APPENDIX 5B. T5 HALOPHOSPHOR MINIATURE BIPIN BASELINE LAMPS

TABLE OF CONTENTS

5B.1 INTRODUCTION .........................................................................................................5B­1

5B.2 HALOPHOSPHOR T5 MARKET ................................................................................5B­1

5B.3 LINEAR GENERAL SERVICE FLUORESCENT LAMP OVERVIEW....................5B­2

5B.4 MODEL FORMULATION, INPUTS, AND ANALYTICAL RESULTS ...................5B­3

5B.4.1 28W 4­foot T5 Miniature Bipin (MiniBP) SO Halophosphor Baseline ......5B­3

5B.4.2 54W 4­foot T5 MiniBP HO Halophosphor Baseline...................................5B­5

REFERENCES ..........................................................................................................................5B­6

LIST OF TABLES

Table 5B.1 T5 Halophosphor Lamps in the Current Market.....................................................5B­2

Table 5B.2: 4­foot T5 SO Lamps Analyzed ..............................................................................5B­5

Table 5B.3: 4­foot T5 HO Lamps Analyzed .............................................................................5B­5

LIST OF FIGURES

Figure 5B.1: A Common Linear General Service Fluorescent Lamp in Operation ..................5B­2

Figure 5B.2: Lamp Efficacy Vs. Lamp Length For Cool White Halophosphor Preheat T5

Fluorescent Lamps.......................................................................................5B­4

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APPENDIX 5B. T5 HALOPHOSPHOR MINIATURE BIPIN BASELINE LAMPS

5B.1 INTRODUCTION

T5 lamps currently on the United States market exist in a variety of lengths and wattages.

DOE’s market research indicates that the primary driver of T5 market growth, however, is

substitution for currently regulated four­foot medium bipin (MBP) lamps of other diameters,

such as T8 and T12 lamps. Manufacturers stated that the most popular wattages of four­foot T5

lamp are currently 28W for standard output (SO) T5 and 54W for high output (HO) T5.

Reduced wattage SO and HO T5 lamps (of 26W and 51W, respectively) are also sold.

Most T5 are efficacious lamps that use rare­earth phosphors. Several stakeholders in this

rulemaking have commented, however, that less­efficacious T5 lamps, particularly those using

1 halophosphors, may enter the US market. (Public Meeting Transcript, No. 21 at pp. 71–73)

Because DOE believes that consumers will purchase low­efficacy 4­foot T5 lamps without a T5

standard if such lamps are brought to market, DOE developed models of 4­foot halophosphor T5

SO and HO lamps as baselines for the SO and HO T5 product classes, respectively. This

appendix details the development of those models. In particular, DOE developed models of a

28W halophosphor SO lamp and a 54W halophosphor HO lamp to represent the most popular

wattages of 4­foot rare­earth phosphor T5 lamps currently commercially available in the US.

5B.2 HALOPHOSPHOR T5 MARKET

DOE surveyed the current market of T5 halophosphor lamps and found that only SO

halophosphor T5 lamps of lengths shorter than four feet are commercially available. These

lamps use one of two types of halophosphors: cool­white and warm­white, with the cool­white

lamps having a slightly lower efficacy. Information on the commercially available halophosphor

T5 lamps is shown in Table 5B.1. Light output refers to the lumens produced by the lamp after

100 hours of initial operation (“seasoning”).

Because none of the available T5 halophosphor lamps have wattages, lumen outputs,

rated lifetimes, or lengths that are similar to 4­foot T5 rare­earth phosphor GSFL, DOE created a

methodology for generating 4­foot T5 halophosphor lamps based on the available market data

and the physical principles of fluorescent lamp operation. DOE investigated the possible

relationship between lamp length and efficacy to develop a lamp model, which is described

below.

1 A notation in the form ‘‘Public Meeting Transcript, No. 21 at pp. 71–73’’ identifies a written comment that DOE

has received and has included in the docket of this rulemaking. This particular notation refers to a comment: (1)

submitted during the public meeting on March 10­11, 2008; (2) in document number 21 in the docket of this

rulemaking; and (3) appearing on pages 71 through 73 of the transcript.

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Table 5B.1 T5 Halophosphor Lamps in the Current Market

Manufacturer Model

Light

Output

Nominal

Power

Nominal

Length Rated Life Efficacy

lm W in hrs lm/W

Atech Lighting 4WT 150 4 6 5000 37.5

GE Lighting F4T5/CW 135 4 6 5000 33.8

OSRAM

Sylvania F4T5/CW 135 4 6 6000 33.8

Philips Lighting F4T5/Soft White 150 4 6 6000 37.5

Atech Lighting 6WT 300 6 9 5000 50.0

GE Lighting F6T5/CW 295 6 9 5000 49.2

OSRAM

Sylvania F6T5/CW 275 6 9 7500 45.8

Philips Lighting F6T5/Soft White 325 6 9 7500 54.2

Atech Lighting 8WT 400 8 12 5000 50.0

GE Lighting F8T5/CW 400 8 12 5000 50.0

OSRAM

Sylvania F8T5/CW 400 8 12 7500 50.0

Philips Lighting F8T5/Soft White 450 8 12 7500 56.3

Atech Lighting 13WT 850 13 21 5000 65.4

GE Lighting F13T5/WW 870 13 21 5000 66.9

OSRAM

Sylvania F13T5/WW 880 13 21 7500 67.7

Philips Lighting F13T5/Soft White 1000 13 21 7500 76.9

5B.3 LINEAR GENERAL SERVICE FLUORESCENT LAMP OVERVIEW

A linear general service fluorescent lamp commonly consists of a tube containing

mercury (Hg) along with other gases such as argon. At each end, the lamp contains an electrode

made from thin tungsten wire. The tube itself is coated with a phosphor. During operation of the

lamp, electrons flowing between the electrodes ionize the mercury in the lamp, which produces

ultraviolet photons that the phosphor converts into visible light. A linear GSFL in operation,

i with electrodes labeled, is shown in Figure 5B.1.

Figure 5B.1: A Common Linear General Service Fluorescent Lamp in Operation

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Several physical and operational characteristics of a fluorescent lamp affect its efficacy.

In particular, longer length lamps are generally more efficacious than shorter length lamps. This

is because the electrodes of the lamp use energy but do not generate any light. Longer length

lamps have more light­generating length relative to the length of the electrodes, making higher

efficacies possible.

5B.4 MODEL FORMULATION, INPUTS, AND ANALYTICAL RESULTS

5B.4.1 28W 4­foot T5 Miniature Bipin (MiniBP) SO Halophosphor Baseline

The model that DOE created to relate SO halophosphor lamp efficacy to other factors

such as end losses is shown below in Eq. 5B.1:

⎛ αL ⎞ Lamp Efficacy = K⎜

⎜ ⎟⎟ Eq. 5B.1

⎝ βL + C ⎠

where α is the amount of light per unit length (in lumens per inch), L is the lamp length (in

inches), β is the amount of arc power per unit length (in watts per inch), C is the wasted power

due to end losses (in watts), and K is a scaling constant. It is assumed that C is constant as the

length of the lamp varies.

Because the cool­white halophosphor lamps shown in Table 5B.2.1 had a slightly lower

efficacy than the other lamps, DOE chose to use the cool­white lamp data in Eq. 5B.1 to derive

values for the constants α, β, C, and K. This allowed DOE to create model lamps that reflected

the possibility of cool­white lower­efficacy halophosphor T5 lamps entering the US market.

DOE performed a statistical assessment of the cool­white lamp data in Table 5B.2.1 in order to

determine constant values that most accurately represented the observed efficacies in the table

for lamps of different lengths. These values were determined to be: α = 2.176 lm in­1, β = ­1 0.02017 W in , C = 0.2478 W, and K = 23.03.

The relationship between lamp length and efficacy based on Eq. 5B.1 and the constant

values derived above is shown as the black line in Figure 5B.2. The cool­white lamp data from

Table 5B.2.1 is also plotted in the figure. Based on the model and model inputs above, the

estimated efficacy of a nominal 4­foot T5 cool­white halophosphor lamp is 86.0 lm/W. This

efficacy would be based on initial values after 100 hours of seasoning. To compute the initial

light output of a 28W 4­foot T5 cool­white halophosphor lamp, DOE multiplied this efficacy by

the ANSI rated lamp wattage. Note that the rated wattage of a T5 with a nominal wattage of

28W is 27.8W. Using this value, DOE determined the initial light output of the 28W

halophosphor T5 baseline lamp to be 2,391 lumens.

The efficacy of the rare­earth phosphor 28W SO T5 lamp that DOE analyzed to

determine the first efficacy level (EL) for the 4­foot T5 MiniBP SO product class is

approximately 20 percent higher (at 103 lumens per watt) than the 28W T5 halophosphor

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85.9

baseline. As a comparison, the average efficacy of the three 800 series T8 lamps that DOE

analyzed in the four­foot MBP product class is approximately 20 percent higher than the average

efficacy of the 34W T12 halophosphor lamps that DOE analyzed (92.8 lumens per watt vs. 77.9

lumens per watt). Thus, DOE believes that the 28W T5 halophosphor baseline is representative

of the lower efficacies that halophosphor lamps achieve in comparison with efficacious rareearth phosphor lamps.

Cool White Halophosphor Preheat T5 Fluorescent Lamps

0

20

40

60

80

100

120

0 20 40 60 80 100

Lamp length (in)

L

a

m

p

Effic

a

c

y (lm/w)

A

B

C

D

4ft estimate

Fit

86.0

Figure 5B.2: Lamp Efficacy Vs. Lamp Length For Cool White Halophosphor Preheat T5

Fluorescent Lamps

Table 5B.2 shows properties of the 4­foot T5 MiniBP SO lamps that DOE analyzed in

this rulemaking, including the model 28W T5 halophosphor baseline lamp. To determine mean

light output and lifetime for the halophosphor baseline lamp, DOE assessed the lumen

depreciation characteristics of halophosphors. DOE found that small diameter halophosphor

lamps can have lumen depreciations of 20 to 40 percent, based on a comparison of initial light

output and mean light output. DOE chose the midpoint of this range, 30 percent, to establish the

mean light output of the 28W T5 halophosphor baseline lamp.

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Table 5B.2: 4­foot T5 SO Lamps Analyzed

EL

Lamp

Diameter

Nominal

Wattage

Rated

Wattage

Rated

Efficacy

Initial Light

Output

Mean Light

Output Life CRI2

W W lm/W lm lm hr

Baseline/0 T5 28 27.8 86.0 2,391 1,674 20,000 62

1 T5 28 27.8 104.3 2,900 2,660 20,000 85

2 T5 28 27.8 109.7 3,050 2,898 20,000 85

2 T5 26 26.0 111.5 2,900 2,660 25,000 85

5B.4.2 54W 4­foot T5 MiniBP HO Halophosphor Baseline

The model that DOE developed to determine the efficacy of a 28W T5 halophosphor

lamp was based on data for short length SO T5 halophosphor lamps. HO lamps, however, use

different electrode designs than SO lamps and also have different power densities. DOE did not

find any lamps on the market that were marketed as HO T5 halophosphor. Because of this, DOE

instead established the efficacy of the 54W T5 HO halophosphor baseline lamp by using the

efficacy difference between the EL1 rare­earth phosphor 28W T5 lamp and the 28W T5

halophosphor lamp. As noted above, the rare­earth 28W T5 lamp at EL1 is approximately 20

percent more efficacious than the 28W T5 halophosphor baseline lamp. DOE assumed that the

rare­earth phosphor 54W T5 HO lamp at EL1 would also be approximately 20 percent more

efficacious than a 54W T5 HO halophosphor lamp. Based on this difference in efficacy, DOE

developed a model 54W T5 halophosphor baseline lamp with an efficacy of 76.6 lm/W.

Table 5B.3 shows properties of the T5 HO lamps that DOE analyzed for this rulemaking,

including the 54W T5 halophosphor baseline lamp. As done for the 28W T5 halophosphor

baseline lamp, DOE determined the initial light output of the 54W HO halophosphor baseline

lamp based on the wattage and efficacy and then computed the mean light output and lamp

lifetime based on halophosphor lumen depreciation characteristics. DOE also selected a 30

percent lumen depreciation to determine these properties for the HO baseline.

Table 5B.3: 4­foot T5 HO Lamps Analyzed

EL

Lamp

Diameter

Nominal

Wattage

Rated

Wattage

Rated

Efficacy

Initial Light

Output

Mean Light

Output Life CRI

W W lm/W lm lm hr

Baseline/0 T5 54 53.8 76.6 4,122 2,885 20,000 62

1 T5 54 53.8 92.9 5,000 4,600 20,000 85

1 T5 51 51.0 98.0 5,000 4,600 20,000 85

CRI is “Color Rendering Index,” a measure of how accurately a lamp can reproduce object colors in comparison

with daylight. The value of CRI ranges from 0 to 100.

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i

REFERENCES

Rea, Mark S., ed. The IESNA Lighting Handbook: Reference & Application, 9th Edition. 2000.

The Illuminating Engineering Society of America: New York, New York.

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