became effective in 1993. 53 There may be limited additional energy savings possible through optimization of automatic defrost.

Adaptive Defrost To reduce the energy used for defrost, adap tive defrost can be used. An adaptive defrost system can control both the defrost time and the amount of defrost heat. Adaptive defrost systems make use of controls to adjust the time between defrost cycles to the appropriate amount for the door opening frequency, ambient conditions , and other consumer usage patterns which affect the introduction of moisture into the cabinet. In a typical automatic defrost system, a mechanical timer initiates defrost after a spec ified time period, usually 10 to 12 hours of compressor on-time. By allowing adjustment of the time between defrosts, energy use can be reduced. The DOE energy test procedure includes modified test procedures for evaluating the energy use of products with adaptive defrost. In its 1995 TSD, DOE estimated that energy consumption can be reduced by three to four percent with adaptive defrost. 53 It is unclear what percentage of the refrigerator market currently uses adaptive defrost.

Condenser Hot Gas Another method of reducing the energy required for defrost is to eliminate the need for electric heaters by substituting c ondenser hot gas in their place. In a condenser hot gas defrost system, the compressor continues to run and a valve opens allowing hot compressed refrigerant to flow to the evaporator. Many frost-free refrige rator-freezers in the 1960s and 1970s used such a defrost system.

3.3.2.11 Control System
The control systems discussed here pertain to those controlling the temperature and airdistribution within the refrigeration product.

Temperature Control

Conventional thermostats are thermomechanical devices that are not very accurate. The inaccuracy of these devices may produce large te mperature fluctuations within the cabinet and, in turn, thermodynamic inefficiencies. Electronic th ermostats are available that can provide more precise and repeatable temperat ure control than conventional th ermostats. This can result in improved efficiency. Electronic thermostat syst ems can also account for more parameters than just the cabinet temperature, su ch as the room temperature, to better regulate product operation and reduce compressor run times.

Air-Distribution Control For refrigerator-freezers, better air distribution between the freezer and fresh food compartments can improve temperature contro l and reduce energy consumption. Improving the distribution of cold air within the refrigerator-freezer allows the temperature difference between the air and foodstuffs to be minimized, enabling the evaporation temperature to be raised and, thereby, reducing energy consumption. It is uncert ain to what degree the air distribution control in current refrigerator-freezer models can be im proved. However, the fact that several patents

3-65have been issued in the U.S. since 1995 regarding air distributi on implies that improvements in air distribution control are possible. 55

3.3.2.12 Other Technologies
Alternative refrigerants and changing the lo cation of refrigeration components can also improve the efficiency of refrigeration produc ts. These two technology options are discussed below.

Alternative Refrigerants Through the 1980s, CFC-12, a chlorofluorocarbon, was used as the refrigerant in almost all refrigerators, refrigerato r-freezers, and freezers. However, under the Montreal Protocol, all CFCs were banned from use by the mid-1990s due to their high ozone depletion potential (ODP). In the early 1990s, many alternative refrigerants were evaluated as a replacement for CFC-12. Of the alternatives considered, th e industry settled on HFC-134a as the replacement for CFC-12. Although initial research demonstrated that HFC-134a as a drop-in replacement yielded efficiencies which were four to 10 percent less than CFC-12, further work showed that with the appropriate superheat and subcoo ling taken into consideration, HF C-134a could yield essentially equivalent system efficiencies as CFC-12. 86

Because HFC-134a exhibits some global warm ing potential (GWP), research continued to find an alternative refrigerant with less or no GWP. For example, R-152a has a lower GWP than HFC-134a but, primarily due to flammability concerns and the potentia l liability issues it posed to refrigerator manufacturers, it wa s dismissed as a potential alternative.

Naturally occurring substances such as carbon dioxide, ammonia, and hydrocarbons are all considered to be environmentally safe refr igerants with very low GWP. Hydrocarbons in particular are attractive due to their similar thermodynamic prope rties to CFC-12. Much research has been conducted showing the efficiency benefits of hydrocarbons. For example, the performance of propane/isobutane and propane/butane mixtures in domestic refrigerators has been shown to be equal to or better than products using CFC-12. 87, 88 Hydrocarbon flammability has been pointed out as a significant drawback an d has prevented their adoption in U.S. products. In contrast, European refriger ator manufacturers started manuf acturing products with isobutane in the 1990s. However, recently the General El ectric Company announced the intention to introduce this refrigerant in the U.S. 89

Component Location In its 1995 TSD, DOE saw energy savings poten tial in more optimal placement of certain components. For example, if the compressor and condenser are loca ted on the top of the refrigerator-freezer, DOE determined that they can operate more efficiently because heat is more readily convected away from the system and, in addition, the condenser fan can be eliminated. As described previously, traditionally, the compressor and condenser are located at the bottom rather than the top of the refrigerator-freeze r so the user can have easy access to the food compartments, to key center of gravity low, and to provide air flow and a heat source near the tray which collects defrost water to assure quick re-evaporation of water. Locating the condenser and compressor at the top of th e unit would require modification of traditional practice and

3-66consumer preference. It would also require product redesign, wh ich could potentially increase manufacturing costs.

Another option is to locate the evaporator fan mo tor outside the cabinet to reduce internal loads from the heat loss of the motor. However, it is difficult to prevent air leakage where the motor shaft penetrates the cabinet wa ll. The 1995 TSD concluded that th e lack of experimental data prevented the evaluation of component relocation. 53

3.3.2.13 Alternative Refrigeration Cycles
Alternative refrigeration cycles may have the potential to improve system efficiency. Several alternative refrigeration cycles for refr igerator-freezers are described below. Dual-loop refrigerator-freezers using two independent refr igeration cycles (one for the fresh foodcompartment and the other for the freezer compartment) are available on the market. Also, dualevaporator units likely utilizing a control valv e system are also being marketed. The other alternatives listed below have been demonstrated in prototypes to reduce energy consumption but it is uncertain as to whether they can be mass produced as a practical alternative to today’s current conventional refrigeration systems.

Lorenz-Meutzner Cycle In a conventional refrigerator-freezer, th e temperature of the freezer and fresh food compartments are around 5oF (-15 oC) and 38oF (3.3oC), respectively. This suggests that the fresh food compartment with a smaller temperature lift (i.e., the temperature difference between the evaporator and condenser) can operate with a higher efficiency than that of the freezer. By using zeotropic g refrigerant mixtures, the Lorenz-Meutzner cycle exploits the inherent thermodynamic advantages of the temperature glide exhibite d during evaporation or condensation of the refrigerant mixture. By choosing a refrigerant mi xture with very wide temperature glide, the refrigerant mixture can pass sequentially th rough the freezer and fresh food compartment evaporators, providing refrigera tion at the two evaporating temp erature levels using a single compressor. As compared to a conventional re frigerator-freezer, the hardware differences include a high-temperature evaporator for the fresh food compartment and a low-temperature heat exchanger between the fresh food and freezer evaporators. Lorenz and Meutzner in their research determined that their cycle using an R- 22/R-11 refrigerant mixture (50 percent of each) achieved up to 20 percent energy savings compared to a conventional refrig erator-freezer using R-12 only. 90

Subsequent research validated Lorenz a nd Meutzner’s findings and demonstrated the viability of the cycle based on the use of different zeotropic refrigerant mixtures, including mixtures composed of hydrocarbons. For example, as compared to a conventional refrigeratorfreezer, experimentation on an 18 ft 3 top-mount refrigerator-freezer demonstrated that a modified

g A zeotropic mixture consists of two or more refrigerant components. Zeotropic mixtures have what is referred to as a temperature glide when they boil and condense: at a fixe d pressure, the temperature is higher for higher quality (i.e. vapor fraction). Unlike zeotropes, azeotropic mixtures consist of two or more refrigerant components that behave like a single refrigerant, exhibiting no temperature glide. 3-67Lorenz-Meutzner cycle yielded 16.6 percent, 14.6 per cent, and 16.7 percent energy savings with binary mixtures of R-22/R-123, propane/n-pe ntane, and propane/n-butane, respectively. 91

Because the industry settled on the use of HF C-134a to replace CFC-12, interest in the Lorenz-Meutzner cycle as an alternative to conventional re frigeration cycles declined.

Dual-Loop System

One of the best methods to reduce the ther modynamic irreversibilities resulting from the operation with a single evaporat or in a refrigerator-freezer is to employ two separate refrigeration cycles. This system, referred to as a dual-loop system, has tw o completely separate refrigeration cycles which provide cooling for the freezer and fresh food compartments independently. In practice, the theo retical benefits of such a cycle are not achieved due to the use of two compressors that are smaller and less effici ent than the original single compressor. Also, dual-loop systems are physically larger and would either increase th e product’s external dimensions or decrease the usable refrigerator volume.

Research has demonstrated that the ener gy savings due to a dual-loop system are a function of the cabinet load ratio (defined as the ratio of the fresh food to the freezer cabinet loads) and the ratio of the fr eezer and refrigerator cycle effi ciencies. Depending on these two parameters, a dual-loop system using HFC-134a can reduce energy consumption by up to 30 percent compared to a conventional refrigerator-freezer. 92

There are numerous products currently on th e market that incorporate dual-compressor systems, including Bosch’s Integra line of bottom-mount refrigerator-freezers, 93 Sun Frost’s RF19 model, 94 Northland’s 48-inch side-mount refrigerator-freezer, 95 Sub-Zero’s built-in line of refrigerator-freezers, 96 Liebherr refrigerators, 97 etc.

Two-Stage System The two-stage system employs one condenser , two evaporators, tw o compressors, and at least one suction-line heat ex changer. The increased efficiency of this system over aconventional system is obtained due to a smaller work requirement that results from the lowpressure ratio for each of the two compressors. 98 The two-stage system offers the advantage of having one fewer component (a condenser) than th e dual-loop system, but has many of the same disadvantages (e.g., either increas ed external dimensions or d ecreased internal volume).

Control Valve System The control valve system has two evaporat ors, one for the fresh food compartment and one for the freezer compartment, but only one compressor and one condenser. Two different length capillary tubes and a control valve are installed between the fresh food and freezer evaporator inlets and the condenser outlet. The valve directs the flow of the refrigerant through one of the evaporators at a time. That is, only one of the two compartments is cooled at any given time. With this configuration, the fresh food compartment is cooled at a higher evaporator temperature than the freezer compartment. E xperimental research conducted on this system configuration indicated that the energy efficiency can be improved by 8.5 percent over that of a conventional refrigerator-freezer. 99

3-68GE offers a refrigerator-freezer system calle d the ClimateKeeper2TM system that uses two evaporators. 100 Also, KitchenAid and Jenn-Air both o ffer under-counter compact refrigeratorfreezers that use dual evaporators. 101 102 The system details of none of these products is clearly described in the pr oduct literature.

Ejector Refrigerator

One of the intrinsic losses in a conventiona l refrigeration cycle is the throttling of the refrigerant in the capillary tube. Throttling is an isenthalpic process in which work that could be extracted in the expansion process is not captured. In the ejector re frigerator, some of this work can be captured and used to raise the pressure of refrigerant entering the compressor above that of the evaporator. Simulation research has been c onducted on an ejector refr igerator that consists of one compressor, one condenser, two capillary tubes, two evaporators (one for the fresh food compartment and the other for the freezer compartm ent), and an ejector. In this refrigerator, saturated liquid refrigerant exits the condenser and expands in the capillary tube to the fresh food evaporator. In the fresh-food compartment, the refr igerant is partially evap orated. At the outlet of the evaporator, the liquid refrigerant is separated from the vapor in a separator. The vapor flows to the ejector, where it is accelerated to high velocity. The liquid expands in a second capillary tube to the freezer evaporator, where it evapor ates entirely. The vapor leaving the freezer evaporator is entrained in th e high-velocity flow of the va por which left the fresh food evaporator. The mixed flow is decelerated to increase its pressure. The mixed flow higher pressure flow passes to the compressor suction po rt to be compressed. This particular ejector refrigerator was shown to have an efficiency which is 12.4 percent higher than a conventional refrigerator-freezer. 103

Tandem System Like the control valve system and the ejec tor refrigerator, the tandem system uses two evaporators (one for the fresh food compartment and another for the freezer compartment), one condenser, and one compressor. Refrigerant fl ows in series first through the fresh food evaporator, then the freezer evaporator, and it passes a second time through the fresh food evaporator. The warm liquid refrigerant leaves th e condenser and flows to fresh food evaporator without a first expansion. In the fresh food ev aporator the refrigerant liquid undergoes heat exchange with the evaporating refrigerant wh ich has passed through the freezer evaporator. The temperature of the liquid is reduced by this heat exchange. The liqui d then passes through the capillary tube where its pressure is reduced. The two-phase refrigerant then passes through the freezer evaporator and absorbs heat from the freezer compartment. This vaporization process only occurs when the freezer evaporator fa n is turned on by the freezer thermostat. The refrigerant then passes back through the fresh f ood evaporator. Here, if the refrigerant has not already been vaporized (i.e., the freezer compartm ent does not require cooling), it vaporizes as a result of absorbing heat from the fresh food compartment and the warm liquid. The superheated refrigerant then flows to the compressor suction port. At the beginning of the compressor run, the fresh-food compartment fan is turned on first. Th us, the fresh food compartment is cooled before the system reaches steady state. As a result, the system uses the pull-down period of each cycle, which is generally not suitable for cooling the fr eezer, to cool the fresh food compartment. This particular tandem system was shown to reduc e energy use by 18 percent compared to a conventional refrigerator-freezer. 104

3-693.3.2.14 Alternative Refrigeration Systems
Alternative refrigeration systems do not us e vapor compression to provide refrigeration. Three alternative refrigeration systems are discu ssed below: the Stirling cycle, thermoelectric cooling, and thermoacoustic cooling. Although re search and development has been conducted on each of these systems, and thermoelectric compact refrigerators and wine coolers are currently being marketed, none are a viable alternative for st andard-size refrigerators, refrigerator-freezers, and freezers.

Stirling Cycle A Stirling-cycle machine is a device that operates on a closed regenerative thermodynamic cycle, with cyclic compression and expansion of th e working fluid at different temperature levels, and where the flow is contro lled by volume changes, so that there is a net conversion of heat to work or vice versa. ‘Regen erative’ refers to the us e of an internal heat exchanger, the regenerator, which is an esse ntial part of the Stirling cycle. A Stirling refrigeration cycle compresses and expands an inert gas in a single cylinder. Heat is rejected at one end of the cylinder and absorbed at the opp osite end. In the absence of all thermodynamic losses, the efficiency could be higher than for vapor compression systems, but there are various technical difficulties that have so far limited the use of Stirling-cycle cooling to small prototype domestic refrigerators. There is no circulating refrigerant fluid and the hot and cold heat areas are relatively small, which creates heat exchange cha llenges for any but the lo west-capacity systems.

Thermoelectric Thermoelectric cooling occurs when a curr ent is passed across the junction of two dissimilar metals. One side of the device becomes hot and the other cold. Materials (semiconductors) have relatively recently been de veloped that have allowed for the use of this type of cooling in some applications. Thermo electric cooling devices have no moving parts, do not age, and have extremely long lifetimes. Ther e are several compact re frigerators and wine coolers using thermoelectric cooling that are be ing marketed, including several models offered by Avanti Products. 105 However, they have very low effi ciency and are not yet suitable for standard-size domestic refrigerator-freezers.

Thermoacoustic Acoustic cooling uses a sound generator inside a closed tube to vi brate a gas and cause alternate compression and expans ion and therefore heating and cooling. The efficiency of prototypes have not been as high as vapor compression systems and the devices have been physically large for the amount of cooling produced.

3.3.3 Energy Efficiency
DOE gathered data on the energy efficiency ofresidential refrigerators, refrigeratorfreezers, and freezers currently available in the marketplace. DOE created a database of the current models by surveying manufacturers’ webs ites. The data provid e an overview of the energy efficiency of each product class covered by this rulemaking.

3-70For the models in the DOE database, Figure 3.3.3 through Figure 3.3.22 present by product class the relationship between rated annual energy use and adjusted volume. In each figure, lines representing the maximum allo wable energy consumption (i.e., the current minimum efficiency standard) and the current ENERGY STAR level (that took effect in April 2008 for standard-size refrigerator s and refrigerator-freezers), ar e provided. This allows for a quick visual inspection of th e number of models that met the ENERGY STAR level.

The data representing all-refrigerators are hi ghlighted in the figures for product classes 1, 3, 11, and 13. For product classes 1 and 11, the produc ts which are not all-refrigerators could be either basic refrigerat ors or manual defrost refrigerator-fre ezers. For product classes 3 and 13, the products which are not all-refrigerators are refrigerator-freezers. The percentage of allrefrigerators is high for product class 11 and very high for product class 13.

The DOE survey found no current models in product class 6, top-mount refrigeratorfreezers with through the door ice and with automatic defrost. DOE still provides a figure for this class (Figure 3.3.9) to show the maximum allowa ble energy consumption for this product class. Many of the other product cla sses also have few products.

3-710 100 200 300 400 500 600 700 800

0 5 10 15 20 25 30 35 40Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star
Other Refrigerators
All-Refrigerators

Adjusted Volume (ft 3 ) Figure 3.3.3 Annual Energy Consumption for Re frigerators and Refr igerator-Freezers with Manual Defrost (Product Class #1)

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600

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0 5 10 15 20 25 30 35 Adjusted Volume (ft 3 )
Figure 3.3.4 Annual Energy Consumption fo r Refrigerator-Freezers with Partial Automatic Defrost (Product Class #2)

3-72 40Annual Energy Consumption (kWh/yr) 800

700

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0 100 200

0 5 10 15 20 25 Adjusted Volume (ft 3 ) 30 35 40 Federal Minimum Standard Energy Star Refrigerator-Freezers All-Refrigerators

Figure 3.3.5 Annual Energy Consumption for Top-Mount Refrigerator-Freezers with Automatic Defrost without TTD Ice Service a nd All-Refrigerators with Automatic Defrost (Product Class #3)

800

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0 100

0 5 10 15 20 25 Adjusted Volume (ft 3 ) 30 35 Federal Minimum Standard
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Figure 3.3.6 Annual Energy Consumption for Side-Mount Refrigerator-Freezers with Automatic Defrost without TTD Ice Service (Product Class #4)

3-730 100 200 300 400 500 600 700 800Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star

0 5 10 15 20 25 30 35 40 Adjusted Volume (ft 3 ) Figure 3.3.7 Annual Energy Consumption for Bo ttom-Mount Refrigerator-Freezers with Automatic Defrost without TTD Ice Service (Product Class #5)

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700Annual Energy Consumption (kWh/yr) 600

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Energy Star

0 5 10 15 20 25 30 35 40 Adjusted Volume (ft 3 ) Figure 3.3.8 Annual Energy Consumption for Bo ttom-Mount Refrigerator-Freezers with Automatic Defrost with TTD I ce Service (Product Class 5A)

3-740 100 200 300 400 500 600 700 800Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star No current products within this class could be found.

0 5 10 15 20 25 30 35 Adjusted Volume (ft 3 ) Figure 3.3.9 Annual Energy Consumption for Top-Mount Refrigerator-Freezers with Automatic Defrost with TTD Ice Service (Product Class #6)

800

700Annual Energy Consumption (kWh/yr) 600

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0 Federal Minimum Standard
Energy Star

0 5 10 15 20 25 30 35 Adjusted Volume ft 3 ) Figure 3.3.10 Annual Energy Consumption for Si de-Mount Refrigerator-Freezers with Automatic Defrost with Through-the- Door Ice Service (Product Class #7)

3-75 40

400 100 200 300 400 500 600 700 800 900

0 5 10 15 20 25 30 35 40 45Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star

Adjusted Volume (ft 3 ) Figure 3.3.11 Annual Energy Consumption for Upright Freezers with Manual Defrost (Product Class #8)

900

800Annual Energy Consumption (kWh/yr) 700

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0 Federal Minimum Standard
Energy Star

0 5 10 15 20 25 30 35 40 45 Adjusted Volume (ft 3 ) Figure 3.3.12 Annual Energy Consumption for Up right Freezers with Automatic Defrost (Product Class #9)

3-760 100 200 300 400 500 600 700 800 900Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star

0 5 10 15 20 25 30 35 40 45 Adjusted Volume (ft 3 ) Figure 3.3.13 Annual Energy Consumption for Ch est Freezers and all other Freezers except Compact Freezers (Product Class #10)

900

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0 Federal Minimum Standard
Energy Star

0 5 10 15 20 25 30 35 40 45 Adjusted Volume (ft 3 ) Figure 3.3.14 Annual Energy Consumption for Ch est Freezers with Automatic Defrost (Product Class #10A)

3-770 100 200 300 400 500 600Annual Energy Consumption (kWh/yr)

Federal Minimum Standard Energy Star All-Refrigerators Other Refrigerators

0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.15 Annual Energy Consumption for Compact Refrigerators and RefrigeratorFreezers with Manual Defrost (Product Class #11)

600Annual Energy Consumption (kWh/yr) 500

400

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0 Federal Minimum Standard
Energy Star

0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.16 Annual Energy Consumption for Compact Refrigerator-Freezers with Partial Automatic Defrost (Product Class #12)

3-780 100 200 300 400 500 600Annual Energy Consumption (kWh/yr)

Federal Minimum Standard Energy Star All-Refrigerators Refrigerator-Freezers

0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.17 Annual Energy Consumption for Compact Top-Mount Refrigerator-Freezers with Automatic Defrost and All-Refrigerator s with Automatic Defrost (Product Class #13)

0 100 200 300 400 500 600Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star

0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.18 Annual Energy Consumption for Co mpact Side-Mount Refrigerator-Freezers with Automatic Defrost (Product Class #14)

3-790 100 200 300 400 500 600Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star

0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.19 Annual Energy Consumption fo r Compact Bottom-Mount RefrigeratorFreezers with Automatic Defrost (Product Class #15)

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0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.20 Annual Energy Consumption for Compact Upright Freezers with Manual Defrost (Product Class #16)

3-800 100 200 300 400 500 600Annual Energy Consumption (kWh/yr)

Federal Minimum Standard
Energy Star

0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.21 Annual Energy Consumption for Co mpact Upright Freezers with Automatic Defrost (Product Class #17)

600

500Annual Energy Consumption (kWh/yr)

400

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Energy Star

0 2 4 6 8 1 0 1 2 1 4 Adjusted Volume (ft 3 ) Figure 3.3.22 Annual Energy Consumption for Compact Chest Freezers (Product Class #18)

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. Energy. Energy Efficiency, Domestic refrigerators and freezers

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3-90CHAPTER 4: SCREENING ANALYSIS

TABLE OF CONTENTS

4.1 INTRODUCTION ............................................................................................................... 4-1 4.2 SCREENED-OUT TECHNOLGIES............................................................................... 4-2 4.2.1 Improved Resistivity of Insulation....................................................................... 4-2 4.2.2 Gas-Filled Panels ................................................................................................. 4-2 4.2.3 Improved Gaskets, Double Gaskets, Improved Door Face Frame ...................... 4-3 4.2.4 Reduced Heat Load for TTD Feature .................................................................. 4-3 4.2.5 Warm Liquid or Hot Gas Refrigerant Anti-Sweat Heating ................................. 4-4 4.2.6 Electric Anti-Sweat Heater Sizing.......................................................................4-4 4.2.7 Linear Compressors ............................................................................................. 4-4 4.2.8 Improved Evaporator Heat Exchange.................................................................. 4-5 4.2.9 Improved Condenser Heat Exchange................................................................... 4-5 4.2.10 Fan Blade Improvements ..................................................................................... 4-6 4.2.11 Improved Expansion Valve.................................................................................. 4-6 4.2.12 Off-Cycle Valve................................................................................................... 4-7 4.2.13 Reduced Energy for Automatic Defrost .............................................................. 4-7 4.2.14 Condenser Hot Gas Defrost ................................................................................. 4-7 4.2.15 Electronic Temperature Control .......................................................................... 4-8 4.2.16 Air-Distribution Control ...................................................................................... 4-8 4.2.17 Alternative Refrigerants....................................................................................... 4-8 4.2.18 Component Location............................................................................................ 4-9 4.2.19 Lorenz-Meutzner Cycle ....................................................................................... 4-9 4.2.20 Dual-Loop System ............................................................................................... 4-9 4.2.21 Two-Stage System ............................................................................................. 4-10 4.2.22 Control Valve System and Tandem System ...................................................... 4-10 4.2.23 Ejector Refrigerator ........................................................................................... 4-10 4.2.24 Stirling Cycle ..................................................................................................... 4-10 4.2.25 Thermoelectric ................................................................................................... 4-11 4.2.26 Thermoacoustic.................................................................................................. 4-11 4.3 REMAINING TECHNOLOGIES ................................................................................. 4-12

LIST OF TABLES

Table 4.2.1 LG Linear Compre ssor Performance Data ............................................................... 4-4

LIST OF FIGURES

Figure 4.2.1 Comparison of Stirling and Vapor Compression Technologies............................ 4-11

4-iCHAPTER 4. SCREENING ANALYSIS

4.1 INTRODUCTION

This chapter details the screening analysis that the U.S. Department of Energy (DOE) conducted in support of the ongoing energy conservati on standards rulemakings for refrigerators, refrigerator-freezers, and freezers.

In chapter 3, the market and technology asse ssment (MTA), DOE presented an initial list of technologies that can improve the energy efficiency of reside ntial refrigeration products. The purpose of the screening analysis is to evalua te the technologies that improve equipment efficiency to determine which technologies to consider further and which to screen out. DOE consulted with a range of partie s, including industry, technical expe rts, and others to develop a list of technologies for consideration. DOE evaluated the technologies pursua nt to the criteria set out in the Energy Policy and Conservation Ac t (EPCA), as amended. (42 U.S.C. 6311-6317)

Section 325(o) EPCA establishes criteria for prescribing new or amended standards designed to achieve the maximum improvement in energy efficiency. Further, EPCA directs the Secretary of Energy to determine whether a standard is technologi cally feasible and economically justified. (42 U.S.C. 6295(o)(2)(A), as directed by 42 U.S.C. 6316(a)(1)-(3)). EPCA also establishes guidelines for determinin g whether a standard is economically justified. (42 U.S.C. 6295(o)(2)(B)) Appendix A to subpart C of Title 10, Code of Federal Regulations, Part 430 (10 CFR Part 430), “Procedures, Interpre tations and Policies for Consideration of New or Revised Energy Conservation St andards for Consumer Products” (the Process Rule), sets forth procedures to guide DOE in its consideration and promulgation of new or revised equipment energy conservation standards. Thes e procedures elaborate on the statutory criteria provided in 42 U.S.C. 6295(o) and, in part, eliminate problematic technologi es early in the process of prescribing or amending an energy efficiency standa rd. In particular secti ons 4(b)(4) and 5(b) of the Process Rule guide DOE in determining wh ether to eliminate from consideration any technology that presents unacceptable problems with respect to the following criteria:

Technological feasibility. Technologies incorporated in commercial equipment or in working prototypes will be consid ered technologically feasible.

Practicability to manufacture, install, and service. If mass production of a technology in commercial equipment and reliable installa tion and servicing of the technology could be achieved on the scale necessary to serve the relevant market at the time of the effective date of the standard, then that technology will be consid ered practicable to manufacture, install, and service.

Impacts on equipment utility or equipment availability. If a technology is determined to have significant adverse impact on the utility of the equipment to significant subgroups of customers, or result in the unavailability of any covered equipment type with performance characteristics (including reliability), features, sizes, capacities, and volumes that are substantially the same as equipment generally ava ilable in the United States at the time, it will not be considered further.

4-1Adverse impacts on health or safety. If it is determined that a technology will have significant adverse impacts on health or safety, it will not be considered further.

In sum, if DOE determines that a tec hnology, or a combination of technologies, has unacceptable impacts on the policie s stated in section 5(b) of the Process Rule, it will be eliminated from consideration. If a particular t echnology fails to meet one or more of the four criteria, it will be screened out. Section 4.2 documents the reasons for eliminating any technology.

4.2 SCREENED-OUT TECHNOLGIES

This section describes the techno logies that DOE eliminated for failure to meet one of the following four factors: (1) technolo gical feasibility; (2) practicabil ity to manufacture, install, and service; (3) impacts on equipment utility or equi pment availability; and (4) adverse impacts on health or safety.

4.2.1 Improved Resistivity of Insulation

Past research has demonstrated that the re sistivity of polyurethane (PU) foam insulation can be improved through the use of additives th at reduce the thermal c onductivity of the foam.

Research conducted in 1996 demonstrated that adding carbon black provides a means of improving the thermal insulation properties of PU foam using both HCFC-141b or cyclopentane blowing agents. 1 However, DOE is not aware that this process has been ad opted by any supplier of PU foam insulation or any re frigerator manufacturer. Manuf acturers have reported that it darkens the interior of a refrigerator lined with white plastic, and it stains anything it contacts.

Discussion with PU foam insulation vendors indicates that there is work ongoing which may lead to improvement in insulation performance but that any such technology would not likely be ready for introduction to the mark et by 2014. Discussion with manufacturers has confirmed that there are no available options for improvement in PU foam insulation performance (other than reverting to use of banne d blowing agents). Due to the lack of available information and predictions that there is no sign ificant benefit to be expected from PU foam improvements, DOE has eliminated this option from consideration in the engineering analysis.

4.2.2 Gas-Filled Panels

Investigation of the status of gas-filled panels suggest s that there has been some evaluation of this technology by ma nufacturers of residential refrig eration equipment, but that no manufacturers are using it in thei r products. The costs are reported to be as high as for vacuum insulation panels (VIPs), with less reduction in ther mal load. DOE has not been able to identify a credible supplier that would provide gas filled panel products to the refrigeration industry. DOE has eliminated this technol ogy from further consideration.

4-24.2.3 Improved Gaskets, Double Gasket s, Improved Door Face Frame

Past investigation on reduction of heat load in the gasket and door face frame area has focused on (1) limiting the conduction of heat th rough metal casing material passing underneath the gasket magnet on the cabinet side or in the re gion of the gasket clip on the door side into the cabinet interior, (2) using a gasket which provid es additional cover of frame surfaces towards the interior of the magnet to prevent cold air fr om reaching the high-conductivity metal casing near the gasket magnet, and (3) providing a long thin “throat” area betw een the gasket and the interior to limit convection heat transfer. Most current de signs are effective in addressing these issues.

Limited information is publicly available which would allow quantification of additional improvement potential for the door frame/gasket ar ea of refrigerators. Some manufacturers use extra-strong gasket magnets to limit infiltration and thermal loss, but it is unclear whether significant thermal improvement is possible with such systems. Manufact urers indicated during pre-NOPR discussions that properl y designed and installed gasket systems provide a tight seal and that there isn’t any furt her reduction in air leakage th at could be achieved with improvements in the gasket system such as incr easing the magnetic force. In addition, consumer safety laws preclude use of ex cessive door sealing force.

Based on information drawn from DOE’s 1995 TSD, double door gaskets were not adopted by many manufacturers in the mid-1990s b ecause of performance problems and cost. Ice has a tendency to form between the gaskets, greatly reducing their effectiv eness. In addition, the gaskets tend to be visually unattractive and th ey make it more difficult to meet the consumer safety regulations for minimum door-opening force.

It is expected that incremental improvement may be possible for some products, however, the lack of good quantified information on general improvement potential in this area makes this technology option unsuitable for co nsideration as a design option.

4.2.4 Reduced Heat Load for TTD Feature

During Pre-NOPR analysis discussions, manufactur ers indicated that there is little or no reduction in load which can be achieved through redesign of TTD features. DOE inspected the TTD system of a side-by-side refr igerator and concluded that the lo ad impact of this feature is modest. The door insulation thickness is maintained behind the recess except within an inch or two of the chute opening, and low-conductivity pl astic is used on all surfaces. The chute door closes reliably. A calculation of the thermal load suggests that it is on the or der of 3W (10 Btu/hr). The reverse engineering of this feature shows that a 2W el ectric anti-sweat heater is used to prevent condensation of th e exterior surfaces nearest th e ice chute opening. Manufacturers indicated that these load levels are typical for TTD features. Even if the chute door was insulated with 1⁄2-inch of insulation (w hich would likely interfere with chute door operation), the load impact would be minimal, due to the very lo w surface area of this door. Based on the very low potential for improvement, DOE has eliminated redu ced heat load TTD feat ures as an option for further analysis.

4-34.2.5 Warm Liquid or Hot Gas Refrigerant Anti-Sweat Heating

Although some refrigerators do still use electric anti-sweat heating, th e typical anti-sweat heater for baseline units, according to the re verse engineering work and discussion with manufacturers, is warm liquid refrigerant. A po ssible exception is French door refrigerators. In these products, providing heat to the gasket surf aces which seal between the French doors (or to the flip-mullion used in some designs for seali ng in this region) is not possible using warm refrigerant liquid or hot gas. Fren ch door refrigerators may use electr ic anti-sweat heaters in this region, but for these products conversion to refrig erant line anti-sweat is impractical. Due to the current use of refrigerant-line anti-sweat in situ ations where it can be used, DOE has eliminated this option from furt her consideration.

4.2.6 Electric Anti-Sweat Heater Sizing

Because the baseline products considered in the engineering analysis predominantly use warm liquid anti-sweat, the consideration of adju stment of the sizing of electric anti-sweat heaters is not relevant.

4.2.7 Linear Compressors

While promising potential has been reported fo r linear compressors, there is very little information available for commercialized linear compressors that allows confident prediction of performance and cost impacts of this technol ogy. Information for some LG linear compressors has been reported at “LG Reference Conditions ,” which are significantly different than the standard ASHRAE rating conditions. Under ASHR AE conditions, compresso rs are rated at -10 oF (-23.3 oC) evaporating temperature and 130 oF (54.4 oC) condensing te mperature. The “LG Reference Conditions” are based on -14.8 oF (-26 oC) evaporating and 100.4 oF (38 oC) condensing temperatures. It is not clear what th e liquid and suction vapor temperatures for the LG conditions are—these temperatures also im pact capacity and power input. The performance of some of LG’s linear compressors at the LG conditions is presented in Table 4.2.1 below. At the same evaporating and condensing temperatures and with liquid and su ction vapor conditions consistent with the ASHRAE test conditions, a high efficiency rotating-shaft reciprocating compressor such as the Embraco EGX70HLC would have an ope rating EER of about 6.9 Btu/hrW. Hence, the LG linear compressor may be abou t 9% more efficient than the best currenttechnology rotating-shaft r eciprocating compressors.

Table 4.2.1 LG Linear Compressor Performance Data

Model Capacity Range* Efficiency*
W Btu/hr COP EER DLF81LACT 310 1058 2.14 7.3 FA81LACT 293 1000 2.20 7.5 FA72LACT 276 941 2.20 7.5 FA63LACT 241 823 2.20 7.5 FA54LACT 207 706 2.20 7.5
Source: LG, 2007. * Performance based on ‘LG Reference’ rating conditions. Models utilize refrigerant R134a.

4-4In the trade press, LG has expressed willingness to license the linear compressor technology to competitors. 2 However, because the LG design is proprietary, the widespread use of linear compressors is highly uncertain. Use of linear compressors in LG refrigerators is less explicit in LG product data than it was a few y ears ago, so it is unclear how many products are actually using these compressors. Other compressor manufacturers who have indicated that they have investigated linear t echnology have stated that lin ear compressor technology does not provide a clear path to improved efficiency, and some have indi cated that they are no longer actively pursuing this technology. He nce, availability of linear compressor technology as an option for improved efficiency is uncertain. Furthe r, DOE was not able to obtain cost estimates for linear compressors. For these reasons, DOE ha s eliminated linear compressors from further consideration in the analyses.

4.2.8 Improved Evaporator Heat Exchange

Improving heat exchanger performance can be achieved through the use of enhanced fins and/or tubes. These types of fin and tube enhancements are common in air-conditioning applications where slit and louve red designs are used to enhance the fin surface and different types of internally-grooved su rfaces are used to enhance the tubing. Application of similar enhancements in refrigerator evaporators is complicated by frost accumulation on the evaporators. Effectiveness of the fine slit and louver features for refrigerator evaporators is dubious because they would be blocked quickly w ith frost. In order to avoid the energy use associated with frequent defrost, fin spacing in refrigerator eva porators is comparatively sparse. This allows the evaporator to work effectivel y without blocking airflow with a considerable accumulation of frost. During defrost, the typical flat fin design of these evaporators assures that the frost slides rapidly off the fins and doesn ’t get stuck on fin enhancement features. During discussions with manufacturers, li ttle indication was provided that efficiency could significantly be enhanced through the use of fin or tube enha ncements. DOE has eliminated this option from consideration in subsequent analysis.

4.2.9 Improved Condenser Heat Exchange

Use of heat exchanger enhancements for th e condenser are complicated by the need for adequate performance when the heat exchange r has not been cleane d. Most refrigerator condensers (other than hot wall condensers integr ated into the outer shells of the products) are made of steel tubes and steel wire fins. These condensers have a very open construction which allows dust to flow through easily and which reduces blockage of air flow if dust does collect on the condenser surfaces. Flat fin condensers used in refrigerators are known to require more careful attention to cleaning. Use of high fin densities is more accepted in air-conditioning applications because periodic ma intenance is expected and because size would get enormous if aggressive fin spacing wasn’t employed, whereas cleaning of refrigerat or condensers occurs infrequently or never, and the loads are small enough so that maximizing use of space is not critical. DOE has eliminated this option fr om consideration in subsequent analysis.

4-54.2.10 Fan Blade Improvements

Refrigerator fan blades use an axial design. They are typically injection molded plastic with a three-dimensional shape for improved performance as compared with older stamped sheet metal designs. One source of inefficiency for axial fans lies in their tendency to throw air outward, necessitating a shroud to collect and redi rect airflow along the axis as intended. The Pax GroupTM has developed a fan (PAX fan) that employs streamlined blades with patented geometrical shapes derived from a naturalis tic design approach, providing better airflow direction and improved efficiency. Tests performe d when replacing existing motor combinations with A.O.Smith motors and PAX fan blades show power input reductions in the range of roughly 10% to 35%. 3 It is impossible to tell how much of this benefit is associated with the fan blade and how much with the motor. Also, because the PAX fan is proprietary, the widespread use of the design is highly uncertain. There is in gene ral little data available to quantify the energy benefit possible with improvement in fan blade design in today’s refrig eration products. Fan performance is highly dependent on details of in tegration with the system: orifice geometry, tolerance of blade/orifice gap, match of system flow impedence to fan performance, etc. Hence, making credible estimates of energy savings potential through fan blade replacement requires testing fan blade swaps in baseline products. Th e cost of fabrication of improved fan blade geometries should be low, so most of the cost increase associated with this technology option would be associated with paying for the blade de velopment and/or licensing fees. It is very difficult to predict what these costs would be unless specific vendors of high efficiency fan blades can be identified who provide comp lete information. During discussions with manufacturers, no information was provided whic h would allow credible calculation of savings and costs associated with improved fan blades. Hence, DOE has eliminated this option from further consideration.

4.2.11 Improved Expansion Valve

Residential refrigeration pr oducts exclusively use capillary tubes for refrigerant flow metering. These tubes are inexpensive and they lend themselves easily to low-cost fabrication of suction line heat exchangers by brazing the capillary to the suc tion line. Automatic, adjustable thermostatic or electronic expansion valves are available, but they generally are oversized for residential refrigeration. Furthermore, it is unc lear whether there is any potential for energy savings using alternative expansi on devices. The DOE Energy test is conducted with a single set of standardized temperatures for the ambient ai r (90 °F) and for the compartments. A capillary tube can be designed to provide optimized performance for this se t of temperatures. Systems are generally designed to operate with evaporator exit conditions having little or no superheat during energy testing, thus maximizing use of the evapor ator. In the lower ambi ent temperature typical in homes, the pressure available to move refrig erant through the capillary tube is lower, thus possibly leading to increased s uperheat and less than optimum pe rformance. An automatic valve could provide optimum performance for a wide r range of operating conditions, but such improvement is not reflected in current energy testing. DOE has eliminated this option from further consideration.

4-64.2.12 Off-Cycle Valve

Off-cycle refrigerant migration reduces a re frigeration product’s efficiency by allowing warm and/or vapor-phase refrigerant to pass into the cabinet. A fluid cont rol or solenoid valve installed after the condenser to effectively isolate the evaporator from the condenser during the off-cycle can be used to prevent refrigerant mi gration. Research has demonstrated that solenoid valves can yield substantial energy savings. 4 Such a solenoid valve represents a possible reliability issue, although many wine storage pr oducts use similar solenoid valves to allow control of multiple compartments with a single compressor. Also, operation with an off-cycle valve requires that the compressor motor can star t up against a substantial pressure difference. The starting windings of compressors that can do this reliably over the life of a refrigerator draw more power and hence reduce the compressor’s stea dy-state efficiency. The different efficiency levels of commercial refrigerati on compressors designed for instan t restart versus restart after pressure equalization have EER ratings which differ by 10% or more. Such a difference would be expected for residential compressors operating with an off cycle valve, and this difference would more than neutralize any benefit accrued from using the off-cycle valve. Hence, DOE has eliminated this option from further consideration.

4.2.13 Reduced Energy for Automatic Defrost

In some cases, the defrost heat supplied is more than required. Thus, energy savings can be achieved by reducing the defrost heat by either using smaller heaters, reducing the heater ontime, reducing the frequency of defrost, or a co mbination of these. In its 1995 TSD, DOE found that most manufacturers had alread y significantly reduced the electr ic heat for auto defrost in order to comply with the energy efficiency standards that became effective in 1993. 5 The percent of energy represented by defrost for the refrigerat or-freezers tested as pa rt of this rulemaking ranged from 4% to 5% for products without adap tive defrost and from 1% to 5% for products with adaptive defrost. It is unlikely that si gnificant energy savings ar e achievable by further reducing the energy for automatic defrost wit hout compromising defrost performance, except through use of adaptive defrost.

4.2.14 Condenser Hot Gas Defrost

Another method of reducing the energy required for defrost is to eliminate the need for electric heaters by substituting c ondenser hot gas in their place. In a condenser hot gas defrost system, the compressor continues to run and a valve opens allowing hot compressed refrigerant to flow to the evaporator. Many frost-free refri gerator-freezers in the 1960s and 1970s used a condenser hot gas defrost system. In its 1995 TS D, DOE was not able to identify data that demonstrated that the condenser hot gas method was more cost-eff ective than adaptive defrost. Therefore, DOE dropped the condens er gas defrost as a technology option in favor of adaptive defrost. 6 Hot gas defrost would potentially save ener gy because a large portion of the heat for defrost could be provided by heat generated by th e compressor motor during the on-cycle rather than from new electricity use. The compressor is at an elevated temperature with respect to ambient during the on-cycle and is certainly much warmer than freezing temperature. The heat would be transported to the evaporator with ci rculating refrigerant du ring the defrost cycle. However, in spite of this poten tial reduction in use of electric ity to provide defrost heat, the

4-7energy savings potential is not we ll documented. Also, there are c oncerns regarding reliability of the required valve.

4.2.15 Electronic Temperature Control

DOE has not identified any relevant informa tion showing the energy benefit of electronic temperature control. Potential be nefits of electronic control wh en operating with single-speed compressors are fine-tuning of the run times and fine-tuning of th e cut-in and cut-out temperatures. While there may be potential for incremental improvement associated with such fine-tuning, the lack of data supporting claims for energy savings make it difficult to properly analyze this option.

4.2.16 Air-Distribution Control

Air temperature distribution in refrigeration pr oducts with fan-forced evaporator air flow is generally good, in contrast with some products w ith cold wall or roll bond evaporators. Hence, it is not clear that improvements in air distribution will provide significant reduction in energy use. Redirection of air flows in a cabinet could potentially provide a false indication of efficient operation, for instance if the coldest air from the ev aporator discharge is di rected at the locations used for the energy test thermoc ouples. It is conceivable that va lid reduction in energy use could occur if the air flow distribution keeps cold ai r away from the walls of the cabinet. However, there is insufficient information regarding the desi gns of air flow distribution systems to quantify potential energy savings.

4.2.17 Alternative Refrigerants

R-600a (isobutane) is the most logical alte rnative to the HFC-134a refrigerant used exclusively in U.S. residential refrigeration products. Isobutane is a hydrocarbon refrigerant which has been used for many years in refrig eration products in Europe and other foreign countries. The theoretical efficiency of isobutane is higher than that of HFC-134a, however, the U.S. refrigeration industry has not adopted hydrocarbon refrigerants (likewise for the U.S. air conditioning industry) due to concerns regardi ng flammability. Recent shifts in this viewpoint are the result of pressures regarding the direct global warming impact of the refrigerant rather than the energy use impacts. Comments from manufacturers regardi ng the potential for efficiency improvement using isobutane are mixe d. In any case, it is not expected that U.S. manufacturers will switch to isobutane to redu ce energy use and that there will be limited conversion unless legislation is enacted wh ich mandates phaseouts for global warming substances such as HFC refrigerants. In the case of such legislation, the potential improvement in energy use associated with isobut ane will be balanced by a potent ial increase in energy use associated with reduced resistivity of PU fo am insulation made with cyclopentane blowing agent, the most likely replacement for currentl y-used HFC blowing agents. DOE will consider the impacts of switch to hydrocar bon refrigerants and blowing ag ents if such legislation is enacted, but DOE will not consider use of isobutane as a design option to improve efficiency in the absence of such legislation.

4-84.2.18 Component Location

Locating the compressor at the top of the re frigerator was noted as a potential technology option. However, this change would increase struct ural requirement for the refrigerator cabinet, increase risk of product tip-over, and provide much less practical use of space from the consumer perspective. It also makes desi gn for re-evaporation of defrost water more challenging. It is unlikely that the savings would ju stify all of these drawbacks.

Another option is to locate the evaporator fa n motor outside the cabinet to reduce internal loads from the heat loss of the motor. Evaporat or fan motor input wattages are now in the range 3W to 7W, with fan blade efficiency in the rang e 20% to 30% and motor efficiency in the range 20% to 50%. Hence, load reduction, associated with moving the motor loss outside the cabinet, is only in the range 1W to 5W for the typically less than 50% of the time that the evaporator fan is in operation. The loss associated with the adde d infiltration and conduction is likely to be comparable to this level. Additional issues with this approach include reliability, reduced design flexibility, and the fact that re duction of motor losse s (by using more efficient fan motors) may be a more effective approach to reducing th e impact of the fan motor power input.

No options for relocation of components ha ve been identified which merit further consideration in the engineering analysis.

4.2.19 Lorenz-Meutzner Cycle

Research on Lorenz-Meutzner cycles reported in the literature invol ve binary mixtures HCFC-22/CFC-11, HCFC-22/HCFC-123, propane/n -pentane, and propane/n-butane. These systems achieved efficiency levels from 15 to 20 percent better than the baseline systems with which they were compared. 7,8 Because the industry settled on the use of HFC-134a to replace CFC-12, interest in the Lorenz-M eutzner cycle as an alternativ e to conventional refrigeration cycles declined. All of the refrigerant combinat ions discussed above have specific problems, the first two with phaseout of constituent refrigeran ts CFC-11 and HCFC-22, and the last two with flammability of the hydrocarbon blends involved. Wh ile it is possible that HFC mixtures could be developed to create a viable Lorenz-Meutzner cycle refrigerator, DOE is not aware that such a prototype has been built and test ed successfully. Hence, DOE has not considered this technology in the engineering analysis.

4.2.20 Dual-Loop System

Dual-loop systems have difficulty achieving th eir theoretical improvement potential due to the significantly reduced efficiency for sma ller-capacity compressors. If the two compressors of a dual-loop system serving a refrigerator-freez er were sized appropriate ly for their respective loads, the freezer compressor capacity would nomina lly be roughly half that of a single-system compressor. A fresh food compressor typically operat es at a capacity significantly higher than its nominal capacity because of the higher evaporating temperature when cooling just the fresh food compartment. Hence, the nominal capacity of a fresh food compartment compressor serving a dual-loop system is generally 30 to 40 percent th at of the single-system compressor. Even with the efficiency improvement associated with higher evaporating temper ature operation of the fresh food compartment compressor, this compressor still would not operate at an efficiency

4-9level better than that of the single-system co mpressor for freezer conditions. Hence, with the efficiency characteristics of available compresso rs, it is not clear that the dual-loop architecture will provide any energy savings. Hence, DOE has not considered this technology in the engineering analysis.

4.2.21 Two-Stage System

In practice, a two-stage syst em would suffer the same disadvantages associated with a dual-loop system. Furthermore, it is not clear that a suitable compressor is available for the lower stage of such a system. DOE is not aware of any prototypes of such a system using compressors which their manufacturers would warrantee for su ch a product. Hence, DOE has not considered this technology in the engineering analysis.

4.2.22 Control Valve System and Tandem System

There are many patents covering dual-evaporator refr igerator designs. It is not clear how many of these were developed to improve system efficiency, since one of the benefits of using dual evaporators is avoiding excessively low humi dity levels in the fresh food compartment. While there is research involving laboratory test ing which shows that these technology options can save energy, DOE is not aware of any commer cialized refrigerators using either of these approaches. In discussions with manufacturers none identified th ese options as being interesting approaches for energy use reduction. Further, due to the extensive patent literature discussing dual-evaporator systems, it is likely that produc ts requiring dual evaporator designs would be restricted to the patentholders. Hence, DOE has not considered th is technology in the engineering analysis.

4.2.23 Ejector Refrigerator

Energy savings have been reported for use of an ejector system in laboratory testing. In discussions with manufacturers there was lim ited familiarity with this concept and no acknowledgement that it has been proven through prototype testing a nd/or that it is an interesting concept for improving efficiency. Hence, DOE has not considered this technology in the engineering analysis.

4.2.24 Stirling Cycle

In principle, the efficiency of Stirli ng cycles could be higher than for vapor compression systems, but there are various technical difficulties that have so far limited the use of Stirling-cycle cooling to small prototype dom estic refrigerators. Th ere is no circulating refrigerant fluid and the hot and cold end areas are very small, which creates heat exchange difficulties. Heat pipes may be required to transfer heat to and from the system. A comparison of the performance of Stirling cycle with vapor co mpression compressors is shown in Figure 4.2.1 below. The Stirling cycle data was obtained from the Global Cooling website 9 and from data presented at the Purdue Re frigeration Conference in 2002. 10 The figure shows that Stirling technology is not currently rea dy to improve upon the efficien cy of conventional technology. Hence, DOE has not considered this technology in the engineering analysis.

4-100 2 4 6 8 10 12EER (Btu/hr-W)

Conventional: Danfoss TTE4.6FK, Nominal 4.62 EER Conventional: Tecumseh TPG1370YXA, Nominal 5.82 EER Stirling: Purdue 2002 Paper Stirling: Global Cooling M100

40 60 80 100 120 140 160 Temperature Lift (F) Figure 4.2.1 Comparison of Stirling and Vapor Compression Technologies

4.2.25 Thermoelectric

Thermoelectric cooling technol ogies currently do not achieve efficiency levels which make them attractive as a design option for improv ing residential refriger ation energy efficiency. As an example, DOE tested a thermoelectric refrig erator as part of the re verse engineering effort of this rulemaking. This refrig erator was a Haier model HRT02W NC, a 1.7 cuft all-refrigerator. In an 80 °F ambient with the system operating at full power, this unit was able to cool the interior to 47 °F while drawing 50W total. The fa ns serving the inside a nd outside heat sinks of the thermoelectric unit are rated at a voltage of 12 Volts and currents of 0.13 Amps and 0.16 Amps respectively, and a control board power input of 1W is a ssumed. The thermal load for the cabinet was estimated as 12 W. Hence the thermo electric module EER was 0.9 at a temperature lift of at most 33 °F, an order of magnitude less than is achieved by conventional technology. Hence, DOE has not considered this technology in the engineering analysis.

4.2.26 Thermoacoustic

While research suggests that thermoacoustic cooling systems could achieve respectable efficiencies, the technology has not reached a level of maturity sufficient for serious consideration as the basis for efficiency impr ovement in residential refrigeration products. Hence, DOE has not considered this technology in the engineering analysis.

4-114.3 REMAINING TECHNOLOGIES

After eliminating those technologies that ha ve no effect or do not increase EER and screening out those technologies that that do not meet the requir ements of sections 4(a)(4) and 5(b) of the Process Rule, DOE is consider ing the technologies in the following list.

• Increased Insulation Thickness

• Vacuum Insulation Panels (VIPs)

• Variable Anti-sweat Heating

• Improved Compressor Efficiency

• Variable Speed Compressors

• Increased heat exchanger area (extension of surface area or addition of coil rows).

• Use of forced convection conde nser (for upright freezers)

• Improved efficiency fan motors (brushless DC)

• Adaptive Defrost

4-12REFERENCES

1 Pisipati, J.S. and Godbey, J.A. “Perform ance of Carbon Black-Cont aining Polyurethane Foam in Domestic Refrigerators,” Journal of Cellular Plastics , 1996. Vol. 32, No. 2, 108­ 138. < http://cel.sagepub.com/cgi/c ontent/abstract/32/2/108 >

2 American Council for an Energy-Effici ent Economy. "One kW h/day Refrigerator," Emerging Technologies & Practices , 2004. Washington, DC.

3 Belko, John. Novel Fan Design Offers Energy Sa vings to Refrigeration Market , 2007. A.O. Smith Electrical Products Company.

< http://www.aosmithmotors.com/pdf/documents/pax%20fan%20evap%20%20technical%20 paper%20_j%20belko_-2007.pdf > (Accessed September 26, 2007.)

4 Coulter, W.H. and Bullard, C.W. “ An Experimental Analysis of Cycling Losses in Domestic Refrigerator-Freezers,” ASHRAE Transactions , 1997. Vol. 103, Pt. 1.

5 U.S. Department of Energy- Office of Codes and Standards. Technical Support Document: Energy Efficiency Standards for Consumer Produc ts: Refrigerators, Re frigerator-Freezers, and Freezers , July 1995. Washington, DC. DOE/EE-0064. p. 3-8.

6 U.S. Department of Energy- Office of Codes and Standards. Technical Support Document: Energy Efficiency Standards for Consumer Produc ts: Refrigerators, Re frigerator-Freezers, and Freezers , July 1995. Washington, DC. DOE/EE-0064. p. 3-8.

7 Lorenz, A. and Meutzner, K. “On applica tion of non-azeotropic two component refrigerants in domestic refrigerator and home freezers,” Proceedings of the XIV International Congress of Refrigeration , 1975. Moscow.

8 Liu, Z., Haider, I., and Radermacher, R. “S imulation and Test Results of Hydrocarbon Mixtures in a Modified-Lorenz-Meutzn er Cycle Domestic Refrigerator,” HVAC&R Research , Vol. 1, No. 2, April,, 1995.

9 http://www.globalcooling.nl/t echnologyoverview.html#perform

10 Janssen, M. and P.Beks, “Measurement and A pplication of Performance Characteristics of a Free Piston Stirling Cooler”, presented at th e Ninth International Refrigeration and Air Conditioning Conference at Purdue, 2002.

4-13CHAPTER 5: ENGINEERING ANALYSIS

TABLE OF CONTENTS

5.1 INTRODUCTION ........................................................................................................... 5-1 5.2 PRODUCT CLASSES ANALYZED.............................................................................. 5-1 5.3 METHODOLOGY OVERVIEW .................................................................................... 5-2 5.4 EFFICIENCY LEVELS................................................................................................... 5-3 5.4.1 Baseline Units based on the Cu rrent Test Procedure........................................... 5-3 5.4.2 Baseline Efficiency Definitions Based on the Expected Test Procedure ............ 5-6 5.4.2.1 Data Illustrating the Impact of Test Procedure Changes ......................... 5-7 5.4.2.2 Establishment of Baseline Energy—Adjusted Volume Relationships Based on the New Test Procedure .................................. 5-11 5.4.2.3 Investigation of the Slope of the Energy Use Curve.............................. 5-14 5.4.3 Incremental Efficiency Levels ........................................................................... 5-15 5.4.4 Maximum Technology Level............................................................................. 5-16 5.5 DATA COLLECTION .................................................................................................. 5-18 5.5.1 Manufacturer-Submitted Shipment a nd Cost Data from AHAM...................... 5-18 5.5.2 Component Vendor Data ................................................................................... 5-19 5.5.3 Reverse Engineering .......................................................................................... 5-20 5.5.3.1 Selection of Products for Reverse Engineering ..................................... 5-20 5.5.3.2 Collection of Energy Modeling Data..................................................... 5-22 5.5.4 Manufacturer Interviews.................................................................................... 5-23 5.5.5 Energy testing .................................................................................................... 5-23 5.6 MANUFACTURING COST MODELING................................................................... 5-24 5.6.1 Generation of Bills of Materials ........................................................................ 5-24 5.6.2 Cost Structure of the Spreadsheet Models......................................................... 5-25 5.6.3 Cost Model and Definitions............................................................................... 5-25 5.6.3.1 Cost Definitions ..................................................................................... 5-26 5.6.4 Cost Model Assumptions Overview .................................................................. 5-26 5.6.4.1 Fabrication Estimates............................................................................. 5-27 5.6.4.2 Production Volumes Assumptions......................................................... 5-28 5.6.4.3 Factory Parameters Assumptions........................................................... 5-28 5.6.4.4 Material Cost Assumptions.................................................................... 5-28 5.6.5 Manufacturing Production Cost......................................................................... 5-30 5.6.6 Incremental Cost Estimates................................................................................ 5-31 5.6.6.1 Overhead and Depreciation Costs.......................................................... 5-31 5.6.6.2 Depreciation Costs for Insu lation Thickness Increases ......................... 5-32 5.6.6.3 G&A and Profit...................................................................................... 5-33 5.7 ENERGY MODELING................................................................................................. 5-34 5.7.1 Energy Model development............................................................................... 5-34 5.7.2 Supplemental Spreadsheet Models .................................................................... 5-35 5.7.3 Development and Calibration of ER A Current Energy Test Models ................ 5-36 5.7.4 Adjustments to Energy Models to Represent Baseline Products Tested Under the Proposed Test Procedure................................................................... 5-40

5-i5.8 DESIGN OPTIONS....................................................................................................... 5-42 5.8.1 Increased Insulation Thickness.......................................................................... 5-43 5.8.2 Vacuum-Insulated Panels................................................................................... 5-44 5.8.3 Improved Compresso r Efficiency...................................................................... 5-45 5.8.4 Variable-Speed Compressor .............................................................................. 5-48 5.8.5 Increased Evaporator Surface Area ................................................................... 5-50 5.8.6 Increased Condenser Surface Area .................................................................... 5-50 5.8.7 Brushless DC Fan Motors.................................................................................. 5-50 5.8.8 Adaptive Defrost................................................................................................ 5-51 5.8.9 Variable Anti-Sweat Heater Control.................................................................. 5-52 5.8.10 Forced Convection Condenser........................................................................... 5-53 5.9 ENGINEERING ANALYSIS RESULTS ..................................................................... 5-53 5.9.1 DOE Cost-Efficiency Curves............................................................................. 5-53 5.9.2 AHAM Incremental Cost Data .......................................................................... 5-57 5.9.2.1 Product Class 3 ...................................................................................... 5-59 5.9.2.2 Product Class 5 ...................................................................................... 5-62 5.9.2.3 Product Class 7 ...................................................................................... 5-64 5.9.2.4 Product Class 9 ...................................................................................... 5-66 5.9.2.5 Product Class 11 .................................................................................... 5-68

LIST OF TABLES

Table 5.2.1 Product Classes Analyzed in Engineering Analysis ............................................... 5-2 Table 5.4.1 Refrigerator, Refrigerator-F reezer, and Freezer Energy Conservation Standards and Proposed Baselin e Model Efficiencies............................................ 5-5 Table 5.4.2 Expected Cabinet Temperature Ch anges for the DOE Test Procedure .................. 5-6 Table 5.4.3 Volume Adju stment Factors ................................................................................... 5-6 Table 5.4.4 Compartment Volume Calculation Changes .......................................................... 5-7 Table 5.4.5 Compartment Temperature and Ad justed Volume Change Data provided by AHAM—Current Test ............................................................................................ 5-8 Table 5.4.6 Compartment Temperature and Ad justed Volume Change Data provided by AHAM--Proposed Test........................................................................................... 5-9 Table 5.4.7 Compartment Temperature and Ad justed Volume Change Data provided by AHAM—Impact ................................................................................................... 5-10 Table 5.4.8 Energy Use Impact of Compartmen t Temperature Changes: Data Developed by DOE ................................................................................................................. 5-11 Table 5.4.9 Approach for Establishing Baseline Energy--Adjusted Volume Relationships......................................................................................................... 5-12 Table 5.4.10 New Baseline Energy Consumption based on Proposed Test Procedure............. 5-14 Table 5.4.11 DOE Assessment of the Slope of the Energy Use Curve ..................................... 5-15 Table 5.4.12 Incremental Efficiency Levels (% Energy Use Less than Baseline) .................... 5-16 Table 5.4.13 Maximum Available Levels (% Energy Use Less than Baseline)......................... 5-16 Table 5.4.14 Maximum Technology Levels.............................................................................. 5-18 Table 5.5.1 Component Vendors Contacted by DOE during Engineering Analysis............... 5-20 Table 5.5.2 Selected Units for Revers e-Engineering and Energy Testing............................... 5-21

5-iiTable 5.5.3 Additional Thermocouple Locations for Energy Test .......................................... 5-24 Table 5.6.1 Cost Model In-House Manuf acturing Operation Assumptions ............................ 5-27 Table 5.6.2 Refrigerator & Freezer Factory Parameter Assumptions...................................... 5-28 Table 5.6.3 Five-Year Meta l Prices (2003-2008) .................................................................... 5-29 Table 5.6.4 Most Prevalent Resin Prices as of December 2007 .............................................. 5-30 Table 5.6.5 Overhead and Depr eciation Cost Ratios............................................................... 5-32 Table 5.6.6 Greenfield Deprecia tion Costs per Product .......................................................... 5-33 Table 5.8.1 Design Options by Product Class ......................................................................... 5-43 Table 5.8.2 Teardown Product Fan Power Input ..................................................................... 5-51 Table 5.9.1 DOE Incremental Costs ........................................................................................ 5-54 Table 5.9.2 AHAM Incremental Cost Data for Product Class 3.............................................. 5-59 Table 5.9.3 AHAM Incremental Cost Data for Product Class 5.............................................. 5-62 Table 5.9.4 AHAM Incremental Cost Data for Product Class 7.............................................. 5-64 Table 5.9.5 AHAM Incremental Cost Data for Product Class 9.............................................. 5-66 Table 5.9.6 AHAM Incremental Cost Data for Product Class 11............................................ 5-68

LIST OF FIGURES

Figure 5.3.1 Flow Diagram of Engine ering Analysis Methodology........................................... 5-3 Figure 5.4.1 Maximum Efficiency Leve ls Available by Product Class.................................... 5-17 Figure 5.6.1 Full Production Costs............................................................................................ 5-30 Figure 5.7.1 ERA Analysis for Refrigerato r-Freezers Compared with EnergyGuide Labels and Energy Test Measurements ................................................................ 5-38 Figure 5.7.2 ERA Analysis for Freezers Compar ed with EnergyGuide Labels and Energy Test Measurements ............................................................................................... 5-39 Figure 5.7.3 ERA Analysis for Compact Re frigerators and Freezers Compared with EnergyGuide Labels and Energy Test Measurements.......................................... 5-39 Figure 5.8.1 Compressor Efficiency Data................................................................................. 5-46 Figure 5.8.2 Incremental Cost for Single-Speed Compressors for Standard-Size Products ..... 5-47 Figure 5.8.3 Efficiency Curve for Low Capacity Compressors................................................ 5-48 Figure 5.9.1 Incremental Manufacturer Selli ng Price for Standard-Size RefrigeratorFreezers................................................................................................................. 5-55 Figure 5.9.2 Incremental Manufacturer Selli ng Price for Standard-Size Freezers ................... 5-56 Figure 5.9.3 Incremental Manufacturer Selli ng Price for Compact Refrigerators and Freezers................................................................................................................. 5-57 Figure 5.9.4 Incremental Cost Cu rves for Product Class 3....................................................... 5-60 Figure 5.9.5 Incremental Cost Cu rves for Product Class 5....................................................... 5-63 Figure 5.9.6 Incremental Cost Cu rves for Product Class 7....................................................... 5-65 Figure 5.9.7 Incremental Cost Cu rves for Product Class 9....................................................... 5-67 Figure 5.9.8 Incremental Cost Cu rves for Product Class 11..................................................... 5-69 Figure 5.9.9 Product Class 11 Refr igerators listed in the ENERGY STAR Database.............. 5-69

5-iiiCHAPTER 5. ENGINEERING ANALYSIS

5.1 INTRODUCTION

The engineering analysis establishes the relationship between manufacturer production cost and energy consumption for th e refrigerators, refrigerator-freezers, and freezers covered in this rulemaking. The “cost-e fficiency” relationship serves as the basis for cost-benefit calculations in terms of i ndividual customers, manufacturers, and the Nation, from which the most economically-justifi ed, technically feasible standard level is ultimately determined.

The inputs into the engineering analysis in clude baseline characteristics for each product class addressed in the market and t echnology assessment (chapter 3), the design options from the screening analysis (chapter 4), as well as cost and energy use data collected from manufacturers, component vendors, reverse-engineering, and energy testing. The output of the engine ering analysis is the cost-effi ciency relationship for each product class independent of cabinet volume, which will be used in the life-cycle and payback period analyses (chapter 8).

This chapter covers the product classes DOE analyzed, and the methodology used by DOE to develop manufacturing costs, energy consumption, and extend the analysis to low-volume product classes, as well as the results of these analyses.

5.2 PRODUCT CLASSES ANALYZED

In the engineering analysis for the pr eliminary notice of proposed rulemaking (Pre-NOPR), DOE analyzed the seven pr oduct classes listed in Table 5.2.1. DOE considers these classes to be representa tive of products currently shipped by the residential refrigerator, freezer, and refrigerat or-freezer industry based on total shipments. These product classes represent close to 90% of the shipments of refrigerators, refrigerator-freezers, and freezers. DOE did not directly analyze all covered product classes in order to carry out the analysis as efficiently as possible. DOE proposes extrapolation of energy standard s to the remaining product cla sses as described in section 2.15 of chapter 2.

5-1Table 5.2.1 Product Classes Analyzed in Engineering Analysis Product Class Equipment Description

3 Refrigerator-freezers—automatic defr ost with top-mounted freezer without TTD ice service

5 Refrigerator-freezers—automatic defrost with bottom-mounted freezer without TTD ice service

7 Refrigerator-freezers—automatic defros t with side-mounted freezer with TTD ice service 9 Upright freezers with automatic defrost 10 Chest freezers and all other freezers except compact freezers 11 Compact refrigerators and refrigerator-freezers with manual defrost 18 Compact chest freezers

5.3 METHODOLOGY OVERVIEW

This section describes the analytical methodology DOE used in the engineering analysis. In this rulemaking, DOE has adopted a combined efficiency level, design option approach to developing cost-efficiency curves . DOE established efficiency levels defined on percent energy use lower than that of base line efficiency products in order to allow comparison of information developed from different sources. However, DOE’s analysis is based on the efficiency improvements asso ciated with groups of design options.

Figure 5.3.1 presents the steps in the anal ysis and illustrates how they contribute to developing the cost-efficiency curves. Th e process begins with data collection and ends with the incremental cost curve results.

As input to the analysis, DOE requested in cremental cost-efficiency data from the industry. The Association of Home Appliance Manufacturers (AHAM) provided aggregated incremental cost data for a numbe r of the product classe s under analysis. This information was supplemented by analytically -derived cost-efficiency curves for the seven product classes listed in Table 5.2.1.

To develop the analytically-derived cost-efficiency curves, DOE collected information from various sources on the manufacturing cost and energy use reduction characteristics of each of the design options . DOE reviewed product literature, conducted reverse-engineering of current products, and interviewed component vendors of compressors, fan motors, insulation, and heat exchangers. DOE also conducted interviews with manufacturers, using an e ngineering questionnaire which is reproduced in appendix 5-A.

5-2Figure 5.3.1 Flow Diagram of Engineering Analysis Methodology

Cost information from the vendor inte rviews and engineering questionnaires provided input to the manufacturing cost m odel. Incremental costs associated with specific design options were calculated usi ng the cost model. Energy use reduction was modeled with a modified version of the es tablished EPA Refrigerator Analysis (ERA) program which was used in the previous refrigerator rulemaking. The reverse engineering, vendor intervie ws, and manufacturer interv iews provided input for the energy analysis. The incremental cost estimates and the energy modeling results together constitute the energy efficiency curves presented in this chapter.

5.4 EFFICIENCY LEVELS

5.4.1 Baseline Units based on the Current Test Procedure

DOE selected baseline units as referen ce points for all of the product classes, against which DOE determined changes resu lting from use of energy saving design options. The baseline unit in each product cl ass represents the basic characteristics of equipment in that class. A baseline unit is a unit that just meets current required energy conservation standards and provides basic consumer utility.

As discussed in chapter 3, DOE has init iated a rulemaking to revise the energy test procedure for refrigerators, refrigerator-freezers, and freezers. Some of the anticipated changes to the test procedure su ch as changes in compartment temperatures will result in changes in the measured energy consumption. The test procedure change will also affect the measured size of the refrigerators, expressed as adjusted volume.

5-3Since the maximum energy use for residential refrigeration products is expressed as a function of adjusted volume, the change in ad justed volume also affects the definition of baseline products. This section discusses defi nitions of baseline units for the engineering analysis based on the current test procedure, while the next section discusses modified definitions for baseline refrigeration pr oducts based on the expected revised test procedure.

For this rulemaking, DOE established baseline efficiency levels as the current federal energy conservation standards, expressed as maximum annual energy consumption as a function of the product’s adjusted volume, as shown in Table 5.4.1. These definitions are based on testing accordi ng to the current energy test procedure.

5-4Table 5.4.1 Refrigerator, Refrigerator-Freez er, and Freezer Energy Conservation Standards and Proposed Baseline Model Efficiencies

Product Class Equations for Maximum Energy Use (kWh/yr)
1. Refrigerators and refrigerat or-freezers with manual defrost. 8.82AV + 248.4 0.31av + 248.4
2. Refrigerator-freezer—partial automatic defrost. 8.82AV + 248.4 0.31av + 248.4 3. Refrigerator-freezer—automatic defr ost with top-mounted freezer without TTD ice service and all-refrig erator—automatic defrost. 9.80AV + 276.0 0.35av + 276.0 4. Refrigerator-freezers—automatic defros t with side-mounted freezer without TTD ice service. 4.91AV + 507.5 0.17av + 507.5 5. Refrigerator-freezers—automatic de frost with botto m-mounted freezer without TTD ice service. 4.60AV + 459.0 0.16av + 459.0 6. Refrigerator-freezers—automatic defr ost with top-mounted freezer with TTD ice service. 10.20AV + 356.0 0.36av + 356.0 7. Refrigerator-freezers—automatic defros t with side-mounted freezer with TTD ice service. 10.10AV + 406.0 0.36av + 406.0
8. Upright freezers with manual defrost. 7.55AV + 258.3 0.27av + 258.3
9. Upright freezers with automatic defrost. 12.43AV + 326.1 0.44av + 326.1
10. Chest freezers and all other freezers except compact freezers. 9.88AV + 143.7 0.35av + 143.7
11.Compact refrigerators and refrig erator-freezers with manual defrost. 10.70AV + 299.0 0.38av + 299.0
12. Compact refrigerator-freezer —partial automatic defrost. 7.00AV + 398.0 0.25av + 398.0 13. Compact refrigerator-freezers—automatic defrost with top-mounted freezer and compact all-refrigerator—automatic defrost. 12.70AV + 355.0 0.45av + 355.0 14. Compact refrigerator-freezers—automatic defrost with side-mounted freezer. 7.60AV + 501.0 0.27av + 501.0 15. Compact refrigerator-freezers—automatic defrost with bottom-mounted freezer. 13.10AV + 367.0 0.46av + 367.0
16. Compact upright freezers with manual defrost. 9.78AV + 250.8 0.35av + 250.8
17. Compact upright freezers with automatic defrost. 11.40AV + 391.0 0.40av + 391.0
18. Compact chest freezers. 10.45AV + 152.0 0.37av + 152.0 5A. Refrigerator-freezer—aut omatic defrost with botto m-mounted freezer with TTD ice service. 5.0AV + 539.0 0.18av + 539.0

10A. Chest freezers with automatic defrost. 14.76AV + 211.5 0.52av + 211.5 AV= adjusted volume in cubic feet; av = adjusted volume in liters; Refrigerator-Freezers: AV = fresh food intern al volume + 1.63 * freezer internal volume Freezers: AV = 1.73 * freezer internal volume Refrigerators (single-door): AV = fresh food inte rnal volume + 1.44 * freezer internal volume All-Refrigerators: AV = internal volume

5-55.4.2 Baseline Efficiency Definitions Based on the Expected Test Procedure

As discussed in chapter 3, DOE expects to propose revisions in the energy test procedure to harmonize with expected test te mperatures under consideration for IEC test procedure 62552 and to simplify calculation of refrigerated volumes. The expected test temperature changes are summari zed in Table 5.4.2 below.

Table 5.4.2 Expected Cabinet Temperature Changes for the DOE Test Procedure Fresh Food Compartment Temperature ° F Freezer Compartment Temperature ° F Equipment Type Current Expected Current Expected Refrigerator-Freezer 45 39 5 0

All-Refrigerator 38 39 Not Applicable Refrigerator w/ Freezer Compartment 45 39 15 15 (No Change)

Freezer Not Applicable 0 0 (No Change)

The temperature changes also impact the volume adjustment factor used to determine the adjusted volume. This factor is multiplied by the freezer compartment volume in the adjusted volume calculation. Current and expected volume adjustment factors are summarized in Table 5.4.3 below.

Table 5.4.3 Volume Adjustment Factors Product

Refrigerator-Freezer Current Test Procedure

1.63 Expected Test Procedure Revisions 1.76 Basic Refrigerator* 1.44 1.47 Freezer 1.73 1.76 All-Refrigerator** 1.00 1.00 *A basic refrigerator is a single-door refrigerator with a freezer compartment with volume greater than 0.5 ft 3

. **An all-refrigerator can have a freezer compartment with volume less than 0.5 ft 3

. The key changes in the volume measurem ent calculation between the current test procedure and the expected revised test pr ocedure are summarized in Table 5.4.4 below. Adjusted volume will be impacted both by the change in the volume adjustment factor and the change in the volume measurement.

5-6Table 5.4.4 Compartment Volume Calculation Changes

Item AHAM HRF-1-1979 AHAM HRF-1-2008 Expected Effect on Volume

Automatic Ice Maker Storage Bin Included (4.2.1.1a) Would be included under “removable containers” but dispenser MAY NOT be included None*

Ice Makers Included (4.2.1.1a) No Mention None*

Water Coolers Included (4.2.1.1a) No Mention None*

Door Shelf Fronts and Bottoms Included (4.2.1.1b) Shelves molded into the inner door panel NOT included (4.2.2) Decrease

Volume between the Deductible Door Dikes and Cabinet Breaker Strips or Adjacent Liner Wall Not Included (4.2.1.2d) No mention of exclusion, so probably included. Increase

Shelf Hangers & Shelf and Pan Rails Not included for fixed projections if collective volume is >0.05 ft 3 (4.2.1.2e) Could be interpreted as part of shelving and would thus be included. Increase

*Although AHAM HRF-1-2008 either doesn’t mention this item or is not fully clear regarding its treatment fo r the volume calculation, it is expected that manufacturers would use the AHAM HRF-1-1979 approach.

5.4.2.1 Data Illustrating the Impact of Test Procedure Changes

The different compartment temperatures of the expected revised energy test procedure will change test energy use for refrigerators and refrigerator-freeze rs. In addition, both the impact of the modified temperatures on the adjusted volume and the modified volume calculation method will change adjusted volum es. For these reasons, it is necessary to establish modified relationships between en ergy use and adjusted volume to define baseline products. AHAM provided data for a nu mber of the product classes, presented in Table 5.4.5 through Table 5.4.7 below (this is re ferred to as the AHAM TP Change data).

The AHAM TP Change data for product classes 11 and 13 both show energy use reductions, indicating that the products repr esented by these data are primarily allrefrigerators. AHAM was not able to separately provide da ta for the all-refrigerators of these product classes, because insuffici ent data was provided by manufacturers for aggregation.

5-7Additional data sources which provide i ndication of the imp acts of the test temperature changes for standard-size refr igerator-freezers include (1) energy test measurements for the refrigerator-freezers te sted as part of this rulemaking, and (2) calculation of the energy impacts using ERA, the energy modeling tool used for this rulemaking. The energy use impacts indicated by these sources are shown in Table 5.4.8. DOE conducted these energy tests and calcula tions for three products of each of the seven analyzed product cla sses (see Section 5.5.3.1 for discussion on selection of products for reverse engin eering and energy testing).

Table 5.4.5 Compartment Temperature and Adjusted Volume Change Data provided by AHAM—Current Test Product Class Fresh Food Volume Freezer Volume Adjusted Volume Energy Use Average 12.82 5.02 20.92 420 3 (R-F) Standard Deviation 3.54 1.82 6.53 55 Number of Samples 19 19 19 19 Average 19.26 19.26 374 3A (AR) Standard Deviation 3.4 3.4 54 Number of Samples 11 11 11 Average 14.21 5.15 22.62 493 5 Standard Deviation 1.85 1.02 3 55 Number of Samples 18 18 18 18 Average 15.77 9.32 30.95 617 7 Standard Deviation 1.61 0.87 2.53 68 Number of Samples 24 24 24 24 Average 16.85 29.14 603 9 Standard Deviation 4.88 8.45 136 Number of Samples 18 18 18 Average 4.38 4.65 334 11 Standard Deviation 1.38 1.38 44 Number of Samples 13 13 13 Average 4.75 4.77 296 13 Standard Deviation Number of Samples 1.18 1.15 77 12 12 12 Note: R-F refers to refrigerator-freezers; AR refers to all-refrigerators.

5-8Table 5.4.6 Compartment Temperature and Adjusted Volume Change Data provided by AHAM--Proposed Test Product Class Fresh Food Volume Freezer Volume Adjusted Volume Energy Use Average 12.79 4.96 21.44 472 3 (R-F) Standard Deviation 3.51 1.78 6.59 53 Number of Samples 19 19 19 18 Average 19.51 19.51 364 3A (AR) Standard Deviation 3.51 3.51 53 Number of Samples 11 11 11 Average 14.42 5.25 23.12 582 5 Standard Deviation 1.88 1 3.01 68 Number of Samples 18 18 18 18 Average 15.95 9.01 31.45 702 7 Standard Deviation 1.79 0.75 2.49 82 Number of Samples 24 24 24 24 Average 16.84 29.47 603 9 Standard Deviation 5.04 8.73 136 Number of Samples 18 18 18 Average 4.34 4.61 324 11 Standard Deviation 1.36 1.36 48 Number of Samples 13 13 13 Average 4.8 4.83 285 13 Standard Deviation Number of Samples 1.23 1.2 73 12 12 12 Note: R-F refers to refrigerator-freezers; AR refers to all-refrigerators.

5-9Table 5.4.7 Compartment Temperature and Adjusted Volume Change Data provided by AHAM—Impact Product Class Fresh Food Volume Freezer Volume Adjusted Volume Energy Use Average -0.1% -1.1% 2.8% 12.4% 3 (R-F) Standard Deviation 0.6% 0.9% 2.3% 6.9% Number of Samples 19 19 19 18 Average 1.2% 1.2% -2.6% 3A (AR) Standard Deviation 1.0% 1.0% 1.1% Number of Samples 11 11 11 Average 1.5% 2.2% 2.2% 18.2% 5 Standard Deviation 1.2% 2.2% 1.2% 3.7% Number of Samples 18 18 18 18 Average 1.0% -3.1% 1.6% 14.0% 7 Standard Deviation 2.0% 4.6% 2.0% 6.7% Number of Samples 24 24 24 24 Average -0.4% 0.9% 0.0% 9 Standard Deviation 2.5% 2.2% 0.0% Number of Samples 18 18 18 Average -0.7% -0.6% -3.1% 11 Standard Deviation 1.9% 1.6% 1.4% Number of Samples 13 13 13 Average 0.9% 1.0% -3.6% 13 Standard Deviation Number of Samples 1.6% 1.4% 0.8% 12 12 12 Note: R-F refers to refrigerator-freezers; AR refers to all-refrigerators.

5-10Table 5.4.8 Energy Use Impact of Compartm ent Temperature Changes: Data Developed by DOE Product Class

3 Product Description

16 ft 3 Top-Mount R-F Impact based on
energy measurements 19.1% Impact based on ERA modeling

14.2% 21 ft 3 Top-Mount R-F 27.7% 16.0% 21 ft 3 E* Top-Mount R-F 26.6% 14.1% 5 18.5 ft 3 E* Bottom-Mount R-F 12.5% 22.1% 25 ft 3 E* Bottom-Mount R-F 1 27.6% 13.8% 25 ft 3 E* Bottom-Mount R-F 2 17.3% 14.4% 4 22 ft 3 Side-Mount R-F† 17.7% 12.5% 7 26 ft 3 Side-Mount R-F 24.5% 12.4% 26 ft 3 E* Side-Mount R-F 25.0% 12.2% 11 1.7 ft 3 Compact Refrigerator -4.5% -2.4% 4.0 ft 3 Compact Refrigerator Not Tested 13.4% † This product was thought to be product class 7 when purchased.

The AHAM TP Change data shows reasona ble agreement with the DOE modeled energy use impacts. However, the DOE energy measurements indicate a higher sensitivity to the temperature change of th e new test procedure. The AHAM data shows that there can be significant variation in th e sensitivity of different refrigerator-freezer products to the test temperature changes, part icularly for product classes 3 and 7. The two compact refrigerators of Ta ble 5.4.8 exhibit different res ponses to the compartment temperature change because the 1.7 ft 3 refrigerator has a freezer compartment smaller than 0.5 ft 3 and is tested as an all-refrigerator, while the 4.0 ft 3 refrigerator has a freezer compartment just larger than 0.5 ft 3 , requiring that it be tested as a basic refrigerator.

5.4.2.2 Establishment of Baseline Energy—Adjusted Volume Relationships Based on the New Test Procedure

The available data to inform the establis hment of baseline energy versus adjusted volume relationships based on the expected revi sed test procedure is discussed in Section 5.4.2.1. While this data does not address ever y product class, DOE proposes to use it as the basis for establishing the baseline relati onships. The approach DOE used to develop these relationships for all the product classe s is summarized in Table 5.4.9 below. Note that product classes 1, 3, 11, and 13 are split be cause, while the all-refrigerators have reduced energy use with the new test procedur e, the products which include freezers have significantly higher energy use. This applies to product cl ass 11, since many of these units have freezer compartments smaller than 0.5 ft 3 , which allows them to be classified and tested as all-refrigerators rather than ba sic refrigerators. The test procedure impact of this classification is that the refrigerator co mpartment temperature will be raised for allrefrigerators, while it will be reduced for basic refrigerators under the proposed test procedure.

5-11Table 5.4.9 Approach for Establishing Baseline Energy--Adjusted Volume Relationships Product Class 1 Approach Use modeling with ERA for temp erature, assume negligible adjusted volume impact based on AHAM data for PC11. 1A (All-Refrigerators) Use AHAM TP Change aggregated data of product class 3 allrefrigerators. 2 Trend consistent with PC1.3 (RefrigeratorFreezers) Use AHAM TP Change aggregated data.

3A (All-Refrigerators) Use AHAM TP Change aggregated data.

4 Use AHAM TP Change aggregat ed data of product class 7. 5 Use AHAM TP Change aggregated data. 5A Use AHAM TP Change aggreg ated data of product class 5. 6 Use AHAM TP Change aggregat ed data of product class 3 refrigerator-freezers. 7 Use AHAM TP Change aggregated data. 8 (volume only) Assume negligible volume impact due to simplicity of manual defrost freezer interior. 9 (volume only) Use AHAM TP Change aggregated data. 10 (volume only) Assume negligible imp act due to simplicity of manual defrost freezer interior. 10A (volume only) Use AHAM TP Ch ange aggregated data for PC9. 11 Use modeling with ERA for temp erature, assume negligible adjusted volume impact based on AHAM data.* 11A (All-Refrigerators) Use modeling with ERA for temperature, assume negligible adjusted volume impact based on AHAM data.* 12 Trend consistent with PC11.13 (RefrigeratorFreezers) Use AHAM TP Change aggregated data of product class 3 refrigerator-freezers.* 13A (All-Refrigerators) Use AHAM TP Change aggregated data of product class 3 allrefrigerators.* 14 Use AHAM TP Change aggregat ed data of product class 7. 15 Use AHAM TP Change aggregat ed data of product class 5. 16 (volume only) Assume negligible volume impact due to simplicity of manual defrost freezer interior. 17 (volume only) Use AHAM TP Cha nge aggregated data for PC9. 18 (volume only) Assume negligible volume impact due to simplicity of manual defrost freezer interior.

*The AHAM energy use increase data canno t be used for this product class, because it is not known how many of these products are all-refrigerators.

5-12Note: For product classes 8, 10, 16, and 18, while the volume impact is assumed to be negligible, the adjusted volume incr eases according to the increase in the volume adjustment factor.

The methodology for determining new ba seline energy—adjusted volume curves given the data indicating the impacts on the en ergy use and adjusted volume for a given product class is as follows. The proposed en ergy use and the current energy use for a product are represented as being proportiona l using an Energy Standard Adjustment Factor (ESAF).

BEC = ESAF × BEC Equation 5.4.1 NEWTP CURTP Where: BEC NEWTP = Baseline energy consumption us ing the new test procedure; BEC CURTP = Baseline energy consumption using the current test procedure.

The ESAF is considered to be a func tion only of product class. Dependence on adjusted volume or efficiency level cannot be determined based on the available data.

Similarly, the adjusted volume for a produc t under the proposed test procedure is related to the adjusted volume under the current test procedure using a Volume Calculation Adjustment Factor (VCAF).

AV = VCAF × AV Equation 5.4.2 NEWTP CURTP

Where: AV NEWTP = Adjusted Volume using the new test procedure; AV CURTP = Adjusted Volume using the current test procedure.

The VCAF, like the ESAF, is considered to be a function only of product class. Baseline energy use for the current test procedure is expressed as follows, where the constants A and B are a function of product class.

BEC = A × AV + B Equation 5.4.3 CURTP CURTP
Combining Equations 5.4.1 through 5.4.3 give s the following relationship for the baseline energy consumption base d on the new test procedure. ⎛ AV NEWTP ⎞ ⎛ ESAF ⎞ BEC = ESAF × ⎜ A × + B ⎟
= ⎜ × A ⎟ × AV + 

## ( ESAF × B 

## )
NEWTP NEWTP ⎝ VCAF ⎠ ⎝ VCAF ⎠

Hence, the baseline energy consumption for the product class for the new test procedure can be represented as a straight -line relationship based on new constants A NEW and B NEW , where the new constants are related to the current constants as follows.
⎛ ESAF ⎞ A NEW = ⎜ ⎟ × A ; B NEW = ESAF × B ⎝ VCAF ⎠

5-13The baseline energy use based on the expect ed revised test pro cedure is presented in Table 5.4.10 below for each of the product classes.

Table 5.4.10 New Baseline Energy Consumption based on Proposed Test Procedure Product Class

1 ESAF

1.132 VCAF

1 Current Baseline Energy Use (kWh/year) 8.82 AV + 248.4 Expected Test Procedure Baseline Energy Use (kWh/year) 9.98 AV + 281.2 1A 0.974 1.012 8.82 AV + 248.4 8.49 AV + 241.9 2 1.132 1 8.82 AV + 248.4 9.98 AV + 281.2 3 1.124 1.028 9.8 AV + 276 10.72 AV + 310.2 3A 0.974 1.012 9.8 AV + 276 9.43 AV + 268.8 4 1.14 1.016 4.91 AV + 507.5 5.51 AV + 578.6 5 1.182 1.022 4.6 AV + 459 5.32 AV + 542.5 5A 1.182 1.022 5 AV + 539 5.78 AV + 637.1 6 1.124 1.028 10.2 AV + 356 11.15 AV + 400.1 7 1.14 1.016 10.1 AV + 406 11.33 AV + 462.8 8 1 1.017 7.55 AV + 258.3 7.42 AV + 258.3 9 1 1.009 12.43 AV + 326.1 12.32 AV + 326.1 10 1 1.017 9.88 AV + 143.7 9.71 AV + 143.7 10A 1 1.009 14.76 AV + 211.5 14.63 AV + 211.5 11 1.125 1 10.7 AV + 299 12.04 AV + 336.4 11A 0.977 1 10.7 AV + 299 10.45 AV + 292.1 12 1.125 1 7 AV + 398 7.88 AV + 447.8 13 1.124 1.028 12.7 AV + 355 13.89 AV + 399.0 13A 0.974 1.012 12.7 AV + 355 12.22 AV + 345.8 14 1.14 1.016 7.6 AV + 501 8.53 AV + 571.1 15 1.182 1.022 13.1 AV + 367 15.15 AV + 433.8 16 1 1.017 9.78 AV + 250.8 9.61 AV + 250.8 17 1 1.009 11.4 AV + 391 11.3 AV + 391 18 1 1.017 10.45 AV + 152 10.27 AV + 152 Note: In the “Current Baseline” equations, AV is calculated using the current volume calculation method and adjustment factor, while in the “Proposed” equations, AV is calculated using the proposed volume calculation method and adjustment factor (see Table 5.4.3)

5.4.2.3 Investigation of the Slope of the Energy Use Curve

DOE carried out analysis to confirm wh ether the slopes of the baseline energy use—adjusted volume curves for the product cl asses analyzed in de pth as part of the engineering analysis are repr esentative of the energy us e of typical products. DOE conducted these analyses based on the expected revised test procedure. The analysis started with an energy model of a minimally -compliant product and examined the trend in calculated energy use as the product size changes with constant insulation thickness. For the analysis of compact refrigerators, DOE considered the change in efficiency of typically available compressors sized appropr iately for the product. For standard-size

5-14products the DOE used a constant compresso r efficiency in the analysis, based on observation that compressor efficiency does not vary significantly in the capacity range suitable for most standard-size products (this is discussed in greater detail in section 5.8.3). The energy—adjusted volume slopes calculat ed in this analysis are presented in Table 5.4.11 below. The table also shows th e slopes of the proposed baseline energy use—adjusted volume relationships of Ta ble 5.4.10 above. The comparison provides an indication of whether adjustment might be re quired to the proposed baseline energy use relationships, which are based on the curre nt energy conservation standards and the expected impacts of the expected revised test procedure. The comparison shows that consideration may need to be given to wh ether the slope for the baseline energy use relationships should be adjusted for pr oduct classes 5, 11, 11A, and 18. By extension, similar consideration should be given to the slopes for pr oduct classes 4 and 5A, which were not directly examined, but the trends for which should be predicted by the analyses for product classes 7 and 5, resp ectively. The question of wh ether adjustments should be made to the baseline energy use relationshi ps of Table 5.4.10 is a topic on which DOE requests comment from stakeholders.

Table 5.4.11 DOE Assessment of the Slope of the Energy Use Curve

Product Class Calculated Energy Curve Slope from ERA Models* Slope from Proposed Baseline Energy Use Equation (Table 5.4.10) 3 13.3 10.7 5 12.3 5.3 7 11.9 11.3 9 9.4 12.3 10 7.7 9.7 11 16.4 12.0 11A 20 to 35** 10.5 18 4.5 10.3 * Analysis was conducted for both the small and large units analyzed for product classes 3, 5, 7, 9, 10, 18. Values shown are averages of slopes for the two ERA models. ** The energy use—adjusted volume relationship is nonlinear, with higher slope at lower volumes. The slopes indicated are applicable for a range of adjusted volumes from 1.7 to 3.6 ft 3

.

5.4.3 Incremental Efficiency Levels

DOE established a series of incrementa l efficiency levels, for which it has developed incremental cost da ta and quantified the cost-effi ciency relationship for each of the seven analyzed product classes. The in cremental efficiency levels are shown in Table 5.4.12 below. Maximum available effi ciency levels for the analyzed product classes, which are based on a survey of pr oduct databases and manufacturer websites, are tabulated in Table 5.4.13 below. Maximum technology levels, which are based on DOE energy modeling using all app licable design options, are discussed in Section 5.4.4.

5-15Table 5.4.12 Incremental Efficiency Levels (% Energy Use Less than Baseline)

Level Standard-Size Refrigerator-Freezers (PC 3, 5, 7) Standard-Size Freezers (PC 9, 10) Compact Refrigerators and Freezers (PC 11, 18)

1 10% 10% (Current ENERGY STAR) 10%

2 15% (Former ENERGY STAR) 15% 15%

3 20% (Current ENERGY STAR *) 20% 20% (Current ENERGY STAR *) 4 25% (CEE Tier 2) 25% 25% (CEE Tier 2) 5 30% (CEE Tier 3) 30% 30% (CEE Tier 3) 6 35% 35% 35% 7 40% 40% 40% 8 45%** 45% 45%*Current ENERGY STAR is equivalent to CEE Tier 1 for standard-size refrigerators and refrigeratorfreezers and for all compact products. **The 45% efficiency level was not analyzed fo r product class 7 because it is beyond maximum technology according to DOE analysis

.

Table 5.4.13 Maximum Available Levels (%Energy Use Less than Baseline)

Maximum Available Level** PC % Volume (ft 3 ) Brand & Model #
3 22% 18 Frigidaire FRT18HS7J 5 26% 19 Sub-Zero BI30US8 7 30% 26 Whirlpool GS5VHA 9 43% 8 Gaggenau RF411700 10 16% 9 W.C.Wood C09 11 26% 6 MicroFridge 5.6MFR 18 21% 5 Haier ESCM050 ** Source: ENERGY STAR Database (4/7/2009), CEE Database (3/16/2009), CEC Database (4/1/2009), Manufacturer websites

5.4.4 Maximum Technology Level

DOE defines a maximum technology level to represent the theoretical maximum possible efficiency if all available desi gn options are incorporated. The maximum technology level is not to be confused with the maximum available level, which is the highest efficiency unit currently availabl e on the market. In many cases the maximum technology level is not commer cially available because it is not yet economically feasible. Figure 5.4.1 below shows the maximu m available efficiency levels, based on the ENERGY STAR database of 4/9/09, with ad justments including deleting products which are no longer for sale based on the CEC da tabase and manufactur ers’ and retailers’

5-16websites. For this chart, the all-refrigera tor products of product classes 1, 3, 11, and 13 were not included—some of thes e have higher efficiency leve ls than those shown in the chart. The maximum available efficiency pr oduct varies significan tly among the product classes, from 1% for product cla ss 13 to 51% for product class 2.

As mentioned, the maximum technology level may not represent available products because they may not be economi cally feasible. DOE determined maximum technology levels using energy modeling. The energy models for the maximum technology levels were based on use of all de sign options applicab le for the specific product classes. While these product configur ations have not likely been tested as prototypes, all of the indivi dual design options have been incorporated in available products. The maximum technology efficiency le vels for the analyzed product classes are presented in Table 5.4.14 below. These efficien cy levels are signifi cantly higher than the maximum available products. The costs of the maximum technology efficiency level designs are also quite high, being based on exte nsive use of high-cost design options such as vacuum insulating panels as well as al l applicable lower-cost design options. Table 5.4.14 indicates which design options were used for each of the product classes.

Figure 5.4.1 Maximum Efficiency Levels Available by Product Class

5-17Table 5.4.14 Maximum Technology Levels Design Options UsedProduct Class% Lower EnergyBrushless DCEvaporator FanBrushless DCCondenser FanForced ConvectionCondenserLarger EvaporatorLarger CondenserThicker InsulationVIPsVariable SpeedCompressorAdaptive DefrostVariable AntiSweat

3 56% 9 9 9 9 9 9 9

5 53% 9 9 9 9 9 9 9 9

7 45% 9 9 9 9 9 9 9

9 55% 9 9 9 9 9 9 9 9

10 51% 9 9 9 9 9

11 75% 9 9 9 9 9

18 52% 9 9 9 Note: Levels indicated are the average dete rmined for the two products of each product class analyzed in detail.

5.5 DATA COLLECTION

DOE collected data from a number of sour ces to support the e ngineering analysis. The key sources include the following.

• AHAM

• Component Vendors

• Reverse-Engineering of Products

• Manufacturer Interviews

• Energy Tests

The data collection process is described in greater detail in the following sections.

5.5.1 Manufacturer-Submitted Shipment a nd Cost Data from AHAM

DOE included draft data requests sheets to support the engineering and other DOE analyses in the framework document as Tables A1 through A10 of that document. Some of these tables were revised base d on comments received during the framework comment period. For example, incremental cost data was provided for up to 35% efficiency level, and included a 10% efficien cy level, which replaced the 15% efficiency level of the draft tables. Other requests DOE made to AHAM in addi tion to the requests made in the framework document include the following.

5-18• Historical shipment data for Wine Co olers, broken out by key types: manual defrost/auto defrost.

• Historical shipment data for Built-in Refr igerators, disaggregated by product class.

• Recent shipment data for products incorpor ating a wine cooler compartment with either (1) a fresh food compartment, (2) a freezer compartment, or (3) both a fresh food and a freezer compartment.

• Recent shipment data for French Door refrigerators broken out between products with and without TTD ice service.

• Recent shipment data for convertible-botto m-drawer refrigerators (products with three doors configured as a side-by-side arrangement on top with a single drawer below, and for which the upper compartments are freezer and fresh food compartments and the drawer is convertible).

• Percent of refrigerator-freezers shipped with ice makers for app licable product classes (3, 4, 5, 13, 14, 15), historical data if possible.

• Total shipments of ice makers (any breakdown by (a) installed at factory, (b) installed by dealer, (c) installed by homeowner? ), historical data if possible.

• For as many refrigerator, refrigerator-freeze r, and freezer models as practical, data on the impact of the proposed changes in compartment temperature and volume calculation method:

o Compartment Volumes: volumes calculated according to the current procedure and according to the new pr ocedure, with indication of product class.

o Energy use (for refrigerators and refri gerator-freezers only): Annual energy use measurements for units tested for both temperatures (i.e. not Energy Label data—this should be energy test values calculated based on test data for the old temperatures and the new temperatur es for sequential tests of the same unit. This will typically require three te sts to make sure that both sets of temperatures are bracketed.

o It is anticipated that data for produc t classes 3 and 13 would be separated according to whether the product is a refr igerator-freezer or all-refrigerator.

AHAM supported the rulemaking by s upplying much of this data. AHAM supplied DOE with aggregated shipment-w eighted average data for many of the submittals in order to avoid divulging da ta submitted by individual manufacturers. The AHAM incremental cost data included incremen tal material, labor, and overhead costs as well as conversion capital expenditures a nd one-time product conversion expenses for each efficiency level. These data are pres ented in Section 5.9.2, where they can more readily be compared with the results of DO E analysis. Data associated with other AHAM submittals are presented in the relevant chapters and sections most directly related to the data in question.

5.5.2 Component Vendor Data

DOE directly contacted major supplie rs of key refrigerator and freezer components to obtain performance and cost da ta to support its design option analysis. The data received from vendors was comp ared with information received from

5-19manufacturers during the manufact urer interviews in order to develop input values for performance and cost parameters for th e energy modeling and manufacturing cost modeling. This vendor solicitation effort consisted of phone interviews, email correspondence, and in-person interviews . Table 5.5.1 lists the vendors contacted.

DOE also obtained from the compressor vendors or their websites complete performance data for compressors used in many of the energy analyses, including analyses for baseline and impr oved-efficiency configurations.

Table 5.5.1 Component Vendors Contacted by DOE during Engineering Analysis Component Type Vendors Compressors Embraco Tecumseh Matsushita Danfoss LG Huayi ACC (ZEL) Jiangsu Baixue Electric Appliances Co.,Ltd Fan Motors Matsushita VIPs va-Q-tec Matsushita Foam Insulation BASF Foam Supplies Heat Exchangers Brazeway

5.5.3 Reverse Engineering

DOE purchased a number of representative refrigerators and freezers as part of the engineering analysis in order to examine design and fabrication details. This reverseengineering included detailed measurement of dimensions, system and component-level power measurements, measurement of air flow s for products with forced convection heat exchangers, and physical teardowns. The result s of the reverse engineering process were used as input to the manufacturing cost modeling and the energy use modeling. This section describes the selection of products for reverse-engineer ing as well as some of the measurements made to support subsequent modeling. Section 5.6 provides a more thorough description of the physical teardown process used to support manufacturing cost modeling.

5.5.3.1 Selection of Products for Reverse Engineering

DOE performed reverse engineering on units rated at baseline and improved (i.e., ENERGY STAR) energy consumption levels fo r the seven analyzed product classes. DOE chose at least one representative sma ll-size and one large-si ze unit to cover the range of volumes within each product class. In order to best examine the design choices associated with efficiency improvements, DOE selected baseline efficiency/ENERGY

5-20STAR product pairs if possible, for which th e two products were identical other than the differences necessary for the ENERGY STAR-ra ted product to achieve higher efficiency. Such product pairs included the 21 ft 3 Top-Mount refrigerator-freezers, the 26 ft 3 SideMount refrigerator-f reezers, the 20 ft 3 upright freezers, and the 4 ft 3 compact refrigerators. Table 5.5.2 lists descriptions of the selected units and i ndicates whether energy testing was performed (see Section 5.5.5 for more on energy testing).

Table 5.5.2 Selected Units for Reverse-Engineering and Energy Testing

PC Product Description Energy % Less than Baseline Energy Test Physical Teardown Energy Use Model

16 ft 3 Top-Mount R-F 0% 9 9 9
21 ft 3 Top-Mount R-F 0% 9 9 9 3 21 ft 3 E* Top-Mount R-F 20% 9 9 9
4 22 ft 3 Side-Mount R-F† 0% 9 9 9
18.5 ft 3 E* Bottom-Mount R-F 15%* 9 9 9
25 ft 3 E* Bottom-Mount R-F 1 20% 9 9 5 25 ft 3 E* Bottom-Mount R-F 2 20% 9 9 25 ft 3 French Door E* BottomMount R-F 20% 9

5A 26 ft 3 French Door E* BottomMount R-F 20%

26 ft 3 Side-Mount R-F 0% 9 9 9 7 26 ft 3 E* Side-Mount R-F 20% 9 9 9
14 ft 3 Upright Freezer 0% 9 9
20 ft 3 Upright Freezer 2% 9 9 9
20 ft 3 E* Upright Freezer 1 12% 9 9 9

20 ft 3 E* Upright Freezer 2 10% 15 ft 3 Chest Freezer 1% 9 9 9
15 ft 3 E* Chest Freezer 11% 9 9 10 20 ft 3 Chest Freezer 0% 9 9
1.7 ft 3 Compact Refrigerator 7% 9 9 9
4 ft 3 Compact Refrigerator 2% 9 9 11 4 ft 3 E* Compact Refrigerator 22% 9 9
3.4 ft 3 Compact Chest Freezer 0% 9 9
7 ft 3 Compact Chest Freezer 1 1% 9 9 18 7 ft 3 Compact Chest Freezer 2 1% 9 9 *Exact efficiency level is not known because product literature did not include indication of separate compartment volumes. †This product was thought to be product class 7 when purchased.

5-215.5.3.2 Collection of Energy Modeling Data

DOE examined each unit prior to teardown to record details to be used as input for the energy modeling. The key measurem ents are described in this section.

The rated refrigerated volumes for each product’s compartments and its rated energy use were based on product literature or the ENERGY GUIDE. In the case of the 3.4 ft 3 chest freezer, the product literature did not provide an indication of energy use, and the product did not arri ve with an ENERGY GUIDE. Fo r this product, DOE assumed that energy use was exactly equal to ma ximum allowable energy use for the product class.

Power input for the product was measured for a period of 24 or more hours. This measurement was not intended to be an ener gy test, but provided useful information regarding the product controls, including off-cycle wattage, defrost heater on-time, and defrost interval (or indication of variable defrost). The power measurements for the products were made in the reverse engi neering test laboratory, whose ambient temperature may have cove red a broad range from 65  ̊ F to 85  ̊ F during the time that these measurements were carried out. Als o, careful attention was not paid to the temperature setpoints for this measurement—th e setpoints generally were left in the asshipped positions.

Component-level power measur ements were carried out for fans, defrost heaters, and manual defrost controls for the products which had these components. Power was also measured for some pr oducts’ anti-sweat heaters.

Air flow measurements were made for all forced-convection heat exchangers. These measurements were made with a hot wire anemometer. The location of these measurements varied depending on the heat exchanger type an d configuration. The determination of air flows based on these measurements is not very reliable, so this measurement was used as an indication of air flow trends more than exact indication of air flow for the various products.

Details of the cabinet size and insulation thickness were based on direct physical measurements. Most of these measurements were made prior to the teardown, but measurements of some parameters, such as outer shell thickness, inner liner thickness, and insulation thickness, were made during th e teardown process. Use of insulation other than polyurethane foam was not ed as part of the teardown process. Frame area details including gasket details were observed, and recorded with pictur es as part of the teardown process.

Heat exchanger details were recorded, including type, configuration, numbers of tubes and fins, dimensions, etc. For cold wall and hot wall heat exchangers this data was recorded during the product teardown process. Th e details of anti-sweat heaters were also determined during the teardown process, incl uding the layout for refrigerant anti-sweat loops. The details of suction line heat exch angers were similarly determined during teardown.

5-22Component manufacturer and model data were recorded for key components such as compressors, fans, and controls.

The energy modeling data for the teardow n products are presented in detail in appendix 5-A.

5.5.4 Manufacturer Interviews

DOE’s contractor discussed engineering issues with manufacturers during the preNOPR interviews. The engineering questions were consolidated into an engineering questionnaire, which guided the interview pr ocess for all of these discussions. The engineering questionnaire is shown in appendix 5-A. Key technical topics addressed during these discussions include the following:

• Typical characteristics of components and typical design details (i.e. such as insulation thicknesses) used for key product classes.

• Typical design differences between baseline and ENERGY STAR products.

• Differences in design pathways and incremen tal costs across different product classes

• Viability of technology options , and their typical costs.

All of these interviews we re conducted under non-disclosu re agreements with the manufacturers. Hence, none of the individua l responses can be reported. However, values for many of the parameters and costs used in the engineering analysis were based on aggregated input from these discussions.

5.5.5 Energy testing

DOE conducted energy testing to verify energy use of many of the products obtained for reverse engineeri ng, to provide refrigeration sy stem data to support energy use modeling, and to evaluate the difference in energy use between current energy test compartment temperatures and the new temperat ures associated with the expected revised test procedure.

Twelve of the 24 units were tested, as i ndicated in Table 5.5.2, including all of the refrigerator-freezer models and one each of the upright freezers, chest freezers, and compact refrigerators. No compact chest freezers were tested.

Energy testing was carried out by an inde pendent test lab acc ording to the DOE Energy Test Procedure as desc ribed in 10 CFR Part 430 Subpart B, Appendix A1 or B1, with reference to AHAM Standard HRF-1-1979 as applicable. In addition to the standard energy test results, DOE requested specific te mperature measurements to be taken in various locations during the test to better understand the refrigeration system operating characteristics. Specifically, low-mass ther mocouples were mounted in good thermal contact with the surface of refr igerant tubing, insulated externa lly from local ambient air. Table 5.5.3 lists the additional measurements.

5-23Table 5.5.3 Additional Thermocouple Lo cations for Energy Test Thermocouple Location RefrigeratorFreezers Upright Freezer Chest Freezer Compact Refrigerator Discharge 4” from shell 9 9 9 9 Condenser Inlet 9 Condenser Mid 9 Condenser Outlet 9 9 9 9 Evaporator Inlet 9 9 9 Evaporator Outlet 9 9 9 9 Suction 4” from shell 9 9 9 9 Condenser Air Inlet 9
Pan Heater In 9 Pan Heater Out 9 Hot Wall Condenser Surface 9 9 9
Compressor Compartment Air 9 9 9
Cold Wall Evaporator Surface 9 9

Two units of the 1.7 ft 3 compact refrigerator were test ed because the first of these was not able to hold proper internal temperatures.

5.6 MANUFACTURING COST MODELING

5.6.1 Generation of Bills of Materials

The end result of each teardown is a stru ctured bill of materials (BOM). DOE developed structured BOMs for each of the physical teardowns. Structured BOMs describe each product part and its relationship to the other part s in the estimated order in which manufacturers assembled them. The BO Ms describe each fabrication and assembly operation in detail, including the type of equipment needed (e.g., presses, drills), the process cycle times, and the labor associated with each manufacturing step. The result is a thorough and explicit model of the production process, which includes space, conveyor, and equipment requirements by planned production level.

The BOMs incorporate all materials, com ponents, and fasteners classified as either raw materials or purchased parts a nd assemblies. The classifications into raw materials or purchased parts were based on DOE’s previous industr y experience, recent information in trade publications, and discus sions with high- and low-volume original equipment manufacturers (OEMs). DOE also vi sited manufacturing plants to reinforce its understanding of the industry’s current manufacturing practices for each of the three product categories.

5-24For purchased parts, the purchase price is estimated based on volume-variable price quotations and detailed discussions w ith manufacturers and component suppliers. For fabricated parts, the pri ces of “raw” materials (e.g., tube , sheet metal) are estimated on the basis of 5-year aver ages (see Section 5.6.4.4). The cost of transforming the intermediate materials into finished parts is estimated based on current industry pricing. DOE shared major estimates with manufactur ers during the engin eering manufacturer interviews to gain feedback on the analys is, its methodology, and preliminary results.

5.6.2 Cost Structure of the Spreadsheet Models

The manufacturing cost assessment met hodology used is a detailed, componentfocused technique for calculating the manufact uring cost of a product (direct materials, direct labor, and the overhead costs associat ed with production). Th e first step in the manufacturing cost assessment was the creati on of a complete and structured BOM from the disassembly of the units selected for teardown. The units were dismantled, and each part was characterized according to weight , manufacturing processes used, dimensions, material, and quantity. The BOM incorporates a ll materials, components, and fasters with estimates of raw material costs and purchase d part costs. Assumptions on the sourcing of parts and in-house fabrication were based on industry experience, information in trade publications, and discussions with manufactur ers. Interview and plant visits were conducted with manufacturers to add i ndustry experience on the methodology and pricing.

The last step was to convert this inform ation into dollar values. To perform this task, DOE collected information on labor rates, tooling costs, raw material prices, and other factors. DOE assumed values for these parameters using internal expertise and confidential information available to DOE cont ractors. Although most of the assumptions are manufacturer specific and cannot be reve aled, Section 5.6.4.3 provi des a discussion of the values used for each assumption.

In summary, DOE assigned costs of labor, materials, and overhead to each part whether purchased or produced in-house. DOE then aggregated single-part costs into major assemblies (e.g., door assembly, heat exchanger assembly, shelving, packaging, controls, bottom components assembly, wiring harnesses, inner/outer wrapper assembly, etc.) and summarized these costs in a work sheet. During engineering interviews with manufacturers, DOE showed key estimates fr om the cost model and asked for feedback. DOE considered any information manufacturers ga ve that was relevant to the cost model and incorporated it into th e analysis, if appropriate.

5.6.3 Cost Model and Definitions

Once DOE disassembled selected units, gath ered information from manufacturer catalogs on additional products, and identified technologies, DOE created an appropriate manufacturing cost model that could translat e physical information into manufacturer production costs (MPCs). The cost model is based on production activities and divides factory costs into the following categories:

5-25• Materials: Purchased parts (i.e. compressor, fan motors, control boards, door handles, shelf frames, etc.), raw material s (i.e., cold rolled steel, copp er tube, etc.), and indirect materials that are used for processing and fabrication.

• Labor: Fabrication, assembly, indirect, and supervisor labor. Fabrication and assembly labor cost are burdened with benefits and supervisory costs.

• Overhead: Equipment, tooling, and buildi ng depreciation, as we ll as utilities, equipment and tooling maintenance, insurance, and property taxes.

5.6.3.1 Cost Definitions

Because there are many different accoun ting systems and methods to monitor costs, DOE defined the above terms as follows:

• Direct material: Purchased parts (out-sour ced) plus manufactured parts (made inhouse from raw materials).

• Indirect material: Material used during manufacturing (e .g., welding rods, adhesives).

• Fabrication labor: Labor associated with in-house piece manufacturing.

• Assembly labor: Labor associ ated with final assembly.

• Indirect labor: Labor costs that scaled with fabrication and assembly labor. This included the cost of technicians, manuf acturing engineering support, stocking, etc. that were assigned on a span basis.

• Equipment and plant depreciation: Money allocated to pay for initial equipment installation and replacement as the production equipment wears out.

• Tooling depreciation: Cost for initial tool ing (including nonrecurr ing engineering and debugging of the tools) and tooli ng replacement as it wears out.

• Building depreciation: Money allocated to pay for the building space and the conveyors that feed and/or make up the assembly line.

• Utilities: Electricity, gas, telephones, etc.

• Maintenance: Annual money spent on maintaining tooli ng and equipment.

• Insurance: Appropriated as a function of unit cost.

• Property Tax: Appropriated as a function as unit cost.

5.6.4 Cost Model Assumptions Overview

As discussed in the previous section, assumptions about manufacturer practices and cost structure played an important role in estimating the final product cost. Some assumptions were different for specific ma nufacturers, depending on their market position, manufacturing practices, and size.

In converting physical information about the product into cost information, DOE reconstructed manufacturing processes for each component using internal expertise and knowledge of the methods used by the indus try. DOE used assumptions regarding the manufacturing process parameters (e.g., equipment use, labor rates, tooling depreciation, and cost of purchased raw materials) to determine the value of each component. DOE then summed the values of the components into assembly costs and, finally, the total product cost. The product cost included the ma terial, labor, and overhead costs associated
5-26with the manufacturing facility. The material costs included both direct and indirect materials. The labor costs included fabricati on, assembly, indirect, di rect, and supervisor labor rates, including th e associated overhead.

The labor costs included assembly, fabric ation, supervisor, an d indirect labor. Overhead costs included equipment depr eciation, tooling depreciation, building depreciation, utilities, equipment, tooling maintenance, insurance, property, and taxes.

DOE used the information gathered from manufacturer interviews to make updates to the cost model. These change s involved updating com ponent and material pricing.

The next sections discuss specific assumptions about outsourcing, factory parameters, production volumes, and materi al prices. When the assumptions are manufacturer-specific, they are presented as industry averages to prevent disclosure of confidential information.

5.6.4.1 Fabrication Estimates

DOE characterized parts based on whethe r manufacturers purchased them from outside suppliers or fabricated them in-hous e. For purchased parts, DOE estimated the purchase price. For fabricated parts, DOE es timated the price of raw materials (e.g., tube, sheet metal) and the cost of transforming them into finished parts. Whenever possible, DOE obtained price quotes directly fr om the manufacturers’ suppliers.

DOE based the manufacturing operations assumptions on internal expertise, interviews with manufacturers, and manuf acturing facilities site visits. The major manufacturer processes identified and devel oped for the spreadsheet model are listed in Table 5.6.1. Fabrication process cycle times we re estimated and entered into the BOM.

Table 5.6.1 Cost Model In-House Manufac turing Operation Assumptions Fabrication Finishing Assembly/Joining Quality Control Fixturing Stamping/Pressing Turret Punch Tube Forming Brake Forming Cutting & Shearing Insulating &

Insulation Injection Tube/Wire Bending Brazing Vacuum Forming Blow Molding Washing Painting Powder Coating De-burring Polishing Refrigerant Charging Adhesive Bonding Spot Welding Seam Welding Packaging Inspecting & Testing

5-275.6.4.2 Production Volumes Assumptions

A manufacturer’s production volumes vary depending on several factors, including market share, the type of product produced (i.e., standa rd- size refrigeratorfreezer, compact refrigerator-freezer, etc.), a nd if the manufacturer produces other similar products. DOE based production volume assumpti ons for these reside ntial refrigeration products on shipment data, industry know ledge, and engineering manufacturer interviews. The manufacturing plant annual pr oduction capacities used for the analyses differ by product class as follows.

• Product Classes 3 and 6: 1.5 million

• Product Classes 5 and 5A: 0.5 million

• Product Classes 4 and 7: 1 million

• Product Class 9: 150,000

• Product Class 10: 100,000

• Product Class 11: 0.5 million

• Product Class 18: 100,000

5.6.4.3 Factory Parameters Assumptions

DOE used information gathered from pub licly available literature, manufacturer interviews, and analysis of common industry practices to formulate factory parameters for each type of manufacturer. DOE first ma de assumptions about a set of preliminary factory parameters before the manufactur er interviews. DOE then revised the assumptions using comments and information gathered during the in terviews. Table 5.6.2 lists DOE’s assumptions for refrigerator manufacturers.

Table 5.6.2 Refrigerator & Freezer Factory Parameter Assumptions

Parameter Assumption

Plant Capacity (units /yr) see section 5.6.4.2 Actual Annual Production Volume ( units/yr) 5/6 of plant capacity Fabrication Labor Wages ($/hr) 16.00 Fringe Benefits Ratio 50%

5.6.4.4 Material Cost Assumptions

DOE determined the cost of raw material s using publicly available information such as the American Metals Market a , interviews with manuf acturers, and direct discussions with material suppl iers. Common metals used in th e fabrication of residential refrigerator products in clude plain cold rolled steel (CRS), copper tubing, and aluminum. There have been large fluctuations in metal pr ices over the last few years. To account for these fluctuations, DOE used a 5-year average of metal prices from the Bureau of Labor

a American Metals Market. Last accesse d November 2008. <http://www.amm.com>.
5-28Statistics Producer Price Indi ces (PPIs) spanning 2003 to 2008 with an adjustment to 2008$. b DOE used the PPIs for copper rolli ng, drawing, and extruding and steel mill products, and made the adjustments to 2008$ using the gross domestic product implicit price deflator. c Table 5.6.3 shows the 5-year averag e metal prices DOE used for the analysis.

Table 5.6.3 Five-Year Metal Prices (2003-2008)

Metals Cost ($/lb) ($2008) Plain Cold Rolled Steel (CRS) $0.36 Painted CRS $0.57 Galvanized CRS $0.48 Aluminized CRS $0.54 Textured CRS $0.61 CRS Tube $0.74 Stainless Steel $2.06 Fin Aluminum $1.64 Plain Copper $2.13 Copper Tube – Plain $2.76 Brass $1.45 Galvanized Wire $0.60 Standard Aluminum $1.26 Copper Tube – Rifled $2.96 Aluminum Tube $1.89 Hot Rolled Steel $0.37 Hot Rolled Steel Pipe $0.47

Between 2003 and 2006, the price of steel ro se over 60 percent and the price of copper rose over 140 percent. DOE used a 5-year average in material prices from 2003 to 2008 to normalize these drastic increases to better represent long-te rm material price
averages.

For resins used in the fabrication of these refrigeration products, DOE used current resin prices gathered from industry research, publications such as Plastics News, d and interviews with manufacturers. Resin pr ices are determined by quantity and supplier (i.e., contract specific) and therefore have no true fixed market price. For this analysis, DOE used market resin prices current as of November 2008. The pric es of resins have been constantly increasing and closely follo w petroleum prices. Table 5.6.4 shows the current resin prices used in the analysis.

b U.S. Department of Labor, Bureau of Labor Statistics, Producer Price Indices. Last accessed November 2008. <http://www.bls.gov/ppi>.

c U.S. Department of Commerce, Bureau Economic Analysis, Gross Domestic Product Implicit Price Deflator. Last accessed November 2008. <https ://bea.gov/bea/dn/nipaweb /TableView.asp#Mid>.
d Plastic News, Resin Pricing. Last accessed March 21, 2008. <http://www.plasticsnews.com/subscriber/headlines.phtml>.

5-29‐ Table 5.6.4 Most Prevalent Resin Prices as of December 2007

Resins Cost ($/lb) ($2008) Polystyrene (PS) $0.66 Polypropylene (PP) $0.67 Low Density Polyethylene $0.73 Polyurethane Foam (non-HCFC blowing agent) $1.29 PVC (Hard) $0.47

5.6.5 Manufacturing Production Cost

Once the cost estimate for each teardow n unit was finalized, a detailed summary was prepared for relevant components, s ubassemblies, and processes. The BOM thus details all aspects of product costs. DOE totaled the cost of materials, labor, and direct overhead used to manufacture a product in order to calculate the manufacturing production cost. e Figure 5.6.1 shows the general brea kdown of costs associated with manufacturing a product.

Manufacturer Selling Price

Full Cost of

Product Profit

Manufacturer Production Cost

Direct Labor Direct Material Overhead

Indirect Labor

Indirect Material

Maintenance

Depreciation

Taxes

Insurance related
to assets

Figure 5.6.1 Full Production Costs

e When viewed from the companywid e perspective, the sum of all material, labor, and overhead costs equals the company’s sales cost, also referre d to as the cost of goods sold (COGS). Non Production Cost

Selling

Market Research

Advertising

POS Promotion

Salesperson Comp & Travel

Logistics (Warehousing, Delivery, Record

‐ Keeping, Order

Processing) General & Admin.

Costs of Service & Staff Units

General Corporate

Costs (Comp, etc) R & D

Costs associated with finding new

and improved

products or processes

Code Compliance

Modernization Interest

Cost of borrowing

funds

5-30The full cost of product is broken down in to two main costs, the full production cost or MPC, and the non-production cost . The non-production cost is equal to the manufacturer markup minus profits.

Technologies used in the units subject to teardown are noted in the summary sheet of each cost model and are cost-estimated i ndividually. Thus, various implementations of technologies can be accommodated, ranging from assemblies that are entirely purchased to units that are entirely from raw materials. Hybrid assemblies, consisting of purchased parts and parts made on site are thus also accommodated.

5.6.6 Incremental Cost Estimates

Incremental costs were determined for design options applied to the baselineefficiency refrigerator models. The approach for estimating the incremental costs varied depending on the design option. Details in this calculation which are specific to individual design options are discussed in Section 5.8, which discusses design options. Aspects of the incremental cost calculation which were generally applied to multiple design options are discus sed in this section.

Many of the design options involve repla cement of a current component with a higher-efficiency component. For these desi gn options, the increased price paid by the OEM for the new component represents the manufacturing cost increase—other elements of product cost such as overhead and capit al expenditures would be insignificantly affected by these design changes. The appropria te price increases are discussed in Section 5.8 by design option.

For some design changes, calculating the cost impact of the design change required direct use of the manufacturing cost model to determine changes to a number of parts. The baseline manufacturing cost was subtracted from the manufacturing cost of the modified design to determine the incrementa l cost of the design option. This approach was used in particular for insulation thickness increases and heat exchanger size increases for cold wall and hot wall heat exchangers.

5.6.6.1 Overhead and Depreciation Costs

Some design options involve costs in a ddition to the price increase associated with a new component. For such options, there may be overhead and capital expenses which must be added to the direct costs asso ciated with the design option. Estimates of typical additional costs associated with ove rhead and depreciation for manufacture of refrigeration products were made for the reve rse-engineering models, using estimates of these costs provided by the manu facturing cost model. These calculations were carried out based on proposed typical production pl ant capacities, with actual production volumes estimated to be 5/6 of plant cap acities. The annual plant capacities for the product classes used in these calculati ons are as indicated in section 5.6.4.2.

The additional costs are presented as percen tage of direct material and labor costs in Table 5.6.5 below. The averages for the listed product class categ ories were used to

5-31increase direct material and labor costs for some design options for which this adjustment
was necessary.

Table 5.6.5 Overhead and Depreciation Cost Ratios Product Class Product Product Percent Average Percent Group Class Cost Cost Ratio for Ratio Product Class Group Standard- 16 ft 3 Top-Mount R-F 31.2%

23.4% Size 3 21 ft 3 Top-Mount R-F 23.2% Refrigerator- 21 ft 3 E* Top-Mount R-F 23.2% Freezers 4 22 ft 3 Side-Mount R-F† 22.0% 19 ft 3 E* Bottom-Mount R-F 23.5% 5 25 ft 3 E* Bottom-Mount R-F 1 20.9% 25 ft 3 E* Bottom-Mount R-F 2 23.3%

7 26 ft 3 Side-Mount R-F 20.7% 26 ft 3 E* Side-Mount R-F 22.5% Standard- 14 ft 3 Upright Freezer 28.6%

28.5% Size Freezers 9 20 ft 3 Upright Freezer 26.2% 20 ft 3 E* Upright Freezer 1 25.0% 15 ft 3 Chest Freezer 35.5% 10 15 ft 3 E* Chest Freezer 33.2% 20 ft 3 Chest Freezer 22.5% Compact 1.7 ft 3 Compact Refrigerator 40.2%

39.2% Refrigerators, 11 4 ft 3 Compact Refrigerator 35.6%RefrigeratorFreezers, and Freezers 4 ft 3 E* Compact Refrigerator 36.5%

18 3.4 ft 3 Compact Chest Freezer 42.3% 7 ft 3 Compact Chest Freezer 1 36.6% 7 ft 3 Compact Chest Freezer 2 44.2%

The manufacturing cost model estimates are consistent with overall industry trends. Census data shows that the average value of this cost adder for NAICS code 335222 (Household Refrigerator and Home Freezer Manufacturing) is 27.7%.

5.6.6.2 Depreciation Costs for Insu lation Thickness Increases

DOE considered that increas es in cabinet wall and door thicknesses would require redesign of the entire refrigerator or freeze r platform and lead to building of a new production plant. This conservative approach to the analysis was based on input from manufacturers. For such design change s, the difference in greenfield costs f of two designs would not capture the deprec iation costs which would be incurred by the manufacturer and which would add to the product cost after such a platform conversion. DOE conservatively used the greenfield deprecia tion costs per product determined by the

f Greenfield costs are defined as the costs associated with building a new manufacturing facility, to be distinguished from the costs required to upgrade or modify a facility.

5-32manufacturing cost model as an additiona l cost for wall thickness increases. The calculation of manufacturing co sts for all of the teardown pr oducts based on typical plant capacities described above was used as the basis for the determination of greenfield depreciation costs per product. The results of the calculations are summarized in Table 5.6.6 below. Average depreciation costs were applied in the engineering analyses for product class groups with similar levels of depr eciation costs, as indi cated in the table.

Table 5.6.6 Greenfield Depreciation Costs per Product Product Product Product Depreciation Average Class Group Class Cost Depreciation Cost for Product Class GroupStandardSizeRefrigeratorFreezers 3 16 ft 3 Top-Mount R-F $29.60 $27.05 21 ft 3 Top-Mount R-F $23.55 21 ft 3 E* Top-Mount R-F $23.97 4 22 ft 3 Side-Mount R-F† $28.95 19 ft 3 E* Bottom-Mount R-F $27.49 5 25 ft 3 E* Bottom-Mount R-F 1 $27.95 25 ft 3 E* Bottom-Mount R-F 2 $39.57

7 26 ft 3 Side-Mount R-F $26.74 26 ft 3 E* Side-Mount R-F $28.14 Freezers 9 14 ft 3 Upright Freezer $19.08 $18.26 20 ft 3 Upright Freezer $18.21 20 ft 3 E* Upright Freezer 1 $18.41 15 ft 3 Chest Freezer $18.54 10 15 ft 3 E* Chest Freezer $19.59 20 ft 3 Chest Freezer $17.31

18 3.4 ft 3 Compact Chest Freezer $21.00 7 ft 3 Compact Chest Freezer 1 $16.91 7 ft 3 Compact Chest Freezer 2 $15.32 Compact Refrigerators 11 1.7 ft 3 Compact Refrigerator $8.35 $8.98 4 ft 3 Compact Refrigerator $9.29 4 ft 3 E* Compact Refrigerator $9.29

5.6.6.3 G&A and Profit

DOE estimated the further addition to th e manufacturer selling price associated with G&A and profit for the appliance indus try as 26% of manufact urer production cost. This adder was applied to all of the MPC estimates in orde r to determine manufacturer selling price (MSP) numbers. This markup is described in more detail in chapter 6.

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