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APPENDIX A. IMPROVED R20 SHORT LAMP

TABLE OF CONTENTS

A.1 INTRODUCTION .................................................................................................... A-1

A.2 INTERNAL DIMENSIONAL COMPATIBILITY OF HALOGEN BURNER 

CAPSULES................................................................................................................................. A-2

A.3 EFFICACY OF IMPROVED DESIGN OPTIONS .................................................. A-3

A.4 MODELED R20 SHORT LAMPS AS SUBSTITUTES.......................................... A-6
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APPENDIX A. IMPROVED R20 SHORT LAMP

A.1 INTRODUCTION

This appendix provides detailed information on the analysis conducted for the final rule 

to determine if the efficacy of 100-watt (W) R20a short (having a maximum overall length 

[MOL] of 3 and 5/8 [or 3.625] inches) lamps (hereafter “R20 short lamps”) could be improved to 

meet energy conservation standards. The existing R20 short lamps use incandescent technology 

and do not meet previous energy conservation standards or the existing standards that began 

requiring compliance in July 2012b

 (hereafter “July 2012 standards”). Specifically, the U.S. 

Department of Energy (DOE) examined the addition of halogen capsules to existing R20 short 

lamps. Tungsten-halogen lamps are a specific type of incandescent reflector lamp (IRL) that 

contain a small diameter fused quartz envelope filled with a halogen molecule, referred to as a 

capsule, that surrounds the filament. The use of halogen capsules is known to improve efficacy 

of IRLs. Halogen infrared (HIR) technology, in addition to the halogen capsules, uses coatings 

on the inside outside of the capsule that reflect infrared light back onto the filament, while letting 

the visible energy pass through the coating. These infrared coatings increase the filament 

operating temperature, further improving lamp efficacy. In this final rule analysis, DOE modeled 

R20 short lamps utilizing HIR technology. 

The halogen capsules in tungsten-halogen lamps are available in two designs: (1) a 

single-ended burner that contains a lead wire inside the capsule and (2) a double-ended burner 

that features a lead wire outside the capsule. Single-ended burners are less efficacious than 

double-ended due to the presence of the lead wire inside the capsule, which prevents a certain 

amount of energy from reaching the capsule wall and being reflected back to the capsule 

filament. Single-ended burners are also typically smaller in size. Hence in modeling R20 short 

lamps using HIR technology, DOE examined two specific scenarios, one using a single-ended 

burner and the other using a double-ended burner. 

DOE was unable to identify any commercially available R20 short lamps using HIR 

technology with single-ended or double-ended halogen burners. Therefore, DOE used 

commercially available lamps from which to scale more efficacious R20 short lamps. Before 

doing so, DOE first confirmed through teardowns that the halogen capsules of the commercial 

lamps could fit in an R20 short lamp. Section A.2 of this appendix describes the teardown testing 

conducted by DOE for this final rule to determine if halogen capsules are dimensionally 

compatible with R20 short lamps. Section A.3 presents results of DOE’s modeling analysis to 

determine whether HIR R20 short lamps could meet energy conservation standards. Section A.4

discusses whether HIR R20 short lamps would meet the special characteristic requirements of 

the R20 short lamp and if an improved R20 short lamp is a potential substitute. 

 

a “R” denotes a reflector lamp type and “20” denotes diameter in 1/8 inch increments, which translates to 2.5 inches. b Existing standards were established as amendments to previous standards in a final rule published July 2009, 

requiring compliance in July 2012. 74 FR 34080 (July 14, 2009). Information regarding the 2009 Lamps Rule can be 

found at on regulations.gov, docket number EERE-2006-STD-0131 at 

www.regulations.gov/#!docketDetail;D=EERE-2006-STD-0131 and on DOE’s Building and Technologies webpage 

for Incandescent Reflector Lamps: 

http://www1.eere.energy.gov/buildings/appliance_standards/product.aspx/productid/58 
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A.2 INTERNAL DIMENSIONAL COMPATIBILITY OF HALOGEN BURNER 

CAPSULES

In response to a request for informationc (RFI) for this rulemaking, DOE received 

conflicting comments regarding the feasibility of incorporating halogen capsules in R20 short 

lamps. Therefore, DOE performed teardowns to determine the dimensional compatibility of both 

single-ended and double-ended halogen capsules with R20 short lamps. 

For the notice of proposed rulemaking (NOPR) analysis,d DOE had torn down two 100 

W R20 short lamp models, one from each of the two known manufacturers of R20 short lamps. 

DOE had also torn down one 60 W HIR PARe30 short lamp containing a double-ended halogen 

burner. For the final rule, DOE tore down additional commercially available lamps for use in the 

modeling analysis of an HIR R20 short lamp. Specifically, DOE tore down one 40 W HIR R20 

model containing a single-ended burner, one 45 W HIR R20 model containing a double-ended 

burner, and two 40 W HIR R20 models containing double-ended burners. DOE gathered internal 

and external dimensions of the lamp components, as well as general design information from 

these teardowns.

DOE first compared the dimensions of the 100 W R20 short lamps to that of the 40 W 

HIR R20 model with single-ended burner to determine if the burner could be utilized in an R20 

short lamp. DOE measured the length of the reflectorf of the R20 short lamp to be 67.0 mm for 

the first model and 67.3 mm for the second model. DOE determined that the 40 W HIR R20 

reflector length was 75.7 mm and the distance from the end of the halogen capsule to the 

reflector wall was 16.0 mm. Thus, the length required to fit the halogen capsule was 59.7 mm. 

Therefore, DOE expects that if this halogen capsule was mounted in an R20 short lamp, there 

would be an additional 7.3 to 7.6 mm of vertical space between the halogen capsule and reflector 

wall.

Based on these teardown results, DOE concluded that the single-ended burner found in 

the 40 W HIR R20 lamp is dimensionally compatible with an R20 short lamp. 

DOE also compared the dimensions of the 100 W R20 short lamps to that of the HIR R20 

lamps with double-ended burners to determine dimensional compatibility. As stated previously, 

DOE measured the length of the reflector of the R20 short lamp to be 67.0 mm for the first 

model and 67.3 mm for the second model. For the 45 W HIR R20 model with a double-ended 

burner, DOE determined that the reflector length was 72.3 mm and the distance from the end of 

the halogen capsule to the reflector wall was 4.9 mm. Thus, the length required to fit the halogen 

capsule of the 45 W HIR R20 was 67.4 mm, which was greater than the reflector length of both 

R20 short lamp models.

 

c The RFI and associated comments can also be found at regulations.gov under Docket No. EERE–2010–BT–PET– 

0047. d Appendix A from the NOPR can be found on regulations.gov, under docket number EERE–2010–BT–PET–0047, 

at www.regulations.gov/#!docketDetail;D=EERE-2010-BT-PET-0047. e “PAR” denotes a parabolic aluminum reflector lamp type. f The length of the reflector is the distance from the top of the lamp base to the end of the reflector.
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DOE also examined two 40 W HIR R20 models containing double-ended burners. For 

the first 40 W HIR R20 model, DOE measured the reflector length to be 74.4 mm and the 

distance from the end of the halogen capsule to the reflector wall was 6.2 mm. The length 

required to fit the halogen capsule of this lamp was therefore 68.2 mm, which was greater than 

the reflector length of both R20 short lamp models. For the second 40 W HIR R20 model, DOE 

determined that the reflector length was 74.1 mm and the distance from the end of the halogen 

capsule to the reflector wall was 7.7 mm. Therefore, the length required for the halogen capsule 

was 66.4 mm, which was 0.6 mm less than the reflector length of the first R20 short lamp model 

and 0.9 mm less than the reflector length of the second. 

Based on these teardown results, DOE found that the required length of the 45 W HIR 

R20 double-ended burner and one model of 40 W HIR R20 double-ended burner were greater 

than the measured length of the R20 short lamp reflector. For the second 40 W HIR R20 model, 

because there would be less than 1 mm of space between the halogen capsule and reflector wall 

when mounted in the R20 short lamp, DOE determined it would be extremely difficult to reliably 

fit the double-ended burner in an R20 short lamp. Therefore, DOE concluded that the doubleended burners found in the commercially available HIR R20 lamps were not dimensionally 

compatible with the R20 short lamps. 

However, as stated previously, DOE conducted a teardown of a 60 W HIR PAR30 short 

lamp with a double-ended burner in the NOPR analysis. DOE determined based on a similar 

teardown analysis that the halogen capsule found in the 60 W HIR PAR30 short lamp could fit in 

an R20 short lamp. Thus, DOE maintains that double-ended burners exist that are dimensionally 

compatible with R20 short lamps. 

Therefore, through the results of the independent teardown testing discussed in this 

section, DOE was able to confirm that a single-ended burner from a 40 W HIR R20 lamp and a 

double-ended burner from a 60 W HIR PAR30 short lamp would fit in an R20 short lamp. DOE 

then proceeded to use these commercially available lamps to model a more efficacious R20 short 

lamp.

A.3 EFFICACY OF IMPROVED DESIGN OPTIONS

After establishing that single-ended and double-ended halogen burners are dimensionally 

compatible with R20 short lamps, DOE next performed testing to determine the potential 

improvement in efficacy for R20 short lamps through the use of these technologies. As 

mentioned previously, DOE was unable to identify any R20 short lamps using HIR technology 

with single-ended or double-ended burners. Therefore, to determine the improvement in efficacy 

of a 100 W R20 short lamp using these technology options, DOE developed theoretical models 

by scaling from commercially available products. 

A.3.1 Single-Ended Burner Modeling Analysis

DOE tested the efficacy of the 120 V, 40 W HIR R20 lamp that contained a 

dimensionally compatible single-ended burner to determine the lamp’s performance. Next, DOE 
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used Illuminating Engineering Society of North America (IESNA) equations relating lifetime, 

lumens, and wattage to scale the 40 W HIR R20 lamp to meet the performance specifications 

(i.e., lumen output and lifetime) of the R20 short lamp. DOE conducted three modeling 

scenarios, scaling the lumen output of the 40 W lamp to be comparable to the minimum, 

maximum, and average lumen output of the established performance range (637 and 1,022 

lumens) of R20 short lamps. Typically R20 short lamps have a lifetime of 2,000 or 2,500 hours. 

For this analysis, DOE assumed the maximum rated lifetime of 2,500 hours. The results of this 

scaling analysis are presented in Table A.1. 

Table A.1 Results of R20 Short Lamp Single-Ended Burner Modeling Analysis 

Scaling 

Scenario

Lifetime 

(hours)

Lumens Watts

(W)

Efficacy 

(lm/W)

Standardg

Average lumen 

output

2,500 828.8 55 15.1 14.8

Maximum 

lumen output

2,500 1,011.1 66 15.3 15.5

Minimum 

lumen output 

2,500 649.8 44 14.8 N/Ah

 

Based on these results, DOE determined that the efficacy of an R20 short lamp improves 

with the use of a single-ended halogen burner. The efficacy of the 100 W R20 short lamp was 

measured to be 8.5 lumens per watt (lm/W), while the theoretical efficacy of the modeled HIR 

R20 short lamp with single-ended burner was calculated to be between 14.8 lm/W and 15.3 

lm/W. For the average lumen output scenario, the efficacy of the modeled lamp improved to 

meet the July 2012 standards. For the maximum lumen output scenario, the efficacy of the 

modeled lamp did not meet the July 2012 standards. In the case of the minimum lumen output 

scenario, the modeled lamp wattage was reduced to lower than 45 W, thereby excluding the lamp 

from existing standards for IRLs specified in 10 CFR 430.32(n)(5).i

A.3.2 Double-Ended Burner Modeling Analysis 

DOE utilized a similar scaling process to determine if the incorporation of a doubleended halogen burner would successfully increase the efficacy of an R20 short lamp by a 

sufficient amount to meet the July 2012 standards. As stated previously, DOE found, based on 

teardowns, that the double-ended burners found in commercially available HIR R20 lamps were 

likely not dimensionally compatible with the R20 short lamp. DOE did however identify a 

commercially available 120 V, 60 W HIR PAR30 short lamp that contained a double-ended 

burner that was dimensionally compatible with an R20 short lamp (see section A.2) in the NOPR 

analysis. Therefore, DOE maintained the use of the 60 W HIR PAR30 short lamp to model an 

R20 short lamp with double-ended burner. As noted previously, due to the lead wire being 

outside of the capsule, a double-ended burner is more efficacious than a single-ended burner, and 

therefore, could possibly result in an even more efficacious R20 short lamp. 

 

g The minimum efficacy required by existing IRL standard specified in 10 CFR 430.32(n)(5), given the modeled 

lamp wattage.

h This lamp is excluded from the existing IRL standards specified in 10 CFR 430.32(n)(5). See 10 CFR 

430.32(n)(6)(ii) for a list of exclusions. 

i

For a full list of exclusions see 10 CFR 430.32(n)(6)(ii).
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DOE acknowledges that a lamp’s reflector efficiency, which affects the overall lamp 

efficacy, is dependent on the envelope shape. Therefore, DOE applied the efficiency of R20-

shaped reflectors to the efficacy of the HIR PAR30 short lamp burner with PAR-shape reflector 

removed. For the final rule, DOE revised the analysis to examine both an average reflector 

efficiency, as well as a higher reflector efficiency, as suggested in a joint comment by California 

investor-owned utilities. (CA IOUs, No. 16 at p. 2) During previous reflector efficiency testing, 

DOE determined the average reflector efficiency of R20-shaped lamps to be 62.2 percent. Of the 

R20 lamp models tested, DOE identified a higher performing lamp model that had a reflector 

efficiency of 66.3 percent. In order to determine the efficacy of the double-ended halogen burner 

with an R-shaped reflector efficiency, DOE applied the average reflector efficiency value of 62.2 

percent to the tested efficacy of the HIR PAR30 short lamp’s halogen capsule with the PARshaped reflector removed. DOE then repeated this assessment using the higher reflector 

efficiency value of 66.3 percent. 

Next, DOE used IESNA equations relating lifetime, lumens, and wattage to scale the

resulting theoretical 60 W HIR R20 lamps to meet the performance specifications (i.e., lumen 

output and lifetime) of the R20 short lamp. DOE first conducted three modeling scenarios for the 

HIR R20 lamp with double-ended burner and average reflector efficiency, scaling the lumen 

output to be comparable to the minimum, maximum, and average lumen output of the established 

performance range (637 and 1,022 lumens) of R20 short lamps. As stated previously, R20 short 

lamps typically have a lifetime of 2,000 or 2,500 hours. For this analysis, DOE again assumed 

the maximum rated lifetime of 2,500 hours. The results of this scaling analysis are presented in 

Table A.2. 

Table A.2 Results of R20 Short Lamp Double-Ended Burner with Average Reflector 

Efficiency Modeling Analysis 

Scaling 

Scenario

Lifetime 

(hours)

Lumens Watts

(W)

Efficacy 

(lm/W)

Standardj

Average lumen 

output 

2,500 839.9 58 14.5 15.0

Maximum 

lumen output

2,500 1,031.0 70 14.7 15.7

Minimum 

lumen output

2,500 652.3 46 14.2 14.1

 Based on the results of these scaling calculations, DOE determined that the efficacy of an 

R20 short lamp improves using a double-ended halogen burner with average reflector efficiency 

applied. The efficacy of the 100 W R20 was measured to be 8.5 lm/W, while the efficacy of the 

modeled HIR R20 short lamp with double-ended burner and average reflector efficiency was 

calculated to be between 14.2 lm/W and 14.7 lm/W. For the average lumen output and maximum 

lumen output scenarios, the efficacy of the modeled lamps did not meet the July 2012 standards. 

However, for the minimum lumen output scenario, the efficacy of the modeled lamp improved to 

meet the July 2012 standards. 

 

j

The minimum efficacy required by existing IRL standard specified in 10 CFR 430.32(n)(5) given the modeled 

lamp wattage.
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DOE then conducted the same analysis for the HIR R20 lamp with double-ended burner 

and higher reflector efficiency. DOE again scaled the lumen output to be comparable to the 

minimum, maximum, and average lumen output of the established performance range (637 and 

1,022 lumens) of R20 short lamps. DOE assumed the maximum rated lifetime for R20 short 

lamps of 2,500 hours. The results of the scaling analysis are presented in Table A.3. 

Table A.3 Results of R20 Short Lamp Double-Ended Burner with Higher Reflector 

Efficiency Modeling Analysis 

Scaling 

Scenario

Lifetime 

(hours)

Lumens Watts

(W) 

Efficacy 

(lm/W)

Standardk

Average lumen 

output

2,500 828.1 54 15.3 14.7

Maximum 

lumen output

2,500 1,013.7 65 15.6 15.4

Minimum

lumen output

2,500 646.0 43 15.0 N/Al

DOE determined through the scaling calculations that the efficacy of an R20 short lamp 

improves further with the use of a double-ended halogen burner and higher reflector efficiency 

applied. The efficacy of the 100 W R20 was measured to be 8.5 lm/W, while the efficacy of the 

modeled HIR R20 lamp with double-ended burner and higher reflector efficiency was calculated 

to be between 15.0 lm/W and 15.6 lm/W. For the average lumen output and maximum lumen 

output scenarios, the efficacy of the modeled lamps improved to meet the July 2012 standards. In 

the case of the minimum lumen output scenario, the modeled lamp wattage was reduced to lower 

than 45 W, thereby excluding the lamp from existing standards for IRLs specified in 10 CFR 

430.32(n)(5).m

A.4 MODELED R20 SHORT LAMPS AS SUBSTITUTES

DOE believes there is uncertainty with the results of the modeling analysis presented in 

section A.3 due to the difference in MOL of the commercially available R20 lamps used for 

scaling. Because no R20 short lamps exist with halogen technology, DOE had to scale from 

lamps that have longer MOLs than the R20 short lamp’s 3.625 inches. The scaling analysis for 

the HIR R20 lamp with a single-ended burner was based on such a standard R20 lamp. Similarly, 

when modeling the HIR R20 lamps with double-ended burners, DOE utilized the reflector 

efficiencies of standard R20 lamps. DOE used these efficiencies because testing the efficiency of 

a reflector requires the lamp to contain a halogen capsule. The lumen output of the lamp is first 

measured with the reflector intact. Next, the lumen output of the halogen capsule alone is 

measured. The reflector efficiency is then calculated as the ratio of the lamp lumen output to the 

 

k The minimum efficacy required by existing IRL standard specified in 10 CFR 430.32(n)(5), given the modeled 

lamp wattage.

l

This lamp is excluded from the existing IRL standards specified in 10 CFR 430.32(n)(5). See 10 CFR 

430.32(n)(6)(ii) for a list of exclusions.

m For a full list of exclusions see 10 CFR 430.32(n)(6)(ii).
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capsule lumen output. As no commercially available R20 short lamps utilize halogen technology, 

DOE was unable to test the reflector efficiency of R20 short lamps. 

DOE attempted to determine if a relationship between efficacy and MOL exists in order 

to account for the difference in MOL with the modeled lamps. DOE compared the catalog 

efficacy of standard length and long length halogen lamps that had the same shape, diameter, 

lifetime, voltage, and wattage, and could not find a consistent relationship between lamp length 

and efficacy. DOE found that efficacy sometimes increased with increased MOL, sometimes 

decreased, and in other cases there was no change in efficacy when there was a change in MOL. 

Therefore, it is unclear if shortening the length of the reflector would impact the efficacy of the 

improved R20 short lamp models. 

DOE evaluated whether the standards-compliant R20 short lamps based on the modeling 

successfully replicated the necessary performance specifications of lumen output and beam 

spread using the theoretical calculations described in section A.3. Based on its theoretical 

modeling, DOE determined that an HIR R20 short lamp may be able to achieve lumen output 

within the established range for R20 short lamp of 637 to 1,022 lumens. However, because the 

position of the filament affects the beam angle, DOE anticipates that the beam angle could be 

affected by the use of a halogen capsule. Because standards-compliant R20 short lamps are not 

commercially available, DOE is unable to confirm the beam angle of R20 short lamps that utilize 

an HIR capsule.

Therefore, the results of the modeling analysis were inconclusive. While the theoretical 

analysis for each of the three modeled lamps (i.e., HIR with single-ended burner, HIR with 

double-ended burner and average reflector efficiency, and HIR with double-ended burner and 

higher reflector efficiency) resulted in at least one potentially compliant lamp, some of the 

scenarios indicated the lamp could not be improved to meet standards and remain within the 

required lumen range for an R20 short lamp. Additionally, it is unclear if the variation in 

reflector length would impact the modeled efficacy and it is unknown if the standards-compliant 

lamp would be able to achieve the special characteristics of the R20 short lamp.