Lighting Information

Approximately half of energy used for lighting is wasted on empty rooms or as heat produced by inefficient bulbs and lighting fixtures.

More Statistics!

Incandescent Bulbs
Halogen Bulbs
Fluorescent Tubes
Compact Fluorescent
Ballasts
Hight Intensity Discharge (HID)
Light Emitting Diode
Color Temperature

Incandescent Bulbs

Standard incandescent light bulbs produce light by passing an electric current through a filament in a vacuum or gas-filled bulb. Incandescent light bulbs have low initial cost, good color rendition and excellent optical control.

A Short History
The first incandescent lamp was introduced on October 21,1879, by Thomas Edison. The original bulb used a carbon filament in a bulb containing a vacuum. Modern bulbs now primarily use tungsten filaments with a gas fill instead of a vacuum, though bulbs using thin filaments and lower currents still utilize a vacuum because they function more efficiently.

The Filament
The filament acts as a resistor. An electric current passes through the filament, and resistance in the filament causes it to heat and incandesce. Filaments typically reach temperatures well over 2000 degrees Celsius.

Most of the energy consumed by the bulb is given off as heat, causing its Lumens per Watt (LPW) performance to be low. Because of the filament's high temperature, the tungsten tends to evaporate and collect on the sides of the bulb. The inherent imperfections in the filament causes it to become thinner unevenly. When a bulb is turned on, the sudden surge of energy can cause the filament to break, because the thin areas heat up so much faster than the rest of the filament, leading to bulb failure.

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Halogen Bulbs

Halogen light bulbs also use a filament; but because it is sealed in a pressurized capsule containing halogen gas, the lamp provides brighter, whiter light, longer service life and improved energy efficiency.

The halogen cycle describes a complex chemical interaction between tungsten, oxygen and a halide that makes tungsten halogen lamps possible. Incandescent lamps operate by using an electric current to heat a filament so that it glows. The material that evaporates from the hot filament builds up on the inner bulb-wall and darkens the lamp. This "lamp blackening" becomes even more severe when the filament is situated near the bulb-wall, as in thin tubular lamps. The halogen cycle prevents lamp blackening and extends the service life of the bulb.

The cycle works like this:

  1. Tungsten atoms evaporate from the hot filament and diffuse toward the cooler bulb wall. The filament temperature is about 3030º Celsius (or about 5480º Fahrenheit). The temperature at the bulb wall is about 730º C (or about 1340º F).
  2. Tungsten, oxygen and halogen atoms combine on or near the bulb-wall to form tungsten oxyhalide molecules. Bromine is now the most common halogen. Chlorine is used in some special photocopying lamps that operate only for brief intervals.
  3. Tungsten oxyhalides remain in a vapor phase at the bulb-wall temperatures and this vapor moves toward the hot filament. A combination of diffusion and convection currents are responsible for the movement.
  4. High temperatures near the filament break the tungsten oxyhalide molecules apart. The oxygen and halogen atoms move back toward the bulb wall and the tungsten atoms are re-deposited on the filament. The cycle then repeats.

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Fluorescent Tubes

In a fluorescent lamp, an electric arc passing between cathodes in a tube excites mercury vapor and other gases and produces UV radiant energy. A phosphor coating on the tube then converts this energy to visible light. Fluorescent lamps are very efficient and provide a wide range of color temperatures. Ballasts must be used to operate fluoresent tubes.

How does it work?
A fluorescent lamp is a gaseous discharge light source. Light is produced by passing an electric arc between tungsten cathodes in a tube filled with a low pressure mercury vapor and other gases. The arc excites the mercury vapor which generates radiant energy, primarily in the ultraviolet range. This energy causes the phosphor coating on the inside of the tube to fluoresce, converting the ultraviolet into visible light.

Electrical Requirements
To start the lamp, a high voltage surge is needed to establish an arc in the mercury vapor. Once the lamp is started, the gas offers a decreasing amount of resistance, which means that the current must be regulated to match this drop. Without regulation, the lamp would draw power unceasingly and would rapidly burn out. By using a ballast the starting voltage is provided and the subsequent flow of current to the lamp is controlled. Using a balanced lamp/ballast system extends lamp life, increases energy efficiency, improves color characteristics, and enhances luminous efficacy.

Phosphor Coatings
Fluorescent lamps offer more color options than any other lamp type. This is due to the phosphor coating on the inside of the tube. Halophosphor is the basic coating. Along with rare earth and triphosphor coatings a control over the generation of red, green and blue is achieved. This has enabled the development of high lumens per watt (LPW) lamps in a variety of color temperatures that feature excellent color quality and provide spectacular renditions of virtually all colors.

 

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Compact Fluorescent

Compact Fluoresent Lamps operate in the same way as larger fluoresent tubes. Some compact fluoresent lamps feature integral ballasts, which make it possible to use these products as direct replacements for inefficient incandesent light bulbs.

These lamps feature a narrow tube space (1/2 to 5/8 in diameter) that is doubled back on itself and terminated in a plastic base. Compact fluorescent lamps are small enough to replace incandescent lamps in diffuse source applications and therefore bring the increased efficiency of fluorescent technology to a much larger variety of fixtures. Lamps with an internal ballast can be used in a typical incandescent socket. Other lamps use an external magnetic or electronic ballast.

How does it work?
A fluorescent lamp is a gaseous discharge light source. Light is produced by passing an electric arc between tungsten cathodes in a tube filled with a low pressure mercury vapor and other gases. The arc excites the mercury vapor which generates radiant energy, primarily in the ultraviolet range. This energy causes the phosphor coating on the inside of the tube to fluoresce, converting the ultraviolet into visible light.

Electrical Requirements
To start the lamp, a high voltage surge is needed to establish an arc in the mercury vapor. Once the lamp is started, the gas offers a decreasing amount of resistance, which means that the current must be regulated to match this drop. Without regulation, the lamp would draw power unceasingly and would rapidly burn out. By using a ballast the starting voltage is provided and the subsequent flow of current to the lamp is controlled. Using a balanced lamp/ballast system extends lamp life, increases energy efficiency, improves color characteristics, and enhances luminous efficacy.

Phosphor Coatings
Fluorescent lamps offer more color options than any other lamp type. This is due to the phosphor coating on the inside of the tube. Halophosphor is the basic coating. Along with rare earth and triphosphor coatings a control over the generation of red, green and blue is achieved. This has enabled the development of high lumens per watt (LPW) lamps in a variety of color temperatures that feature excellent color quality and provide spectacular renditions of virtually all colors.

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Ballasts

The electronic arc in any fluorescent system is generated by a ballast. The ballast starts the lamp, then limits its operating current and provides power factor correction. Modern electronic ballasts perform these functions with great efficiency and provide other control functions as well.

What is the ballast's function?
A ballast serves to start a fluorescent or HID bulb by causing an arc to form inside the bulb. Once the bulb is lit, the current flowing through the bulb must be regulated to keep the arc operating at peak efficiency.

Magnetic vs. Electronic Ballasts
High frequency electronic ballasts operate bulbs more efficiently and eliminate the hum and visible flicker normally associated with standard magnetic ballasts. With respect to linear fluorescent lamps, electronic ballasts are designed to operate T8 fluorescent tubes, while older-style magnetic ballasts are designed to operate T12 fluorescent lamps.

Instant Start, Rapid Start, and Programmed Start Electronic Ballasts
Many ballasts feature instant start circuitry. Instant start ballasts are very efficient, leading to a reduction in energy costs. They have parallel circuitry that allows lamps to remain lit even after one lamp has failed. They use 1.5 to 2 watts less per lamp than rapid start electronic ballasts. Instant start ballasts also allow longer remote wiring distance, easier installation, and the capability to start lamps at 0ºF (versus 50ºF for rapid start). Programmed start ballasts heat the electrodes to their optimum operating temperature, before voltage is applied to start the lamp. This greatly reduces stress on the electrodes, and increases lamp life.

Safety
Ballasts should be installed and operated in compliance with the National Electronic Code, (NEC), Underwriters Laboratories Inc., (UL), requirements, and all applicable codes and regulations. As it is possible to come in contact with potentially hazardous voltages, only qualified personnel should perform ballast installation. All installation, inspection, and maintenance of lighting fixtures should be done with the power to the fixture turned off. The ballast case and fixture must ALWAYS be grounded in order to insure safety, proper start-up, and acceptable electromagnetic and radio frequency interference.

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High Intensity Discharge (HID)

In HID lamps, an arc passing between two cathodes in a pressurized tube causes various metallic additives to vaporize and release a large amount of light. All HID lamps offer outstanding energy efficiency and service life. Metal halide lamps also offer good to excellent CRI.

Basic Facts
There are three primary types of HID lamps: metal halide, sodium, and mercury vapor. HID technology is very similar to fluorescent technology: an arc is established between two electrodes in a gas filled tube which causes a metallic vapor to produce radiant energy. The major difference is that HID lamps can produce visible light without any phosphors. In addition, the electrodes are only a few inches apart and the gases in the tube are highly pressurized. The arc acquires an extremely high temperature, causing metallic elements within the gas atmosphere to vaporize and release massive amounts of radiant energy.

Electrical Requirements
A ballast is required in order to operate the HID lamp. Unlike fluorescent lamps, the ballast must be specifically designed for the lamp type and wattage being used. Also, the lamps require a warm-up period to achieve full light output, and in some cases require several minutes before they can be re-ignited after they are shut off.

Metal Halide
Metal Halide lamps offer high efficacy, excellent color rendition, long service life, and good lumen maintenance. They are used often in outdoor applications and in commercial interiors.

Sodium
High pressure sodium lamps are very energy efficient. Mercury and sodium vapors produce a yellow/orange light with extremely good lumens per watt performance. Although they tend to render colors poorly they have an exceptionally long service life, (up to 40,000 hours).

Mercury Vapor
Mercury vapor is the oldest HID technology. The light within the arc is bluish making it poor for rendering colors accurately. Because of this, a phosphor coating is sometimes applied to alter the color temperature and to improve color rendering.

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Light Emitting Diode (LED)

A light-emitting diode (LED) is a semiconductor diode that emits incoherent narrow-spectrum light when electrically biased in the forward direction of the p-n junction. This effect is a form of electroluminescence.

An LED is usually a small area source, often with extra optics added to the chip that shapes its radiation pattern. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or near-ultraviolet.

Most typical LEDs are designed to operate with no more than 30–60 milliwatts of electrical power. Around 1999, Philips Lumileds introduced power LEDs capable of continuous use at one watt. These LEDs used much larger semiconductor die sizes to handle the large power input. Also, the semiconductor dies were mounted to metal slugs to allow for heat removal from the LED die.

One of the key advantages of LED-based lighting is its high efficiency, as measured by its light output per unit power input. White LEDs quickly matched and overtook the efficiency of standard incandescent lighting systems. In 2002, Lumileds made 5-watt LEDs available with efficacy of 18–22 lumens per watt. For comparison, a conventional 60–100 watt incandescent lightbulb produces around 15 lumens/watt. However, note that standard fluorescent lights produce up to 100 lumens/watt.

In September 2003 a new type of blue LED was demonstrated by the company Cree, Inc. to give 24 mW at 20 mA. This produced a commercially packaged white light giving 65 lumens per watt at 20 mA, becoming the brightest white LED commercially available at the time, and over four times more efficient than standard incandescents. In 2006 they demonstrated a prototype with a record white LED efficacy of 131 lm/W at 20 mA. Also Seoul Semiconductor has plans for 135 lm/W by 2007 and 145 lm/W by 2008, which would be approaching an order of magnitude improvement over standard incandescents and better even than standard fluorescents. Nichia Corp. has developed a white light LED with efficacy of 150 lm/W at a forward current of 20 mA.

It should be noted that high-power (≥ 1 Watt) LEDs are necessary for practical general lighting applications. Typical operating currents for these devices begin at 350 mA. The highest efficiency high-power white LED is claimed by Philips Lumileds Lighting Co. with a luminous efficacy of 115 lm/W (350 mA).

Today, OLEDs operate at substantially lower efficiency than inorganic (crystalline) LEDs. The best efficacy of an OLED so far is about 10% of the theoretical maximum of 683, so about 68 lm/W. These claim to be much cheaper to fabricate than inorganic LEDs, and large arrays of them can be deposited on a screen using simple printing methods to create a color graphic display.

Source: Wikipedia

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Color Temperature

Color Temperature describes certain color characteristics of light sources. A "blackbody" is a theoretical object which is a perfect radiator of visible light. As the actual temperature of this blackbody is raised, it radiates energy in the visible range, first red, changing to orange, white, and finally bluish white.

Color temperature describes the color of a light source by comparing it to the color of a blackbody radiator at a given temperature. For example, the color appearance of a halogen lamp is similar to a blackbody radiator heated to about 3000 degrees Kelvin. Therefore it is said that the halogen lamp has a color temperature of 3000 degrees K- which is considered to be a warm color temperature. The hotter the blackbody, the cooler the color temperature!(Note: The Kelvin temperature scale uses the same size degree as the centigrade scale, but its zero point is at absolute zero, or -273 degrees C). Sunlight can be "warm" or "cool" depending on the time of day and the ambient conditions.

Though color temperature is not a measure of the physical temperature of the light source, it does correspond to the physical temperature of the blackbody radiator when the color appearance is the same as the source being tested.

Most bulbs have a specific color temperature rated light output, which is shown in the bulb's specifications. For best aesthetics the bulbs in a multi-bulb fixture or matching adjacent light fixtures should be of matched color temperatures unless for a specific reason. This error typically happens when bulbs are replaced without an understanding or lack of controls when purchasing replacement bulbs. This error can be easily rectified by using the proper bulbs to be used in each specified area as documented in the self-audit created using the EcoGreen Award™ process.

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