglow in California, the CFLs win: 5.3 grams CO2-equivalent for a 13-watt CFL; 9.4 grams CO2-equivalent for a 23-watt CFL. 

Other Earth Hour skeptics have raised concerns that the shutting off of lights en masse does not mean the power plants behind them slow down. Those fossil-fuel-burning plants remain in “spinning reserve” mode, anticipating the return of electricity demand.

"Electrical engineers also know that when an appliance is first turned on, there is a higher current needed at the start as opposed to what is needed when the appliance is already operating," Forbes notes. "In effect, the end of Earth Hour is actually more detrimental to climate mitigation because simultaneously turning on so much equipment all at once creates a surge current that results in a sudden spike in power demand."

The events organizers counter that not all participants turn their lights off when the hour is technically over.

Hausfather reaches a nuanced conclusion: "Given the low penetration rates of CFLs in most parts of the country, its uncontrovertibly [true] that Earth Hour will result in a net reduction of carbon, especially as many places turning off light (e.g. commercial buildings) will not be replacing them with anything during the hour," he writes. "However, it's useful to note that 'green' alternatives like candles are not completely carbon-free."

Earth Hour organizers encourage the use of 100 percent beeswax or soy candles. They aren't made with petroleum so they are effectively carbon-neutral, the organizers say, because the CO2 they emit has already been taken from the atmosphere to produce the wax.

Ultimately, nitpicking over how much energy, if any, the event actually saves may be missing the broader point. Earth Hour is about awareness, the organizers stress, and mobilizing people to participate in other year-round programs the organization offers.

"Earth Hour does not purport to be an energy/carbon reduction exercise, it is a symbolic action," the event's website reads. "Therefore, we do not engage in the measurement of energy/carbon reduction levels."