When it comes to lighting, though, we’re stuck in the past. The incandescent light bulb that you probably have in your bedside lamp is based on the same technology invented by Thomas Edison more than a century ago. Electricity flows into a metal filament, and the filament heats up and emits light as a byproduct.

Now, the same technology that forms the basis for our computers is set to revolutionize electric lighting as well. It’s known as solid-state lighting, and it has the potential to transform the way we use light.

Light from Computers

Computer chips are made up of what are known as semiconductors. These are solid materials (such as silicon) that can carry an electrical current but, unlike regular conductors like copper wire, can also be easily turned off so that electricity will not flow through it.

LEDs and their organic cousins, OLEDs, will one day make our homes and offices much brighter, while using less energy.

RPI Lighting Res. Center

Solid-state lighting includes two similar technologies: light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). A diode is a simple form of a semiconductor, so both LEDs and OLEDs are like tiny computer chip parts that give off light.

Both technologies are composed of layers: one is negatively charged, and one is positively charged. When electric current flows through the diode, it excites negatively charged particles, or electrons, in one layer and causes them to fall into holes in the other layer. The energy released in that fall is emitted as light. The color of the LED depends on the material used in the layers and the distance the electrons fall.

Why LEDs?

We don’t think about it much when we flick on the lights, but keeping our houses lit uses up roughly 10 percent of all the electricity we use in homes. Add the lighting needs of businesses and the percentage is even higher. Incandescent light-bulbs are horribly inefficient: only about 5 percent of the energy goes into creating light. The rest is wasted as heat. Fluorescent bulbs are more efficient and last longer, but the toxic mercury in the bulbs means they have to be thrown out in special collections.

Depending on the color, LEDs are 20 to 50 percent efficient, so they save a tremendous amount of energy. The rest of the energy becomes heat, but they’re not hot to touch like incandescent bulbs. Researchers at Sandia National Lab estimate that within a little more than a decade, LEDs could cut the energy used for lighting in half!

LEDs also produce more than 70,000 hours of light — they last a long, long time. And they’re encased in plastic, not glass, so they’re nearly impossible to break.

These digital lights have already replaced traditional bulbs in traffic lights and in displays on clocks and cell phones. They’re used to colorfully light up bridges at night, and for larger-than-life videos, such as the enormous sign that hangs on the corner of a building in New York’s Times Square.

White LEDs are still too expensive to replace all our home and office lighting. But they make great camping flashlights, because they’re bright, tiny, energy-efficient, long-lasting, unbreakable, and can be powered by rechargeable batteries.

Many poor people around the world have no electricity in their homes, so they rely on expensive and polluting kerosene lamps. The same characteristics that make LEDs perfect for camping lights also make them ideal an ideal way to provide light for families who have never owned a bulb.

Groups such as the Light up the World Foundation have designed LEDs, powered by renewable energy, for people who lack electricity. Suddenly, children can study at night, and parents can keep working into the evening. LEDs have already improved the lives of thousands of people around the world!

The firm Kennedy and Violich Architecture created a fabric woven with tiny LEDS for a community in Mexico. It can be worn as a bag during the day, and turns into a lamp at night. (Read more about how it works here.)

New Ideas in Lighting

Imagine a room where you could push a button and change the color of the light. LEDs come in red, green and blue. Each one can be the size of a dot, and when those dots are combined, they can be lit up in different combinations to create an endless variety of colors. Companies have created LEDs that flow from one color to another, all through the rainbow.

“With the touch of a button you can create pretty much any color scheme,” explains Nadarajah Narendran, research director at the Lighting Research Center of Rensselaer Polytechnic Institute. “You could change the color in your room to suit your mood.”

Designers are developing new ways to use LEDs in a building. Light glows from a tile on the floor, or a panel on the wall. (This is hard to do with the breakable glass bulbs used today.) These tiles have already been built, but they don’t fit the standard systems in houses today, where bulbs get screwed into sockets. Narendran says that houses would have to be designed differently to create the right wiring for these blocks of light. He has some lighting up his lab!

But the uses of LEDs don’t end with indoor and outdoor light. Babak Parviz, a scientist at the University of Washington, is designing special lenses that use dust-sized particles of LEDs to display information. Parviz wants to create futuristic contact lenses that could sense changes in your body, such as from a disease, and notify you on the corner of the lens. These don’t exist yet, but someday you might be able to read information broadcast by LEDs literally right in front of your eyes.

LEDs, the Next Generation

LEDs are manufactured in the same manner as computer chips. The materials are deposited in very thin layers under extremely hot temperatures, as high as almost 1,000 degrees Fahrenheit. That costs a great deal of money. They’re also based on the material silicon, the same material that forms the basis for computer semiconductors.

OLEDs function similarly to LEDs, however, they can be manufactured much more easily; use even less power, and can be made extremely thin to be used on paper or even fabric.

Yogurt6255520 / Wikimedia Commons

Organic LEDs (OLEDs), on the other hand, have a carbon base instead of a silicon base. (Carbon forms the building-blocks of life on earth, which is why these are called “organic.”)They work in somewhat the same way as LEDs do: a current flows into the material, one layer gives off electrons, and those electrons fall into another layer. Then there’s a layer that transmits that energy into light we can see. The color of the light depends on the material in that final layer, and most OLEDs have different layers that emit different colors.

Unlike those super high LED manufacturing temperatures, OLEDs can be created at room temperature, which is significantly cheaper. Layers are deposited on a surface, as ink is layered on paper. OLEDs are also extremely thin and can be potentially printed on any substance, even paper or fabric.

“This flexibility is what makes people dream about all the different ways to use OLED technology,” says Bernard Kippelen, an OLED researcher at the Georgia Institute of Technology in Atlanta.

With OLEDs, Narendran imagines entire wall-sized sheets. He says, “You could hang one up and change lighting designs easily, like a shifting wallpaper of light design.” Because OLEDs are transparent when they’re off, a window covered by an OLED could glow brightly when night comes. Or a shimmering picture could be printed directly on a T-shirt.

OLEDs are used today in cell phone screens, but most of those other ideas are still in the design phase. Recently, though, Sony showed off the world’s very first OLED television. It’s only 11 inches large, and it costs about $2,500. It’s incredibly thin, only 3 millimeters at its widest spot — thinner than your finger from front to back — and uses about 40 percent less energy than other thin-screen televisions. The colors and picture are said to be some of the best yet. But with an expensive price-tag, and because it can’t yet be easily scaled up into a bigger screen, it may take years before you buy an OLED TV for the living room.

The path ahead

There are still challenges to overcome before solid-state lighting replaces all the bulbs in our sockets. Scientists are investigating ways to make both LEDs and OLEDs still more efficient and cheaper. The organic materials in OLEDs are fragile and don’t last as long as traditional LEDs, so scientists are looking for ways to make them sturdier. Plus, moisture harms OLEDs, so researchers are trying to figure out how to protect these lights of the future.

Kippelen says the scientists at his lab, like others around the world, are the innovators who are advancing the technology. But as for all the potential uses, Kippelen says, “I leave it to artists and designers to predict what can be done.”

Going Deeper:

You might want to dwell a little longer on the conditioned air that magically wafts out of household vents, however. The way you heat or cool your home has a big effect on the Earth, says John Carmody. He’s director of the Center for Sustainable Building Research at the University of Minnesota in Minneapolis.

“Most people don’t usually think about where their heat comes from,” Carmody says. Yet nearly every type of energy source dumps waste or spews pollution into the air.

Heating and cooling the millions of buildings in the United States require a lot of energy and have a huge impact on the environment.

South Florida Restoration Science Forum, U.S. Geological Survey

Buildings have a huge impact on the environment. There are more than 81 million buildings in the United States, according to the U.S. Department of Energy. Buildings consume more energy than any other economic category, including transportation and industry. Almost half of the energy that buildings use goes into heating and cooling.

Like Carmody, a growing number of engineers, planners, and architects have been looking for new ways to make buildings less wasteful and kinder to the environment. Improvements have come in many forms, including better insulation, windows, and construction materials.

Architects are also realizing that the size, location, and positioning of a building affects how much energy it uses. Even the arrangement of buildings in a neighborhood makes a difference.

“In the last 10 years,” Carmody says, “there has been a major movement toward what you’d call ‘green’ buildings.” Such buildings are sometimes also described as sustainable, environmentally friendly, or healthy.

Temperature control

The amount of energy you use for heating and cooling depends on where you live.

In places such as San Diego, Calif., for instance, the temperature is mild all year round. People rarely have to regulate the temperature of their homes.

Where I live in Minnesota, on the other hand, winters are unbearably cold, and summers can be unbearably hot. Without heaters and air conditioners, we’d be in big trouble. (At least, I know I would be pretty miserable.)

Transmission lines carry electricity from power plants to communities.

Oak Ridge National Laboratory

To get a sense of your own environmental impact, you can look at the climate where you live. Ask yourself how often you turn on the heater or the air conditioner, and how high you pump them up.

You might also want to figure out the source of the energy that your house or school uses for temperature control. Most air conditioners run on electricity. Some heaters do, too. If you find a furnace in the basement and radiators around your house, though, that probably means you have a system that burns natural gas or oil to heat water.

These energy sources have their downsides. Electricity, for example, usually comes from power plants that burn coal or use nuclear fuel. Both produce dangerous waste.

And there’s energy lost along the way. “Only about a third of the energy generated at a power plant makes its way to a house,” Carmody says.

One alternative energy source is to use wind to generate electricity.

U.S. Department of Energy

As an alternative energy source, harnessing the power of the wind or sun is becoming more popular in some places. Windmills for generating electricity are springing up from California to Germany. And researchers are working to make solar cells, which absorb light from the sun and convert it into electricity, more efficient.

Sunlight can also be used to heat tanks of water. Still, the technology needs some work. For now, solar power is more expensive than traditional sources. And some places don’t have enough reliable sunshine or wind to make these approaches practical.

Windows, walls, and roofs

No matter where the energy comes from to heat or cool your home, simple design and construction choices can have a big effect on how much energy you end up using.

First, consider when your home was built. Old houses tend to be drafty, Carmody says. They lose energy to the outdoors.

Newer buildings have more insulation packed into the walls. Fluffy materials such as fiberglass and Styrofoam have lots of pockets for trapping air. Such a structure holds heat in, just like a cozy sleeping bag. Many environmentalists prefer cellulose fiber, which is made from recycled paper and wood, for insulation.

When it comes to energy efficiency, windows are a big issue. Instead of just looking through them, take a closer look at the windows where you live. If you can feel cold air rushing in even when the window is closed, that’s a good sign that you’re wasting a lot of energy.

Researchers can monitor the energy efficiency of a wall and window combination.

Oak Ridge National Laboratory

New technologies are drastically improving window performance.

Windows used to be made from single sheets of glass. Today, windows are almost always double-glazed. This means there are two panes of glass set in a frame with an air space between them for insulation. Sometimes, windows are triple-glazed.

Scientists have also developed special coatings for windows. These invisible materials reflect heat. In a double-glazed window, coating the two sides of glass that face each other traps heat between the panes and increases insulation.

Chemists in England recently developed a kind of “smart” window coating. It reflects heat, but only when the window gets warmer than room temperature. If the technology becomes more affordable and practical, it could make windows even better at keeping the inside air in and the outside air out.

On the other side of the temperature fence, researchers from Oak Ridge and Lawrence Berkeley National Laboratories are working on a new type of roofing material that they hope will cut the cost of air conditioning by 20 percent.

At Oak Ridge National Laboratory, researchers test “cool-color” roofing materials, which reflect more sunlight than typical shingles or tiles do.

Oak Ridge National Laboratory

If you’ve ever worn a black T-shirt on a sunny day, you know that dark colors absorb light and create heat. Most roofs are dark, so they absorb infrared and visible light, which makes a building warmer. The idea is to make shingles with colors that reflect certain wavelengths of sunlight. Such “cool” roofs should be available in 3 to 5 years, the scientists say.

Living spaces

Perhaps the most innovative strategy for increasing energy efficiency actually has nothing to do with technology. Instead, architects take advantage of the environment and landscape to control temperature inside a building.

In the northern hemisphere, this can mean installing lots of south-facing windows so that plenty of sunlight can pour in. At the same time, well-designed overhangs keep summer sun out but let winter sun in.

Some people are choosing to live in communities that have been specifically designed to promote energy-efficient living. Village Homes in Davis, Calif., was one of the first of such green, or sustainable, developments.

Completed in 1981, the neighborhood has a network of paths that encourages people to bike or walk instead of drive (and pollute). The development’s 240 houses face south for lots of exposure to the sun. Overhangs provide shade. Houses run on solar power. There are lots of trees. And narrow streets have as little pavement as possible.

The strategy seems to be working. The air temperature around Village Homes is 15 degrees F. cooler than surrounding areas that have more pavement. And residents spend between one-third and one-half as much on energy bills compared to more conventional homes in nearby neighborhoods.

“We have a shadier, cooler microclimate,” says developer and resident Judith Corbett, who spoke at an environmental design conference in Minneapolis last April. “I don’t even have an air conditioner.”

As people see communities such as Village Homes thrive, these types of developments are becoming more popular. They’re springing up in places such as Colorado, Arizona, Virginia, and Australia.

Zero energy

The U.S. government itself is taking steps to boost the energy efficiency of the nation’s buildings. In one project, the Department of Energy has a long-term goal to create a “net-zero-energy” house—a house that wastes no energy.

In Tennessee, builders are putting up a house that should produce about as much energy as it uses. The roof and walls are made from special insulated panels, and solar cells on the roof generate electricity for the home.

Oak Ridge National Laboratory

The Department of Energy’s development of “near-zero-energy” homes is one step in that direction. One such house in Tennessee runs completely on electricity for just 82 cents a day. Conventional homes in the same area use between $4 and $5 in electricity a day.

As research on efficient energy use continues, think about what you can do to live a more energy-efficient life in the meantime.

Keep the heat low or off when you’re not home. Make sure leaks around doors and windows get patched. Turn off lights, TVs, and computers when they’re not needed.

Better yet, if you’re cold, put on a sweater and have a hot drink. If you’re hot, consider having an ice cream cone or going for a swim.

Going Deeper:

Word Find: Hot and Cold

Additional Information

Questions about the Article

Energy Facts

Energy use in the United States (Quadrillion Btu)

Btu, short for British Thermal Unit, is a unit of heat energy. One Btu is the amount of heat needed to raise the temperature of one pound of water 1° F. The heat given off by burning one wooden kitchen match is about 1 Btu.

Source: Energy Information Administration, U.S. Department of Energy