Lighting

Lighting, also called illumination, is the careful use of light to create practical or beautiful effects. It includes using both man-made light sources like lamps and light fixtures, as well as natural light. One way to use natural light is through daylighting, which means letting sunlight into buildings using windows, skylights, or special structures called light shelves. Daylighting can help save energy because buildings often use a lot of power for artificial lighting.

Proper lighting can make tasks easier, improve how things look, and even make people feel better. Inside buildings, lighting is usually done with special light fixtures and is an important part of interior design. Lighting can also be a key part of outdoor landscape projects, helping to make gardens and other outside spaces more pleasant and functional.

History

For a chronological guide, see Timeline of lighting technology.

When people first found fire, they used it to light up areas, like around campfires or with torches. Early humans like Peking Man lit fires in their caves over 400,000 years ago. They made simple oil lamps from rocks and shells, filled them with grease, and used a fiber wick to burn fats for light. Many of these lamps were found in the Lascaux caves in France, about 15,000 years old. People also used oily animals and fireflies for light. Over time, they made candles and lamps from glass and pottery. Chandeliers were an early type of "light fixture".

A big change came when people used whale oil for lighting. This changed again in the 1840s when Abraham Gesner, a Canadian geologist, made kerosene, which was brighter and cheaper. By the 1850s, whale oil became too expensive, so kerosene became more popular. In 1859, the discovery of crude oil started the petroleum industry.

In the early 1800s, gas lighting became common for street lights in big cities and in some shops and homes. The gas mantle made these lights brighter. Then in the 1880s, electric lighting arrived, starting with arc lights for big spaces and streets, and later the incandescent light bulb for homes and outdoors. Electric lights changed how people lived at night and helped make cities safer.

Fixtures

Main article: Light fixture

Lighting fixtures come in many styles for different uses. They hold the light source, guide the light, and help stop glare. Some fixtures are simple, while others are artistic. Many materials can be used for fixtures as long as they are safe for heat. An important feature of fixtures is how well they change electricity into light, measured in lumens per watt. Clear fixtures usually work better, while shaded ones give more comfort.

The color temperature of white light is important for different jobs. It is measured in kelvins and shows how warm or cool the light looks. Lower temperatures give a yellow-red light, while higher temperatures give a blue-white light. This choice matters for tasks like checking colors or showing off food and clothes in stores.

Lighting is grouped by its purpose: general, accent, or task lighting. Task lighting is strong and focused, good for reading or inspecting things. Accent lighting is decorative, used to highlight pictures, plants, or parts of a room or garden. General lighting fills in the rest, providing basic light for an area, like a lamp on a table or ceiling lights in a parking lot.

Downlighting, where lights on or in the ceiling shine downward, is very common in homes and offices. Uplighting bounces light off the ceiling to reduce glare and give even lighting. Front lighting makes objects look flat, while side lighting can cause glare. Backlighting shines behind or through an object to add depth or drama.

Indoor lighting includes many types such as alcove lighting, which is indirect and often uses fluorescent or LED lights. Soffit lighting can show off wall textures. Recessed lights, hidden in the ceiling, are popular and come in various forms. Track lighting, which can be aimed at different spots, has become popular again with safer, thinner designs. Other indoor lights include sconces, torchères, chandeliers, pendant lights, and portable table lamps.

Outdoor lighting serves many purposes like lighting up areas, advertising, and decoration. Street lights help people see roads at night, while floodlights can light up work zones or sports fields. Beacon lights guide drivers, security lights aim to prevent crime, and entry lights mark home entrances. Underwater lights can decorate ponds or pools. All outdoor lighting can add to light pollution, which harms the environment.

Fixture components

Lamps

Main article: Lamp (electrical component)

Lamps, often called "light bulbs," are the parts of a light fixture that change electricity into light. There are many types of lamps now, so the best way to compare them is by how much light they make, measured in lumens. A small candle gives about 13 lumens, and a typical old bulb gives around 700 lumens.

There are several kinds of lamps:

• Fluorescent light: A tube that uses a special coating and gas to make white light.
• Halogen: These are like old bulbs but with special gases that make them more efficient.
• Neon: A glass tube with gas inside that glows in different colors.
• Light-emitting diodes (LED): These are modern lights that shine by moving electrons in special materials.
• Compact fluorescent lamps: These are designed to fit in places where old bulbs used to go.

Ballasts

Ballast: A ballast is a helper part that starts and controls the power for certain types of lights, like fluorescent lights. It also helps keep the lamp safe by protecting it from too much heat.

Vehicle use

Main article: Automotive lighting

Vehicles have headlamps and tail lights. Headlamps are white or yellow lights on the front. They light the road so other drivers can see the car. Many cars use LED headlights because they save energy. Tail and brake lights are red and shine from the back. They show where the car is going. White reversing lamps show when a car is going backward. Flashing turn signals tell other drivers when a car is turning. In the late 1950s, some car companies began using special lights for speedometers and logos.

Lighting practice

Architectural lighting design

Main article: Architectural lighting design

Lighting design for buildings is called 'architectural lighting design'. Some designers use natural light, called daylighting, or light outdoors in landscape lighting. When designing lighting, they think about how it looks, how much light is needed, who will be there, saving energy, and the cost. They also think about how much natural light comes into a space using daylight factor calculations. For simple setups, they use tables. For more complex designs, they use computer programs like Radiance to test ideas.

The colors and materials on walls and furniture can change how a room looks with light. Dark paint can make a room seem smaller, while light paint can make it feel bigger. Shiny surfaces can also affect how light behaves in a room.

Stage lighting

Main article: Stage lighting

Lighting helps show off performers in live shows like plays, dances, or musicals. It is arranged to create special effects for each scene. Stage lighting uses many tools, such as dimmers, colored filters, mirrors, lenses, and different types of lamps. These tools are adjusted for each show. A lighting plan is made so the lighting operator can change the lights at the right times. Modern cameras for movies and TV need less light and create less heat.

Measurement

Main article: Photometry (optics)

Measuring light helps us know how much light reaches a surface and how much comes from a lamp or other source. We also look at the colors this light can show. Our eyes see light differently depending on its color, so special methods are used to measure light that is useful to us. The basic unit for measuring light is called the candela (cd). Other units come from this.

We also measure how much light falls on a surface, called illuminance, using a unit called lux. This helps us understand how bright something looks to our eyes.

Color properties

To describe the color of light, we use two main ideas. One tells us if the light feels warm or cool, and the other tells us how well the light shows true colors.

Light exposure

Special tools can measure how much light a person or object is exposed to. One small device, worn on the head, can track the light that enters our eyes. This helps scientists study how light affects our body’s natural clock and activity patterns. It records light and activity at regular times.

Secondary effects

Lighting helps us see, but it can also affect our health and the environment. Good lighting is important for tasks and can improve how we feel and work. But too much light or the wrong kind of light can cause problems like headaches, stress, and higher blood pressure. Bright light can make feelings feel stronger, while dim light may help people make clearer decisions.

Using natural light from windows and skylights can save energy and help health. Natural light can improve learning for students and help older people with memory. Lighting design should use the right amount and type of light for different times of day to support healthy body rhythms.

There are many ways to save energy with lighting, such as using controls that turn lights off when not needed, choosing energy-saving lights, and using natural light when possible. Lighting control systems can adjust lights based on time, if people are present, and how much daylight there is to use less energy. Daylighting, which uses natural light inside buildings, saves energy and can improve health and performance. Solid-state lighting, like LEDs, is becoming more common because it uses less energy and lasts longer than older bulbs.

Environmental issues with lighting include throwing away bulbs that contain harmful materials and light pollution. Light pollution happens when too much artificial light spreads into places where it isn’t needed, wasting energy and affecting wildlife. This extra light can harm animals by changing their natural patterns.

Main articles: Light pollution, Over-illumination, and Light effects on circadian rhythm

See also: Ecological light pollution

Professional organizations

International

The International Commission on Illumination (CIE) is an international group that sets rules for color and lighting. It makes tools that help people understand color and how lights show colors.

The Illuminating Engineering Society (IES) works with groups like ANSI and ASHRAE to create rules for lighting in buildings. Companies that make lighting tools share how their products spread light using formats the IES helps create.

The International Association of Lighting Designers (IALD) helps people who design lighting learn more about their work. Designers who follow certain rules can add "IALD" to their names.

The National Council on Qualifications for the Lighting Professions (NCQLP) offers a test to see if someone knows basic lighting design ideas. People who pass can call themselves "Lighting Certified" and add "LC" to their names. This test is one of three big tests in the lighting field in the U.S., and anyone can take it.

The Professional Lighting And Sound Association (PLASA) is a group in the UK for people who work with lighting, sound, and similar tools for shows. They help protect their members' interests and talk to governments about rules.

National

• Association de Concepteurs Eclairage (ACE) in France
• American Lighting Association (ALA) in the United States
• Associazione Professionisti dell'Illuminazione (APIL) in Italy
• Hellenic Illumination Committee (HIC) in Greece
• Indian Society of Lighting Engineers (ISLE)
• Institution of Lighting Engineers (ILE) in the United Kingdom
• Schweizerische Licht Gesellschaft (SLG) in Switzerland
• Society of Light and Lighting (SLL), part of the Chartered Institution of Building Services Engineers in the United Kingdom.
• United Scenic Artists Local 829 (USA829), membership for lighting designers as a category, with scenic designers, projection designers, costume designers, and sound designers, in the United States