TORRANCE, CA — October 10, 2001 — Hillsboro, Oregon faced an ongoing problem: its Arch, the embodiment of civic pride,
had become an eyesore in the city’s nightscape. Marring the grandeur
of 90-foot Arch was the failure of many of the 580 incandescent lights adorning
its contours. The burnt-out bulbs prompted complaints from city residents.
With an average operating life of just 14 months, replacing the failed lights
was a frequently needed chore, but one not often nor easily performed due
to the logistics involved.
Compounding the problem was the light rail line running beneath the Arch,
and the transit authority’s reluctance to stop rail service, reroute
trains and inconvenience commuters to enable maintenance crews to relamp
the Arch. Two or three times a year, the transit authority gave city maintenance
an hour, usually at 2 A.M., to replace any failed incandescent bulbs. Not
only was the time less than ideal, it was costly. Overtime labor expenditures
for a relamping crew of four and a flag crew of two, amounted to about $1000
plus $1100 for renting a 100-foot lift truck.
With goals of minimizing the frequency with which the Arch had to be relamped
and reducing maintenance costs, Hillsboro Facilities Manager Mike Klein
searched for an alternative to the incandescent lights. “We considered
using flood lights to wash the structure in color, but then started to research
something with a longer life. We knew about LED technology, so we looked
for and found a company that made LED bulbs that we could use on the Arch.”
Mike contacted LEDtronics (www.ledtronics.com), a premier light emitting
diode (LED) lamp manufacturer located in Torrance, California. LEDtronics’ answer:
a four-LED cluster 470nm Blue LED (LEDtronics part number WN304CPB1KB-24VAC-SLD)
that uses a tenth of power required by an equivalent incandescent lamp and,
most importantly, operates for 11 years. An LED is a diode chip made from
semiconductor materials, usually from groups III and IV of the periodic
table. When current flows across the junctions of the different materials
the energy level in the semiconductor changes. This change in energy generates
photons, some of which are emitted as light. The color wavelength of the
light is determined by the composition of the semiconductor material and
is independent of the lens color.
With an average 100,000-hour operating life, LEDs last 30 – 50 times
longer than any incandescent lamp, making them the perfect solution for
a maintenance-intensive lighting application like the Hillsboro Arch. While
hair-thin metal filaments and glass make incandescent lights vulnerable
to damage, LEDs are solid-state with no fragile filaments to break. The
results? LEDs are impervious to electrical and mechanical shock, vibration,
frequent switching and environmental extremes so they operate year-after-year.
In the four months since the 580 LEDs have been installed on the Arch there
have been no failures.
“Over a similar four month period, we would lose 5-10 percent of the
incandescent lamps to burnout,” says Mike Klein. Between the cost
of the incandescent lamps and labor expenditures, it was costing almost
$2500 each time lamps were replaced. This became a $5000 to $7500 per year
expenditure that has now been virtually eliminated by using LED lamps manufactured
LED lamps use 80% to 90% less operating power than standard incandescent
bulbs, which expend 90% or more their energy in the formation of heat. LEDs
emit 100% of their energy as colored light while generating negligible heat.
In the short time since the Arch was relamped, Hillsboro has already seen
considerable savings in operating costs. The Arch now operates at 0.6kW
for the entire 580 lamps compared with 2.7kW for incandescents — a
four-fold reduction in the operating costs and a 75% decrease in energy
While LED lamps seemed the most logical choice based on life expectancy,
the price when compared with similar incandescent lamps made Hillsboro skittish.
Hillsboro’s financial concerns were soothed when analysis showed that
the cost of the LEDs would be off set by the reduced number of times the
Arch had to relamped. Typically, savings from reduced power usage, maintenance
cost and downtime return the capital investment in six to eight months!
While the purchase price of an incandescent appears as pennies in the books,
the true cost lies in squandered energy and labor costs. Depending on what
it costs to pay a maintenance worker – even if it’s just for
15 minutes – the real cost of relamping incandescent bulbs skyrockets.
Cost savings aside, the Arch is more attractive. The LEDs create a soft
electric-blue halo against the night sky – a dramatic departure from
the harsh corona made by the incandescent lamps. LEDtronics provided Mike
Klein with lamps of various colors from which to select. After seeing the
different colors, city staff members voted for the blue. “The lighting
is different as well,” Klein said. “In some ways, it’s
more intense and more directional. It depends on the angle from where you’re
viewing it. I think you’ll see the Arch from a lot farther away now,” Klein
said. “From farther away, it looks better. From a distance the two
lines of blue kind of merge together.”
LED lighting is emerging as a viable, provocative alternative to incandescent
lighting. Fueling the migration of LEDs into general lighting applications
are new manufacturing technologies, packaging innovations and the increasing
number of colors. These factors along with a growing awareness of the advantages
of LEDs (e.g., a life span measured in years not hours, vivid sunlight-visible
colors and low-power requirements) have engineers, architects and the residents
of Hillsboro viewing LEDs in a whole new light.