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Originally featured on BroadcastEngineering.com
Dec 28

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12/28/2009 6:00 AM  RssIcon

green-lighting.jpgWhen it comes to saving money, broadcasters are not much different from the average consumer. They say, “sign me up.” It’s the details that matter. For broadcasters, maximum operational savings (OPEX) typically first come from installing a new transmitter. The power saving from a new solid-state or liquid-cooled transmitter is typically significant. With increased efficiency, the ROI on a new transmitter may be as little as three years. But, given that most U.S. broadcasters have already invested in new transmission technology, where else can a TV station engineer look to save money? Begin with lighting.

Where there is light — there is heat

Lighting is a surprisingly significant component in the OPEX of a facility. When electricity costs .02/KWh, it might not matter if the conference room lights are left on 24/7. Now that power costs may be 10 times that amount, it matters a great deal.

Before we look at general office and operational areas, let’s first briefly look at studio lighting. Measured on a per square foot basis, studio lighting has historically been a significant consumer of electrical power. A large studio using tungsten-halogen, or quartz, lamps can consume hundreds of kilowatts of power. In addition, the heat produced by the tungsten lamps will require thousands of BTUs of air-conditioning and a significant amount of power. The bottom line, as we’ll show later, says creating heat along with light is not an efficient way to illuminate a studio.

122809_table1.jpgLet’s compare lighting technology, and we’ll use the common incandescent lamp as a reference. The common incandescent lamp has an efficacy of 12 lumens/watt. It has a color rendering index of 1A and produces a warm color temperature between 2500K–2700K. Lamp life is short, often 1000 to 2000 hours. A comparison of various lamp types and their performance is shown in Table 1 to the right.

Halogen lamps

The common halogen lamp is one type of incandescent lamp. It uses a tungsten filament like a regular incandescent bulb. However, the bulb is filled with halogen gas. Tungsten atoms evaporate from the hot filament and move toward the cooler wall of the bulb. Tungsten, oxygen and halogen atoms combine at the bulb wall to form tungsten oxyhalide molecules. The molecules cool and return to the hot filament.

Halogen maps typically produce about 18 lumens/watt. They have a color temperature of 3K to 3.2K, which makes them good for studio lighting. Lamp life ranges from 2000 to 4000 hours. Disadvantages of these lamps include higher cost than tungsten lamps, and they produce more IR and UV light, which isn’t wanted in the studio. Plus, halogen lamps are difficult to handle. Depositing even a small amount of skin oil by touching the bulb during installation will cause it to prematurely fail — often with explosive results.

Fluorescent lighting

General-purpose fluorescent lamps are three to five times more efficient than standard incandescent lamps and can last about 10 to 20 times longer. The old-style F40T12 4ft fluorescent lamp produces 64 lumens/watt. The fluorescence occurs by passing electricity through a gas or metallic vapor to cause electromagnetic radiation at specific wavelengths according to the chemical constitution and the gas pressure within the tube.

A fluorescent tube operates under a low pressure of mercury vapor and without correction will emit a small amount of blue/green radiation, but the majority of radiation is in the UV range. The inside of the glass wall has a thin phosphor coating, selected to absorb the UV radiation and pass visible light. This process is approximately 50 percent efficient.

Fluorescent lights contain a small amount of mercury, typically 12mg. For this reason, care is required at disposal. See the accompanying sidebar article below, which provides additional information on the legalities of mercury disposal.

LED lighting

LED lamps are the latest addition to the list of energy-efficient light sources. While LED lamps emit visible light in a narrow spectral band, they can produce "white light." This is accomplished with either a red-blue-green array or a phosphor-coated blue LED lamp. LED lamps have long lives, typically lasting from 40,000 to 100,000 hours depending on the color.

LED retrofit products come in various forms including light bars, panels and screw-in LED lamps. Because LED lamps draw significantly less power, OPEX costs are reduced. And their much longer life means they have to be replaced less often.

LED lamps produce more light per watt than their incandescent cousins. A modern studio LED lighting grid can reduce power consumption by 90 percent. And because they produce almost no heat, they can reduce cooling costs.

LED fixtures can produce almost any array of color lights without color filters. This reduces fixture costs and permits remote adjustment. A companion feature is that LED lights can be dimmed without affecting colorimetry, which is not the case with tungsten lamps.

LED lighting is rugged. While this may not seem like an important aspect in studio applications, consider how many times a stage hand has dropped an expensive bulb in the studio. It’s an occupational hazard. Then there’s the environmental hazard of broken lamps; think mercury. LEDs have none of those drawbacks.

An LED caveat

The benefits of LED lighting come with some caveats. Most noticeable is that the fixture cost is higher than other solutions. Even so, ROI can be achieved in only a few years. And if electrical costs go up as predicted, the return on investment will occur even quicker and continue to pay benefits.

LED fixtures still require a proper operating environment. Should you mount an LED fixture directly next to a heat-producing quartz lamp, you risk shortening the life of the LED solution. The bottom line as far as heat for LEDs is concerned is if humans are comfortable, so too will be your LED lighting systems.

Finally, the quality of LED light (much like other fixtures) decays over time. The lamp may last for 50,000 hours. However, by 30,000 hours, the intensity and color rendering index may diminish by 10 percent to 20 percent.

Sidebar: Disposing of mercury-containing lamps — beware

Disposing of CFL and other mercury-containing lamps is increasingly being regulated. Each state has its own program for management of mercury-containing lamps. Most states have adopted and currently implement the federal Universal Waste Rule (UWR). You can learn about your state’s rules for hazardous waste lamps on the NEMA State-by-State Stringency Comparison chart.

Note that several states have regulations that are more stringent than the federal UWR. For example, all mercury-containing wastes are banned from landfills in Vermont regardless of whether they were disposed of by Conditionally Exempt Small Quantity Generators (CESQG), which basically means small business or households. New Hampshire does not have reduced requirements for CESQGs in its hazardous waste regulations. Businesses in Florida must dispose of less than 10 lamps to qualify for the CESQG reduced requirements.

Several other states (CA, CT, ME, MN, NY and RI) either ban the disposal of mercury-containing lamps or have limited the amount of lamps entering disposal facilities. Other states are contemplating similar bans. The EPA encourages you to check with your state to determine your regulatory requirements. For more information on hazardous substance disposal regulations specific to your state, contact your state environmental regulatory agency.

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