Lighting

Lighting or illumination is the deliberate use of light to achieve a practical or aesthetic effect. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. Daylighting (using windows, skylights, or light shelves) is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.

Indoor lighting is usually accomplished using light fixtures, and is a key part of interior design. Lighting can also be an intrinsic component of landscape projects.

Cherry blossoms with Isuzu-Chaya and Akafuku store at Night
Illuminated cherry blossoms, light from the shop windows, and Japanese lantern at night in Ise, Mie, Japan
Gare de l'Est Paris 2007 033
Daylight used at the train station Gare de l'Est Paris
Classical spectacular laser effects
Low-intensity lighting and haze in a concert hall allows laser effects to be visible

History

With the discovery of fire, the earliest form of artificial lighting used to illuminate an area were campfires or torches. As early as 400,000 BCE, fire was kindled in the caves of Peking Man. Prehistoric people used primitive oil lamps to illuminate surroundings. These lamps were made from naturally occurring materials such as rocks, shells, horns and stones, were filled with grease, and had a fiber wick. Lamps typically used animal or vegetable fats as fuel. Hundreds of these lamps (hollow worked stones) have been found in the Lascaux caves in modern-day France, dating to about 15,000 years ago. Oily animals (birds and fish) were also used as lamps after being threaded with a wick. Fireflies have been used as lighting sources. Candles and glass and pottery lamps were also invented.[1] Chandeliers were an early form of "light fixture".

A major reduction in the cost of lighting occurred with the discovery of whale oil.[2] The use of whale oil declined after Abraham Gesner, a Canadian geologist, first refined kerosene in the 1840s, allowing brighter light to be produced at substantially lower cost.[3] In the 1850s, the price of whale oil dramatically increased (more than doubling from 1848 to 1856) due to shortages of available whales, hastening whale oil's decline.[3] By 1860, there were 33 kerosene plants in the United States, and Americans spent more on gas and kerosene than on whale oil.[3] The final death knell for whale oil was in 1859, when crude oil was discovered and the petroleum industry arose.[3]

Gas lighting was economical enough to power street lights in major cities starting in the early 1800s, and was also used in some commercial buildings and in the homes of wealthy people. The gas mantle boosted the luminosity of utility lighting and of kerosene lanterns. The next major drop in price came about in the 1880s with the introduction of electric lighting in the form of arc lights for large space and street lighting followed on by incandescent light bulb based utilities for indoor and outdoor lighting.[2][4]

Over time, electric lighting became ubiquitous in developed countries.[5] Segmented sleep patterns disappeared, improved nighttime lighting made more activities possible at night, and more street lights reduced urban crime.[6][7][8]

Fixtures

Lighting fixtures come in a wide variety of styles for various functions. The most important functions are as a holder for the light source, to provide directed light and to avoid visual glare. Some are very plain and functional, while some are pieces of art in themselves. Nearly any material can be used, so long as it can tolerate the excess heat and is in keeping with safety codes.

An important property of light fixtures is the luminous efficacy or wall-plug efficiency, meaning the amount of usable light emanating from the fixture per used energy, usually measured in lumen per watt. A fixture using replaceable light sources can also have its efficiency quoted as the percentage of light passed from the "bulb" to the surroundings. The more transparent the lighting fixture is, the higher efficacy. Shading the light will normally decrease efficacy but increase the directionality and the visual comfort probability.

Color temperature for white light sources also affects their use for certain applications. The color temperature of a white light source is the temperature in kelvins of a theoretical black body emitter that most closely matches the spectral characteristics of the lamp. An incandescent bulb has a color temperature around 2800 to 3000 kelvins; daylight is around 6400 kelvins. Lower color temperature lamps have relatively more energy in the yellow and red part of the visible spectrum, while high color temperatures correspond to lamps with more of a blue-white appearance. For critical inspection or color matching tasks, or for retail displays of food and clothing, the color temperature of the lamps will be selected for the best overall lighting effect.

Types

SameEyes4
A demonstration of the effects of different kinds of lighting

Lighting is classified by intended use as general, accent, or task lighting, depending largely on the distribution of the light produced by the fixture.

  • Task lighting is mainly functional and is usually the most concentrated, for purposes such as reading or inspection of materials. For example, reading poor-quality reproductions may require task lighting levels up to 1500 lux (150 footcandles), and some inspection tasks or surgical procedures require even higher levels.
  • Accent lighting is mainly decorative, intended to highlight pictures, plants, or other elements of interior design or landscaping.
  • General lighting (sometimes referred to as ambient light) fills in between the two and is intended for general illumination of an area. Indoors, this would be a basic lamp on a table or floor, or a fixture on the ceiling. Outdoors, general lighting for a parking lot may be as low as 10-20 lux (1-2 footcandles) since pedestrians and motorists already used to the dark will need little light for crossing the area.

Methods

  • Downlighting is most common, with fixtures on or recessed in the ceiling casting light downward. This tends to be the most used method, used in both offices and homes. Although it is easy to design it has dramatic problems with glare and excess energy consumption due to large number of fittings.[9] The introduction of LED lighting has greatly improved this by approx. 90% when compared to a halogen downlight or spotlight. LED lamps or bulbs are now available to retro fit in place of high energy consumption lamps.
  • Uplighting is less common, often used to bounce indirect light off the ceiling and back down. It is commonly used in lighting applications that require minimal glare and uniform general illuminance levels. Uplighting (indirect) uses a diffuse surface to reflect light in a space and can minimize disabling glare on computer displays and other dark glossy surfaces. It gives a more uniform presentation of the light output in operation. However indirect lighting is completely reliant upon the reflectance value of the surface. While indirect lighting can create a diffused and shadow free light effect it can be regarded as an uneconomical lighting principle.[10][11]
  • Front lighting is also quite common, but tends to make the subject look flat as its casts almost no visible shadows. Lighting from the side is the less common, as it tends to produce glare near eye level. Backlighting either around or through an object is mainly for accent.
  • Backlighting either around or through an object is mainly for accent. Backlighting is used to illuminate a background or backdrop. This adds depth to an image or scene. Others use it to achieve a more dramatic effect.
BWLight
Wall-mounted light with shadows

Forms of lighting

Indoor lighting

Forms of lighting include alcove lighting, which like most other uplighting is indirect. This is often done with fluorescent lighting (first available at the 1939 World's Fair) or rope light, occasionally with neon lighting, and recently with LED strip lighting. It is a form of backlighting.

Soffit or close to wall lighting can be general or a decorative wall-wash, sometimes used to bring out texture (like stucco or plaster) on a wall, though this may also show its defects as well. The effect depends heavily on the exact type of lighting source used.

Recessed lighting (often called "pot lights" in Canada, "can lights" or 'high hats" in the US) is popular, with fixtures mounted into the ceiling structure so as to appear flush with it. These downlights can use narrow beam spotlights, or wider-angle floodlights, both of which are bulbs having their own reflectors. There are also downlights with internal reflectors designed to accept common 'A' lamps (light bulbs) which are generally less costly than reflector lamps. Downlights can be incandescent, fluorescent, HID (high intensity discharge) or LED.

Track lighting, invented by Lightolier,[12] was popular at one period of time because it was much easier to install than recessed lighting, and individual fixtures are decorative and can be easily aimed at a wall. It has regained some popularity recently in low-voltage tracks, which often look nothing like their predecessors because they do not have the safety issues that line-voltage systems have, and are therefore less bulky and more ornamental in themselves. A master transformer feeds all of the fixtures on the track or rod with 12 or 24 volts, instead of each light fixture having its own line-to-low voltage transformer. There are traditional spots and floods, as well as other small hanging fixtures. A modified version of this is cable lighting, where lights are hung from or clipped to bare metal cables under tension.

A sconce is a wall-mounted fixture, particularly one that shines up and sometimes down as well. A torchère is an uplight intended for ambient lighting. It is typically a floor lamp but may be wall-mounted like a sconce. Further interior light fixtures include chandeliers, pendant lights, ceiling fans with lights, close-to-ceiling or flush lights, and various types of lamps[13]

The portable or table lamp is probably the most common fixture, found in many homes and offices. The standard lamp and shade that sits on a table is general lighting, while the desk lamp is considered task lighting. Magnifier lamps are also task lighting.

Fountain Europe Square Moscow
Animated fountain in Moscow's Square of Europe, lit at night.

The illuminated ceiling was once popular in the 1960s and 1970s but fell out of favor after the 1980s. This uses diffuser panels hung like a suspended ceiling below fluorescent lights, and is considered general lighting. Other forms include neon, which is not usually intended to illuminate anything else, but to actually be an artwork in itself. This would probably fall under accent lighting, though in a dark nightclub it could be considered general lighting.

In a movie theater, steps in the aisles are usually marked with a row of small lights for convenience and safety, when the film has started and the other lights are off. Traditionally made up of small low wattage, low voltage lamps in a track or translucent tube, these are rapidly being replaced with LED based versions.

Outdoor lighting

Highway 401 Night Lapse Busy
High mast lighting along Highway 401 in Ontario, Canada.

Street Lights are used to light roadways and walkways at night. Some manufacturers are designing LED and photovoltaic luminaires to provide an energy-efficient alternative to traditional street light fixtures.[14][15][16]

Floodlights
Floodlights are used to illuminate outdoor playing fields or work zones during nighttime.

Floodlights can be used to illuminate work zones[17] or outdoor playing fields during nighttime hours.[18][19] The most common type of floodlights are metal halide and high pressure sodium lights.

Beacon lights are positioned at the intersection of two roads to aid in navigation.

Sometimes security lighting can be used along roadways in urban areas, or behind homes or commercial facilities. These are extremely bright lights used to deter crime. Security lights may include floodlights.

Entry lights can be used outside to illuminate and signal the entrance to a property.[20] These lights are installed for safety, security, and for decoration.

Underwater accent lighting is also used for koi ponds, fountains, swimming pools and the like.

Vehicle use

Vehicles typically include headlamps and tail lights. Headlamps are white or selective yellow lights placed in the front of the vehicle, designed to illuminate the upcoming road and to make the vehicle more visible. Many manufactures are turning to LED headlights as an energy-efficient alternative to traditional headlamps.[21] Tail and brake lights are red and emit light to the rear so as to reveal the vehicle's direction of travel to following drivers. White rear-facing reversing lamps indicate that the vehicle's transmission has been placed in the reverse gear, warning anyone behind the vehicle that it is moving backwards, or about to do so. Flashing turn signals on the front, side, and rear of the vehicle indicate an intended change of position or direction. In the late 1950s, some automakers began to use electroluminescent technology to backlight their cars' speedometers and other gauges or to draw attention to logos or other decorative elements.

Lamps

Commonly called 'light bulbs', lamps are the removable and replaceable part of a light fixture, which converts electrical energy into electromagnetic radiation. While lamps have traditionally been rated and marketed primarily in terms of their power consumption, expressed in watts, proliferation of lighting technology beyond the incandescent light bulb has eliminated the correspondence of wattage to the amount of light produced. For example, a 60 W incandescent light bulb produces about the same amount of light as a 13 W compact fluorescent lamp. Each of these technologies has a different efficacy in converting electrical energy to visible light. Visible light output is typically measured in lumens. This unit only quantifies the visible radiation, and excludes invisible infrared and ultraviolet light. A wax candle produces on the close order of 13 lumens, a 60 watt incandescent lamp makes around 700 lumens, and a 15-watt compact fluorescent lamp produces about 800 lumens, but actual output varies by specific design.[22] Rating and marketing emphasis is shifting away from wattage and towards lumen output, to give the purchaser a directly applicable basis upon which to select a lamp.


Lamp types include:

  • Ballast: A ballast is an auxiliary piece of equipment designed to start and properly control the flow of power to discharge light sources such as fluorescent and high intensity discharge (HID) lamps. Some lamps require the ballast to have thermal protection.
  • fluorescent light: A tube coated with phosphor containing low pressure mercury vapor that produces white light.
  • Halogen: Incandescent lamps containing halogen gases such as iodine or bromine, increasing the efficacy of the lamp versus a plain incandescent lamp.
  • Neon: A low pressure gas contained within a glass tube; the color emitted depends on the gas.
  • Light emitting diodes: Light emitting diodes (LED) are solid state devices that emit light by dint of the movement of electrons in a semiconductor material.[23]
  • Compact fluorescent lamps: CFLs are designed to replace incandescent lamps in existing and new installations.[24][25]

Design and architecture

Architectural lighting design

Giovanni Paolo Panini - Interior of the Pantheon, Rome - Google Art Project
Lighting without windows: The Pantheon in the 18th century, painted by Giovanni Paolo Panini.[26]

Lighting design as it applies to the built environment is known as 'architectural lighting design'. Lighting of structures considers aesthetic elements as well as practical considerations of quantity of light required, occupants of the structure, energy efficiency, and cost. Artificial lighting takes into account the amount of daylight received in a space by using daylight factor calculations. For simple installations, hand calculations based on tabular data are used to provide an acceptable lighting design. More critical or complex designs now routinely use computer software such as Radiance for mathematical modeling, which can allow an architect to quickly evaluate the benefit of a proposed design.

In some instances, the materials used on walls and furniture play a key role in the lighting effect. For example, dark paint tends to absorb light, making the room appear smaller and more dim than it is, whereas light paint does the opposite. Other reflective surfaces also have an effect on lighting design.[11][27]

Photometric studies

Photometric studies (also sometimes referred to as "layouts" or "point by points") are often used to simulate lighting designs for projects before they are built or renovated. This enables architects, designers, and engineers to determine which configuration of lighting fixtures will deliver the amount of light needed. Other parameters that can be determined are the contrast ratio between light and dark areas. In many cases these studies are referenced against IESNA or CIBSE recommended practices for the type of application. Depending on the building type, client, or safety requirements, different design aspects may be emphasized for safety or practicality. Specialized software is often used to create these, which typically combine the use of two-dimensional CAD drawings and lighting calculation software (i.e. AGi32, Visual, Dialux).

On stage and set

Female in red pullover and blue jeans -coloured lights-2Nov2003
Lighting and shadows
Ivan-rogue-hybrid
Moving heads in a photo studio set.
ScaryVampire
Illuminating subject from beneath to achieve a heightened dramatic effect.

Lighting illuminates the performers and artists in a live theatre, dance, or musical performance, and is selected and arranged to create dramatic effects. Stage lighting uses general illumination technology in devices configured for easy adjustment of their output characteristics. The setup of stage lighting is tailored for each scene of each production. Dimmers, colored filters, reflectors, lenses, motorized or manually aimed lamps, and different kinds of flood and spot lights are among the tools used by a stage lighting designer to produce the desired effects. A set of lighting cues are prepared so that the lighting operator can control the lights in step with the performance; complex theatre lighting systems use computer control of lighting instruments.

Motion picture and television production use many of the same tools and methods of stage lighting. Especially in the early days of these industries, very high light levels were required and heat produced by lighting equipment presented substantial challenges. Modern cameras require less light, and modern light sources emit less heat.

Measurement

Measurement of light or photometry is generally concerned with the amount of useful light falling on a surface and the amount of light emerging from a lamp or other source, along with the colors that can be rendered by this light. The human eye responds differently to light from different parts of the visible spectrum, therefore photometric measurements must take the luminosity function into account when measuring the amount of useful light. The basic SI unit of measurement is the candela (cd), which describes the luminous intensity, all other photometric units are derived from the candela. Luminance for instance is a measure of the density of luminous intensity in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square metre (cd/m2). The CGS unit of luminance is the stilb, which is equal to one candela per square centimetre or 10 kcd/m2. The amount of useful light emitted from a source or the luminous flux is measured in lumen (lm).

The SI unit of illuminance and luminous emittance, being the luminous power per area, is measured in Lux. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface. It is analogous to the radiometric unit watts per square metre, but with the power at each wavelength weighted according to the luminosity function, a standardized model of human visual brightness perception. In English, "lux" is used in both singular and plural.[28]

Several measurement methods have been developed to control glare resulting from indoor lighting design. The Unified Glare Rating (UGR), the Visual Comfort Probability, and the Daylight Glare Index are some of the most well-known methods of measurement. In addition to these new methods, four main factors influence the degree of discomfort glare; the luminance of the glare source, the solid angle of the glare source, the background luminance, and the position of the glare source in the field of view must all be taken into account.[10][29]

Color properties

To define light source color properties, the lighting industry predominantly relies on two metrics, correlated color temperature (CCT), commonly used as an indication of the apparent "warmth" or "coolness" of the light emitted by a source, and color rendering index (CRI), an indication of the light source’s ability to make objects appear natural.

However, these two metrics, developed in the last century, are facing increased challenges and criticisms as new types of light sources, particularly light emitting diodes (LEDs), become more prevalent in the market.

For example, in order to meet the expectations for good color rendering in retail applications, research[30] suggests using the well-established CRI along with another metric called gamut area index (GAI). GAI represents the relative separation of object colors illuminated by a light source; the greater the GAI, the greater the apparent saturation or vividness of the object colors. As a result, light sources which balance both CRI and GAI are generally preferred over ones that have only high CRI or only high GAI.[31]

Light exposure

Typical measurements of light have used a Dosimeter. Dosimeters measure an individual's or an object's exposure to something in the environment, such as light dosimeters and ultraviolet dosimeters.

In order to specifically measure the amount of light entering the eye, personal circadian light meter called the Daysimeter has been developed.[32] This is the first device created to accurately measure and characterize light (intensity, spectrum, timing, and duration) entering the eye that affects the human body's clock.

The small, head-mounted device measures an individual's daily rest and activity patterns, as well as exposure to short-wavelength light that stimulates the circadian system. The device measures activity and light together at regular time intervals and electronically stores and logs its operating temperature. The Daysimeter can gather data for up to 30 days for analysis.[33]

Energy consumption

Several strategies are available to minimize energy requirements for lighting a building:

  • Specification of illumination requirements for each given use area.
  • Analysis of lighting quality to ensure that adverse components of lighting (for example, glare or incorrect color spectrum) are not biasing the design.
  • Integration of space planning and interior architecture (including choice of interior surfaces and room geometries) to lighting design.
  • Design of time of day use that does not expend unnecessary energy.
  • Selection of fixture and lamp types that reflect best available technology for energy conservation.
  • Training of building occupants to use lighting equipment in most efficient manner.
  • Maintenance of lighting systems to minimize energy wastage.
  • Use of natural light
    • Some big box stores were being built from 2006 on with numerous plastic bubble skylights, in many cases completely obviating the need for interior artificial lighting for many hours of the day.
    • In countries where indoor lighting of simple dwellings is a significant cost, "Moser lamps", plastic water-filled transparent drink bottles fitted through the roof, provide the equivalent of a 40- to 60-watt incandescent bulb each during daylight.[34]
  • Load shedding can help reduce the power requested by individuals to the main power supply. Load shedding can be done on an individual level, at a building level, or even at a regional level.

Specification of illumination requirements is the basic concept of deciding how much illumination is required for a given task. Clearly, much less light is required to illuminate a hallway compared to that needed for a word processing work station. Generally speaking, the energy expended is proportional to the design illumination level. For example, a lighting level of 400 lux might be chosen for a work environment involving meeting rooms and conferences, whereas a level of 80 lux could be selected for building hallways.[35][36][37][38][39] If the hallway standard simply emulates the conference room needs, then much more energy will be consumed than is needed. Unfortunately, most of the lighting standards even today have been specified by industrial groups who manufacture and sell lighting, so that a historical commercial bias exists in designing most building lighting, especially for office and industrial settings.

Lighting control systems

Lighting control systems reduce energy usage and cost by helping to provide light only when and where it is needed. Lighting control systems typically incorporate the use of time schedules, occupancy control, and photocell control (i.e.daylight harvesting). Some systems also support demand response and will automatically dim or turn off lights to take advantage of utility incentives. Lighting control systems are sometimes incorporated into larger building automation systems.

Many newer control systems are using wireless mesh open standards (such as ZigBee),[40] which provides benefits including easier installation (no need to run control wires) and interoperability with other standards-based building control systems (e.g. security).[41]

In response to daylighting technology, daylight harvesting systems have been developed to further reduce energy consumption. These technologies are helpful, but they do have their downfalls. Many times, rapid and frequent switching of the lights on and off can occur, particularly during unstable weather conditions or when daylight levels are changing around the switching illuminance. Not only does this disturb occupants, it can also reduce lamp life. A variation of this technology is the 'differential switching or dead-band' photoelectric control which has multiple illuminances it switches from so as not to disturb occupants as much.[9][42]

Occupancy sensors to allow operation for whenever someone is within the area being scanned can control lighting. When motion can no longer be detected, the lights shut off. Passive infrared sensors react to changes in heat, such as the pattern created by a moving person. The control must have an unobstructed view of the building area being scanned. Doors, partitions, stairways, etc. will block motion detection and reduce its effectiveness. The best applications for passive infrared occupancy sensors are open spaces with a clear view of the area being scanned. Ultrasonic sensors transmit sound above the range of human hearing and monitor the time it takes for the sound waves to return. A break in the pattern caused by any motion in the area triggers the control. Ultrasonic sensors can see around obstructions and are best for areas with cabinets and shelving, restrooms, and open areas requiring 360-degree coverage. Some occupancy sensors utilize both passive infrared and ultrasonic technology, but are usually more expensive. They can be used to control one lamp, one fixture or many fixtures.[43][44]

Daylighting

Daylighting is the oldest method of interior lighting. Daylighting is simply designing a space to use as much natural light as possible. This decreases energy consumption and costs, and requires less heating and cooling from the building. Daylighting has also been proven to have positive effects on patients in hospitals as well as work and school performance. Due to a lack of information that indicate the likely energy savings, daylighting schemes are not yet popular among most buildings.[9][45]

Solid-state lighting

In recent years light emitting diodes (LEDs) are becoming increasingly efficient leading to an extraordinary increase in the use of solid state lighting. In many situations, controlling the light emission of LEDs may be done most effectively by using the principles of nonimaging optics.[46]

Health effects

It is valuable to provide the correct light intensity and color spectrum for each task or environment. Otherwise, energy not only could be wasted but over-illumination can lead to adverse health and psychological effects.

Beyond the energy factors being considered, it is important not to over-design illumination, lest adverse health effects such as headache frequency, stress, and increased blood pressure be induced by the higher lighting levels. In addition, glare or excess light can decrease worker efficiency.[47]

Analysis of lighting quality particularly emphasizes use of natural lighting, but also considers spectral content if artificial light is to be used. Not only will greater reliance on natural light reduce energy consumption, but will favorably impact human health and performance. New studies have shown that the performance of students is influenced by the time and duration of daylight in their regular schedules. Designing school facilities to incorporate the right types of light at the right time of day for the right duration may improve student performance and well-being. Similarly, designing lighting systems that maximize the right amount of light at the appropriate time of day for the elderly may help relieve symptoms of Alzheimer's Disease. The human circadian system is entrained to a 24-hour light-dark pattern that mimics the earth’s natural light/dark pattern. When those patterns are disrupted, they disrupt the natural circadian cycle. Circadian disruption may lead to numerous health problems including breast cancer, seasonal affective disorder, delayed sleep phase syndrome, and other ailments.[48][49]

A study conducted in 1972 and 1981, documented by Robert Ulrich, surveyed 23 surgical patients assigned to rooms looking out on a natural scene. The study concluded that patients assigned to rooms with windows allowing lots of natural light had shorter postoperative hospital stays, received fewer negative evaluative comments in nurses’ notes, and took fewer potent analegesics than 23 matched patients in similar rooms with windows facing a brick wall. This study suggests that due to the nature of the scenery and daylight exposure was indeed healthier for patients as opposed to those exposed to little light from the brick wall. In addition to increased work performance, proper usage of windows and daylighting crosses the boundaries between pure aesthetics and overall health.[45][50]

Alison Jing Xu, assistant professor of management at the University of Toronto Scarborough and Aparna Labroo of Northwestern University conducted a series of studies analyzing the correlation between lighting and human emotion. The researchers asked participants to rate a number of things such as: the spiciness of chicken-wing sauce, the aggressiveness of a fictional character, how attractive someone was, their feelings about specific words, and the taste of two juices–all under different lighting conditions. In their study, they found that both positive and negative human emotions are felt more intensely in bright light. Professor Xu stated, "we found that on sunny days depression-prone people actually become more depressed." They also found that dim light makes people make more rational decisions and settle negotiations easier. In the dark, emotions are slightly suppressed. However, emotions are intensified in the bright light.[51][52][53][54]

Environmental issues

Compact fluorescent lamps

Compact fluorescent lamps (CFLs) use less power than an incandescent lamp to supply the same amount of light, however they contain mercury which is a disposal hazard. Due to the ability to reduce electricity consumption, many organizations encourage the adoption of CFLs. Some electric utilities and local governments have subsidized CFLs or provided them free to customers as a means of reducing electricity demand. For a given light output, CFLs use between one fifth and one quarter the power of an equivalent incandescent lamp. Unlike incandescent lamps CFLs need a little time to warm up and reach full brightness. Not all CFLs are suitable for dimming.

LED lamps

LED lamps have been advocated as the newest and best environmental lighting method.[55] According to the Energy Saving Trust, LED lamps use only 10% power compared to a standard incandescent bulb, where compact fluorescent lamps use 20% and energy saving halogen lamps 70%. The lifetime is also much longer — up to 50,000 hours. A downside is still the initial cost, which is higher than that of compact fluorescent lamps. Recent findings about the increased use of blue-white LEDs may be a policy mistake. The wide-scale adoption of LEDs will reap energy savings but the energy savings may be compromising human health and ecosystems.[56] The American Medical Association[57] warned on the use of high blue content white LEDs in street lighting, due to their higher impact on human health and environment, compared to low blue content light sources (e.g. High Pressure Sodium, PC amber LEDs, and low CCT LEDs).

Light pollution

Light pollution is a growing problem in reaction to excess light being given off by numerous signs, houses, and buildings. Polluting light is often wasted light involving unnecessary energy costs and carbon dioxide emissions. Light pollution is described as artificial light that is excessive or intrudes where it is not wanted. Well-designed lighting sends light only where it is needed without scattering it elsewhere. Poorly designed lighting can also compromise safety. For example, glare creates safety issues around buildings by causing very sharp shadows, temporarily blinding passersby making them vulnerable to would-be assailants.[58][59] The ecologic effects of artificial light have been documented. The World Health Organization in 2007 [60] issued a report that noted the effects of bright light on flora and fauna, sea turtle hatchlings, frogs during mating season and the migratory patterns of birds. The American Medical Association in 2012[61] issued a warning that extended exposure to light at night increases the risk of some cancers.[56] Two studies in Israel from 2008 have yielded some additional findings about a possible correlation between artificial light at night and certain cancers.[62]

Professional organizations

International

The International Commission on Illumination (CIE) is an international authority and standard defining organization on color and lighting. Publishing widely used standard metrics such as various CIE color spaces and the color rendering index.

The Illuminating Engineering Society of North America (IESNA), in conjunction with organizations like ANSI and ASHRAE, publishes guidelines, standards, and handbooks that allow categorization of the illumination needs of different built environments. Manufacturers of lighting equipment publish photometric data for their products, which defines the distribution of light released by a specific luminaire. This data is typically expressed in standardized form defined by the IESNA.

The International Association of Lighting Designers (IALD) is an organization which focuses on the advancement of lighting design education and the recognition of independent professional lighting designers. Those fully independent designers who meet the requirements for professional membership in the association typically append the abbreviation IALD to their name.

The Professional Lighting Designers Association (PLDA), formerly known as ELDA is an organisation focusing on the promotion of the profession of Architectural Lighting Design. They publish a monthly newsletter and organise different events throughout the world.

The National Council on Qualifications for the Lighting Professions (NCQLP) offers the Lighting Certification Examination which tests rudimentary lighting design principles. Individuals who pass this exam become ‘Lighting Certified’ and may append the abbreviation LC to their name. This certification process is one of three national (U.S.) examinations (the others are CLEP and CLMC) in the lighting industry and is open not only to designers, but to lighting equipment manufacturers, electric utility employees, etc.

The Professional Lighting And Sound Association (PLASA) is a UK-based trade organisation representing the 500+ individual and corporate members drawn from the technical services sector. Its members include manufacturers and distributors of stage and entertainment lighting, sound, rigging and similar products and services, and affiliated professionals in the area. They lobby for and represent the interests of the industry at various levels, interacting with government and regulating bodies and presenting the case for the entertainment industry. Example subjects of this representation include the ongoing review of radio frequencies (which may or may not affect the radio bands in which wireless microphones and other devices use) and engaging with the issues surrounding the introduction of the RoHS (Restriction of Hazardous Substances Directive) regulations.

National

See also

Inventors

Lists

References

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  2. ^ a b "The History of Light". Planet Money. Episode 534. NPR. April 25, 2014. Retrieved June 20, 2016.
  3. ^ a b c d Eric Jay Dolin (2007). Leviathan: The History of Whaling in America. W.W. Norton & Co. pp. 339–40.
  4. ^ The First Form of Electric Light History of the Carbon Arc Lamp (1800 - 1980s)'.Edison Tech Center, edisontechcenter.org
  5. ^ James L. Kirtley (5 July 2011). Electric Power Principles: Sources, Conversion, Distribution and Use. John Wiley & Sons. pp. 11–. ISBN 978-1-119-95744-7.
  6. ^ Vito, Gennaro F.; Maahs, Jeffrey R. (2011). Criminology: Theory, Research, and Policy (revised ed.). Jones & Bartlett. p. 70. ISBN 9780763766658.
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External links

Automotive lighting

The lighting system of a motor vehicle consists of lighting and signalling devices mounted or integrated to the front, rear, sides, and in some cases the top of a motor vehicle. This lights the roadway for the driver and increases the visibility of the vehicle, allowing other drivers and pedestrians to see a vehicle's presence, position, size, direction of travel, and the driver's intentions regarding direction and speed of travel. Emergency vehicles usually carry distinctive lighting equipment to warn drivers and indicate priority of movement in traffic.

Cinematographer

A cinematographer or director of photography (sometimes shortened to DP or DOP) is the chief over the camera and light crews working on a film, television production or other live action piece and is responsible for making artistic and technical decisions related to the image. The study and practice of this field is referred to as cinematography.

The cinematographer selects the camera, film stock, lenses, filters, etc., to realize the scene in accordance with the intentions of the director. Relations between the cinematographer and director vary; in some instances the director will allow the cinematographer complete independence; in others, the director allows little to none, even going so far as to specify exact camera placement and lens selection. Such a level of involvement is not common once the director and cinematographer have become comfortable with each other; the director will typically convey to the cinematographer what is wanted from a scene visually, and allow the cinematographer latitude in achieving that effect.

Several American cinematographers have become directors, including Reed Morano, ASC who lensed Frozen River and Beyonce's Lemonade before winning an Emmy for directing The Handmaid's Tale. Barry Sonnenfeld, originally the Coen brothers' DP; Jan de Bont, cinematographer on films as Die Hard and Basic Instinct, directed Speed and Twister. Ellen Kuras, ASC photographed Eternal Sunshine of The Spotless Mind as well as a number of Spike Lee films such as Summer of Sam and He Got Game before directing episodes of Legion and Ozark. In 2014, Wally Pfister, cinematographer on Christopher Nolan's three Batman films, made his directorial debut with Transcendence; whilst British cinematographers Jack Cardiff and Freddie Francis regularly moved between the two positions.

Cinematography

Cinematography (from ancient greek κίνημα, kìnema "movement" and γράφειν, gràphein "to write") is the science or art of motion-picture photography by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as film stock.Cinematographers use a lens to focus reflected light from objects into a real image that is transferred to some image sensor or light-sensitive material inside a movie camera. These exposures are created sequentially and preserved for later processing and viewing as a motion picture. Capturing images with an electronic image sensor produces an electrical charge for each pixel in the image, which is electronically processed and stored in a video file for subsequent processing or display. Images captured with photographic emulsion result in a series of invisible latent images on the film stock, which are chemically "developed" into a visible image. The images on the film stock are projected for viewing the motion picture.

Cinematography finds uses in many fields of science and business as well as for entertainment purposes and mass communication.

DMX512

DMX512 (Digital Multiplex) is a standard for digital communication networks that are commonly used to control stage lighting and effects. It was originally intended as a standardized method for controlling light dimmers, which, prior to DMX512, had employed various incompatible proprietary protocols. It soon became the primary method for linking controllers (such as a lighting console) to dimmers and special effects devices such as fog machines and intelligent lights. DMX has also expanded to uses in non-theatrical interior and architectural lighting, at scales ranging from strings of Christmas lights to electronic billboards. DMX can now be used to control almost anything, reflecting its popularity in theaters and venues.

DMX512 employs EIA-485 differential signaling at its physical layer, in conjunction with a variable-size, packet-based communication protocol. It is unidirectional.

DMX512 does not include automatic error checking and correction, and so is not an appropriate control for hazardous applications, such as pyrotechnics or movement of theatrical rigging. False triggering may be caused by electromagnetic interference, static electricity discharges, improper cable termination, excessively long cables, or poor quality cables.

Electric light

An electric light is a device that produces visible light from electric current. It is the most common form of artificial lighting and is essential to modern society, providing interior lighting for buildings and exterior light for evening and nighttime activities. In technical usage, a replaceable component that produces light from electricity is called a lamp. Lamps are commonly called light bulbs; for example, the incandescent light bulb. Lamps usually have a base made of ceramic, metal, glass or plastic, which secures the lamp in the socket of a light fixture. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap.

The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor.

Before electric lighting became common in the early 20th century, people used candles, gas lights, oil lamps, and fires. English chemist Humphry Davy developed the first incandescent light in 1802, followed by the first practical electric arc light in 1806. By the 1870s, Davy's arc lamp had been successfully commercialized, and was used to light many public spaces. Efforts by Swan and Edison

led to commercial incandescent light bulbs becoming widely available in the 1880s, and by the early twentieth century these had completely replaced arc lamps.The energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern electric lighting is powered by centrally generated electric power, but lighting may also be powered by mobile or standby electric generators or battery systems. Battery-powered light is often reserved for when and where stationary lights fail, often in the form of flashlights, electric lanterns, and in vehicles.

Gas lighting

Gas lighting is production of artificial light from combustion of a gaseous fuel, such as hydrogen, methane, carbon monoxide, propane, butane, acetylene, ethylene, or natural gas.

The light is produced either directly by the flame, generally by using special mixes of illuminating gas to increase brightness, or indirectly with other components such as the gas mantle or the limelight, with the gas primarily functioning as a fuel source.

Before electricity became sufficiently widespread and economical to allow for general public use, gas was the most popular method of outdoor and indoor lighting in cities and suburbs. Early gas lights were ignited manually, but many later designs are self-igniting.

Gas lighting today is generally used for camping, where the high energy density of a hydrocarbon fuel, combined with the modular nature of canisters (a strong metal container) allows bright and long lasting light to be produced cheaply and without complex equipment. In addition, some urban historical districts retain gas street lighting, and gas lighting is used indoors or outdoors to create or preserve a nostalgic effect.

Gaslighting

Gaslighting is a form of psychological manipulation that seeks to sow seeds of doubt in a targeted individual or in members of a targeted group, making them question their own memory, perception, and sanity. Using persistent denial, misdirection, contradiction, and lying, it attempts to destabilize the victim and delegitimize the victim's belief.Instances may range from the denial by an abuser that previous abusive incidents ever occurred up to the staging of bizarre events by the abuser with the intention of disorienting the victim. The term owes its origin to the 1938 Patrick Hamilton play Gaslight and its 1940 and 1944 film adaptations, in which a man dims the gas lights in his home and then persuades his wife that she is imagining the change. The term has been used in clinical and research literature, as well as in political commentary.

Headlamp

A headlamp is a lamp attached to the front of a vehicle to light the road ahead. Headlamps are also often called headlights, but in the most precise usage, headlamp is the term for the device itself and headlight is the term for the beam of light produced and distributed by the device.

Headlamp performance has steadily improved throughout the automobile age, spurred by the great disparity between daytime and nighttime traffic fatalities: the US National Highway Traffic Safety Administration states that nearly half of all traffic-related fatalities occur in the dark, despite only 25% of traffic travelling during darkness.Other vehicles, such as trains and aircraft, are required to have headlamps. Bicycle headlamps are often used on bicycles, and are required in some jurisdictions. They can be powered by a battery or a small generator mechanically integrated into the workings of the bicycles.

Incandescent light bulb

An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated to such a high temperature that it glows with visible light (incandescence). The filament is protected from oxidation with a glass or fused quartz bulb that is filled with inert gas or a vacuum. In a halogen lamp, filament evaporation is slowed by a chemical process that redeposits metal vapor onto the filament, thereby extending its life.

The light bulb is supplied with electric current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections.

Incandescent bulbs are manufactured in a wide range of sizes, light output, and voltage ratings, from 1.5 volts to about 300 volts. They require no external regulating equipment, have low manufacturing costs, and work equally well on either alternating current or direct current. As a result, the incandescent bulb is widely used in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting.

Incandescent bulbs are much less efficient than other types of electric lighting; incandescent bulbs convert less than 5% of the energy they use into visible light, with standard light bulbs averaging about 2.2%. The remaining energy is converted into heat. The luminous efficacy of a typical incandescent bulb for 120 V operation is 16 lumens per watt, compared with 60 lm/W for a compact fluorescent bulb or 150 lm/W for some white LED lamps.Some applications of the incandescent bulb (such as heat lamps) deliberately use the heat generated by the filament. Such applications include incubators, brooding boxes for poultry, heat lights for reptile tanks, infrared heating for industrial heating and drying processes, lava lamps, and the Easy-Bake Oven toy. Incandescent bulbs typically have short lifetimes compared with other types of lighting; around 1,000 hours for home light bulbs versus typically 10,000 hours for compact fluorescents and 30,000 hours for lighting LEDs.

Incandescent bulbs have been replaced in many applications by other types of electric light, such as fluorescent lamps, compact fluorescent lamps (CFL), cold cathode fluorescent lamps (CCFL), high-intensity discharge lamps, and light-emitting diode lamps (LED). Some jurisdictions, such as the European Union, China, Canada and United States, are in the process of phasing out the use of incandescent light bulbs while others, including Colombia, Mexico, Cuba, Argentina and Brazil, have prohibited them already.

LED lamp

An LED lamp or LED light bulb is an electric light for use in light fixtures that produces light using one or more light-emitting diodes (LEDs). LED lamps have a lifespan many times longer than equivalent incandescent lamps, and are significantly more efficient than most fluorescent lamps, with some LED chips able to emit up to 303 lumens per watt (as claimed by Cree and some other LED manufacturers). However, LED lamps require an electronic LED driver circuit when operated from mains power lines, and losses from this circuit mean the efficiency of the lamp is lower than the efficiency of the LED chips it uses. The most efficient commercially available LED lamps have efficiencies of 200 lumens per watt (Lm/W). Commercially available LED chips have efficiencies of over 220 Lm/W. The LED lamp market is projected to grow by more than twelve-fold over the next decade, from $2 billion in the beginning of 2014 to $25 billion in 2023, a compound annual growth rate (CAGR) of 25%. As of 2016, LEDs use only about 10% of the energy an incandescent lamp requires.Similar to incandescent lamps (and unlike most fluorescent lamps), LEDs come to full brightness immediately with no warm-up delay. Frequent switching on and off does not reduce life expectancy as with fluorescent lighting. Light output decreases gradually over the lifetime of the LED (see Efficiency droop section).

Some LED lamps are made to be a directly compatible drop-in replacement for incandescent or fluorescent lamps. LED lamp packaging may show the light outpur in lumens, the power consumption in watts, the color temperature in Kelvin or a colour description such as "warm white", "cool white" or "daylight", the operating temperature range, and sometimes the equivalent wattage of an incandescent lamp delivering the same output in lumens.

The directional emission characteristics of LEDs affect the design of lamps. While a single power LED may produce as much light output as an incandescent lamp using several times as much power, in most general lighting applications multiple LEDs are used. This can form a lamp with improved cost, light distribution, heat dissipation and possibly also color-rendering characteristics.

LEDs run on direct current (DC), whereas mains current is alternating current (AC) and usually at much higher voltage than the LED can accept. LED lamps can contain a circuit for converting the mains AC into DC at the correct voltage. These circuits contain rectifiers, capacitors, and may have other active electronic components, which may also permit the lamp to be dimmed. In an LED filament lamp, the driving circuit is simplified because many LED junctions in series have approximately the same operating voltage as the AC supply.

Light-emitting diode

A light-emitting diode (LED) is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. This effect is called electroluminescence. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device.Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics. The first visible-light LEDs were of low intensity and limited to red. Modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with high light output.

Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Recent developments have produced white-light LEDs suitable for room lighting. LEDs have led to new displays and sensors, while their high switching rates are useful in advanced communications technology.

LEDs have many advantages over incandescent light sources, including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. Light-emitting diodes are used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes, lighted wallpaper and medical devices.Unlike a laser, the color of light emitted from an LED is neither coherent nor monochromatic, but the spectrum is narrow with respect to human vision, and functionally monochromatic.

Light pollution

Light pollution, also known as photopollution, is the presence of anthropogenic light in the night environment. It is exacerbated by excessive, misdirected or obtrusive uses of light, but even carefully used light fundamentally alters natural conditions. As a major side-effect of urbanization, it is blamed for compromising health, disrupting ecosystems and spoiling aesthetic environments.

Lighting control system

A lighting control system is an intelligent network based lighting control solution that incorporates communication between various system inputs and outputs related to lighting control with the use of one or more central computing devices. Lighting control systems are widely used on both indoor and outdoor lighting of commercial, industrial, and residential spaces. Lighting control systems serve to provide the right amount of light where and when it is needed.Lighting control systems are employed to maximize the energy savings from the lighting system, satisfy building codes, or comply with green building and energy conservation programs. Lighting control systems are often referred to under the term Smart Lighting.

Lighting designer

A theatre lighting designer (or LD) works with the director, choreographer, set designer, costume designer, and sound designer to create the lighting, atmosphere, and time of day for the production in response to the text, while keeping in mind issues of visibility, safety, and cost. The LD also works closely with the stage manager or show control programming, if show control systems are used in that production. Outside stage lighting, the job of a Lighting Designer can be much more diverse and they can be found working on rock and pop tours, corporate launches, art installation and on massive celebration spectaculars, for example the Olympic Games opening and closing ceremonies.

Philips

Koninklijke Philips N.V. (literally Royal Philips, stylized as PHILIPS) is a Dutch multinational technology company headquartered in Amsterdam, one of the largest electronics companies in the world, currently focused in the area of healthcare and lighting. It was founded in Eindhoven in 1891 by Gerard Philips and his father Frederik, with their first products being light bulbs. It was once one of the largest electronic conglomerates in the world and currently employs around 74,000 people across 100 countries. The company gained its royal honorary title in 1998 and dropped the "Electronics" in its name in 2013.Philips is organized into two main divisions: Philips Consumer Health and Well-being (formerly Philips Consumer Electronics and Philips Domestic Appliances and Personal Care) and Philips Professional Healthcare (formerly Philips Medical Systems). The lighting division was spun off as a separate company, Signify N.V. (formerly Philips Lighting prior to 2018). The company started making electric shavers in 1939 under the Philishave brand, and post-war they developed the Compact Cassette format and co-developed the Compact Disc format with Sony, as well as numerous other technologies. As of 2012, Philips was the largest manufacturer of lighting in the world as measured by applicable revenues.

Philips has a primary listing on the Euronext Amsterdam stock exchange and is a component of the Euro Stoxx 50 stock market index. It has a secondary listing on the New York Stock Exchange. Acquisitions include that of Signetics and Magnavox. They also have had a sports club since 1913 called PSV Eindhoven.

Runway

According to the International Civil Aviation Organization (ICAO), a runway is a "defined rectangular area on a land aerodrome prepared for the landing and takeoff of aircraft". Runways may be a man-made surface (often asphalt, concrete, or a mixture of both) or a natural surface (grass, dirt, gravel, ice, or salt).

Stage lighting

Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts. Several different types of stage lighting instruments are used in this discipline. In addition to basic lighting, modern stage lighting can also include special effects, such as lasers and fog machines. People who work on stage lighting are commonly referred to as lighting technicians or lighting designers.

The equipment used for stage lighting (e.g., cabling, dimmers, lighting instruments, controllers) are also used in other lighting applications, including corporate events, concerts, trade shows, broadcast television, film production, photographic studios, and other types of live events. The personnel needed to install, operate, and control the equipment also cross over into these different areas of "stage lighting" applications.

Strand Lighting

Strand Lighting is an international theatre and television lighting company founded in 1914 in London's West End that supplies lighting fixtures and controls for the entertainment industry. Strand's products have been used on countless theatre productions and TV shows worldwide.

Street light

A street light, light pole, lamppost, street lamp, light standard, or lamp standard is a raised source of light on the edge of a road or path. When urban electric power distribution became ubiquitous in developed countries in the 20th century, lights for urban streets followed, or sometimes led.

Many lamps have light-sensitive photocells that activate automatically when light is or is not needed: dusk, dawn, or the onset of dark weather. This function in older lighting systems could have been performed with the aid of a solar dial. Many street light systems are being connected underground instead of wiring from one utility post to another.

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