5-1

CHAPTER 5. ENGINEERING ANALYSIS 

TABLE OF CONTENTS 

5.1 INTRODUCTION ........................................................................................................... 5-3 

5.2 METHODOLOGY OVERVIEW .................................................................................... 5-3 

5.3 COST MODEL ................................................................................................................ 5-4 

5.3.1 Manufacturer Production Cost Estimates ............................................................ 5-4 

5.3.2 Structure of the Cost Model Spreadsheet............................................................. 5-5 

5.3.3 Material Prices ..................................................................................................... 5-6 

5.3.4 Results.................................................................................................................. 5-6 

5.4 MANUFACTURER MARKUP ...................................................................................... 5-6 

5.5 ENERGY CONSUMPTION MODEL ............................................................................ 5-7 

5.5.1 Screened-In Technologies.................................................................................... 5-7 

5.5.2 Screened-In Technologies Not Considered in the Engineering Analysis............ 5-8 

5.5.2.1 Higher Efficiency Evaporator and Condenser Fan Blades ...................... 5-8 

5.5.2.2 Low-Pressure Differential Evaporators ................................................... 5-8 

5.5.2.3 Defrost Mechanisms ................................................................................ 5-9 

5.5.3 Design Options..................................................................................................... 5-9 

5.5.3.1 Higher Efficiency Lighting and Ballasts.................................................. 5-9 

5.5.3.2 Higher Efficiency Evaporator Fan Motors ............................................ 5-11 

5.5.3.3 Evaporator Fan Controls........................................................................ 5-11 

5.5.3.4 Improved Evaporator Design................................................................. 5-12 

5.5.3.5 Insulation Increases or Improvements ................................................... 5-13 

5.5.3.6 Improved Glass Pack ............................................................................. 5-14 

5.5.3.7 Higher Efficiency Condenser Fan Motors ............................................. 5-14 

5.5.3.8 Increased Condenser Surface Area ........................................................ 5-15 

5.5.3.9 Higher Efficiency Compressors............................................................. 5-16 

5.5.4 Baseline Specifications ...................................................................................... 5-16 

5.5.5 Non-Numerical Assumptions............................................................................. 5-19 

5.5.6 Numerical Constants and Assumptions ............................................................. 5-19 

5.5.7 Model Components............................................................................................ 5-20 

5.5.7.1 Component Energy Consumption.......................................................... 5-21 

5.5.7.2 Compressor Energy Consumption ......................................................... 5-22 

5.5.7.3 Component Load Model ........................................................................ 5-22 

5.5.7.4 Radiation Load Model ........................................................................... 5-22 

5.5.7.5 Conduction Load Model ........................................................................ 5-22 

5.5.7.6 Infiltration Load Model.......................................................................... 5-23 

5.6 COST-EFFICIENCY CURVES .................................................................................... 5-24 

5.7 SENSITIVITY ANALYSES ......................................................................................... 5-32 

5.7.1 Material Price Sensitivity................................................................................... 5-32 

5.7.2 Alternative Refrigerants..................................................................................... 5-33 

5.8 RESULTS ...................................................................................................................... 5-34 

REFERENCES .......................................................................................................................... 5-35 

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LIST OF TABLES 

Table 5.3.1 Major Manufacturing Processes .............................................................................. 5-6 

Table 5.3.2 Calculated Base Case Costs..................................................................................... 5-6 

Table 5.5.1 Details for “Class A Lighting” Design Option ...................................................... 5-10 

Table 5.5.2 Details for “Class B Lighting” Design Option ...................................................... 5-11 

Table 5.5.3 Details for “Evaporator Fan Motor” Design Option.............................................. 5-11 

Table 5.5.4 Details for “Improved Class A Evaporator Coil” Design Option.......................... 5-12 

Table 5.5.5 Details for “Improved Class B Evaporator Coil” Design Option.......................... 5-12 

Table 5.5.6 Properties of Standard and Enhanced Class B Evaporator Coil ............................ 5-13 

Table 5.5.7 Properties of Standard and Enhanced Class A Evaporator Coil............................ 5-13 

Table 5.5.8 Details for “Improved Glass Pack” Design Option ............................................... 5-14 

Table 5.5.9 Details for “Improved Glass Pack” Design Option ............................................... 5-14 

Table 5.5.10 Details for “Improved Class A Condenser Coil” Design Option ........................ 5-15 

Table 5.5.11 Details for “Improved Class B Condenser Coil” Design Option......................... 5-15 

Table 5.5.12 Properties of Standard and Enhanced Class A Condenser Coil............................ 5-16 

Table 5.5.13 Properties of Standard and Enhanced Class B Condenser Coil............................ 5-16 

Table 5.5.14 Baseline Specifications........................................................................................ 5-17 

Table 5.5.15 Class A Equipment Class Baseline Specifications .............................................. 5-18 

Table 5.5.16 Class B Equipment Class Baseline Specifications .............................................. 5-18 

Table 5.5.17 Energy Consumption Model Numerical Constants and Assumptions................. 5-20 

Table 5.5.18 Engineering Constants ......................................................................................... 5-20 

Table 5.6.1 Cost-Efficiency Data for the Small-Size Class A Equipment Class...................... 5-26 

Table 5.6.2 Cost-Efficiency Data for the Medium-Size Class A Equipment Class ................. 5-27 

Table 5.6.3 Cost-Efficiency Data for the Large-Size Class A Equipment Class...................... 5-28 

Table 5.6.4 Cost-Efficiency Data for the Small-Size Class B Equipment Class...................... 5-29 

Table 5.6.5 Cost-Efficiency Data for the Medium-Size Class B Equipment Class.................. 5-30 

Table 5.6.6 Cost-Efficiency Data for the Large-Size Class B Equipment Class...................... 5-31 

LIST OF FIGURES 

Figure 5.3.1 Components of Manufacturer Production Cost...................................................... 5-4 

Figure 5.3.2 Manufacturer Production Cost Assessment Stages ................................................ 5-5 

Figure 5.5.1 Components of the Energy Consumption Model ................................................. 5-21 

Figure 5.6.1 Cost-Efficiency Curves for the Small-Size Class A Equipment Class................. 5-26 

Figure 5.6.2 Cost-Efficiency Curve for the Medium-Size Class A Equipment Class.............. 5-27 

Figure 5.6.3 Cost-Efficiency Curves for the Large-Size Class A Equipment Class................. 5-28 

Figure 5.6.4 Cost-Efficiency Curve for the Small-Size Class B Equipment Class .................. 5-29 

Figure 5.6.5 Cost-Efficiency Curve for the Medium-Size Class B Equipment Class .............. 5-30 

Figure 5.6.6 Cost-Efficiency Curve for the Large-Size Class B Equipment Class .................. 5-31 

Figure 5.7.1 Material Price Sensitivity for the Medium-Size Class A Machine ...................... 5-32 

Figure 5.7.2 Material Price Sensitivity for the Medium-Size Class B Machine....................... 5-33 

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CHAPTER 5. ENGINEERING ANALYSIS 

5.1 INTRODUCTION 

The engineering analysis establishes the relationship between manufacturer selling price 

(MSP) and daily energy consumption (DEC), measured in kilowatt hours per day (kWh/day), for 

the refrigerated beverage vending machines covered in this rulemaking. This cost-efficiency 

relationship serves as the basis for cost/benefit calculations for individual customers, 

manufacturers, and the Nation. In determining this relationship, the U.S. Department of Energy 

(DOE) estimates the increase in manufacturerproduction cost (MPC) associated with 

technological changes that reduce the energy consumption of the baseline models, then converts 

each MPC to MSP by applying a multiplier to determine the manufacturer markup. 

The primary inputs to the engineering analysis are baseline information and data for each 

equipment class addressed in the market and technology assessment (chapter 3 in the TSD) and 

technology options from the screening analysis (chapter 4 in the TSD). Additional inputs 

include cost and energy consumption data that DOE estimated using a cost model and an energyconsumption model, respectively. The primary output of the engineering analysis is a set of 

cost-efficiency curves and a manufacturer markup multiplier used to convert MPC to MSP. In 

the subsequent markups analysis (chapter 6 in the TSD), DOE determines customer prices by 

applying distribution markups, sales tax, and contractor markups. After applying these markups, 

the data serve as inputs to the energy use characterization (chapter 7 in the TSD) and the lifecycle cost and payback period analyses (chapter 8 in the TSD). 

In this chapter, DOE discusses representative baseline units, methodology used to 

develop MPC, markups to MSP, methodology used to estimate energy consumption, costefficiency curves, sensitivity to material prices, and use of alternative refrigerants. 

5.2 METHODOLOGY OVERVIEW 

This section describes the analytical methodology used in the engineering analysis. In 

this rulemaking, DOE is adopting a design-option approach, which calculates the incremental 

costs of adding specific design options to a baseline model. For each equipment class, DOE 

analyzed three different machine sizes to assess how energy use varies with size. A small-, 

medium-, and large-sized machine was picked for Class A and Class B machines based on 

equipment offerings currently on the market. See chapter 3 of the TSD for a detailed description 

of the Class A and Class B equipment classes and section 5.5.4 below for additional detail on the 

different size machines analyzed. 

For each equipment class and size, DOE developed a core case cost using a 

manufacturing cost model. The core case cost is the MPC of the structure, walls, doors, shelving 

and fascia of the case, but does not include the cost of any energy-using components. DOE 

developed pricing for each design option and added the design option pricing to the core case 

costs to arrive at total MPC for each equipment class and size. DOE also calculated the impact 

EERE-2006-STD-0125 COMMENT 22
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of each design option on DEC using an energy consumption model. DOE then conducted a 

markups analysis to translate MPC to MSP. 

The primary results of the engineering analysis are a set of cost-efficiency curves, in the 

form of MSP versus DEC, for three sizes of each equipment class. The secondary results of the 

engineering analysis are two sensitivity analyses: a sensitivity of MSP to the price of metal a 

sensitivity of DEC to the use of alternative refrigerants. 

5.3 COST MODEL 

The cost model is the first of two key analytical models used in constructing costefficiency curves. A cost model was used to estimate the core case cost of a refrigerated 

beverage vending machine. This cost model was adapted from a cost model developed for 

DOE’s rulemaking on commercial refrigeration equipment (CRE).a The approach for CRE 

involved the disassembly of a self-contained refrigerator, an analysis of the materials and 

manufacturing processes, and the development of a parametric spreadsheet model. DOE 

modified the CRE model for refrigerated beverage vending machines using input from 

stakeholders on beverage vending machine MPC estimates and assumptions to confirm accuracy. 

DOE believes this approach is acceptable given the similarities in materials and manufacturing 

processes between commercial refrigeration equipment and beverage vending machines. 

5.3.1 Manufacturer Production Cost Estimates 

Manufacturer production cost is the sum of direct labor, direct material, and overhead 

(including investment depreciation) costs. Non-production cost elements, 

which are otherwise related to MPC, include sales, general and administrative, 

research and development, and interest. Altogether, these costs make up the 

MPC shown in 

Figure 5.3.1. 

 

a

 See http://www.eere.energy.gov/buildings/appliance_standards/commercial_products.html for further detail on and 

validation of the CRE cost model. 

Manufacturer Production Cost 

Full Production Cost Non-Production Cost 

Research Interest 

& Development Costs 

General & 

Administrative 

Costs 

Sales 

Costs 

Direct Overhead 

Material 

Direct 

Labor 

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Figure 5.3.1 Components of Manufacturer Production Cost 

The cost of specific modelsor cost to an individual manufacturer to produce a 

refrigerated beverage vending machinewill vary depending on the equipment’s precise design 

and features, actual manufacturing processes, the equipment mix in the factory, and other 

production factors. There are also considerable differences in the levels of vertical integration 

that affect cost structure and thus the cost of equipment. That is to say, companies with a large 

market share and/or revenue base tend to be more vertically integrated than their smaller 

competitors. Yet, potentially all manufacturers buy at least some of their parts and/or 

subsystems from outside vendors. 

5.3.2 Structure of the Cost Model Spreadsheet 

DOE used a detailed, component-focused manufacturing cost assessment methodology to 

estimate the MPC of each equipment class analyzed in the cost model, taking into account, for 

example, direct materials, direct labor, and factory overhead costs. Figure 5.3.2 shows the three 

major steps in generating the MPC. 

Figure 5.3.2 Manufacturer Production Cost Assessment Stages 

The first step in the MPC assessment was creating a complete and structured bill of 

materials (BOM) from the disassembly of a commercial refrigerator with transparent doors. The 

commercial refrigerator was dismantled, and each part was characterized according to weight, 

manufacturing processes, dimensions, material, and quantity. The BOM includes the costs of 

materials, components, and fasteners. It also estimates the cost of raw materials and purchased 

parts. DOE based assumptions about the sourcing of parts and in-house fabrication on industry 

experience, information in trade publications, and discussions with manufacturers. During the 

BVM rulemaking, DOE’s contractors conducted interviews and plant visits with manufacturers 

to ensure accuracy of the BVM model’s methodology and pricing. DOE accounted for 

equipment designs pertaining to BVMs by interviewing manufacturers and visiting plants, and 

then made appropriate changes to the BVM cost model. 

After developing a detailed BOM, DOE identified the major manufacturing processes, 

listed in Table 5.3.1, and developed a spreadsheet model. DOE estimated fabrication process 

cycle times and entered them into the BOM. For this analysis, $24.00 per hour was used as the 

average fully burdened labor rate based on typical annual wages and benefits of industry 

employees. In the final step of the cost assessment, DOE estimated assembly times and 

Raw 

Materials 

Bill of 

Materials 

Fabrication 

Processes 

Assembly 

Processes 

Finished 

Materials 

Purchased Parts

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associated direct labor costs. Once the cost estimate for each unit was finalized, DOE prepared a 

detailed summary of relevant components, subassemblies, and processes. 

Table 5.3.1 Major Manufacturing Processes 

Fabrication Finishing Assembly/Joining 

Fixturing Washing Adhesive Bonding 

Stamping/Pressing Powder Coating Spot Welding 

Brake Forming De-burring Seam Welding 

Cut and Shearing Polishing Inspecting & Testing 

Insulating 

5.3.3 Material Prices 

DOE determined the cost of raw materials by using prices for copper, steel, and 

aluminum from the American Metals Market.1 Prices for rifled and unrifled copper tubing were 

obtained directly from a tubing manufacturer. DOE noted that there have been drastic 

fluctuations in metal prices over the last few years. To account for these large fluctuations, DOE 

used prices of metals that reflect a 5-year average of the Bureau of Labor Statistics Producer 

Price Indices (PPIs) spanning 2002 to 2006 with an adjustment to 2007$.2 DOE used the PPIs 

for steel mill products and copper rolling, drawing, and extruding, and adjusted to 2007$ using 

the gross domestic product implicit price deflator.3

Between 2003 and 2006, the price of steel rose over 60 percent and the price of copper 

over 140 percent. Because DOE used a 5-year average in material prices from 2002 to 2006, 

these drastic increases are somewhat normalized to better represent long-term material price 

averages. Because it is not clear if these material price trends will continue, DOE conducted a 

sensitivity analysis to illustrate the effect of raw material price increases on the cost of beverage 

vending machines (see section 5.7.1 below). 

5.3.4 Results 

Core costs, defined as MPC minus the cost of design options, were calculated for three 

sizes of each equipment class. Table 5.3.2 displays these results. 

Table 5.3.2 Calculated Core Case Costs 

Equipment Class 12-Ounce Can 

Capacity Size Designation Calculated Core Cost $ 

Class A 270 Small 1,449 

Class A 350 Medium 1,758 

Class A 410 Large 1,906 

Class B 450 Small 1,159 

Class B 650 Medium 1,330 

Class B 800 Large 1,382 

5.4 MANUFACTURER MARKUP 

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At each stage of the distribution chain, manufacturers, wholesalers, and distributors apply 

a markup to cover their operating costs and profit margins. In the engineering analysis, DOE 

determined a manufacturer markup, and applied this markup to the MPC to arrive at the MSP for 

each equipment class. Wholesaler, distributor, and other markups are determined in the markups 

analysis (see chapter 6 of the TSD). 

The manufacturer markup is a market-share-weighted average value for the industry. 

DOE developed this markup by examining several BVM manufacturers’ gross margin 

information from annual reports and Securities and Exchange Commission 10-K reports. The 

manufacturers analyzed by DOE account for approximately 70 percent of the BVM market, and 

each of these companies is a subsidiary of a more diversified parent company that manufactures 

equipment other than beverage vending machines. Because the 10-K reports do not provide 

gross margin information at the subsidiary level, the estimated markups represent the average 

markups that the parent company applies over its entire range of equipment offerings. 

DOE evaluated markups for 2001 through 2006, calculating the manufacturer markup as 

100/(100 – average gross margin), where average gross margin is calculated as revenue – cost of 

goods sold. To validate the information, DOE reviewed its assumptions with BVM 

manufacturers. During interviews (see chapter 12 of the TSD), BVM manufacturers stated that 

many manufacturers generate revenue and profit by providing other goods and services, and their 

margins for beverage vending machines are lower than their company-wide margin. Taking this 

information into consideration, DOE is using an industry-wide manufacturer markup of 1.03 in 

the engineering analysis. 

5.5 ENERGY CONSUMPTION MODEL 

The energy consumption model is the second of two key analytical models used in 

constructing cost-efficiency curves. This model estimates the DEC of refrigerated beverage 

vending machines in kWh/day at various performance levels using a design-options approach. 

DOE developed the energy consumption model as a Microsoft Excel spreadsheet and is making 

the model available to the public on DOE’s website at 

http://www.eere.energy.gov/buildings/appliance_standards/commercial_products.html. 

Appendix A of the TSD provides instructions for using the spreadsheet. 

For a given equipment class, the model estimates the DEC for the baseline and the DEC 

of several levels of performance above the baseline. The model calculates energy consumption 

at each performance level separately. DOE selected ENERGY STAR Tier 1 as the baseline level 

for each equipment class and machine size.4 For the baseline level, DOE calculated a 

corresponding MPC using the cost model (described in section 5.3 above). For each level above 

the baseline, DOE used the cost increases of the various design options to recalculate the MPC. 

5.5.1 Screened-In Technologies 

In the market and technology assessment (chapter 3 of the TSD), DOE defined an initial 

list of technologies that can be used to reduce the energy consumption of refrigerated beverage 

vending machines. DOE then analyzed the following technology options: 

EERE-2006-STD-0125 COMMENT 22
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• higher efficiency lighting 

• higher efficiency lighting ballasts 

• higher efficiency evaporator fan motors 

• evaporator fan motor controllers 

• higher efficiency evaporator fan blades 

• improved evaporator design 

• low-pressure differential evaporators 

• insulation increases or improvements 

• defrost mechanism 

• improved glass pack (only for Class A machines) 

• higher efficiency condenser fan motors 

• higher efficiency condenser fan blades 

• improved condenser design 

• higher efficiency compressors 

5.5.2 Screened-In Technologies Not Considered in the Engineering Analysis 

In the screening analysis (chapter 4 of the TSD), DOE narrowed this list by eliminating 

those technologies that can reduce annual energy consumption of refrigerated beverage vending 

machines but do not reduce DEC. DOE then screened out those technologies that were not 

feasible, were not practical to manufacture, reduced equipment utility, or were considered 

unsafe. 

The remaining list of screened-in technologies became an input to the engineering 

analysis. However, for reasons noted below, DOE did not incorporate all of these technologies 

in the energy consumption model. These include higher efficiency evaporator and condenser fan 

blades, low-pressure differential evaporators, and defrost mechanisms. 

5.5.2.1 Higher Efficiency Evaporator and Condenser Fan Blades 

Higher efficiency evaporator and condenser fan blades reduce motor shaft power 

requirements by moving air more efficiently. Current BVM designs use stamped sheet metal or 

plastic axial fan blades. These fan blades are lightweight and inexpensive. DOE was not able to 

identify any axial fan blade technology that is significantly more efficient than what is currently 

being used, but did identify one alternative fan blade technology that might improve efficiency: 

tangential fan blades. These blades can produce a wide, even airflow, and have the potential to 

increase saturated evaporator temperature (SET) through improved air distribution across the 

evaporator coil, which would reduce compressor power. However, tangential fan blades are 

small and less efficient at moving air, and thus require greater motor shaft power. Because of 

these competing effects, DOE did not consider tangential fan blades as a design option. 

5.5.2.2 Low-Pressure Differential Evaporators 

Low-pressure differential evaporators reduce energy consumption by reducing the power 

required by evaporator fan motors. However, in space-constrained equipment, such as beverage 

vending machines, this reduction usually comes from a decrease in evaporator coil surface area, 

EERE-2006-STD-0125 COMMENT 22
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which generally requires a lower SET to achieve the same discharge air temperature and cooling 

potential. This, in turn, reduces compressor efficiency. Because of these competing effects, 

DOE did not consider low-pressure differential evaporators as a design option. 

5.5.2.3 Defrost Mechanisms 

Defrosting for refrigerated beverage vending machines is typically accomplished with 

off-cycle defrost. Because off-cycle defrost uses no energy (and decreases compressor on-time), 

there is no defrost mechanism to reduce defrost energy consumption. Therefore, DOE did not 

consider it as a design option. 

5.5.3 Design Options 

After conducting the screening analysis and removing from consideration those 

technologies described above, the following technologies were implemented as design options in 

the energy consumption model: 

• higher efficiency lighting and ballasts (a combination of the first two design options 

listed above) 

• higher efficiency evaporator fan motors 

• evaporator fan motor controllers 

• improved evaporator design 

• insulation increases or improvements 

• improved glass pack (for Class A machines) 

• higher efficiency condenser fan motors 

• improved condenser design 

• higher efficiency compressors 

Each design option has two to four technology levels, ranging from the worst performing 

to the best performing technology. The design options and the technology levels for each design 

option are described below. 

5.5.3.1 Higher Efficiency Lighting and Ballasts 

Lighting is an important characteristic of refrigerated beverage vending machines: it 

makes the product visible to the consumer in Class A machines and provides product advertising 

for Class B machines. Lighting systems typically operate continuously and provide an 

opportunity for significant energy savings. As lighting system efficiency increases, total energy 

consumption can be decreased by reducing the lighting system’s electricity consumption and the 

heat inside the refrigerated volume of Class A machines, which reduces the work of the 

compressor. For Class B machines, increasing lighting system efficiency only reduces direct 

energy consumption, because lamps and ballasts are placed outside the refrigerated space. 

It is important that machine (in the case of Class B machines) or vended product (in the 

case of Class A machines) illumination not degrade with higher design option levels, because 

this would decrease equipment utility. Therefore, DOE made every effort to maintain constant 

EERE-2006-STD-0125 COMMENT 22
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system light output among the lighting design options. This approach meant that DOE had to 

consider lighting as a system, rather than distinguishing lamps and ballasts as separate design 

options. This approach becomes more important when considering light emitting diode (LED) 

lighting systems, which don’t use ballasts, as fluorescent lighting systems do. 

Although LED systems generally have lower efficacy than the fluorescent systems they 

replace, the fixtures used with LEDs direct light more efficiently. Although the total lumen 

output of LED systems is lower than that of comparable fluorescent systems, the amount of light 

incident on a surface (illuminance) is roughly equivalent. BVM manufacturers, lighting 

manufacturers, and other technical experts indicated that current LED technology provides 

adequate product lighting for Class A machines, and in most cases is comparable to fluorescent 

lighting. For Class B machines, DOE originally believed that LED technology would be 

adequate, but BVM manufacturers indicated that they were still exploring LED technology, 

despite the lower lumen outputs. 

To account for variations in design between equipment classes, DOE used two lighting 

design options in the energy-consumption model. The first was for Class A machines and the 

second was for Class B machines. 

Class A machines illuminate the beverage containers being vended. Lamps must be sized 

to fit within the refrigerated space. DOE used 4-foot fluorescent lamps, based on the size of 

machines currently on the market. DOE started with a minimum technology of T12 fluorescent 

lamps and magnetic ballasts, but today is using a baseline of T8 fluorescent lamps with 

electronic ballasts, based on market data and conversations with manufacturers of refrigerated 

BVMs. Additionally, these lamps were required to have a color rendering index (CRI) of 

approximately 80, which is typical for this type of equipment. 

Table 5.5.1 Performance Details for “Class A Lighting” Design Option 

Level Description Lamp Type 

Lamp

Rated 

Power 

[watts (W)] 

Lamp 

Rated Light 

Output 

[Lumens] 

System 

Efficacy 

[Lumens/

W] 

System 

Light 

Output 

[Lumens] 

T12 4-ft T12, Magnetic F34T12 34.0 2,650 68.6 2,332 

T8 4-ft T8, Electric F32T8 32.0 2,850 85.0 2,679 

T8S 4-ft “Super” T8, 

Electric F32T8/HL 32.0 3,100 91.4 2,697 

LED 4-ft LED 4-ft LED 27.2 1,360 50.0 1,360 

Traditionally, Class B machines use 5- or 6-foot, high-output (HO) T12 fluorescent lamps 

and magnetic ballasts to attract as much attention to the machine as possible and to signal that 

the machine was functioning. DOE used this configuration as the minimum technology option. 

However, with the introduction of the ENERGY STAR qualified machines, BVM manufacturers 

have moved to T8 fluorescent lamps, and DOE used this as the baseline. Some beverage 

vending machine customers dictate certain size fluorescent lamps (to reduce the number of lamp 

types that lighting repair personnel carry on their trucks). As a result, DOE used a 4-foot and a 

2-foot T8 lamp to replace a 6-foot T12 lamp. These lamps were also required to have a CRI of 

approximately 80, which is typical for this type of equipment. 

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Table 5.5.2 Performance Details for “Class B Lighting” Design Option 

Level Description Lamp Type 

Lamp

Rated 

Power 

[W] 

Lamp Rated 

Light 

Output 

[Lumens] 

System 

Efficacy 

[Lumens

/W] 

System 

Light 

Output 

[Lumens] 

T12HO 6-ft., T12 HO 

Magnetic 

F72T12/ 

HO/SP 85.0 6,550 64.9 5,960 

T8 2-ft. T8 & 4–ft. T8 

Electric 

F17T8 & 

F32T8 49.0 4,250 90.4 3,910 

LED 6-ft. LED - 34.0 1,700 50.0 1,700 

5.5.3.2 Higher Efficiency Evaporator Fan Motors 

In conjunction with fan blades, fan motors are necessary to transfer heat from the 

refrigerated space to the refrigerant. In most situations they operate nearly continuously, and 

therefore use a significant amount of energy. As motor efficiency increases, energy consumption 

decreases due to a direct reduction in electricity consumption and waste heat inside the 

refrigerated space. 

Table 5.5.3 shows details for the evaporator fan motor design option. Currently, DOE 

considers shaded-pole motors (SPM) as the minimum technology, permanent split capacitor 

(PSC) motors as the mid-level technology, and brushless direct current (DC) or electronically 

commutated motors (ECMs) as the maximum technology. The motor efficiencies listed in Table 

5.5.3 are from Energy Savings Potential for Commercial Refrigeration Equipment, prepared by 

Arthur D. Little in 1996.5 

Table 5.5.3 Performance Details for “Evaporator Fan Motor” Design Option 

Shaded-Pole Motor (SPM) Permanent Split Capacitor 

(PSC) Motor 

Brushless DC Motor 

(ECM) Rated Power 

[W] Actual 

Power 

[W] 

Efficiency 

Actual 

Power 

[W] 

Efficiency 

Actual 

Power 

[W] 

Efficiency 

15.0 75.0 20.0% 33 45.5% 20.5 73.2% 

9.0 53.0 17.0% 21 42.9% 12.5 72.0% 

6.0 40.0 15.0% 15 40.0% 8.5 70.6% 

5.5.3.3 Evaporator Fan Controls 

Beverage vending machine manufacturers typically design evaporator fans to operate 

continuously. Circulating warm air through the case during compressor off-times prevents the 

evaporator coil from icing over. However, manufacturers indicated during interviews that under 

typical conditions, the evaporator fan is not required to run during all compressor off-times to 

keep the coils ice-free. Because of this, DOE developed a design option with controls to turn off 

the evaporator fan during compressor off-time and a period of fan operation to accomplish offcycle defrost. Based on discussions with outside experts and beverage vending machine 

manufacturers, DOE estimated that a total of 1.5 hours of off-cycle defrost operation would be 

required during a 24-hour period. To assess the total cost of this design option, DOE took into 

account the additional cost of parts, engineering, and increased labor for assembly. 

EERE-2006-STD-0125 COMMENT 22
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5.5.3.4 Improved Evaporator Design 

Evaporator coils are another component necessary to transfer heat from the refrigerated 

space to the refrigerant. Table 5.5.4 and 

Table 5.5.5 show details for the evaporator coil design option. Based on available 

information, DOE considered a minimum and a maximum technology level for this design 

option. DOE analyzed different evaporator coils given the differences in design load between 

Class A and Class B machines. For each level, DOE specified an overall UA-valueb and a coil 

cost. The UA-value is normalized to the standard coil, and the coil cost is normalized to the heat 

removal capacity of the coil. This allowed DOE to apply these details of coil design across all 

equipment sizes. In consultation with outside experts, DOE determined that the same coil 

improvements applied to different-sized coils would result in similar performance improvements. 

Table 5.5.4 Performance Details for “Improved Class A Evaporator Coil” Design Option 

Level Description Normalized UA [-] Normalized Coil Cost 

[$/Btu/h] 

FEV1 Standard Coil 1 $0.0058 

FEV2 High-Performance Coil 1.605 $0.0125 

Table 5.5.5 Performance Details for “Improved Class B Evaporator Coil” Design Option 

Level Description Normalized UA [-] Normalized Coil Cost 

[$/Btu/h] 

ZEV1 Standard Coil 1 $0.0066 

ZEV2 High-Performance Coil 1.646 $0.0143 

The details of coil construction (shown in Table 5.5.6 and Table 5.5.7) were based on a 

baseline and prototype high-performance coil evaluated in a study by the Refrigeration and 

Thermal Test Center (RTTC) at Southern California Edison.6 The high-performance coil uses a 

combination of enhancements to the heat transfer surfaces that increased its overall UA-value. 

These enhancements include a slightly higher fin pitch and different fin material. In summary, 

these changes result in an increased UA-value and increased coil cost. The increase in UA-value 

leads to an increase in the coil SET. Because compressor performance is directly related to SET, 

reductions in total case energy consumption are realized through an improved energy efficiency 

ratio (EER) at the condensing unit. In consultation with outside experts, DOE determined that 

the same coil improvements applied to differently sized coils at different temperatures would 

result in similar UA-value improvements. 

 

b

 The overall UA-value is the product of the overall heat transfer coefficient (British thermal units per hour (Btu/h)-

ft2-°F) and the total surface area (ft2

) of the coil. This value can be derived from the total heat transfer rate of the 

coil (Btu/h) divided by the log mean temperature difference of the air and refrigerant flows (∆TLM). 

EERE-2006-STD-0125 COMMENT 22
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Table 5.5.6 Properties of Standard and Enhanced Class B Evaporator Coil 

Property Standard Coil High-Performance Coil 

Overall Width (in) 24 24 

Overall Height (in) 6 6 

Overall Depth (in) 3 3 

Tube Rows per Circuit 15 15 

Number of Parallel Circuits 1 1 

Tubing Material Copper Copper 

Tubing Outer Diameter (in) 3/8 3/8 

Tubing Wall Thickness (in) 0.012 0.012 

Tubing Inner Surface Smooth Smooth 

Fin Material Aluminum Copper 

Fin Surface Flat Wavy 

Fin Dimensions (in) 3 x 6 3 x 6 

Fin Pitch (fins per inch) 6 7 

Table 5.5.7 Properties of Standard and Enhanced Class A Evaporator Coil 

Property Standard Coil High-Performance Coil 

Overall Width (in) 12 12 

Overall Height (in) 8 8 

Overall Depth (in) 3 3 

Tube Rows per Circuit 28 28 

Number of Parallel Circuits 1 1 

Tubing Material Copper Copper 

Tubing Outer Diameter (in) 3/8 3/8 

Tubing Wall Thickness (in) 0.012 0.012 

Tubing Inner Surface Smooth Smooth 

Fin Material Aluminum Copper 

Fin Surface Flat Wavy 

Fin Dimensions (in) 3 x 8 3 x 8 

Fin Pitch (fins per inch) 7 8 

5.5.3.5 Insulation Increases or Improvements 

Increasing or improving insulation decreases the conduction load, which reduces 

compressor energy consumption. DOE looked at two different methods of reducing the 

conduction load. The first method was a 1/8-inch increase in insulation thickness in all insulated 

panels. DOE assumed this addition required the machine to expand outward rather than inward, 

because an expansion inward would likely reduce the capacity to store canned or bottled 

beverages. DOE also accounted for the increased core case costs (due to the larger shell), design 

time, and fixture retooling. 

The second method DOE explored was changing the insulation material. Currently, 

beverage vending machines use foamed-in-place polyurethane as the primary insulation material. 

After discussions with insulation manufacturers, industry experts, and BVM manufacturers, 

DOE concluded that there are no significant variations among different polyurethane foams and 

blowing agents. Thus, DOE did not consider improvements in polyurethane foams or blowing 

agents. DOE also did not consider vacuum panels because they cannot provide the structural 

support of foamed-in-place designs, and cannot accept the bolts and fasteners typically used on 

the skins and frame that house the insulation. However, DOE did consider aerogels as a 

EERE-2006-STD-0125 COMMENT 22
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replacement for foamed-in-place polyurethane. DOE considered an open cell, silica-based 

aerogel that comes in an expansion pack and is expanded to fit the insulation cavity. 

5.5.3.6 Improved Glass Pack 

An improved glass pack design option only applies to Class A machines. Improvements 

to the glass pack (a prefabricated assembly of glass sheets, coatings, framing, and fill gas) result 

in less heat transfer to the refrigerated volume by radiation and conduction. This reduces the 

heat load on the refrigerant and hence the compressor load, thus reducing compressor energy 

consumption. The glass pack can be improved several ways, including adding panes of glass, 

adding low- emissivity (low-E) coating, changing from air fill to argon fill, and changing from 

an aluminum frame to a vinyl frame. Rather than examine each variation as an individual design 

option, DOE looked at three different option packages, shown in Table 5.5.8. 

The design options shown in Table 5.5.8 were then entered into WINDOW 5.27 to yield 

U-valuesc

 that account for heat transfer due to radiation and conduction at each of the test 

conditions set forth in American National Standards Institutue (ANSI)/American Society of 

Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) Standard 32.1–2004, 

Methods of Testing for Rating Vending Machines for Bottled, Canned, and Other Sealed 

Beverages.

 8 Table 5.5.9 catalogs the resulting U-values. 

Table 5.5.8 Performance Details for “Improved Glass Pack” Design Option 

Variable Baseline Enhanced Super Enhanced 

Frame Material Aluminum Aluminum Vinyl 

Number of Panes 2 2 3 

Glass Type: Panel 1 Clear Clear Clear 

Glass Type: Panel 2 Clear Low-E Low-E 

Glass Type: Panel 3 - - Clear 

Gas Fill Air Argon Argon 

Table 5.5.9 Performance Details for “Improved Glass Pack” Design Option 

Level Description 

Overall U-Factor at the 

ASHRAE 32.1 75°F Test 

Condition [Btu/h-ft-°F] 

Overall U-Factor at 

the ASHRAE 32.1 

90°F Test Condition 

[Btu/h-ft-°F] 

DOOR 1 Baseline 0.704 0.717 

DOOR 2 Enhanced 0.447 0.455 

DOOR 3 Super-Enhanced 0.292 0.298 

5.5.3.7 Higher Efficiency Condenser Fan Motors 

 Performance details for the condenser fan motor design option are identical to those 

shown in Table 5.5.3. As with evaporator fan motors, the SPM is the minimum technology 

level, the PSC motor is the mid-level technology, and the DC motor or ECM is the maximum 

technology level. Because condenser fan motors are outside the refrigerated space, efficiency 

 

c

 U-value is a measure of air-to-air heat transmission (loss or gain) due to thermal conductance and the difference in 

indoor and outdoor temperatures. 

EERE-2006-STD-0125 COMMENT 22
5-15

improvements only impact the direct electrical consumption of the motors and not the total case 

heat load. 

5.5.3.8 Increased Condenser Surface Area 

Condenser coils reject heat from the refrigerant to the ambient air. Based on available 

information, DOE considered both minimum and maximum technology levels for this design 

option. For each level, DOE specified an overall UA-value and a coil cost, shown in Table 

5.5.10 and Table 5.5.11. The UA-value is normalized to the standard coil, and the coil cost is 

normalized to the heat removal capacity of the coil. This allowed DOE to apply these details of 

coil design across all equipment sizes. In consultation with outside experts, DOE determined 

that the same coil improvements applied to different-sized coils would result in similar 

performance improvements. 

Table 5.5.10 Performance Details for “Improved Class A Condenser Coil” Design Option 

Level Description Normalized 

UA [-] 

Normalized Coil 

Cost [$/Btu/h] 

FCO1 Standard Coil 1 $0.006 

FCO2 High-Performance Coil 1.74 $0.015 

Table 5.5.11 Performance Details for “Improved Class B Condenser Coil” Design Option 

Level Description Normalized 

UA [-] 

Normalized Coil 

Cost [$/Btu/h] 

ZCO1 Standard Coil 1 $0.006 

ZCO2 High-Performance Coil 1.67 $0.019 

As previously mentioned, details of coil construction (shown in Table 5.5.12 and Table 

5.5.13) were based on a baseline and prototype high-performance coil evaluated in a study by 

RTTC. The high-performance coil uses a combination of enhancements to the heat transfer 

surfaces that increased its overall UA-value. These enhancements include higher fin pitch and 

different fin material. In sum, these improvements give the prototype coil a higher UA-value, 

allowing the coil to run at a saturated condenser temperature (SCT) cooler than the baseline coil 

while maintaining the same heat rejection rate. DOE did not consider rifled tubing because the 

refrigerant flow rates in beverage vending machines are typically not high enough to trigger 

turbulent flow. Because compressor performance is directly related to SCT, reductions in total 

case energy consumption are realized through an improved EER at the condensing unit. 

EERE-2006-STD-0125 COMMENT 22
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Table 5.5.12 Properties of Standard and Enhanced Class A Condenser Coil 

Property Standard Coil High-Performance Coil 

Overall Width (in) 21 21 

Overall Height (in) 10 10 

Overall Depth (in) 4 4 

Tube Rows per Circuit 36 36 

Number of Parallel Circuits 1 1 

Tubing Material Copper Copper 

Tubing Outer Diameter (in) 3/8 3/8 

Tubing Wall Thickness (in) 0.012 in 0.012 in 

Tubing Inner Surface Smooth Smooth 

Fin Material Aluminum Copper 

Fin Surface Flat Wavy 

Fin Pitch (fins per inch) 4 5 

Table 5.5.13 Properties of Standard and Enhanced Class B Condenser Coil 

Property Standard Coil High-Performance Coil 

Overall Width (in) 12.5 24 

Overall Height (in) 10 10 

Overall Depth (in) 2.25 3 

Tube Rows per Circuit 28 16 

Number of Parallel Circuits 3 2 

Tubing Material Copper Copper 

Tubing Outer Diameter (in) 3/8 3/8 

Tubing Wall Thickness (in) 0.012 in 0.012 in 

Tubing Inner Surface Smooth Rifled 

Fin Material Aluminum Aluminum 

Fin Surface Flat Flat 

Fin Pitch (fins per inch) 6 7 

5.5.3.9 Higher Efficiency Compressors 

In consultation with compressor manufacturers and external technical experts, DOE 

determined that two levels of technology were applicable for the compressor design option. The 

minimum technology level is a standard single-speed hermetic compressor, and the maximum 

technology level is a high-efficiency single-speed hermetic compressor (see chapter 4 of the TSD 

for a discussion of why variable-speed compressors were not considered). Reductions in total 

case energy consumption are realized through a reduction in compressor power consumption. 

DOE collected performance data for standard single-speed hermetic compressors from 

several manufacturers over a range of capacities applicable to the covered equipment (1,000 – 

4,000 Btu/h). This data set was used to look up appropriately sized compressors when 

developing each design-option curve (see section 5.5.7.2 below for information on the 

calculation of compressor energy consumption). Although several compressor manufacturers 

produce high-efficiency compressors, little data are currently available on their performance. 

Therefore, DOE approximated a set of high-efficiency compressors by adjusting the power 

consumption of the standard compressors using a constant multiplier. DOE developed this 

multiplier through research and consultation with experts. 

5.5.4 Baseline Specifications 

EERE-2006-STD-0125 COMMENT 22
5-17

DOE defined baseline specifications for each equipment class. These specifications 

include dimensions, numbers of components, temperatures, nominal power ratings, and other 

case features that are necessary to calculate the energy consumption of each equipment class. In 

conjunction with the lowest technological level of each design option (see section 5.5.3 above), 

the baseline specifications define the energy consumption and cost of the typical lowestefficiency equipment on the market. DOE also provided details on minimum technology options 

for design options that are typically below the efficiency of currently available equipment. DOE 

did this because a small portion of the market does not meet the voluntary ENERGY STAR Tier 

1 level. Table 5.5.14 below shows the specifications and units that are defined for each 

equipment class. 

Table 5.5.14 Baseline Specifications 

Specification Units

Refrigerated Volume ft3 

Number of Lamps in Refrigerated Volume - 

Number of Lamps not in Refrigerated Volume - 

Number of Ballasts in Refrigerated Volume - 

Number of Ballasts not in Refrigerated Volume - 

Evaporator Fan Nominal Rated Wattage W (Watts) 

Number of Evaporator Fans - 

Condenser Fan Nominal Rated Wattage W 

Number of Condenser Fans - 

Average Refrigerated Volume Temperature F (Fahrenheit) 

Nominal SET F 

Nominal SCT F 

Nominal Discharge Air Temperature (DAT) F 

Nominal Compressor Sizing Btu/h 

Solid Wall Area (including the door for Class B Machines) ft2

Glass Area ft2

Baseline Air Infiltration lb/hour 

Load from Electronic Components (bill changers, LED displays, etc.) kWh 

DOE established baseline specifications for each of the equipment classes modeled in the 

engineering analysis by reviewing available manufacturer data, selecting several representative 

units from available manufacturer data, and then aggregating the physical characteristics of the 

selected units. The baseline specifications were chosen so that the baseline machines met 

ENERGY STAR’s Tier 1 criteria (see chapter 3 of the TSD for further details on the criteria). 

This process created a representative unit for each equipment class with average characteristics 

for physical parameters (e.g., volume, wall area), and typical performance for energy-consuming 

components (e.g., fans, lighting). Table 5.5.15 and Table 5.5.16 show the results for each 

equipment class and size. Table 5.5.15 and Table 5.5.16 also include the 12-oz. can capacity of 

each size machine, for reference. 

EERE-2006-STD-0125 COMMENT 22
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Table 5.5.15 Class A Equipment Class Baseline Specifications 

Specification Small Medium Large 

Refrigerated Volume [ft3] 19 31 35 

12 oz. Can Capacity [#] 270 350 410 

Number of Lamps in Refrigerated Volume [#] 2 2 2 

Number of Lamps not in Refrigerated Volume [#] 0 0 0 

Number of Ballasts in Refrigerated Volume [#] 0 0 0 

Number of Ballasts not in Refrigerated Volume [#] 1 1 1 

Evaporator Fan Nominal Rated Wattage [W] 9 9 9 

Number of Evaporator Fans [#] 1 1 1 

Condenser Fan Nominal Rated Wattage [W] 9 9 9 

Number of Condenser Fans [#] 1 1 1 

Average Refrigerated Volume Temperature [F] 36 36 36 

Nominal SET [F] 8 8 8 

Nominal SCT [F] 95 95 95 

Nominal Discharge Air Temperature (DAT) [F] 19 19 19 

Nominal Compressor Sizing [Btu/h] 2,400 2,900 2,900 

Solid Wall Area (including the door for Class B Machines) [ft2] 34 46 51 

Glass Area [ft2] 8 9 11 

Baseline Air Infiltration [lb/hour] 5 9 10 

Load from Electronic components (bill changers, LED displays, 

etc.) [kWh] 0.45 0.45 0.45 

 

Table 5.5.16 Class B Equipment Class Baseline Specifications 

Specification Small Medium Large 

Refrigerated Volume [ft3] 19 24 31 

12 oz. Can Capacity [#] 450 650 800 

Number of Lamps in Refrigerated Volume [#] 0 0 0 

Number of Lamps not in Refrigerated Volume [#] 2 2 2 

Number of Ballasts in Refrigerated Volume [#] 0 0 0 

Number of Ballasts not in Refrigerated Volume [#] 1 1 1 

Evaporator Fan Nominal Rated Wattage [W] 9 9 9 

Number of Evaporator Fans [#] 2 2 2 

Condenser Fan Nominal Rated Wattage [W] 9 9 9 

Number of Condenser Fans [#] 1 1 1 

Average Refrigerated Volume Temperature [F] 39 39 39 

Nominal SET [F] 12 12 12 

Nominal SCT [F] 98 98 98 

Nominal Discharge Air Temperature (DAT) [F] 27 27 27 

Nominal Compressor Sizing [Btu/h] 2,300 2,400 2,400 

Solid Wall Area (including the door for Class B Machines) [ft2] 45 56 62 

Glass Area [ft2] 0 0 0 

Baseline Air Infiltration [lb/hour] 10.3 13 17 

Load from Electronic components (bill changers, LED displays, 

etc.) [kWh] 0.2 0.2 0.2 

EERE-2006-STD-0125 COMMENT 22
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5.5.5 Non-Numerical Assumptions 

In developing the energy consumption model, DOE made certain non-numerical 

assumptions concerning the analysis. These include general assumptions about the analysis as 

well as specific assumptions about load components and design options. 

DOE assumed that all conditions are based on new equipment tested in a controlledenvironment chamber and subjected to the methods of testing and rating in ANSI/ASHRAE 

Standard 32.1–2004. Manufacturers that certify their equipment to comply with Federal 

standards will be required to test new units using this method, which specifies ambient 

temperature, humidity, light level, and other requirements. 

DOE did not consider variable-speed compressors as a compressor design option. 

Variable-speed compressors reduce energy consumption under real-world conditions by 

matching their capacity to the refrigeration load, which can change due to variation in ambient 

conditions and product loading. This eliminates the inefficiencies that occur due to mismatched 

capacity and load in a single-speed compressor during part-load operation. The ANSI/ASHRAE 

Standard 32.1-2004 test procedure prescribes steady-state conditions. Thus, a variable-speed 

compressor would be limited to single-speed operation and the resulting EER would be no better 

than that of a properly sized single-speed compressor. Similarly, under ANSI/ASHRAE 32.1–

2004, the performance of a high-efficiency variable-speed compressor would be comparable to a 

high-efficiency single-speed compressor. 

Because baseline models must meet ENERGY STAR’s Tier 1 criteria, DOE assumed that 

Class B machines meet the Tier 1 criteria when tested at the ANSI/ASHRAE Standard 32.1-2004 

required 90°F test condition, and Class A machines meet the Tier 1 criteria when tested at the 

ASHRAE Standard 32.1-2004 required 75°F test condition. 

5.5.6 Numerical Constants and Assumptions 

In developing the energy consumption model, DOE identified constants and made 

assumptions concerning numerical values used in the analysis. These include ambient 

conditions, financial assumptions, and parameters necessary to calculate the component and nonelectric loads. Details of these assumptions are shown in Table 5.5.17 and Table 5.5.18 below. 

EERE-2006-STD-0125 COMMENT 22
5-20

Table 5.5.17 Energy Consumption Model Numerical Constants and Assumptions 

Numerical Constants and Assumptions Value Source 

Test Chamber Temperature [°F] 75 or 90 ASHRAE Standard 32.1-2004 

Test Chamber Relative Humidity [%] 45 or 65 ASHRAE Standard 32.1-2004 

Test Chamber Pressure [pounds per square 

in (psi), absolute] 14.7 Assumed 

Manufacturer Markup [$/$] 1.03 Publicly available corporate financial data; 

discussions with manufacturers. 

List Price Markup [$/$] 2.00 Assumed 

Lighting Operating Time Per Day [hr] 24 Assumed based upon ASHRAE Standard 32.1-

2004 

Evaporator Fan(s) Run Time Per Day [hr] 24 or less, 

Less than 24 hours if the evaporator fan motor 

control option is selected, based on discussions 

with manufacturers 

Off-cycle defrost time per day if 

Evaporator Fan Control is Enabled [hr] 1.5 Assumed 

R Value of Foam Insulation [ft2F·h/Btu·in] 8 Discussions with foam manufacturers; 

manufacturer data sheets 

R Value of Aerogel Insulation 

[ft2·°F·h/Btu·in] 10 Discussions with aerogel manufacturers 

Convective Film Coefficient Inside Case 

Walls With Evap Fan On [Btu/h-ft2-F] 4.00 Communication with RTTC 

Convective Film Coefficient Inside Case 

Walls With Evap Fan Off[Btu/h-ft2-F] 1.00 ASHRAE Handbook–Fundamentals 2005 

Convective Film Coefficient Outside Case 

Walls [Btu/h-ft2-F] 1.46 Communication with RTTC 

Evaporator Coil Overall Bypass Factor [%] 17 DOE estimate 

Density of Air @ Test Temperature [lb/ft3] 0.073 or 

0.071 ASHRAE Handbook–Fundamentals 2005 

High-Efficiency Compressor Cost 

Premium 6% Interviews with compressor manufacturers 

High-Efficiency Compressor Power 

Reduction 3% Interviews with compressor manufacturers 

Electricity Cost [$/kWh] 0.08 

Commercial Building Energy Consumption Survey 

(CBECS), Energy Information Administration 

(EIA), average commercial price in 2004 

Table 5.5.18 Engineering Constants 

Numerical Constants and Assumptions Number Source 

Specific Heat of Air @ Test Conditions 

[Btu/lb-R] 0.24 Thermodynamics by Cengel and Boles, 4th edition, 2002 

Latent Heat of Vaporization of Water/Water 

Vapor @ Test Temp [Btu/lb] 

1050 or 

1044 

Thermodynamics by Cengel and Boles, 4th edition, 

2002 

Latent Heat of Fusion of Water/Ice [Btu/lb] 143.5 ASHRAE Handbook–Fundamentals 2005 

Conversion from Watts to Btu/h [Btu/h-W] 3.415179 ASHRAE Handbook–Fundamentals 2005 

5.5.7 Model Components 

Figure 5.5.1 shows the components of the energy consumption model. The model 

calculates DEC in two major subsections: component energy consumption and compressor 

energy consumption. Component energy consumption is the sum of electrical energy directly 

EERE-2006-STD-0125 COMMENT 22
5-21

consumed by each fan motor and lamp. Compressor energy consumption is calculated from the 

total heat load (expressed as Btu/h). 

The total heat load is the sum of the component load and the non-electric load. The 

component load is a sum of the heat emitted by evaporator fan motors and lighting inside the 

refrigerated space. (Condenser fan motors are outside the refrigerated space and do not 

contribute to the component heat load.) The non-electric load is the sum of the heat contributed 

by radiation through glass (for Class A machines), heat conducted through walls and doors, and 

warm air infiltration. 

Figure 5.5.1 Components of the Energy Consumption Model 

5.5.7.1 Component Energy Consumption 

Component energy consumption is the sum of electrical energy directly consumed by 

each fan motor and lamp. 

Fan motor energy consumption is calculated by summing the power draw of each 

evaporator and condenser fan motor, and multiplying the total motor power by the total running 

time over 24 hours. This analysis assumed condenser fans only run when the compressor is on. 

The evaporator fan is assumed to run 24 hours a day, unless the evaporator fan motor control 

option is selected. In this case, the evaporator fan motor is off during compressor off-cycle times 

except for defrost periods. 

Total Heat 

Load 

[Btu/h]

Component 

Load

[Btu/h]

Non-Electric 

Load

[Btu/h]

Fan Motor 

Heat Load

[Btu/h]

Lighting Heat 

Load

[Btu/h]

Radiation 

Load

[Btu/h]

Conduction 

Load

[Btu/h]

Infiltration 

Load

[Btu/h]

Daily Energy 

Consumption [kWh/day]

Compressor 

Energy 

Consumption 

[kWh/day]

Compressor Model 

(ARI 540)

Electric Energy 

Consumption

[kWh/day]

Heat Load 

[Btu/h]

Legend:

Component 

Energy 

Consumption 

[kWh/day]

Fan Motor 

Energy

 Consumption 

[kWh/day]

Lighting 

Energy 

Consumption 

[kWh/day]

EERE-2006-STD-0125 COMMENT 22
5-22

Lighting energy consumption is calculated by summing the power draw of each lamp and 

ballast, and multiplying the total by the total operating time of the lighting system over a 24-hour 

period. 

5.5.7.2 Compressor Energy Consumption 

DOE calculated compressor energy consumption (CEC) using the compressor model 

described in section 6.4 of Air-Conditioning and Refrigeration Institute (ARI) Standard 540-

2004, Performance Rating of Positive Displacement Refrigerant Compressors and Compressor 

Units. This model is based on a 10-coefficient polynomial derived from empirical compressor 

performance data for power, mass flow, current, and efficiency. The coefficients are derived for 

each of these parameters as a function of SET and SCT. Compressor coefficients, or tabulated 

empirical data (from which coefficients can be derived), are available from compressor 

manufacturers. Similar to the method used for remote condensing equipment, the EER of any 

compressor can be determined given the SET and SCT. 

5.5.7.3 Component Load Model 

The component load is the sum of the heat emitted by each evaporator fan motor and 

lamps inside the refrigerated volume. This waste heat must be removed by the compressor. 

DOE assumed that all electrical energy consumed by the evaporator fan motors ends up 

as heat inside the refrigerated space. In any electric motor, irreversibilities in the motor 

windings, bearings, and other mechanical components convert much of the input electrical 

energy into heat. The rest of the energy is converted to moving air inside the case. This moving 

air is slowed by friction and eventually converted to heat as well. 

DOE assumed that all electrical energy consumed by lamps and ballasts inside the 

refrigerated space ends up as heat inside that space. DOE also assumed that none of the 

electrical energy consumed by lamps and ballasts outside the refrigerated space ends up as heat 

inside that space. (Note that having ballasts inside the refrigerated space is not typical of current 

beverage vending machine designs, but DOE wished to consider the possibility in the model.) 

5.5.7.4 Radiation Load Model 

The radiation heat load model accounts for the gray-body radiation between the warm 

surfaces of the surrounding environment (the test chamber) and the cold inner surfaces of the 

refrigerated space through the glass doors of Class A machines. The net radiation is incorporated 

into the overall U-value of the door calculated by WINDOW 5.2 (see Table 5.5.9 above for the 

U-values calculated). Within the WINDOW 5.2 program, the environmental conditions in the 

refrigerated volume and the test chamber were specified to match the two test conditions defined 

in ASHRAE Standard 32.1-2004. See section 5.5.7.5 below for a discussion of the calculation of 

the combined radiation and conduction loads for glass doors and other glass. 

5.5.7.5 Conduction Load Model 

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The conduction load model accounts for the heat conducted through walls and doors. For 

solid walls and doors, the conduction load is given by: 

Q A

T T

h

d

k h

cond walls

room case

o

ins

ins i

=

−

+ +

1 1 Eq. 5.1 

where 

Awalls is the area of the exterior of the refrigerated volume (ft2), 

ho is the convective film coefficient on the outside of refrigerated volume walls (Btu/h-ft2-°F), 

hi is the convective film coefficient on the inside of refrigerated walls (Btu/h-ft2-°F), 

dins is the insulation thickness (in), and 

kins is the insulation thermal conductivity (Btu-in/h-ft2-°F). 

Because of its high thermal conductivity, the sheet metal that encloses the insulation does 

not have any significant effect on the conduction load, and therefore was not included in the 

calculation of conduction load. See Table 5.5.17 above for numerical constants pertaining to the 

conduction model. 

For glass doors, the conduction load is incorporated into the overall U-factor of the door 

assembly or glass calculated by WINDOW 5.2 (see Table 5.5.9 above for the U-values 

calculated). The combined radiation and conduction load for glass doors and other glass is 

calculated as: 

Q U A T T ( ) glass overall glass room case = − Eq. 5.2 

where 

Uoverall is the overall U-factor, including convection and radiation (Btu/h-ft2-°F), and 

Aglass is the area of the glass (ft2). 

5.5.7.6 Infiltration Load Model 

The infiltration load model accounts for the heat that is added to a display case when 

warm, moist air enters the case (primarily through leaks and vend doors). The infiltration load is 

difficult to model because of the inherent complexity of the fluid phenomena of infiltration. 

Therefore, DOE used empirical data for defrost melt water to back-calculate the infiltration load. 

This approach was correlated using empirical data for infiltration loads provided by Southern 

California Edison’s RTTC from beverage vending machine testing. 

Ambient room air infiltrated into the refrigerated space contributes to the load in two 

ways: a sensible load in the form of the heat contained in the dry air, and a latent load in the 

form of water vapor in the air that condenses on cold surfaces. Assuming the amount of 

condensation on the coil—and thus the amount of defrost melt water—is correlated to the 

amount of water that enters the case through infiltration, the defrost melt water mass flow can be 

EERE-2006-STD-0125 COMMENT 22
5-24

used to estimate the mass flow of water that enters the case as water vapor in the air. Given the 

values both for the humidity level in the case and the ambient room air, the mass flow of air that 

enters the refrigerated case can be calculated as: 

( )( ) m

m

HR HR CBF air

defrostmelt

room case

=

− − 1

Eq. 5.3 

where 

mair is the mass flow of dry air into the case (lbs/hr),

mdefrostmelt is the mass flow of defrost melt water (lbs/hr), 

HRroom is the humidity ratio of the ambient air in the room (dimensionless), 

HRcase is the humidity ratio of the air inside the case (dimensionless), and 

CBF is the coil bypass factor (dimensionless). 

The coil bypass factor is a measure of the fraction of air in the case that is never 

influenced by the evaporator coil (or a measure of the fraction of air that does not deposit its 

moisture onto the evaporator coil). This factor allows the infiltration calculation to be correlated 

to empirical data. Communication with Southern California Edison’s RTTC was used to 

estimate the evaporator coil bypass factor. As shown in Table 5.5.17 above, the coil bypass 

factor was estimated to be 17 percent. 

Once the air flow rates were calculated, they were entered into DOE’s model. The mass 

flow of water vapor into the case is the mass flow of air multiplied by the difference of humidity 

ratios inside and outside the case. Using the mass flows of air and water vapor, the infiltration 

load can be approximated using: 

Q m C T T m H ( ) inf air dryair room case vapor v H O , = − + 2 Eq. 5.4 

where 

Qinf is the infiltration load (Btu/h),

Cair is the specific heat of dry air (Btu/lb-°F), 

mvapor is the mass flow of water vapor into the case (lbs/hr), and 

Hv,H2O is the heat of vaporization of water. 

5.6 COST-EFFICIENCY CURVES 

The result of the engineering analysis is a set of cost-efficiency curves. DOE developed 

six curves representing the two equipment classes and three different size machines in each 

equipment class using the baseline specifications and design options described above. The 

method for developing curves started with determining the baseline energy consumption (chosen 

to be ENERGY STAR Tier 1) and manufacturer production cost. Above the baseline, design 

options were implemented in order of lowest to highest payback, and only one design option was 

EERE-2006-STD-0125 COMMENT 22
5-25

implemented at each design option level. Design options were implemented until all 

technologies were at a maximum level. 

The six cost-efficiency curves are shown in Figure 5.6.1 through Figure 5.6.6 below and 

in tabular form in Table 5.6.1 through Table 5.6.6 below in the form of DEC versus MSP. More 

detailed results, including the design options used at each design option level, are provided in 

appendix B. The cost-efficiency curves were calculated at the 75°F test condition of ASHRAE 

Standard 32.1-2004. 

As stated above, DOE used the cost-efficiency curves from the engineering analysis as an 

input to the life-cycle cost (LCC) analysis to determine the price of beverage vending machines 

to the customer (see chapter 8 of the TSD). 

EERE-2006-STD-0125 COMMENT 22
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$1,500

$1,600

$1,700

$1,800

$1,900

$2,000

$2,100

$2,200

$2,300

$2,400

3.0 3.5 4.0 4.5 5.0 5.5 6.0

Daily Energy Consumption [kWh/day]

Manufacturer Selling Price [$]

Figure 5.6.1 Cost-Efficiency Curves for the Small-Size Class A Equipment Class 

Table 5.6.1 Cost-Efficiency Data for the Small-Size Class A Equipment Class 

Efficiency 

Level 

Daily Energy 

Consumption 

[kWh/day] 

Manufacturer 

Selling Price 

[$] 

1 5.80 1,684.50 

2 5.56 1,688.87 

3 5.21 1,700.65 

4 4.76 1,717.19 

5 4.60 1,724.48 

6 4.41 1,735.04 

7 4.34 1,739.80 

8 4.16 1,762.79 

9 4.12 1,773.35 

10 4.07 1,788.00 

11 3.88 1,890.09 

12 3.76 1,972.75 

13 3.71 2,320.21 

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5-27

$1,900

$2,000

$2,100

$2,200

$2,300

$2,400

$2,500

$2,600

$2,700

$2,800

$2,900

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

Daily Energy Consumption [kWh/day]

Manufacturer Selling Price [$]

Figure 5.6.2 Cost-Efficiency Curve for the Medium-Size Class A Equipment Class 

Table 5.6.2 Cost-Efficiency Data for the Medium-Size Class A Equipment Class 

Efficiency 

Level 

Daily Energy 

Consumption 

[kWh/day] 

Manufacturer 

Selling Price 

[$] 

1 6.36 2,028.10 

2 6.12 2,032.48 

3 5.76 2,044.26 

4 5.30 2,064.24 

5 5.13 2,071.53 

6 4.95 2,082.09 

7 4.86 2,087.71 

8 4.63 2,115.49 

9 4.59 2,126.05 

10 4.52 2,143.79 

11 4.32 2,258.65 

12 4.19 2,341.31 

13 4.14 2,815.25 

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$2,100

$2,300

$2,500

$2,700

$2,900

$3,100

$3,300

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

Daily Energy Consumption [kWh/day]

Manufacturer Selling Price [$]

Figure 5.6.3 Cost-Efficiency Curves for the Large-Size Class A Equipment Class 

Table 5.6.3 Cost-Efficiency Data for the Large-Size Class A Equipment Class 

Efficiency 

Level 

Daily Energy 

Consumption 

[kWh/day] 

Manufacturer 

Selling Price 

[$] 

1 6.72 2,190.22 

2 6.46 2,194.60 

3 6.11 2,206.38 

4 5.60 2,226.36 

5 5.44 2,233.66 

6 5.25 2,244.21 

7 5.16 2,249.84 

8 4.91 2,277.62 

9 4.86 2,288.17 

10 4.78 2,306.94 

11 4.53 2,447.32 

12 4.41 2,529.99 

13 4.34 3,054.38 

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$1,300

$1,400

$1,500

$1,600

$1,700

$1,800

$1,900

$2,000

$2,100

3.0 3.5 4.0 4.5 5.0 5.5 6.0

Daily Energy Consumption [kWh/day]

Manufacturer Selling Price [$]

Figure 5.6.4 Cost-Efficiency Curve for the Small-Size Class B Equipment Class 

Table 5.6.4 Cost-Efficiency Data for the Small-Size Class B Equipment Class 

Efficiency 

Level 

Daily Energy 

Consumption 

[kWh/day] 

Manufacturer 

Selling Price 

[$] 

1 5.49 1,370.33 

2 4.70 1,382.11 

3 4.55 1,386.49 

4 4.18 1,407.60 

5 4.13 1,411.93 

6 3.93 1,430.10 

7 3.48 1,507.20 

8 3.42 1,519.79 

9 3.28 1,551.23 

10 3.26 1,561.79 

11 3.21 2,026.00 

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$1,500

$1,600

$1,700

$1,800

$1,900

$2,000

$2,100

$2,200

$2,300

$2,400

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5

Daily Energy Consumption [kWh/day]

Manufacturer Selling Price [$]

Figure 5.6.5 Cost-Efficiency Curve for the Medium-Size Class B Equipment Class 

Table 5.6.5 Cost-Efficiency Data for the Medium-Size Class B Equipment Class 

Efficiency 

Level 

Daily Energy 

Consumption 

[kWh/day] 

Manufacturer 

Selling Price 

[$] 

1 6.02 1,554.94 

2 5.25 1,566.72 

3 5.07 1,571.09 

4 4.65 1,590.05 

5 4.32 1,611.17 

6 4.26 1,615.93 

7 4.18 1,693.03 

8 3.74 1,707.68 

9 3.58 1,740.48 

10 3.55 1,751.04 

11 3.49 2,327.48 

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$1,500

$1,600

$1,700

$1,800

$1,900

$2,000

$2,100

$2,200

$2,300

$2,400

$2,500

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

Daily Energy Consumption [kWh/day]

Manufacturer Selling Price [$]

Figure 5.6.6 Cost-Efficiency Curve for the Large-Size Class B Equipment Class 

Table 5.6.6 Cost-Efficiency Data for the Large-Size Class B Equipment Class 

Efficiency 

Level 

Daily Energy 

Consumption 

[kWh/day] 

Manufacturer 

Selling Price 

[$] 

1 6.43 1,608.50 

2 5.70 1,620.28 

3 5.49 1,624.65 

4 5.01 1,643.61 

5 4.66 1,664.73 

6 4.60 1,669.49 

7 4.51 1,746.59 

8 4.32 1,779.39 

9 3.88 1,795.07 

10 3.84 1,805.63 

11 3.78 2,446.24 

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5.7 SENSITIVITY ANALYSES 

DOE conducted two sensitivity analyses. The first examined the sensitivity of the costefficiency curves to material prices. The second examined the sensitivity of performance levels 

to the use of alternative refrigerants. 

5.7.1 Material Price Sensitivity 

DOE conducted a sensitivity analysis on material prices to examine the effect of spikes in 

commodity prices that the industry has experienced over the past few years. The sensitivity 

analysis compares the 5-year average prices for 2002–2006 (described in section 5.3.3) with the 

5-year high price for the same period (2006 having the highest material prices ). The results of 

this sensitivity analysis are presented in Figure 5.7.1 below for the medium-size Class A 

machine, and Figure 5.7.2 below for the medium-size Class B machine. 

The most noticeable impact is a 6-percent increase in the Class B machine price and a 3-

percent increase in the Class A machine price. Also, the high material prices increased coil costs 

by roughly 50 percent because of the large increases in copper costs. As a result, design option 

ordering changed because coil improvements became less cost-effective. 

1900

2100

2300

2500

2700

2900

3100

4.0 4.5 5.0 5.5 6.0 6.5

Daily Energy Consumption [kWh/Day]

Manufacturer Selling Price [$]

2002-2006 (5-Yr Avg)

2006 Prices (5-Yr High)

Figure 5.7.1 Material Price Sensitivity for the Medium-Size Class A Machine 

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1400

1600

1800

2000

2200

2400

2600

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5

Daily Energy Consumption [kWh/Day]

Manufacturer Selling Price [$]

2002-2006 (5-Yr Avg)

2006 Prices (5-Yr High)

Figure 5.7.2 Material Price Sensitivity for the Medium-Size Class B Machine

5.7.2 Alternative Refrigerants 

In conducting an engineering analysis, DOE considers the effects of regulatory changes 

outside DOE’s statutory energy conservation standards rulemaking process that can affect the 

manufacturers of the covered equipment. Some of these changes can also affect the energy 

efficiency or energy consumption of that equipment. DOE identified such external engineering 

issues that could affect the engineering analysis. These issues are closely related to the 

cumulative regulatory burden assessment that DOE conducted as part of the manufacturer impact 

analysis (see chapter 12 of the TSD). 

Due to the phaseout of chlorofluorocarbons and hydrochlorofluorocarbons, the beverage 

vending machine industry must transition to non-ozone-depleting refrigerants. As a result, the 

industry is transitioning to hydrofluorocarbon-based (HFC-based) refrigerants in its equipment. 

Much of the beverage vending machine industry is already using HFC-based refrigerants, 

particularly R-134a. Therefore, DOE assumed from the outset that manufacturers would 

continue to use HFC-based refrigerants in their equipment. 

However, some countries where BVM manufacturers sell their equipment and the BVM 

customers in those countries might try to shift away from HFC-based refrigerants. Based on 

conversations with beverage vending machine manufacturers and industry experts, DOE 

examined two classes of non-HFC refrigerants: hydrocarbon-based refrigerants and carbon 

dioxide (CO2). 

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Hydrocarbon-based refrigerants, such as butane and propane, are the first alternative. 

These are extremely volatile and are not currently feasible because of safety risks. If the 

refrigerant leaked, it could ignite and cause personal and property damage. Because of this, 

DOE did not conduct a cost sensitivity analysis on hydrocarbon-based refrigerants. 

The second alternative, CO2, does not have the volatility issues of hydrocarbons, but does 

require design changes from HFC-based refrigerant systems. CO2 operates at a higher pressure, 

so different materials or material thicknesses must be used for coils and compressors. However, 

components do not currently exist in sizes appropriate for beverage vending machines. Thus, 

DOE was not able to conduct a cost sensitivity analysis on CO2-based systems. 

5.8 RESULTS 

DOE presents more detailed results and supporting data for the engineering analysis in 

appendix B of this TSD.

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** DRAFT ** 

5-35

REFERENCES 

1

 American Metals Market, http://www.amm.com/. 

2

 U.S. Department of Labor, Bureau of Labor Statistics, Producer Price Indices, 

http://www.bls.gov/ppi/. 

3

 U.S. Department of Commerce, Bureau Economic Analysis, Gross Domestic Product 

Implicit Price Deflator, https://bea.gov/bea/dn/nipaweb/TableView.asp#Mid. 

4

 Environmental Protection Agency and U.S. Department of Energy’s ENERGY STAR 

program, http://www.energystar.gov. 

5

 Arthur D. Little, Energy Savings Potential for Commercial Refrigeration Equipment, 

June 1996. 

6

 Southern California Edison, Next Generation Vending Machine, 2006 ACEEE Summer 

Study on Energy Efficiency in Buildings. 

7

 Lawrence Berkley National Laboratory, Window 5.0, available at 

http://windows.lbl.gov/software/window/window.html. 

8

 American National Standards Institute/American Society of Heating, Refrigeration and 

Air-conditioning Engineers, 2004. Standard 32.1-2004: Methods of Testing for Rating 

Vending Machine for Bottled, Canned, and Other Sealed Beverages. 

EERE-2006-STD-0125 COMMENT 22