CHAPTER 4. ENGINEERING ANALYSIS 

TABLE OF CONTENTS 

4.1 ENGINEERING ANALYSIS FRAMEWORK............................................................ 4-1 

4.1.1 Representative Equipment Categories ........................................................... 4-2 

4.1.2 Baseline Lamps.............................................................................................. 4-2 

4.1.3 Substitute Lamps ............................................................................................ 4-2 

4.2 EQUIPMENT PRICE DETERMINATION ................................................................. 4-1 

4.3 ENGINEERING ANALYSIS RESULTS .................................................................... 4-3 

LIST OF TABLES 

Table 4.3.1. HID Lamps Determination Engineering Analysis Results.....................................4-4 

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CHAPTER 4. ENGINEERING ANALYSIS 

This chapter provides the technical support documentation for the engineering analysis of 

high-intensity discharge (HID) lamps. For this determination, the engineering analysis identifies 

representative equipment categories with baseline lamps and energy-efficient substitutes and 

develops power rating estimates for the equipment analyzed. The outputs from the engineering 

analysis are critical inputs to subsequent cost-benefit calculations for individual consumers. 

In this determination, the U.S. Department of Energy (DOE) developed end-user prices 

for analyzed lamp, lamp-and-ballast, and luminaire (fixture) designs using a commercially 

available pricing database. By combining the results of the engineering analysis and the 

equipment price analysis, DOE derived the necessary inputs for use in the life-cycle cost (LCC) 

analysis and national energy savings/net present value (NES/NPV) analysis. The LCC and 

NES/NPV analyses are discussed in chapters 5 and 6, respectively, of this technical support 

document. 

4.1 ENGINEERING ANALYSIS FRAMEWORK 

DOE based the engineering analysis on commercially available equipment that 

incorporates the design options identified in the market assessment (chapter 2) and technology 

assessment (chapter 3). For this determination, DOE used the following approach for the 

engineering analysis: 

1.	 Representative Equipment Categories. DOE reviewed potentially covered lamps and 

selected certain broad categories as “representative” based on their market share, wattage, 

and color characteristics. 

2.	 Baseline Lamps. Within the broad equipment categories, DOE selected baseline lamps as 

representative equipment. Generally, a baseline lamp is one that represents the typical 

lamp sold. DOE selected specific characteristics such as certain color rendering index, 

operating lifetimes, and light outputs to characterize the lamps that are most commonly 

purchased by consumers. DOE selected multiple baseline lamps to ensure consideration 

of different high-volume lamps and their associated consumer economics. 

3.	 Substitute Lamps. DOE selected more efficacious substitute lamps for each baseline lamp 

in the representative equipment classes. In identifying more efficacious lamp designs, 

DOE recognizes that a lamp’s lumen package and performance characteristics are 

important design criteria for consumers. For example, if consumers do not have the 

option to purchase substitute lamps, lamp-and-ballast systems, or luminaires with similar 

lumen packages under an energy conservation standard, consumers would need to change 

the lighting design to maintain a similar light output. Therefore, DOE established energyefficient designs for the LCC analysis so that potential light output is equal to or within 

90 percent (or greater) of the mean light output of the baseline system. 

The sections that follow discuss how DOE applied this methodology to create the 

engineering analysis. 

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4.1.1 Representative Equipment Categories 

For this determination, DOE developed equipment categories that represent the plurality 

of total HID lamp shipments in the United States. The equipment is categorized broadly by lamp 

wattage and baseline lamp technology. HID lamp wattages were segregated into three categories: 

low (less than 150 watts [W]), medium (from 150 to 500 W), and high (greater than 500 W). 

Based on its market assessment, DOE selected medium wattage categories as most representative 

of lamp shipments, comprising an estimated 38 percent of total HID lamp shipments in the 

United States. 

DOE further specified the equipment categories by lamp technology—in this case, 

mercury vapor (MV) and probe-start metal halide (MH) lamps—which broadly characterizes the 

color requirements of HID lamp applications. For the MV baseline equipment classes, DOE 

assumed that color appearance and color rendering are not critical (e.g., roadway lighting and 

industrial applications), which allows for energy-efficient substitute lamp types with poor or 

moderate color rendering (e.g., high-pressure sodium [HPS] and probe-start MH). DOE selected 

probe-start MH as the baseline lamp technology for equipment classes where color appearance 

and color rendering may be important (e.g., interior and exterior “white light” applications in 

commercial facilities). 

4.1.2 Baseline Lamps 

Within the broad wattage and lamp technology categories, DOE created multiple 

equipment categories to capture high-volume equipment and the equipment’s associated 

economic impacts. The equipment categories are identified by a nominal initial light output and 

an associated baseline lamp (MV or probe-start MH), and are presented in section 4.1.3. 

In this determination, DOE based its equipment categories on lamps. This is because the 

potential energy conservation standards would apply only to lamps. However, DOE used a 

systems approach in analyzing the representative equipment categories because both lamps and 

ballasts determine a system’s energy use and light output. Accordingly, DOE paired lamps with 

ballasts to develop representative lamp-and-ballast systems, which demonstrate the actual energy 

usage and light output of operating lamps. DOE only considered magnetic ballasts for this 

analysis. Although electronic ballasts exist for some HID lamps, these types of ballasts represent 

a very small segment of the market. 

4.1.3 Substitute Lamps 

For each representative equipment category, DOE considered the following when 

identifying acceptable substitute HID lamps: 

	 Light Output: Some substitutions are not suitable because of light output differences. 

Substitute lamps with significantly increased light output may not be appropriate, despite 

their higher efficacy. Higher light output for a system in an existing luminaire may cause 

glare, which may be a safety hazard or create lighting quality issues, or both. In this 

determination, DOE analyzed lamp-and-ballast systems that both save energy and 

maintain comparable light output. In particular, DOE considered lamp-and-ballast 

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designs that emit mean lumens equal to or within 90 percent (or greater) of the mean light 

output of the baseline system. DOE maintains light output across efficacy levels to ensure 

that products supply comparable service. 

In assessing light output, DOE makes a distinction between mean and initial lumens. 

DOE typically uses initial lumens in its test procedures to measure compliance with a 

standard. This is consistent with consensus industry standards for efficacy measurements. 

However, the light output of a lamp decreases over time. To account for this real-world 

depreciation in lumens, DOE used mean lumens in determining equivalent substitutes in 

the LCC and NES/NPV analyses. 

	 Color Characteristics: Some substitutions are not suitable because of color (i.e., spectral) 

differences, which may exclude some technology options for specific applications. For 

example, an HPS system (with its characteristic amber color appearance and poor color 

rendering) would not be an appropriate substitute for an MH system in color-critical 

“white light” applications (e.g., an interior lobby). However, HPS can be a viable 

substitute for MH in some exterior applications (e.g., parking structures), where energy 

efficiency may be a higher priority than color quality. 

	 Luminaire Constraints: Some substitutions are not suitable because of luminaire 

constraints. A substitution of a different HID technology type may mean the use of a 

lamp with a different socket type (e.g., mogul, medium, pin) that does not exist in the 

luminaire. Replacement lamp options and their ballasts may not fit in the existing 

luminaire. Some HID luminaires are not enclosed and cannot protect against lamp rupture 

for some technology replacements. 

	 Economics: Lighting economics could significantly affect the choice of a substitution. 

Lamps that provide acceptable light output and/or color quality can have a high initial 

cost, making their LCC too high to be a reasonable substitute. Material and maintenance 

costs associated with shorter life and increased lamp replacements can also adversely 

affect the LCC of the substitute product. 

4.2 EQUIPMENT PRICE DETERMINATION 

For substitutions requiring luminaire replacement, it is important to note that 

manufacturers typically package luminaires without a lamp; i.e., they package and sell only the 

luminaire, which includes the housing, ballast, and other associated electrical and mechanical 

components (e.g., wires, sockets, mounting brackets, fasteners). Therefore, to calculate the total 

price of a luminaire for the LCC analysis, DOE determined the price of associated lamps 

separately and added this to the luminaire price. 

4.3 ENGINEERING ANALYSIS RESULTS 

For this determination, DOE identified seven equipment classes of HID lamps that 

represent an estimated 38% of U.S. total HID lamp shipments. The analyzed baseline lamps and 

their energy-efficient substitutes fall in two broad wattage categories—low (less than 150 W) 

and medium (from 150 to 500 W)—and are classified by initial lumen output. The engineering 

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analysis also captures associated lamp-and-ballast input power ratings, light output, lamp life, 

and pricing information needed for the LCC and NES/NPV analyses. Error! Reference source 

not found. summarizes the engineering data for all baseline and substitute equipment. 

Table 4.3.1. HID Lamps Determination Engineering Analysis Results 

Wattage 

Category 

Baseline 

Lamp Type 

Equipment 

Class ID 

Approx. 

Light Output 

mean lumens 

Efficiency 

Level 

Lamp 

Description 

System 

Input Power 

Rating 

W 

Medium 

Wattage 

(150–500W) 

MV 1 6,800 Baseline 175W MV 202 

Substitute 1 150W PMH 185 

Substitute 2 100W HPS 122 

2 10,000 Baseline 250W MV 283 

Substitute 1 150W PMH 185 

Substitute 2 150W HPS 185 

3 14,400 Baseline 400W MV 454 

Substitute 1 250W PMH 285 

Substitute 2 150W HPS 185 

Probe-start 

MH 

4 8,800 Baseline 175W MH 208 

Substitute 1 150W PMH 185 

Substitute 2 100W HPS 122 

5 13,700 Baseline 250W MH 291 

Substitute 1 175W PMH 209 

Substitute 2 150W HPS 185 

6 23,500 Baseline 360W MH 400 

Substitute 1 320W PMH 367 

Substitute 2 250W HPS 295 

7 25,200 Baseline 400W MH 456 

Substitute 1 320W PMH 367 

Substitute 2 250W HPS 295 

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