5B-i APPENDIX 5B. T5 H ALOPHOSPHOR MINIATURE BIPIN BASELINE LAMPS

TABLE OF CONTENTS

5B.1 INTRODUCTION ...................................................................................................5B-1 5B.2 HALOPHOSPHOR T5 MARKET ..........................................................................5B-1 5B.3 LINEAR GENERAL SERVICE FL UORESCENT LAMP OVERVIEW..............5B-2 5B.4 MODEL FORMULATION, INPUTS, AND ANALYTICAL RESULTS .............5B-3 5B.4.1 28W 4-foot T5 Miniat ure Bipin (MiniBP) SO Halophosphor Baseline..................5B-3 5B.4.2 54W 4-foot T5 MiniBP HO Halophosphor Baseline...............................................5B-5 REFERENCES ..........................................................................................................................5B-6

LIST OF TABLES

Table 5B.1 T5 Halophosphor Lamps in the Current Market .....................................................5B-2 Table 5B.2: 4-foot T5 SO Lamps Analyzed ..............................................................................5B-5 Table 5B.3: 4-foot T5 HO Lamps Analyzed .............................................................................5B-5

LIST OF FIGURES

Figure 5B.1: A Common Linear General Se rvice Fluorescent Lam p in Operation ..................5B-2 Figure 5B.2: Lamp Efficacy Vs. Lamp Length For Cool White Halophosphor Preheat T5 Fluorescent Lamps .......................................................................................5B-45B-1 APPENDIX 5B. T5 HALOPHOSPHOR MINIATURE BIPIN BASELINE LAMPS

5B.1 INTRODUCTION

T5 lam ps 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 regulat ed four-foot medium bipin (MBP ) lamps of other diameters, such as T8 and T12 lamps. Manufacturers stated that the most popular wattages of four-foot 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 rare-e arth phosphors. Several stakeholders in this rulemaking have commented, however, that less-e fficacious T5 lamps, particularly those using halophosphors, may enter the US market. (Pub lic Meeting Transcript, No. 21 at pp. 71–73) 1 Because DOE believes that consumers will purchase low-efficacy 4-foot T5 lamps without a T5 standard if such lamps are brought to market, DOE developed mode ls of 4-foot 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 4-foot rare-earth phosphor T5 lamp s currently commercially available in the US.

5B.2 HALOPHOSPHOR T5 MARKET

DOE surveyed the current m arket of T5 halophosphor lamps and found that only SO halophosphor T5 lamps of lengths shorter than fo ur feet are commercially available. These lamps use one of two types of halophosphors: cool -white and warm-white, with the cool-white lamps having a slightly lower efficacy. Inform ation on the commercially available halophosphor T5 lamps is shown in Table 5B.1 . Light output refers to the lu me ns produced by the lamp after 100 hours of initial operation (“seasoning”).

Because none of the available T5 halophos phor lamps have wattages, lumen outputs, rated lifetimes, or length s that are similar to 4-foot T5 ra re-earth phosphor GSFL, DOE created a methodology for generating 4-foot 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 rulema king. This particular notati on refers to a comment: (1) submitted during the public meeting on March 10-11, 2008; (2) in document number 21 in the docket of this rulemaking; and (3) appearing on pages 71 through 73 of the transcript.Table 5B.1 T5 Halophosphor Lamps in the Current Market Light Output Nominal Power Nominal Length Rated Life Efficacy Manufacturer Model

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 FL UORESC ENT LAMP OVERVIEW

A linear general service fluorescent lamp commonly consists of a tube containing mercury (Hg) along with other gases such as arg on. 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, with electrodes labeled, is shown in Figure 5B.1

. i

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

5B-2Several physical and operational characteristics of a fluorescent lamp affect its efficacy. In particular, longer length lamps are generally mo re efficacious than shorter length lamps. This is because the electrodes of th e lamp use energy but do not generate any light. Longer length lamps have more light-generati ng length relative to the length of the electrodes, making higher efficacies possible.

5B.4 MODEL FORMULATION, INPUTS , AND ANALYTICAL RESU LTS

5B.4.1 28W 4-foot T5 Miniature Bipin (M iniBP) 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 :

       

  CL L K Efficacy Lamp   Eq. 5B.1

where  is the amount of light per unit length (in lumens per inch), L is the lamp length (in inches),  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 cool-white halophosphor lamps shown in Table 5B.2.1 had a slightly lower efficacy than the other lamps, DOE chose to use the cool-white lamp data in Eq. 5B.1 to derive
values for the constants   

 C , and K . This allowed DOE to create model lamps that reflected the possibility of cool-white lower-efficacy ha lophosphor T5 lamps entering the US market. DOE performed a statistical assessment of the cool -white 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:  = 2.176 lm in -1

,  = 0.02017 W in -1

, 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 s hown as the black line in Figure 5B.2 . The cool-white lamp data from Table 5B.2.1 is also plotted in the figure. Ba sed on the model and m odel inputs above, the estimated efficacy of a nominal 4-foot T5 cool-white 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 4-foot T5 cool-white halophosphor lamp, DOE multiplied this efficacy by the ANSI rated lamp wattage. Note that the rate d wattage of a T5 with a nominal wattage of 28W is 27.8W. Using this value, DOE determ ined the initial light output of the 28W halophosphor T5 baseline lamp to be 2,391 lumens.

The efficacy of the rare-earth phosphor 28W SO T5 lamp that DOE analyzed to determine the first efficacy level (EL) for the 4-foot T5 MiniBP SO product class is approximately 20 percent highe r (at 103 lumens per watt) th an the 28W T5 halophosphor

5B-3baseline. As a comparison, the average efficacy of the three 800 series T8 lamps that DOE analyzed in the four-foot 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 th e 28W T5 halophosphor base line is representative of the lower efficacies that halophosphor lamp s achieve in comparison with efficacious rareearth phosphor lamps.

Cool White Halophosphor Preheat T5 Fluorescent Lamps

85.9

0 20 40 60 80 100 120

0 2 0 4 0 6 0 8 0 1 0 0
Lamp length (in)Lamp Efficacy (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 4-foot T5 Mi niBP SO lamps that DOE analyzed in this rulem aking, including the model 28W T5 halophosphor baseline lamp. To determine mean light output and lifetime fo r the halophosphor baseline lamp, DOE assessed the lumen depreciation characteristics of halophosphors. DOE found th at small diameter halophosphor lamps can have lumen depreciations of 20 to 40 percent, based on a comp arison 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.

5B-45B-5 Table 5B.2: 4-foot T5 SO Lamps Analyzed

Nominal Wattage Rated Wattage Rated Efficacy Initial Light Output Mean Light Output Life CRI 2

EL Lamp Diameter 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 4-foot T5 MiniBP HO Halophosphor Baseline

The m odel 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 de nsities. 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 rare-earth phosphor 28W T5 lamp and the 28W T5 halophosphor lamp. As noted above, the rare-ear th 28W T5 lamp at EL1 is approximately 20 percent more efficacious than the 28W T5 hal ophosphor baseline lamp. DOE assumed that the rare-earth 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 hal ophosphor baseline lamp with an efficacy of 76.6 lm/W.

Table 5B.3 shows properties of the T5 HO lamps th at DOE analyzed for this rulema king, 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 depreciati on characteristics. DOE also selected a 30 percent lumen depreciation to determine these properties for the HO baseline.

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

Nominal Wattage Rated Wattage Rated Efficacy Initial Light Output Mean Light Output Life CRI
EL Lamp Diameter 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

2 CRI is “Color Rendering Index,” a measure of how accur ately a lamp can reproduce ob ject colors in comparison with daylight. The value of CRI ranges from 0 to 100.5B-6 REFERENCES

i Rea, Mark S., ed. The IESNA Lighting Handbook: Reference & Application, 9th Edition . 2000. The Illuminating Engineering Society of America: New York, New York.