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
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.
Above: Table from the DOE’s 2010 Lighting Market
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.
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
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.
Another graphic in the DOE’s report shows terawatt-hours of
electricity consumed by lighting. Note that a terawatt-hour is one trillion
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
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