Volume 9 Issue 3
May 2000    
A-lamp - The incandescent lamp most commonly used in North American households. The "A" designation refers to the lamp's bulbous shape. ballast - A device required by electric-discharge light sources such as fluorescent or HID lamps to regulate voltage and current supplied to the lamp during start and throughout operation. bi-level switching - Control of light source intensity at two discrete levels in addition to off. compact fluorescent lamp (CFL) - A family of single-ended fluorescent-discharge light sources with small-diameter [16-millimeter (5/8-inch) or less] tubes. continuous dimming - Control of a light source's intensity to practically any value within a given operating range. tri-level switching - Control of light source intensity at three discrete levels in addition to off. indirect lighting - Light arriving at a surface after reflecting from one or more surfaces (usually walls and/or ceilings) that are not part of the luminaire. lamp - A radiant light source. luminaire - A complete lighting unit consisting of a lamp or lamps and the parts designed to distribute the light, to position and protect the lamp(s), and to connect the lamp(s) to the power supply. (Also referred to as fixture.) correlated color temperature (CCT) - A specification for white light sources used to describe the dominant color tone along the dimension from warm (yellows and reds) to cool (blue). Lamps with a CCT rating below 3200 K are usually considered warm sources, whereas those with a CCT above 4000 K usually considered cool in appearance. Temperatures in between are considered neutral in appearance. Technically, CCT extends the practice of using temperature, in kelvins (K), for specifying the spectrum of light sources other than blackbody radiators. Incandescent lamps and daylight closely approximate the spectra of black body radiators at different temperatures and can be designated by the corresponding temperature of a blackbody radiator. The spectra of fluorescent and LED sources, however, differ substantially from black body radiators yet they can have a color appearance similar to a blackbody radiator of a particular temperature as given by CCT. direct light - Light emitted by a luminaire in the general direction of the task to be illuminated. The term usually refers to light emitted in a downward direction. halogen lamp - An incandescent lamp that uses a halogen fill gas. Halogen lamps have higher rated efficacies and longer lives than standard incandescent A-lamps. active power - the system input power (in watts) for a lamp-ballast combination. color rendering index (CRI) - A rating index commonly used to represent how well a light source renders the colors of objects that it illuminates. For a CRI value of 100, the maximum value, the colors of objects can be expected to be seen as they would appear under an incandescent or daylight spectrum of the same correlated color temperature (CCT). Sources with CRI values less than 50 are generally regarded as rendering colors poorly, that is, colors may appear unnatural. efficacy - The ratio of light output (in lumens) to input power (in watts), expressed as lumens per watt (LPW). illuminance - The density of luminous flux incident upon a surface. Illuminance is measured in footcandles (lumens/square foot) or lux (lumens/square meter). One footcandle equals 10.76 lux. lamp life - The number of hours at which half of a large group of lamps have failed when operated under standard testing conditions. lumen (lm) - A unit measurement of the rate at which a lamp produces light. A lamp's lumen output rating expresses the total amount of light the lamp emits in all directions per unit time. metal halide lamp - A high-intensity discharge (HID) lamp that uses mercury and several halide additives as light-producing elements. Metal halide lamps have better color properties than other HID lamp types because the different additives produce light distributed over more visible wavelengths, resulting in a more complete spectrum. Metal halide lamps are available with CCTs from 2300 to 5400 K and with CRI values from 60 to 93. Efficacies of metal halide lamps typically range from 75 to 125 LPW.
How much do the torchieres cost?

As of October 1999, utilities serving California, Connecticut, Idaho, Massachusetts, Montana, New Hampshire, Oregon, Rhode Island, Vermont, Washington, and Wisconsin provided incentives for  ENERGY STAR torchieres (see "ENERGY STAR"). Some utilities offered $20 instant or mail-in rebates, while others offered a trade-in program: turn a halogen torchiere in at the store, and receive a $10-20 discount on a new ENERGY STAR torchiere.

NLPIP acquired samples of four compact-fluorescent-lamp (CFL) torchieres, one metal halide torchiere, one incandescent torchiere, and one halogen torchiere. The following table summarizes the initial and long-term costs of the torchieres tested by NLPIP.

Although the alternative torchieres cost more to purchase, their lower operating expenses (electricity and replacement lamps) make most of them more economical than halogen torchieres. For example, Table 1 shows that to buy and operate a halogen torchiere for one year costs from $59-64. To buy and operate an incandescent-lamp torchiere for one year costs $40-64 (torchiere, electricity, and one replacement lamp). A circular CFL torchiere, while costing more to buy, actually costs less in that first year ($38-58). Over a period of five years, even the $150 torchiere proves to be more economical than a halogen torchiere.

Table 1. Relative Costs of Torchieres

Lamp Type Number & Type(s)
of Lamps in Torchiere
Initial Cost of Torchiere
($U.S.)
Electricity
Cost per Year
($U.S.)a
Rated
Lamp Life
(h)b
Replacement Cost per Lamp
($U.S.)
Approximate
Operating Cost
for Five Years
($U.S.)a, c

Halogen one 300-W tubular 
double-ended halogen
15–20 44 2,000 5–8 234–243

Incandescent
A-lamp
one 3-way (50-100-
150-W) incandescent
16–40 22 1,200–1,500 2 118–122

Quad CFL three 26-W quad-tube CFLs 90 12 10,000 8 58

Flat CFL two 36-W
flat CFLs
150 9 10,000 10 47

Circular CFL one 20-W circular CFL
and
one 30-W circular CFL
30–50 8 10,000 18 40

Long CFL two 40-W long twin-tube CFLs 600 14 12,000–20,000 15 69

Metal halide one 68-W metal halide and
two 25-W incandescent
375 10d 15,000 25 50d

aAssuming the torchiere is operated at full power (or highest switch setting) for four hours per day at 10¢ per kilowatt-hour. Based on rated active power.
b Information has been taken from lamp packaging or manufacturer's information.
c Includes cost of electricity and replacement lamps if necessary (based on rated lamp life).
d With the incandescent lamps switched off.



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