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Tell Congress that Lighting Ain’t Simple

October 1, 2010

There’s more to lighting than, “how many people does it take to change a light bulb”?

People striving to improve energy efficiency often over-simplify lighting, and use jokes for that purpose.

Parents, for good reason, used to tell their children to read where the lighting was good. Even in a home, there are some basic scientific rules that apply to lighting.

Industrial and commercial lighting installations are designed to provide the amount of light required to perform tasks efficiently and safely, and these same rules apply to homes.

Standards have been established for light levels on surfaces under different applications.

Machine tool surfaces require 100-foot candles as do desk tops. Reading also requires 100-foot candles on surfaces. Some precision applications require much higher levels of lighting, while parking lots may only require 15-foot candles on the parking lot floor.

A person knitting or crocheting may require more than 100-foot candles to properly see the work they are doing.

Kitchen surfaces require more lighting than dining room surfaces.

The Illuminating Engineering Society has published tables showing recommended light levels for various tasks.

Reducing the recommended light levels can impede productivity and threaten safety.

Clerestories, or similar architectural features used in buildings to provide for sunlight, may not supply enough light on working surfaces, especially when the windows get dirty or on cloudy days.

Clerestories in factory buildings were eliminated because of poor lighting, and the cost of washing the windows.

Another consideration when selecting lighting is the amount of light, in foot candles, that reaches a surface is determined by the square of the distance from the light source.

This is why fluorescent lighting isn’t suitable for use in factory high bays. High intensity discharge lighting is usually used for these applications.

Homes with twenty-foot high ceilings will require more recessed light fixtures than rooms with eight-foot high ceilings – or bulbs having higher Lumen ratings. When converting incandescent floodlights (R40 ceiling lights) to fluorescents, it’s important to know the Lumen output, and not just the wattage equivalence.

The Lumen output determines the amount of light, in foot-candles, on surfaces.

The same is true when converting to LEDs.

The color of light sometimes plays a role in deciding which light source to use in an application. High pressure sodium vapor street lights have, until now, used the least amount of electricity, but give off a yellowish color that affects how objects are seen at night.

Some have said that high pressure sodium street lights do not provide sufficient brightness to allow people to adequately see objects in or near the roadway.

Color rendering can be important where true-colors are wanted, such as in a dressing area where make-up is applied. Some types of lighting will give people a sallow look.

A graphics studio or art gallery will want true colors and will need to pay attention to color rendering. It may be that incandescent lighting would be best for such an application. The color temperature of incandescent 100-watt bulbs is around 2850K. Fluorescents have difficulty emulating this temperature. With the manufacture of incandescent bulbs being outlawed it will be necessary to find an alternative light source that approaches incandescent in the rendering of true colors.

Beginning sometime in 2011 new labels will be on packaging showing a color rendering index (CRI). Unfortunately, it appears as though 2700K is considered a 100% CRI, but this is already at the lower end of acceptable incandescent color temperatures: Color rendering of the bulbs being purchased will likely be poorer than typical incandescent bulbs regardless of the rating on the package. Any color temperature below 2700K will provide even worse color rendering.

Environmental extremists pushed Congress to ban incandescent bulbs so as to reduce CO2 emissions. Once again, the fear of anthropogenic global warming has distorted the market place – and common sense.

The ban on incandescent bulbs has had negative consequences.

Virtually all compact fluorescent lamps (CFLs) are made in China with the remainder made elsewhere in Asia, while many incandescent bulbs had been made in the United States.

Switching to CFLs from incandescent bulbs has increased our negative balance of payments, mostly in favor of China.

GE and Sylvania had several lamp and glass plants in the United States, some of which have been closed. While the number of workers who are out of a job because of these plant closings is small, banning incandescent bulbs has cost Americans their jobs.

These lost jobs weren’t lost because of competition, they were mandated by Congress.

The law prohibiting the manufacture of incandescent light bulbs will improve energy efficiency, but may also result in lighting that is not appropriate for many applications.

In my view, people should be allowed to choose the light source that suits them best. They should decide whether energy efficiency or color or safety is more important to them and not have Big Brother make the decision for them.

2 Comments leave one →
  1. Alan Simpson permalink
    June 8, 2012 12:01 pm

    Although I generally agree with most of the points you make regarding lighting, the following statement you made in your blog is flawed:

    “Another consideration when selecting lighting is the amount of light, in foot candles, that reaches a surface is determined by the square of the distance from the light source.
    This is why fluorescent lighting isn’t suitable for use in factory high bays. High intensity discharge lighting is usually used for these applications.”

    Fluorescent lamp, ballast and fixture technology advances that have occurred over the last decade make the fluorescent high bay fixture the best option for most factory environments. A 4-lamp T5HO (54-watt) fluorescent high bay fixture equipped with 80+ CRI, 5000 Kelvin lamps will consume approximately 234 input watts and produce 20,000 lumens, approximately 85 lumens per watt consumed. This lumen per watt output plus the 850 color lamp, which provides near daylight color, equals any LED, and far exceeds any High intensity discharge lamp available. If you are addressing pure lumen output, your statement is somewhat correct, but when you take spectral output into consideration (pupil lumens) you find that approximately 30% of the light emitted by an HID source is outside of the spectrum of the human eye, therefore useless in real life analysis. The real advantage the fluorescent high bay fixture offers over the HID is the ability to spread light at the work plane. The HID is a point source light that creates hot spots, therefore providing very poor light uniformity over the entire facility environment. The fluorescent high bay fixture spreads the emitted light approximately 45 degrees from each side of the fixture so that there is light overlap at the work plane. This overlap creates a very uniform coverage over the entire facility. Other reasons not to use HID technology include energy consumption (in some cases the fluorescent high bay consumes up to 50% less energy than the HID), heat creation (the fluorescent will create approximately 60% of the heat of an HID – which is very important in controlled environments), lumen depreciation over the life of the lamp, lamp volatility, color rendering and lamp life.

    • June 12, 2012 11:46 am

      Thanks for the information. Sorry to take so long to respond to your information.
      I’m always open to learning more about energy technologies.
      I must admit that I have never seen fluorescent lighting used at heights of 25 feet or more.
      You describe a lamp that appears to be able to do the job at those levels, so i would encourage anyone interested in this application to investigate it further.
      Technologies are always changing, so new and better products are bound to evolve over time.

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