The earth at night as viewed from a space, in a composite image from NASA.

The world is not as dark as it used to be. Streetlights, parking lot security lights, office building lights, and neon signs shine all through the night. Light pollution can come directly from light bulbs, or it can bounce off of dust and water droplets in the air, creating a bright haze called skyglow. This 24-7 illumination can be seen from space, and it has negative effects on humans and wildlife. But there are ways to dim the lights and reduce their effects—and save energy in the process.

Astronomers have long aware of the problems associated with nighttime illumination—it makes stars disappear. Big telescopes are built away from big cities for this reason, although bright lights have a way of encroaching. QUEST blogger Ben Burress talks about light pollution and astronomy here and here.

Non-astronomers are affected by nighttime lighting, too; exposure to light at night affects our circadian rhythm, the 24-hour cycle deep inside our bodies. Seeing light at night can cause sleep disorders. And long-term exposure to light at night has been linked to breast cancer, because light inhibits the production of melatonin, which slows the growth of cancer cells.

Exposure to light affects animals, too. Anyone who has sat next to a porch light on a summer evening knows that moths are drawn to light—along with a multitude of other insects. Outdoor lights disturb insects’ nighttime navigation, and affect their feeding and mating. Lizards are often found feeding on the tasty insect snacks that gather around lights. Often, these lizards are not normally nocturnal—staying up at night gives them access to a “night-light niche” and an abundant food source. It also creates the opportunity for interactions between animals that would never meet in the dark conditions of previous centuries. Some lizards get a double benefit, basking in the warmth given off by artificial lights (incandescent lights are really inefficient; most of the energy they use goes to producing heat, not light).

Night lights make birds sing at odd hours, and mess with their mating and migration schedules. During migration, birds are drawn to the light from tall buildings and towers, resulting in deadly collisions.

Sea turtles are perhaps the most famous example of animals affected by light. Hatchlings swim towards the light—historically the horizon above the ocean. But now that beaches are backed by well-lit condos and hotels, baby turtles crawl further onshore instead of out to sea. There is evidence that sea turtles are drawn to light with short wavelengths, and using bulbs with longer wavelengths or using filters that cut out short light wavelengths reduces the number of baby turtles crawling in the wrong direction.

Simple fixes, like different bulbs or shades that focus light on the ground, can do a lot to re-darken the night sky, as does turning off unnecessary lighting. Dimmer, more efficient bulbs that provide enough light for human needs—but not too much—are a step in the right direction, and can save on energy costs. Dark sky conservation and stricter lighting ordinances will help.

I was surprised by the negative health effects of exposure to nighttime lighting—something to keep in mind as I work late into the night, basking like a lizard in the glow of my computer screen.

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Which is worse for you, a can of tuna or a broken CFL bulb? Sorry, Charlie… image by Dave Lifson

The researchers point out that there is a distinction between the kind of mercury that you are exposed to from broken CFLs—elemental mercury—and the mercury emitted from power plant smokestacks after it finds it’s way into waterways and oceans, where it becomes methyl mercury. Methyl mercury accumulates all up the food chain, so that large fish like tuna can contain a lot of it. Methyl mercury crosses the blood-brain barrier and passes through a pregnant woman’s placenta to her fetus. Methyl mercury is responsible for developmental problems, while elemental mercury, which is inhaled, appears to be more of a hazard for adults and children, and only then in the case of severe or prolonged exposures. In most mild cases, when the elemental mercury exposure ends, the bad effects diminish and go away. This is unfortunately not true for the developmental problems caused by methyl mercury.

The startling conclusion of the paper is that in a worse case scenario—you break a CFL in a closed, unventilated room; you vacuum the carpet, throwing mercury into the air; you set the vacuum in a corner; and then sit in the room breathing for eight hours—the amount of mercury exposure is about equivalent to the exposure you’d get from eating a can of Albacore tuna.

Eating a can of tuna has positive health effects as well as the negative health effects from the mercury. There are no positive health effects from a broken CFL, and you can reduce your exposure. The researchers suggest that in the case of a broken CFL, you should immediately open a nearby window. You can limit contamination by gathering up the large pieces of the broken bulb into a bag and set the bag outside. The room should then be left to air out for an hour or so. If the lamp broke on a carpet you can vacuum, but it should be done quickly while the room is being ventilated, the vacuum cleaner should be removed to an outside area, and again the room should be left vacated for an hour or so. Once the vacuum cleaner has cooled, you can empty the contents of the vacuum cleaner bag into the bag with the broken bulb. Take the bag to your nearest recycling center.

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I have nothing against solar panels, but they do seem to illustrate our collective love of gadgetry. Why else would we leap (or at least dream of leaping) to spend $5,000-$10,000 on solar panels when many of us could make a significant dent in our utility bills with a trip to Home Depot? Small things, like weather-stripping your doors, or making sure you have a well-insulated attic, can make a big difference in how much heat or AC your house consumes.

If you qualify as low-income (in this case, that's less than $44,000 for a family of four) you can get help with this project. If you live in California, you'll find your local participating agency here (or by calling 1-866-675-6623). Elsewhere, begin by contacting your state agency, found here. The Weatherization Assistance Program has received a 10-fold budget increase under the American Recovery and Reinvestment Act, so now's a great time to apply.

WAP won't replace your TV, but you might consider doing so yourself. Televisions tend to be the third biggest electricity user in the house (after heating/AC and refrigerators). But they don't have to be. All the new features — plasma screens, HD, widescreen — can be (and are, in some models) achieved using less electricity. The California Energy Commission is proposing new TV standards that would cut electricity use by a third.

James Sweeney, who heads the Stanford University Precourt Energy Efficiency Center, calculates that collectively – with current, affordable technologies, and without sacrificing our quality of life – Americans could cut our energy use by 30 percent.

Here's the kicker: To produce that same amount of electricity, we'd have to increase solar and wind by 60-fold. That means, for every solar panel and wind turbine in the country, we'd have to build 59 new ones, plus all the power lines and roads they'd entail. Or, to consider another non-fossil fuels alternative, that's four new nuclear power plants for every existing one.

Listen to the Let's Weatherize! radio report online, and watch our Weatherization Slideshow.

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When you replace incandescents with CFLs, you use less electricity for lighting, but you use more energy for heating your home in the winter, since hot burning incandescents–which produce a lot more heat than light–decrease the heating load. This is called the take-back effect. Anil Parekh, who does research for Natural Resources Canada, and his colleagues, studied the take-back effect. They wanted to know if CFLs really saved energy in a home over the course of a year.

The Canada study, which took place at the Canadian Center for Housing Technology (CCHT)–two identical homes that allow researchers to compare different technologies–showed that even in heating dominated climates, such as in Fairbanks, Alaska, you save energy overall by swapping out incandescents with CFLs. And in cooling climates, such as in Los Angeles, you save on lighting electricity and there is an added bonus (as if Southern Californians deserved it) you use less to cool your home in the summer, since cool CFLs, which put out 90% less heat than incandescents, are not adding to your cooling load.

Some readers may have noted that I declared my allegiance to light-emitting diodes (LEDs), in a recent blog, since they are potentially much more energy efficient than CFLs. But we'll have to live with CFLs until LEDs become more cost effective… kind of like driving my pretty-fuel-efficient 1997 Geo Prizm into the ground before investing in a newer, hybrid car, or until I quit driving. It takes a lot of energy to make a hybrid car.

Sometimes the most efficient car, or appliance, or light bulb, is the one that's already been made.

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Philips Lighting was the first manufacturer to commercialize CFL bulbs in the 1970s, and has long been an innovator, as well as being the largest manufacturer of lighting products in the world. "We aren't even near the limits to this technology," said Dowling. Technically, solid-state lighting, or LED lighting, is ready to be the next big thing after CFLs. The challenge that remains is making LED lighting affordable and ubiquitous. That is a challenge when you consider that today's incandescents work in 1880s-style fixtures. Dowling proved it in a backroom of the Smithsonian in Washington D.C. And in the progressive Pacific Northwest, after 15 years on the market, CFLs have achieved only 8% market penetration.

But LEDs are an easy sell. Compared to incandescent lights, which produce 10–12 lumens per watt (lpw), and fluorescents, which produce 90-100 lpw, the best LEDs produce approximately 100 lpw, have the potential to reach the 150–200 lpw level, can last 35 years and don't release any mercury into the environment. History has shown that the cost of LED technology has decreased, while performance has increased– both exponentially. Dowling expects LED lighting performance to continue increasing 35% per year while the price decreases about 20% per year, and that in 24-36 months LED lighting will reach the level of linear fluorescent lights in light output per watt of energy use.

LEDs have evolved from mostly lighting that attracts attention to lighting that illuminates. LEDs can produce a range of color temperatures, from cool to warm. It has been installed in the Old North Church in Boston to rave reviews from the curators of the historic church. Legislation is supporting the evolution of the lighting technology. Legislation and guidelines will raise lighting efficacy to at least 45 lpw by 2020, according to Dowling, making LEDs an easy choice.

Goodbye CFLs, it was good while it lasted.

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