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Numbers to know: DOE answers your lighting questions

mailto:ecdotcom@gmail.com”>By Joe Salimando

The U.S. Department of Energy (DOE) says fewer than 7 billion lamps were installed in stationary applications in 2001—increasing to more than 8 billion as of 2010.

Those numbers are according to the 2010 Lighting Market Characterization report the DOE posted this year. Considering how important lighting is to just about every electrical distributor, you might characterize this report as a must-read.

Obvious question answered

How did we add more than 1 billion places to put lamps in 10 years? The DOE said the increase in the number of households was one big reason. Also, the national average of sockets-per-household went from 43 in 2001 to 51 in 2010.

Characterize this

Above: Table from the DOE’s 2010 Lighting Market Characterization report

The table above is helpful in looking at the graphic below. While they do not convey the same information, they do complement each other.

Only a bit more efficient

You’ve heard a lot about more-efficient lighting, but what has happened? According to the DOE, “Across all sectors the lighting stock has become more efficient, with the average system efficacy of installed lighting increasing from 45 lumens per Watt in 2001 to 58 lumens per Watt in 2010.

“This rise in efficacy is largely due to two major technology shifts; the move from incandescent to compact fluorescent lamps (CFLs) in the residential sector, and the move from T12 to T8 and T5 fluorescent lamps in the commercial and industrial sectors.”

How many buildings?

Skepticism about government numbers—especially the inflation and employment figures—can be justified. Perhaps that’s why DOE’s report starts with a lengthy section on methodology.

That’s not relevant here, but the information below on how many buildings there are there in the United States and how much floor space is under roof, is of interest.

Energy use

Another graphic in the DOE’s report shows terawatt-hours of electricity consumed by lighting. Note that a terawatt-hour is one trillion watts.

The DOE said the United States consumed 700 terawatt-hours of electricity for lighting in 2010. Here’s the breakdown, which is also shown in the first table above:

  • Commercial buildings: 349 TWh
  • Residential: 175 TWh
  • Outdoor: 118 TWh
  • Industrial: 58 TWh

Table 4.8, which fills a page, provides details on which type of lighting consumed how many terawatt-hours and in which applications. For example, the biggest single consumer of electricity is the four-foot T8 fluorescent lamp, which consumed 123 TWh in 2010. Coming in fourth was the T12 four-footer, at 81 TWh.

Much more information

There’s plenty to glean from this report, including one final table featured below, that includes helpful information on the estimated inventory of lamps.

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