Light bulbs

From GLGI

Jump to: navigation, search

return to energy


Contents

Why It Matters

  • Compact fluorescent lights certified by Energy Star provide the same amount of light as their incandescent counterparts, but use one-quarter of the energy and last up to 10 times longer.
  • Replacing just a single bulb will keep half a ton of CO2 out of the atmosphere and save $30 in energy bills per year.

source: Switch Your Bulb and Save $30 on The Power Bill - Popular Mechanics

What You Can Do

Educate yourself about the various options available before purchasing new bulbs. Below we examine characteristics of bulbs so you'll understand the terminology, and then compare incandescents, CFL's and LED's, including their advantages and disadvantages.

Characteristics of light bulbs

Here are some of the primary characteristics of light bulbs.

  • Type: What is the technology that the lamp uses to produce the light. These include incandescent, florescent, halogen, LED, high/low pressure sodium, induction and more. The first four are currently the most available options for the home.
  • Color: How the light from the bulb looks to our eyes. It is measured as color temperature in Kelvin (K) and ranges from 'warm' (2500K) to 'cool' (5000K) and daylight (6000K) The 'warm' has a yellowish tint and the 'cool' has a blueish tint. All these are white light. Some decorative bulbs come in colors such as red, yellow, blue, green, etc., but this is a separate option. here is a very helpful color measurement chart when selecting your bulb color,
  • Shape/Base: This has two components: 1) the shape of the glass bulb (spiral, globe, spot, etc.) and 2) the size and shape of the base that gets screwed into the socket. The most common bulb is the A19 it fits your standard light fixture.
  • Energy (watts): The amount of energy a bulb uses to produce the light.
  • Brightness (lumens): The amount of light (brightness) the bulb emits. It is measures in lumens. In the lighting world, watts is often used as a surrogate for brightness (lumens), since the more energy that is used the brighter the light. Most bulbs brightness deteriorates over its life span.
  • Efficiency (efficacy): Calculated as units of light (output) per input energy (input.) This is measured in lumens per watt. The higher the efficiency the more light you get for each unit of energy. The lighting industry correctly refers to the "efficiency" of a lamp as the lamp's "efficacy." More info ...
  • Life expectancy: How long a bulb will last, measured in hours. This is the number of hours the bulb will stay lit. The higher the number the longer a bulb will last. People sometimes assume 1,000 hours per year or approximately 3 hours per day so they say a bulb will last 10 years, which is 10,000 hours
  • Instant On: A capability of having the bulb reaches its targeted light output immediately after it is switched on. All incandescents do this. Some Compact Florescent Lights (CFL's) do not.
  • Dimmable: A capability allowing you to modulate the brightness of a bulb with the wall switch. All incandescents and LEDs can do this. Other bulbs have to be designed to accommodate this feature.
  • 3-Way: A capability allowing you to select one of three brightness levels in the bulb. Both the bulb and the switch need to be designed to accommodate this feature.
  • Cost: How much a bulb costs to purchase.
  • Life Cycle Costs: How much a bulb costs for its entire life. This includes the cost of the initial purchase, plus the cost of the energy to operate. It may also include the labor cost of a maintenance person to change the light bulb. It almost never includes the disposal/recycling costs.
  • Health/Safety: How does the light quality effect the people and the environment.
  • Availability: How easy it is to purchase the bulb.
  • Carbon Emissions: This is the amount of carbon produced by the power plant to produce the energy to light the bulb. One CFL can prevent more than 450 pounds of emissions from a power plant over its lifetime.

Bulb Type Comparison

Incandescents

  • Shapes: Wide variety
  • Color: Warm (2700K), Cool (5000K) and natural (day) light (????K)
  • Brightness (lumens) / Energy (watts): Wide variety from 3 watts to 200 watts.
  • Efficiency: Low (ave 15 lumens/watt with range of 8 - 24 lumens/watt)... less than 10% of energy goes o creating light, the remainder goes into heat.
  • Life Expectancy: Typically 1,000 - 2,000 hours, but you can find 5,000 hour lamps
  • Instant On: Standard
  • Dimmable: Standard
  • 3 Way: Optional
  • Health/Safety: None?
  • Availability: Widely available now, will stop making them in 2012
  • Cost: Low initial costs; typical 60 watt bulb is $0.50
  • Life Cycle Costs: High cost - due to high energy costs and need to replace bulbs frequently
  • Carbon Emissions: High
  • Summary:
    • Strengths: low initial cost, high availability, wide variety, good light rendering, full spectrum color, always instant on, always dimmable,
    • Weaknesses:low efficiency + high carbon emissions, high life-cycle costs, increase cooling costs, not be available after 2012 in US,
    • Best Use: use where you seldom have the light on (closet, basement)
    • More info... Incandescent bulbs

Compact Florescent Lights (CFLs)

  • Shapes: Medium variety...getting more options every year
  • Color: Warm (2700K), Cool (5000K)...more options available each year
  • Brightness (lumens) / Energy (watts): Wide variety from 3 watts to 200 watts. (Conversion 2.5 watt CFL = 10 watt Incandescent.)
  • Efficiency: Higher (ave 60 lumens/watt with range of 45 - 83 lumens/watt) ... 4 times as efficient as incandescent
  • Life Expectancy: Typically 7,500 - 10,000 hours, but you can find 15,000 hour lamps
  • Instant On: Optional...often not mentioned on the package. Studies show that slow start-up can extend the life of the bulb.
  • Dimmable: Optional, need to specifically order it. Costs more.
  • 3 Way: Optional. Costs more.
  • Health/Safety: The traces of mercury require proper disposal (see your recycling center for guidelines), sometime a buzzing noise. They are now making low mercury (1 mg) bulbs (e.g. Neolite.)
  • Availability: Widely available now.
  • Cost: Higher initial costs: Typical 60 watt bulb is around $4.50. But prices are falling quickly.
  • Life Cycle Costs: Lower cost - due to lower energy costs and longer life
  • Summary:
    • Advantages: high availability of basic bulbs, rapidly increasing availability of specialty bulbs, higher efficiency, longer life, lower life-cycle costs, lower carbon emissions
    • Disadvantages: higher initial costs, disposal requirements, need to specify instant-on option, sometimes noise, variability in color quality, don't work well for spot lighting, currently don't work well with dimmer switches
    • Best Use: Through-out the home.
    • More info... CFL light bulbs vs traditional bulbs - what is the savings?

Light Emitting Diodes (LEDs)

  • Shapes: Limited variety... just now getting more options
  • Color: Most are Cool (5000K)...more options available each year
  • Brightness (lumens) / Energy (watts): Very limited; lower range of brightness (Conversion 1.2 watt LED = 10 watt Incandescent.)
  • Efficiency: Higher (ave 30 lumens per watt)...two times CFLs and eight times incandescents.
  • Life Expectancy: Very long; Typically 50,000 - 60,000 hours
  • Instant On: Standard
  • Dimmable: Standard, although most are low brightness already.
  • 3 Way: Not available at this time (Jan 2008)
  • Health/Safety: (Needs further investigation)
  • Availability: Very limited
  • Cost: Much higher initial costs: Typical 60 watt bulb is around $25.00.
  • Life Cycle Costs: Lower cost - due to lower energy costs and much longer life
  • Summary:
    • Advantages: higher efficiency, very long life, lower life-cycle costs, lower carbon emissions, generate many colors of light
    • Disadvantages: much higher initial cost, very limited shapes and features, limited availability, become less efficient if you diffuse the light over a wide area, expensive to dissipate their heat
    • Best Use: use in hard to reach areas where long life is an advantage or where you leave lights on..night lights.
    • More info... LED bulbs

Halogen Light Bulbs

Tungsten Halogen Light Bulbs (sometimes called quartz halogen) are in essence improved incandescent lights. They have many of the same qualities--many shapes and uses but are somewhat more efficient than standard incandescents. They are however far less efficient than CFLs.

The difference between the two is in the composition of the glass envelope and the gas inside the envelope. A standard incandescent bulb has a heat sensitive glass envelope that contains an inert gas mixture, usually nitrogen-argon. When the tungsten filament is heated it evaporates and deposits metal on the cooler glass envelope (this is why incandescent bulbs appear black at the end of life). This process requires incandescent bulb filaments to be heated less than optimally to give the bulb a reasonable life. The lower filament temperature gives incandescent bulbs their typical orange-yellow, warm appearing light. Halogen light bulbs utilize a fused quartz envelope ("capsule") allowing for higher temperatures. Inside the quartz envelope is a vapor, originally iodine, now usually bromine. The tungsten filament evaporates as usual but the higher temperatures are sufficient to cause the tungsten to mix with the vapor instead of depositing on the envelope. Some of the evaporated tungsten is re-deposited on the filament. The combination of this "regenerative cycle" and higher filament temperature results in a bulb that has a longer life and slightly higher efficiency than standard incandescent bulbs. The higher temperature filament also produces the "white" light often associated with halogen bulbs. [1]

  • Shapes: Many, varied, from very small with pin-end base to large flood lights--very similar to incandescent.
  • Color: Color temperature of around 3000 degrees K (in the midst of the warm color range).[2] Halogen lights contain more blue and green than standard incandescent lights so appear to be whiter. They fall high on the Color Rendering Index (around 90 out of 100)[3]
  • Brightness: Halogen light bulbs produce a large amount of light from a very small area. They have excellent beam control.
  • Energy: Use low voltage system that operates efficiently at lower wattages but some popular halogen bulbs are as high as 300-watts and newer compact fluorescents can provide the same light on far less wattage [4] Look for A-line halogens that are lower wattage.
  • Efficiency: better than incandescents, not as good as compact fluorescents.
  • Life Expectancy: Anywhere between 2000-6000 hours. The longer life expectancy bulbs typically have an infrared-reflective coating (sometimes called HIR)[5] These lamps trap wasted invisible infrared emissions and redirect them to produce more visible light. This results in a more than 40% efficiency gain over standard halogens, while providing the same amount of light output, beam control, and compactness as the standard halogen.[6]
  • Instant On: yes
  • Dimmable: yes
  • Health/Safety: Halogens burn hotter than other lights, so they must be kept at least six inches away from all flammable materials. They typically come with a glass shield to prevent problems, but it is still a good idea to keep them away from flammable items.
  • Availability: Widely available.
  • Cost: More expensive than incandescent.
  • Life Cycle Costs: Didn't find information on this
  • Summary: Halogen light bulbs were once thought to be the lighting of the future. They have been far surpassed by CFLs as their performance has improved.
  • Advantages: Widely available, good color rendering, excellent beam control.
  • Disadvantages: They burn hotter than other bulbs, creating a possible fire hazard. They are not as efficient as CFLs
  • Best Use: Spotlights, Reading light
  • More Information: See links above.

Where To Buy Bulbs

Online

Locally in Southeast Michigan

The Mercury Issue with CFL's

Compact fluorescent bulbs contain small amounts of mercury, which has generated controversy as to their use and disposal. We have researched the issues and encourage you to look at our light bulbs and mercury page.

Recycling Light Bulbs

  • If you are replacing your incandescent bulbs with CFL's and are wondering what to do with your still useable incandescents, look at our recycling light bulbs page for ideas.
  • Any CFL's that are no longer useable will have to be recycled at the Hazardous Waste Department of your local community recycling center. Those of us in Southeast Michigan can contact SOCCRA.

References

Resources

See Also

Our Stories

Retrieved from "http://www.glgi.org/mediawiki/index.php?title=Light_bulbs"
Personal tools