14. Pierre, Bo, Kytlteknisk Tidskript, 3, May 1957, p. 129. 

15. Lockhart, R. W., and Martinelli, R. C., "Proposed Correlation of Data for Isothermal TwoPhase, Two-Component Flow in Pipes," Chemical Engineering Progress, 45, 1, pp. 39-48. 

16. Wang,, Chi-Chuan, “Recent Progress on the Air-side Performance of Fin-and-Tube Heat 

Exchangers,” International Journal of Heat Exchangers 1524-5608 (Vol 1 (2000), pp. 49-76. 

17. Mirth, D.R. and Ramadhyani, S., “Correlations for Predicting the Air-Side Nusselt Numbers 

and Friction Factors in Chilled-Water Cooling Coils,” Experimental Heat Transfer, 7:143-

162, 1994. 

18. Bansal, P.K. and Chin, T.C., “Modeling and Optimization of Wire-and-Tube Condenser,” 

International Journal of Refrigeration 26 (2003) 601-613. 

19. Tagliafico, L. and Tanda, G., “Radiation and Natural Convection Heat Transfer from Wireand-Tube Heat Exchangers in Refrigeration Appliances,” International Journal of 

Refrigeration, 20 (1997) 461-469. 

20. Vera-Garcia, F., et al., “Assessment of Condensation Heat Transfer Correlations in the 

Modeling of Fin and Tube Heat Exchangers,” International Journal of Refrigeration 30 

(2007) 1018-1028. 

21. Shah, M.M., “A General Correlation for Heat Transfer During Film Condensation in Pipes,” 

International Journal of Heat and Mass Transfer 22 (1979) 547-556. 

22. Lee, Tae-Hee, et al, “Determination of Airside Heat Transfer Coefficient on Wire-on-Tube 

Type Heat Exchanger,” International Journal of Heat and Mass Transfer 44 (2001) 1767-

1776. 

23. http://www.ornl.gov/~wlj/hpdm/Mark_VI_Notes.html 

24. Lemmon, E.W., Huber, M.L. and McLinden, M.O., “Reference Fluid Thermodynamic and 

Transport Properties,” NIST Standard Reference Database 23, Version 8.0. 

25. Lemmon, E.W., “Pseudo-Pure Fluid Equations of State for the Refrigerant Blends R-410A, 

R-404A, R-507A, and R-407C,” International Journal of Thermophysics, Vol 24, No 4, July 

2003, pp. 991-1006. 

26. Rice, C.K., “The ORNL Modulating Heat Pump Design Tool – Mark IV User’s Guide,” Oak 

Ridge National Laboratory Report ORNL/CON-343, September 2001. 

5-B-19
 

EERE-2008-BT-STD-0012 COMMENT 20
CHAPTER 6. MARKUPS FOR EQUIPMENT PRICE DETERMINATION 

TABLE OF CONTENTS 

6.1 INTRODUCTION ........................................................................................................... 6-1 

6.1.1 Distribution Channels ...................................................................................................... 6-1 

6.2 MARKUP CALCULATION PROCEDURE .................................................................. 6-1 

6.2.1 Approach for Manufacturer Markups .............................................................................. 6-2 

6.2.2 Approach for Retailer Markups ....................................................................................... 6-2 

6.3 MANUFACTURER MARKUPS .................................................................................... 6-4 

6.4 RETAILER MARKUP .................................................................................................... 6-5 

6.5 SALES TAXES ............................................................................................................... 6-6 

6.6 SUMMARY OF MARKUPS .......................................................................................... 6-7 

LIST OF TABLES 

Table 6.3.1 Major Appliance Manufacturer Gross Margins and Markups............................. 6-5 

Table 6.4.1 Data Used to Calculate Retailer Markups for Residential Refrigeration 

Products................................................................................................................ 6-5 

Table 6.5.1 Average Sales Tax Rates by Census Division and Large State........................... 6-6 

Table 6.5.2 Average Sales Tax Rates by Product................................................................... 6-7 

Table 6.6.1 Summary of Markups .......................................................................................... 6-7 

6-i 

EERE-2008-BT-STD-0012 COMMENT 20
CHAPTER 6. MARKUPS FOR EQUIPMENT PRICE DETERMINATION 

6.1 INTRODUCTION 

To carry out its analyses, DOE needed to determine the cost to the consumer of baseline 

products and the cost of more-efficient units. As discussed in chapter 8, DOE developed retail 

prices for baseline products using proprietary retail price data collected by The NPD Group. For 

products with higher-than-baseline efficiency, DOE estimated the consumer prices by applying 

appropriate markups to the manufacturer incremental equipment costs estimated in the 

engineering analysis. 

6.1.1 Distribution Channels 

The appropriate markups for determining consumer equipment prices depend on the type 

of distribution channels through which products move from manufacturers to purchasers. At 

each point in the distribution channel, companies mark up the price of the equipment to cover 

their business costs and profit margin. 

Data from the Association of Home Appliance Manufacturers (AHAM)1 indicate that an 

overwhelming majority of residential appliances are sold through retail outlets. Because DOE is 

not aware of any other distribution channel that plays a significant role for residential 

refrigeration products, DOE assumed that all of the residential products are purchased by 

consumers from retail outlets. DOE did not include a separate distribution channel for 

refrigeration products included as part of a new home, as it did not have information on the 

extent to which these products are “pre-installed” by builders in new homes. 

6.2 MARKUP CALCULATION PROCEDURE 

As just discussed, at each point in the distribution channel, companies mark up the price 

of the equipment to cover their business costs and profit margin. In financial statements, gross 

margin is the difference between the company revenue and the company cost of sales or cost of 

goods sold (CGS). Inputs for calculating the gross margin are all corporate costs—including 

overhead costs (sales, general, and administration); research and development (R&D) and 

interest expenses; depreciation, and taxes—and profits. In order for sales of a product to 

contribute positively to company cash flow, the product’s markup must be greater than the 

corporate gross margin. Individual products may command a lower or higher markup, 

depending on their perceived added value and the competition they face from similar products in 

the market. 

In developing markups for manufacturers and retailers, DOE obtained data about the 

revenue, CGS, and expenses of firms that produce and sell the products of interest. For retailers, 

DOE’s approach categorizes the expenses into two categories: labor-scaling costs (LSC), which 

6-1 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

are fixed labor and occupancy expenses that increase in proportion to the amount of labor 

required to produce or sell the product, and non-labor-scaling costs (NLSC), which are variable 

operating costs that do not scale with labor and vary in proportion to CGS. 

6.2.1 Approach for Manufacturer Markups 

DOE uses manufacturer markups to transform a manufacturer’s equipment costs into a 

manufacturer sales price. Using the CGS and gross margin, DOE calculated the manufacturer 

markup (MUMFG) with the following equation: 

CGS MFG + GMMFG MU MFG = 

CGS MFG

where: 

MUMFG = Manufacturer markup, 

CGSMFG = Manufacturer’s cost of goods sold or Manufacturer Production Cost 

(MPC), and 

GMMFG = Manufacturer’s gross margin. 

 The manufacturer’s CGS (or MPC) plus its GM equals the manufacturer selling price 

(MSP). 

6.2.2 Approach for Retailer Markups 

DOE based the retailer markups for residential refrigeration products on financial data 

from the U.S. Census Business Expenditure Survey. DOE organized the financial data into 

balance sheets that break down cost components incurred by firms that sell the products.a The 

key assumptions that DOE used to estimate the retailer markups using these financial data were: 

1.	 The balance sheets faithfully represent the various average costs incurred by firms selling 

home appliances. 

2.	 These costs can be divided into two categories: 

a.	 Costs that vary in proportion to the manufacturer sales price (variable costs); and 

b.	 Costs that do not vary with the manufacturer sales price (fixed costs). 

3.	 Retailer sales prices vary in proportion to retailer costs that are included in the balance 

sheets. 

In support of the first assumption, the balance sheets itemize firm costs into a number of 

expense categories, including CGS, operating labor and occupancy costs, and other operating 

a

 The retailers to whom these financial data refer handle multiple commodity lines. 

6-2 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

 

costs and profit. Although retailers tend to handle multiple commodity lines, the data provide 

the most accurate available indication of home appliance expenses. 

Information obtained from the trade literature pertaining to the heating, ventilation, and 

air-conditioning (HVAC) contracting industry tends to support the second assumption. This 

information indicates that retailer markups should vary according to the quantity of labor and 

materials used to sell or distribute the equipment, with markups on labor tending to be much 

larger than markups on materials.2 This information also describes markups as varying much 

more in relation to sales volume than in relation to other factors, including appliance efficiency. 

This last finding strongly suggests that labor inputs vary more with sales volume than with 

appliance cost or efficiency. In the discussion that follows in section 6.3, DOE assumes a 

division of costs between those that do not scale with the manufacturer sales price (fixed costs— 

labor and occupancy expenses referred to above as LSC), and those that do (variable costs— 

operating expenses and profit referred to above as NLSC). This division of costs led to the 

estimate of retailer markups described below in section 6.3. 

In support of the third assumption, the retailer industries are relatively competitive, and 

consumer demand for residential home appliances is relatively inelastic, i.e. the demand is not 

expected to decrease significantly with a relatively small increase in price. The large number of 

household appliance stores listed by the U.S. Census Bureau in its Statistics of U.S. Businesses 

indicates the competitive nature of the market.3 For example, there are more than 10,000 

household appliance store establishments and over 5000 merchant wholesaler establishments of 

service equipment in the U.S.b According to standard economic theory, competitive firms facing 

inelastic demand either set prices in line with costs or quickly go out of business.4 

Using the above assumptions, DOE developed baseline and incremental markups to 

transform the manufacturer sales price into a consumer equipment price. DOE used the baseline 

markups, which cover all of a retailer’s costs (i.e., both LSC and NLSC), to determine the sales 

price of baseline models. The baseline markup relates the manufacturer sales price to the retailer 

sales price. DOE considers baseline models to be equipment sold under existing market 

conditions (i.e., without new energy efficiency standards). DOE calculated the baseline markup 

(MUBASE) for retailers using the following equation: 

CGS RTL / DIST + GMRTL / DIST CGSRTL / DIST + ( LSCRTL / DIST + NLSCRTL / DIST ) MU = = BASE CGSRTL / DIST CGSRTL / DIST

where: 

MUBASE = Baseline retailer markup, 

CGSRTL/DIST = Retailer’s cost of goods sold, 

GMRTL/DIST = Retailer’s gross margin, 

b

 DOE determined the number of establishments for household appliance stores based on the following North 

American Industry Classification System (NAICS) code and description: 443111, Household Appliance Stores. 

6-3 

EERE-2008-BT-STD-0012 COMMENT 20
LSCRTL/DIST = Retailer’s labor-scaling costs, and 

NLSCRTL/DIST = Retailer’s non-labor-scaling costs. 

Incremental markups cover only those costs that scale with a change in the 

manufacturer’s sales price (i.e., NLSC). Incremental markups are coefficients that relate the 

change in the manufacturer sales price of higher-efficiency models to the change in the retailer 

sales price. DOE considers higher-efficiency models to be equipment sold under market 

conditions with new efficiency standards. It calculated the incremental markup (MUINCR) for 

retailers using the following equation: 

CGSRTL / DIST + NLSCRTL / DIST MUINCR = 

CGSRTL / DIST

where: 

MUINCR = Incremental retailer markup, 

CGSRTL/DIST = Retailer’s cost of goods sold, and 

NLSCRTL/DIST = Retailer’s non-labor-scaling costs. 

6.3 MANUFACTURER MARKUPS 

DOE developed an average manufacturer markup by examining the annual Securities and 

Exchange Commission (SEC) 10-K reports filed by four publicly-traded manufacturers primarily 

engaged in appliance manufacturing and whose combined product range includes residential 

refrigeration products.5 The four manufacturers represent a nearly 50 percent market share for 

major appliances. Because these companies are typically diversified, producing a range of 

different appliances, an industry average markup was assumed by DOE to be representative for 

the manufacture of refrigeration products. DOE evaluated markups for the years 2002─2005. 

Table 6.3.1 lists the average corporate gross margin during the years 2002─2005, and 

corresponding markups, for each of the four manufacturers. The average markup value based on 

these four companies is 1.26, which is the value that DOE used. 

6-4 

EERE-2008-BT-STD-0012 COMMENT 20
 

Table 6.3.1 Major Appliance Manufacturer Gross Margins and Markups 

Mfr A Mfr B Mfr C Mfr D 

Average Net Revenues (Million) $372 $280 $4770 $12,682 

Corporate Gross Margin 15% 28% 16% 22% 

Markup 1.18 1.39 1.19 1.28 

Source: SEC 10-K reports (2002-2005) 

6.4 RETAILER MARKUP 

DOE used financial data from the U.S. Census Business Expenditure Survey (BES), in 

the “Household Appliance Stores” category, to calculate markups used by retailers that apply to 

residential refrigeration products.c 6 Table 6.4.1 shows the BES data that DOE used and the 

estimated retail markups. 

Table 6.4.1	 Data Used to Calculate Retailer Markups for Residential Refrigeration 

Products 

Item Million Dollars 

Sales (revenue) 10343 

Cost of Goods Sold (CGS) 7151 

Gross Margin (GM) 3193 

Labor-Scaling Costs (LSC)

 Payroll 1366 

 Fringe Benefits 208 

Contract Labor 69 

 Taxes and License Fees 53 

 Lease and Rental Payments 238 

 Telephone and Communications 58 

Utilities 70 

Repair and Maintenance 36 

 LCS Subtotal: 2098 

Non-Labor-Scaling Costs (NLSC)

 Depreciation and Amortization 94 

Office Supplies 37 

 Packaging and Other Materials 0 

Advertising Services 274 

c

 DOE used the 1997 BES because the 2002 BES did not contain sufficient data for the calculation of gross margin 

or cost of goods sold. 

6-5 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 Legal Services 8 

Accounting, Auditing, and Bookkeeping 19 

 Computer Related Services 10 

 Other Operating Expenses 389 

 Net Profit Before Taxes 263 

 NLCS Subtotal: 1094 

Baseline Markup (MUBASE) = (CGS+GM)/CGS 1.45 

Incremental Markup (MUINCR) = (CGS+NLSC)/CGS 1.15 

6.5 SALES TAXES 

The sales tax represents state and local sales taxes that are applied to the consumer 

equipment price of the equipment. The sales tax is a multiplicative factor that increases the 

consumer equipment price. 

DOE derived state and local taxes from data provided by the Sales Tax Clearinghouse.7 

DOE derived population-weighted average tax values for each Census division and large state, as 

shown in Table 6.5.1 below. 

Table 6.5.1 Average Sales Tax Rates by Census Division and Large State 

Census Division/State Tax Rate 

New England 4.96% 

Mid Atlantic 6.54% 

East North Central 6.93% 

West North Central 6.77% 

South Atlantic 6.17% 

East South Central 7.90% 

West South Central 8.37% 

Mountain 6.50% 

Pacific 5.20% 

New York State 8.25% 

California 9.00% 

Texas 8.05% 

Florida 6.70% 

DOE then derived U.S. average tax values for each product (as shown in Table 6.5.2 

below) based on the product’s saturation within each Census division and large state. It 

determined the saturations from the DOE Energy Information Administration (EIA)’s 2005 

Residential Energy Consumption Survey.8 

6-6 

EERE-2008-BT-STD-0012 COMMENT 20
Table 6.5.2 Average Sales Tax Rates by Product 

Product Tax Rate 

Refrigerators (Standard-size and compact) 7.08% 

Freezers (Standard-size and compact) 6.94% 

6.6 SUMMARY OF MARKUPS 

Table 6.6.1 summarizes the markups at each stage in the distribution channel and the 

average sales tax. 

Table 6.6.1 Summary of Markups 

Markup Baseline Incremental 

Manufacturer 1.26 

Retailer 1.45 1.15 

Sales Tax 1.069 

6-7 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

 

 

 

 

 

REFERENCES 

1	 Association of Home Appliance Manufacturers. AHAM 2003 Fact Book, 2003. Washington, 

DC. p. 25. 

2	 Skaer, M. What should you charge? Try these Tested Formulas. The Air Conditioning, 

Heating, and Refrigeration News, 2001. 

<http://www.achrnews.com/CDA/ArticleInformation/features/BNP_Features_Item/0,1338,23113,00.html> 

3	 U.S. Census Bureau. Statistics of U.S. Businesses, 2004. Washington, DC. 

<http://www.census.gov/csd/susb/susb04.htm> 

4	 Pindyck, R.S. and D.L. Rubinfeld, Microeconomics, 5th ed., 2000. New Jersey: Prentice Hall. 

5	 Security Exchange Commission, SEC 10-K Reports, Various dates, 2002-2005, Security 

Exchange Commission. <http://www.sec.gov/> 

6	 U.S. Census Bureau. 1997 Economic Census, Business Expenses Survey, Retail Trade, 

Household Appliance Stores, 1997. Washington, DC. 

<http://www.census.gov/csd/bes/bes97.htm> 

7	 Sales Tax Clearinghouse, Inc. State sales tax rates along with combined average city and 

county rates. <http://thestc.com/STrates.stm> 

8	 U.S. Department of Energy-Energy Information Administration. Residential Energy 

Consumption Survey, 2005Public Use Data Files.. Washington, DC. 

<http://www.eia.doe.gov/emeu/recs/recspubuse05/pubuse05.html> 

6-8 

EERE-2008-BT-STD-0012 COMMENT 20
CHAPTER 7. ENERGY USE DETERMINATION 

TABLE OF CONTENTS 

7.1 HOUSEHOLD SAMPLES FOR REFRIGERATION PRODUCTS............................... 7-4 

7.2 APPROACH FOR STANDARD-SIZE PRODUCTS..................................................... 7-6 

7.3 USAGE ADJUSTMENT FACTORS FOR STANDARD-SIZE PRODUCTS............... 7-9 

7.3.1 Field Energy Consumption for One or More Refrigerators .................................. 7-9 

7.3.2 Tested Energy Consumption ............................................................................... 7-11 

7.3.2.1 Size ....................................................................................................... 7-11 

7.3.2.2 Assigning Vintage and ENERGY STAR Status .................................. 7-12 

7.3.3 Energy Use of Second Refrigerators ................................................................... 7-18 

7.3.4 Estimated Number of ENERGY STAR Refrigerators ........................................ 7-19 

7.3.5 Validating Field Energy Consumption................................................................ 7-20 

7.3.6 Maximum Usage Adjustment Factor .................................................................. 7-20 

7.3.7 Minimum Usage Adjustment Factor ................................................................... 7-27 

7.3.8 Results by Product Class ..................................................................................... 7-30 

7.3.9 Distributions: Comparison with Other Studies ................................................... 7-36 

7.4 ENERGY USE OF COMPACT REFRIGERATION PRODUCTS.............................. 7-38 

7.5 ANNUAL ENERGY CONSUMPTION BY EFFICIENCY LEVEL ........................... 7-38 

LIST OF TABLES 

Table 7.1.1 Refrigeration Products in Households by Product Class ..................................... 7-5 

Table 7.3.1 Size Bins for Refrigerators and Freezers ........................................................... 7-12 

Table 7.3.2 Parameters for Calculating Adjusted Volume from Total Volume of 

Refrigerator-Freezers ......................................................................................... 7-12 

Table 7.3.3 Energy Conservation Standards for Refrigeration Products.............................. 7-13 

Table 7.3.4 ENERGY STAR Criteria for Refrigeration Products........................................ 7-13 

Table 7.3.5 Vintage Bins for Refrigeration Products............................................................ 7-14 

Table 7.3.6 Refrigerator Survival Probabilities Associated with Age Bins.......................... 7-18 

Table 7.3.7 Market Share of ENERGY STAR Products ...................................................... 7-20 

Table 7.3.8 Power Consumption for Ice Maker Components............................................... 7-21 

Table 7.3.9 Theoretical Maximum Energy Consumption for Baseline Product Class 3 

Refrigerator-Freezers ......................................................................................... 7-23 

Table 7.3.10 Theoretical Maximum Energy Consumption for Baseline Product Class 5 

Refrigerator-Freezers ......................................................................................... 7-23 

Table 7.3.11 Theoretical Maximum Energy Consumption for Baseline Product Class 7 

Refrigerator-Freezers ......................................................................................... 7-24 

Table 7.3.12 Theoretical Maximum Energy Consumption for Baseline Product Class 9 

Freezers.............................................................................................................. 7-24 

7-1
 

EERE-2008-BT-STD-0012 COMMENT 20
Table 7.3.13 Theoretical Maximum Energy Consumption for Baseline Product Class 10 

Freezers.............................................................................................................. 7-25 

Table 7.3.14 Regression Parameters by Product Class for Maximum Usage Adjustment 

Factor ................................................................................................................. 7-27 

Table 7.3.15 Temperature Settings for Refrigerators Under Test and Ideal Conditions ........ 7-27 

Table 7.3.16 Temperature Settings for Freezers Under Test and Ideal Conditions................ 7-28 

Table 7.3.17 Model Errors by Product Class and Vintage...................................................... 7-28 

Table 7.3.18 Regression Results Based on Unit Vintage ....................................................... 7-30 

Table 7.3.19 Usage Adjustment Factors Before and After Excluding Minimums and 

Maximums ......................................................................................................... 7-36 

Table 7.4.1 Parameters for Calculating Adjusted Volume from Total Volume for 

Compact Refrigerators....................................................................................... 7-38 

Table 7.5.1 Product Class 3, Top-Mount Refrigerator-Freezers Without Through-theDoor Ice Service: Average Annual Energy Use by Efficiency Level ............... 7-39 

Table 7.5.2 Product Class 5, Bottom-Mount Refrigerator-Freezers Without Throughthe-Door Ice Service: Average Annual Energy Use by Efficiency Level ......... 7-40 

Table 7.5.3 Product Class 7, Side-by-side Refrigerator-Freezers with Through-theDoor Ice Service: Average Annual Energy Use by Efficiency Level ............... 7-40 

Table 7.5.4 Product Class 9, Upright Freezers: Average Annual Energy Use by 

Efficiency Level................................................................................................. 7-41 

Table 7.5.5 Product Class 10, Chest Freezers: Average Annual Energy Use by 

Efficiency Level................................................................................................. 7-41 

Table 7.5.6 Compact Refrigerators and Freezers: Average Annual Energy Use by 

Efficiency Level................................................................................................. 7-42 

LIST OF FIGURES 

Figure 7.3.1 Average Unit Energy Consumption, 1961 to 1990 Shipments.......................... 7-14 

Figure 7.3.2 Weighted Households by Refrigerator Vintage................................................. 7-15 

Figure 7.3.3 Survival Probability of Refrigerators by Age .................................................... 7-16 

Figure 7.3.4 Survival Probability of Freezers by Age............................................................ 7-17 

Figure 7.3.5 Maximum Usage Adjustment Factor by Product Age in 2005.......................... 7-26 

Figure 7.3.6 Minimum Plausible Usage Adjustment Factor as a Function of Product 

Age in 2005........................................................................................................ 7-29 

Figure 7.3.7 Initial UAF Distribution for Standard-Size Top-Mount RefrigeratorFreezers (Product Class 3) ................................................................................. 7-31 

Figure 7.3.8 Final UAF Distribution for Standard-Size Top-Mount RefrigeratorFreezers (Product Class 3) ................................................................................. 7-31 

Figure 7.3.9 Initial UAF Distribution for Standard-Size Bottom-Mount RefrigeratorFreezers (Product Class 5) ................................................................................. 7-32 

Figure 7.3.10 Final UAF Distribution for Standard-Size Bottom-Mount RefrigeratorFreezers (Product Class 5) ................................................................................. 7-32 

7-2
 

EERE-2008-BT-STD-0012 COMMENT 20
Figure 7.3.11 Initial UAF Distribution for Standard-Size Side-by-side RefrigeratorFreezers (Product Class 7) ................................................................................. 7-33 

Figure 7.3.12 Final UAF Distribution for Standard-Size Side-by-side RefrigeratorFreezers (Product Class 7) ................................................................................. 7-33 

Figure 7.3.13 Initial UAF Distribution for Standard-Size Upright Freezers (Product 

Class 9)............................................................................................................... 7-34 

Figure 7.3.14 Final UAF Distribution for Standard-Size Upright Freezers (Product Class 

9) ........................................................................................................................ 7-34 

Figure 7.3.15 Initial UAF Distribution for Standard-Size Chest Freezers (Product Class 

10) ...................................................................................................................... 7-35 

Figure 7.3.16 Final UAF Distribution for Standard-Size Chest Freezers (Product Class 

10) ...................................................................................................................... 7-35 

7-3
 

EERE-2008-BT-STD-0012 COMMENT 20
CHAPTER 7. ENERGY USE DETERMINATION 

To perform the life-cycle cost (LCC) and payback period (PBP) calculations described in 

chapter 8, the U.S. Department (DOE) needed to determine the savings in operating cost that 

consumers would derive from more efficient products. DOE uses data on annual energy 

consumption, along with energy prices, to develop the most significant component of consumer 

operating cost. (Maintenance and repair costs are the other components.) This chapter describes 

how DOE determined the annual energy consumption of refrigeration products. 

The engineering analysis described in chapter 5 reports energy use derived from the DOE 

test procedure. This test produces standardized results that can be used o compare the 

performance of different brands of the same product class operating under similar conditions. 

Actual energy usage in the field, however, often differs from that estimated by the test procedure. 

Researchers have conducted studies that measure the field consumption of refrigerator-freezers, 

comparing such measurements to the DOE test results. DOE’s review of several such studies is 

described in appendix 7-A and summarized in section 7.3.9. The review confirmed that energy 

use measured in the field often differs considerably from the usage measured by the DOE test 

procedure. 

To determine the field energy use by products that would meet potential new energy 

efficiency standards, DOE used data from the Energy Information Administration’s 2005 

Residential Energy Consumption Survey (RECS).1

 RECS queries a national sample of 

households to collect statistical information on household consumption of and expenditures for 

energy, along with data on energy-related characteristics of the housing units and households. 

RECS provides enough information to establish the type of refrigeration product (the product 

class) used in each household, and provides an estimate of the household energy consumption 

attributable to refrigerators or freezers. As a result, DOE was able to develop a unique household 

sample for most of the representative product classes for standard-size units. 

DOE did not use RECS to evaluate energy consumption by compact refrigerators and 

freezers, because many of those products are used outside the residential sector, such as in 

college dormitories, hotels and motels, and offices. 

7.1 HOUSEHOLD SAMPLES FOR REFRIGERATION PRODUCTS 

DOE developed household samples for refrigeration products from the 2005 RECS. The 

survey, which sampled 4,382 housing units, was constructed to represent the household 

population throughout the United States. 

RECS results reveal whether a household uses a standard-size refrigerator or freezer. For 

households that have a standard-size refrigerator, RECS specifies whether the freezer is top- or 

bottom-mounted or is side-mounted. Thus units in the sample that have top-mounted freezers 

7-4
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

cannot be distinguished from those having bottom-mounted freezers (product classes 3 and 5). 

For a household’s primary (or “first”) refrigerator, RECS specifies whether there is through-thedoor ice service. For households that have standard-size freezers, RECS specifies whether the 

unit is upright or a chest-type. With the above data, DOE was able to assign each household 

record to one of the five product classes considered for potential new efficiency standards (Table 

7.1.1). 

Table 7.1.1 Refrigeration Products in Households by Product Class 

Product Class Number of 

Household 

Records* 

Percent of Total 

Household 

Records* 

Relative Standard 

Error Due to 

Sampling* 

3. Refrigerator-freezer: 

automatic defrost with topmounted freezer and no TTD† 

ice service 2,303 52.6% 2.1% 5. Refrigerator-freezer: 

automatic defrost with 

bottom-mounted freezer and 

no TTD ice service 

7. Refrigerator-freezer: 

automatic defrost with sidemounted freezer and TTD ice 

service 

1,026 23.4% 3.1% 

9. Upright freezer with 

automatic defrost 248 5.7% 6.4% 

10. Chest freezer and all other 

freezers except compact 

models 

369 8.4% 5.2% 

* From the Energy Information Administration’s 2005 Residential Energy Consumption Survey (RECS). 

† Through-the-door. 

The relative standard errors associated with the subsamples that contain specific product 

classes are not considered so large as to affect the validity of the derived results presented in this 

chapter. Specifically, the relative standard error of a sample of size N, expressed as a percentage, 

is 100 divided by the square root of (N-1). For the full 2005 RECS sample, the associated 

relative standard error due to sampling is 1.5 percent. For the subsamples containing product 

classes 9 and 10, the associated relative standard errors are 6.4 percent and 5.2 percent, 

respectively. Although the standard error for the smallest subsample is more than four times the 

error for the entire 2005 RECS, it still is less than 10 percent, a relative standard error considered 

small enough to yield meaningful results. Therefore, DOE believes the results generated from the 

household samples for refrigeration products are representative of U.S. households using those 

appliances. 

7-5
 

EERE-2008-BT-STD-0012 COMMENT 20
 

7.2 APPROACH FOR STANDARD-SIZE PRODUCTS 

The Residential Energy Consumption Survey (RECS) reports the annual field energy 

consumption of each household’s refrigeration product(s), a quantity referred to as FECRECS. 

DOE treated the reported energy consumption as the actual consumption of the refrigeration 

product(s) in each household. Because the energy consumed by a household’s refrigerator or 

freezer varies depending on operating conditions, user behavior, and other factors, DOE applied 

a multiplicative usage adjustment factor (UAF) to the labeled energy use of each product to 

reflect those factors. 

To develop a UAF for each RECS household, DOE utilized information that RECS 

provides on the interior volume and age of each refrigeration product. Using this information and 

the unit’s product class, DOE determined for each household unit the maximum allowable tested 

energy consumption, referred to as TECSTD, as stipulated by the energy conservation standard in 

effect at the time the household purchased the product. Because TECSTD differentiates among 

current levels of energy efficiency, it guards against overestimating the energy savings to be 

derived from potential new standards. Using FECRECS and TECSTD, DOE developed the UAF for 

each household to capture the combined effects of consumer behavior (e.g., door openings); 

operating conditions (e.g., room temperature and humidity); and product characteristics (e.g., 

efficiency relative to the maximum allowable). The UAF adjusts the maximum allowable energy 

use when the unit was tested to arrive at the field energy consumption of the refrigeration 

product. UAF is represented by the following expression. 

FECRECS UAF = TECSTD 

Eq. 7.1 

Where: 

UAF = usage adjustment factor; 

FECRECS = refrigeration product’s field energy consumption as reported for the RECS 

household; and 

TECSTD = maximum allowable tested energy consumption based on the standard in effect at 

the time the household purchased the refrigeration product; for products purchased 

before 1990 (when the first national standard came into effect), DOE used the 

shipments-weighted average energy consumption for that vintage to scale the 

standard. 

DOE was better able to estimate the efficiency of ENERGY STAR products and thus 

develop a UAF that more accurately represents only behavior and operating conditions. DOE 

used an income-based statistical model, described in section 7.3.4, to identify households likely 

to own an ENERGY STAR appliance. In those cases, UAF was defined as follows. 

7-6
 

EERE-2008-BT-STD-0012 COMMENT 20
 

FECRECS UAF = TECES 

Eq. 7.2 

Where: 

UAF = usage adjustment factor, 

FECRECS = refrigeration product’s field energy consumption as reported for the RECS 

household, and 

TECES = tested energy consumption based on the ENERGY STAR criteria in effect at the 

time the household purchased the refrigeration product. 

DOE conducted its analysis with an awareness of proposed revisions to the DOE test 

procedure for refrigerator-freezers, which will stipulate lower temperatures for the fresh food 

compartment and the freezer than those the currently prescribed. DOE has not identified how the 

tested energy consumption under the new procedure will compare to that determined under the 

current procedure. DOE expects this adjustment to take the form of a multiplicative factor 

termed the “efficiency standard adjustment factor,” or ESAF. The ESAF is expected to be 

multiplicative, because the energy use for a refrigeration unit is close to proportional to the 

difference between its interior and exterior temperatures. For the current preliminary analysis, 

DOE assumed that this factor is constant for each product class, and does not vary with product 

efficiency or adjusted volume. See chapter 5 for a complete discussion of the derivation of these 

values. DOE determined the preliminary value of the ESAF for refrigerator-freezers to be: 

• 1.124 for product class 3, 

• 1.18 for product class 5, 

• 1.14 for product class 7, 

• 1.00 for product class 9, and 

• 1.00 for product class 10. 

If the ESAF is multiplicative, it does not affect DOE’s estimate of appliance energy 

consumption by consumers, FEC The mathematical demonstration of this equivalence is shown 

below, after several additional terms are defined. Fundamentally, the value of the ESAF does not 

affect estimates of field energy use, because changes in the test procedure do not affect consumer 

behavior or operation of an appliance within a household. Field energy consumption of future 

appliances built to meet a national standard, however, may be affected by the test procedure used 

to define the standard. For this reason, DOE assumed that the effects of consumer behavior and 

operating conditions, characterized by the UAF, are separate from the effects of the test 

procedure, characterized by the ESAF. DOE therefore separated the UAF values calculated from 

the RECS household sample from the ESAF, which does not vary across the household sample. 

If appropriate, DOE will incorporate a more complete and accurate model for the ESAF 

based on ongoing analysis and additional information collected from interested parties. 

Therefore, although a constant, multiplicative ESAF does not affect estimated annual energy use, 

7-7
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

DOE has chosen to show where the factor would enter into its calculations. To that end, DOE 

defined a new term, TECSTD-REV-TP , which is determined with the following expression. 

TEC STD−REV −TP	 = ESAF ×TEC	 STD−EXIST −TP Eq. 7.3

Where: 

TECSTD-REV-TP = maximum allowable tested energy consumption based on the standard in 

effect at the time the household purchased the refrigeration product, revised to 

reflect proposed lower temperatures for the fresh food and freezer 

compartments; 

ESAF = efficiency standard adjustment factor; and 

TECSTD-EXIST-TP = maximum allowable tested energy consumption based on the standard in 

effect at the time the household purchased the refrigeration product, reflecting 

current DOE test procedure conditions. 

 Substituting TECSTD-REV-TP for TECSTD in Eq. 7.1 produces the following expression for 

UAF. 

FECRECS UAF = ESAF ×TECSTD−EXIST −TP	 Eq. 7.4 

After the UAFs were determined for each household within a given sample, DOE 

adjusted the tested energy consumption for a new refrigeration product (TECNEW) (such as those 

analyzed in the engineering analysis) into a field-adjusted annual energy consumption, referred 

to as FECNEW, using the following expression. 

FEC = TEC ×UAF	 Eq. 7.5 NEW NEW 

Where: 

FECNEW = field-adjusted annual energy consumption of new refrigeration product, and 

TECNEW = tested energy consumption of new refrigeration product. 

DOE assumed that the UAF a given household would be the same for products that meet 

some future energy efficiency standard as it is for their current appliance. In conducting the lifecycle cost analysis (chapter 8), DOE substituted the refrigeration product recorded in RECS with 

a new product of identical product class and size that the household is assumed to purchase in the 

year when the new standard goes into effect. 

If the ESAF is a multiplicative factor, as DOE assumed for this analysis, and the energy 

use required by the new standard is reduced from the current standard by a factor R (e.g., a 10­

7-8
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

percent efficiency improvement would mean R = 0.1), then for an appliance that meets the new 

standard, tested under the new test procedure, the field energy consumption is 

FEC

FEC = TEC ×UAF = TEC × RECS 

NEW −STD NEW −STD NEW −STD ESAF ×TECSTD−EXIST −TP 

TECNEW −STD 

TECSTD−EXIST −TP = FECRECS ×

ESAF 

Eq. 7.6

(1− R)× ESAF ×TECSTD−EXIST −TP 

TECSTD−EXIST −TP = FECRECS ×

ESAF 

= (1− R)× FECRECS 

A multiplicative ESAF therefore is not needed to calculate energy savings related to a 

higher efficiency standard, which can be calculated using only FECRECS and R. 

7.3 USAGE ADJUSTMENT FACTORS FOR STANDARD-SIZE PRODUCTS 

This section describes how DOE developed usage adjustment factors (UAFs) from the 

data provided for each household in RECS. It also describes how DOE developed minimum and 

maximum UAFs based on the highest and lowest plausible energy consumption of refrigeration 

products in the field. DOE’s methods of acconting for second refrigerators and ENERGY STAR 

products are also described. 

7.3.1 Field Energy Consumption for One or More Refrigerators 

RECS reports the annual energy consumption of each household’s refrigerator(s) or 

freezer in terms of thousands of British thermal units (BTUs) per year, which DOE converted to 

kilowatt-hours (kWh) per year. The reported end-use quantities were not based on data obtained 

by placing meters on individual appliances; rather, a regression technique was used to estimate 

how much of the total annual electricity consumption for each household can be attributed to 

each end-use category.a

 The regression equations also were used to infer energy consumption 

when the billing data were missing or inadequate. The refrigerator component for electricity 

consisted of all electricity used to operate refrigerators. The electricity used to operate freezers 

was assigned to a separate component under the category of “general appliance.” 

a

 The desire to use a large number of independent variables without using a large number of interaction terms and 

the desire to adapt the regression procedures to account for heteroscedastic error terms led to the use of a nonlinear 

regression technique. For more information, see: http://www.eia.doe.gov/pub/consumption/residential/append_c.pdf 

7-9
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

 

When a house has two or more refrigerators in RECSb

, the energy consumption of all the 

refrigerators is included in the term for “electric refrigerator use.” DOE’s analysis required 

separate consideration of each individual refrigerator in a household. 

Total refrigerator field energy consumption (FEC) for households having two 

refrigerators can be expressed as: 

FEC = (UAF1 ×TECSTD1) + ( Mon ×UAF2 ×TECSTD2 ) Eq. 7.7 12 

Where: 

UAF = usage adjustment factor, 

TEC = test energy consumption, and 

Mon = number of months per year the second refrigerator is on.c
 

The subscript numerals 1 and 2 refer to the first and second refrigerator, respectively. 

TECSTD refers to the maximum annual energy consumption allowed by the efficiency 

standards in effect when the product was manufactured. This value depends on the age and 

adjusted volume of the refrigerator. DOE assigned values for the age and adjusted volume of the 

second refrigerator the same way as for the first refrigerator. After these were assigned, the 

TECstd for the second refrigerator was calculated. 

The location of the second refrigerator, often in either a garage or basement, affects its 

UAF. DOE assumed that for most households, the second refrigerator is in the garage. In those 

cases the UAF of the second refrigerator is the same as that of the first. If the second refrigerator 

operates for 12 months of the year, and the house is in the northern part of the country, however, 

the unit was assumed to be in a basement. (North is defined as Census Districts 1, 2, 3, and 4 

plus New York, as well as other areas experiencing at least 5,000 heating degree-days. Because 

the operating environment of a basement on average is colder than that of the first refrigerator, 

DOE estimated the UAF of the second refrigerator to be 70 percent of the UAF of the first. This 

estimate was based on results of a simulation performed under basement conditions versus 

Results from the DOE test procedure. Although DOE did not use RECS to develop a household 

sample for compact refrigerators, DOE included in its analysis of standard-sized products those 

households having a second refrigerator that was a compact. The compact was assigned a 

volume based on the volume distribution in the California Energy Commission appliance 

database,2

 and assigned a UAF as if it were standard-sized. 

b Of the households in RECS 2005, 19.6 percent reported having two refrigerators; 1.2 percent reported having 

three. DOE considered only those households having one or two refrigerators. 

c

 RECS reports months of operation for a second refrigerator. 

7-10
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

The UAF for each refrigerator can be calculated based on the above assumptions. For 

most households, the UAF for both first and second refrigerators is calculated as: 

FEC UAF = Eq. 7.8 ⎛ Mon ⎞ ⎜TECSTD + ( 12 

×TECSTD2 )⎟ 1 ⎝ ⎠

For households in which the second refrigerator is assumed to be in the basement, the 

UAF for the first refrigerator is calculated as: 

FEC UAF1 = Eq. 7.9 ⎛ Mon ⎞ ⎜TECSTD + (0.70× ×TECSTD2 )⎟ 1 ⎝ 12 ⎠

and the UAF for the second refrigerator is calculated as: 

UAF = 0.70 ×UAF Eq. 7.10 2 1 

7.3.2 Tested Energy Consumption 

For each refrigeration unit in a RECS home, the maximum allowable tested energy 

consumption based on the standard in effect at the time the refrigeration product was 

manufactured (TECSTD) depends on the unit’s product class, size, and age (vintage). If the 

household was assigned a refrigerator having an ENERGY STAR designation (using the model 

derived in section 7.3.4), DOE calculated the maximum allowed tested energy consumption for 

an ENERGY STAR unit of the appropriate vintage rather than the maximum allowed by the 

concurrent standard. 

Each unit’s product class was identified as described in section 7.1. The size and vintage 

were determined as described below. 

7.3.2.1 Size 

The possible answers to the RECS question regarding the size of the first refrigerator or 

freezer are shown in Table 7.3.1. The distribution of actual sizes is not uniform within the RECS 

size bins. To estimate the actual size of each unit, DOE estimated the distribution of sizes within 

each bin. To approximate that distribution, DOE used data on refrigerator models from the 2009 

California Energy Commission (CEC) appliance model database.2 The figures in appendix 7-B 

show the number of models by size within each RECS size bin for each considered product 

classes. The size assigned to a sample refrigerator within a RECS size bin was assigned 

randomly using probabilities derived from the CEC data. 

7-11
 

EERE-2008-BT-STD-0012 COMMENT 20
 

Table 7.3.1 Size Bins for Refrigerators and Freezers 

Bin* Size of First Refrigerator 

cu ft† 

1 Very small (10 or fewer) 

2 Small (11 to 14) 

3 Medium (15 to 18) 

4 Large (19 to 22) 

5 Very large (more than 22) 

* Bins defined in Residential Energy Consumption Survey, 2005.

† Cubic feet. 

The maximum allowed energy consumption depends on the year the product was 

produced, its product class, and adjusted volume. For a refrigerator-freezer, the adjusted volume 

is equal to the internal volume of the fresh food compartment plus 1.63 times the internal volume 

of the freezer compartment.3

 Using the CEC database,2 DOE used the following linear regression 

to calculate the adjusted volume (Voladj) from the total volume (Voltot): 

Voladj =Voltot × Slope + Intercept Eq. 7.11 

DOE performed this calculation for each product class, deriving the parameters shown in 

 Table 7.3.2. 

Table 7.3.2 Parameters for Calculating Adjusted Volume from Total Volume of 

Refrigerator-Freezers 

Product Class Slope Intercept R2 † Count 

3. Refrigerator-freezers: automatic defrost 

with top-mounted freezer and no TTD* ice 

service 

1.2205 -1.1049 0.9691 1,803 

5. Refrigerator-freezers: automatic defrost 

with bottom-mounted freezer and no TTD 

ice service 

1.1851 0.0159 0.9929 778 

7. Refrigerator-freezers: automatic defrost 

with side-mounted freezer and TTD ice 

service 

1.3170 -1.9992 0.9906 1,866 

*Through-the-door. 

† R2

 is the coefficient of determination, a measure of how well the model fits the data. 

7.3.2.2 Assigning Vintage and ENERGY STAR Status 

The vintage of a refrigerator reflects the minimum efficiency standards that were in effect 

at the time it was purchased. Table 7.3.3 lists the relevant energy efficiency standards and the 

7-12
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

dates each became effective. The formula that expresses the standard is for maximum allowable 

kWh per year as a linear function of adjusted volume (AV).4, 5 

Table 7.3.3 Energy Conservation Standards for Refrigeration Products 

Product Class 1990 Jan. 1, 1993 July 1, 2001 

3. Top-mount refrigerator-freezers 

without TTD* ice service 23.5AV+471 16.0AV + 355 9.80AV+276.0 

5. Bottom-mount refrigerator-freezers 

without TTD ice service 27.7AV+488 16.5AV + 367 4.60AV+459.0 

7. Side-by-side refrigerator-freezers 

with TTD ice service 30.9AV+547 16.3AV + 527 10.10AV+406.0 

9. Upright freezers with automatic 

defrost 16.0AV+623 14.9AV + 391 12.43AV+326.1 

10. Chest freezers 14.8AV+233 11.0AV + 160 9.88AV+143.7 

*Through-the-door. 

The vintage also reveals which ENERGY STAR criteria were in effect. The effective 

dates of successive ENERGY STAR specifications are shown in Table 7.3.4.6 7 

Table 7.3.4 ENERGY STAR Criteria for Refrigeration Products 

ENERGY STAR Criterion Effective Date 

Refrigerators* 

 15% less energy than NAECA†

 2001 maximum allowed January 1, 2004 

 10% less energy than NAECA 2001 maximum allowed January 1, 2001 

 20% less energy than NAECA 1993 maximum allowed June 1996 

Freezers 

 10% less energy than NAECA 2001 maximum January 1, 2003 

* The criteria that became effective in 2008 (20% less energy than NAECA 2001 maximum) do not apply to 

units described in RECS 2005. 

† National Appliance Energy Conservation Act 

RECS assigns the age of a refrigeration product to one of the five bins listed in Table 

7.3.5. 

7-13
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

Table 7.3.5 Vintage Bins for Refrigeration Products 

Bin* Age of Unit 

years 

1 Less than 2 

2 2 to 4 

3 5 to 9 

4 10 to 19 

5 20 or more 

* Bins defined in Residential Energy Consumption Survey, 2005. 

The dates refrigerator standards took effect do not correspond exactly to the age bins in 

RECS. When the age bin of a refrigerator is insufficient to determine which standard applied, 

DOE chose a year from within the bin to assign as the vintage of that refrigerator. After the year 

was chosen using the survival curve developed for appliance lifetime, the standard appropriate to 

that vintage was applied. 

For refrigeration products shipped before 1990, DOE derived an efficiency index based 

on trends in the average unit energy consumption (UEC) for historical shipments of refrigerators 

and freezers. Figure 7.3.1shows the trends in UEC from 1960 to 1990. 

0 

200 

400 

600 

800 

1000 

1200 

1400 

1600 

1800 

2000 

1960 1965 1970 1975 1980 1985 1990 

UEC 

Refrigerators 

Freezers 

Source: AHAM Factbooks 

Figure 7.3.1 Average Unit Energy Consumption, 1961 to 1990 Shipments 

7-14
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

There are likely to be fewer of the oldest refrigerators within any vintage bin, both 

because older refrigerators tend be replaced and because fewer refrigerators were produced in 

earlier years. This trend is revealed in Figure 7.3.2, which shows the weighted number of 

households by vintage from the 2005 RECS. For this figure, the refrigerators in each bin were 

assigned equally to each year. A better approach would be to assign more refrigerators to the 

more recent years within each bin by calculating the survival probability [that is, the probability 

of a refrigerator surviving (remaining in use)] for a number of years. The survival probability is 

calculated using the number of refrigerators of each vintage bin reported by RECS as a fraction 

of the number of refrigerators shipped in that range of years. The survival probability accounts 

for the increases in shipments over time, as well as the refrigerators that retire from use. The 

survival probability function used to assign vintages is the same as the lifetime function derived 

for use in the life-cycle cost analysis. The derivation of all parameter values is described in 

chapter 8. 

0 

2 

4 

6 

8 

10 

12 

14 

20052003200119991997199519931991198919871985198319811979197719751973197119691967 

Year 

Households (weighted, in millions) 

Figure 7.3.2 Weighted Households by Refrigerator Vintage 

The survival probability was calculated as: 

⎛ ⎞β ⎜ x−θ ⎟ −⎜ ⎟ ⎜ α ⎟

P = e ⎝ ⎠ for x > θ

P = 1 for x ≤ θ Eq. 7.12 

Where: 

x = number of years (appliance age), 

7-15
 

EERE-2008-BT-STD-0012 COMMENT 20
α = 13.91, Weibull scale parameter, 

β = 1.68, Weibull shape parameter, and 

θ = 5, Weibull delay parameter. 

Figure 7.3.3 shows the survival probability curve for standard-sized refrigerators. 

16.18 

17.43 

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

Fraction surviving 

Survival function 

Median lifetime 

Mean lifetime 

0 5 10 15 20 25 30 35 40 45 50 

Age (years) 

Figure 7.3.3 Survival Probability of Refrigerators by Age 

The same fitting technique was used for freezers. The scale, shape, and delay parameters 

for freezers are: 

α = 19.49, Weibull scale parameter, 

β = 2.40, Weibull shape parameter, and 

θ = 5, Weibull delay parameter. 

The survival curve for freezers ( Figure 7.3.4) does not fall off as quickly as does the one 

for refrigerators ( Figure 7.3.3), indicating a longer mean product lifetime. 

7-16
 

EERE-2008-BT-STD-0012 COMMENT 20
21.73 

22.28 

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

Fraction surviving 

Survival function 

Median lifetime 

Mean lifetime 

0 5 10 15 20 25 30 35 40 45 50 

Age (years) 

Figure 7.3.4 Survival Probability of Freezers by Age 

A multistep process was followed to assign an age to a given refrigeration product in a 

REC household. First, the product’s age range (based on RECS bin) was compared with the 

Weibull delay parameter. For both refrigerators and freezers, the delay was fixed at 5 years, 

which falls between two RECS age bins. If the age bin contained appliances younger than the 

delay (in years), then an age within the bin was assigned randomly to the product, with no age 

preferred. If the bin contained appliances older (in years) than the delay, a survival value was 

selected randomly from within the range given for the relevant bin. For this purpose, each bin 

was assumed to extend to the beginning of the next bin. Table 7.3.6 shows the survival values 

assigned to household refrigerators by age bin. 

7-17
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

Table 7.3.6 Refrigerator Survival Probabilities Associated with Age Bins 

Age Bin Age years Survival Value 

Start Less than Start End 

1 0 2 NA NA 

2 2 5 NA NA 

3 5 10 1.000 0.8196 

4 10 20 0.8196 0.3051 

5 20 100 0.3051 0.0000 

The age of the unit was calculated from the assigned survival value using the inverse 

survival probability function: 

⎛ 1 ⎞ ⎜ ⎟

⎛ ⎛ 1 ⎞⎞⎜

⎜

⎜

β ⎟

⎟

⎟

Age = α × ⎝ ⎠ ⎜

⎜ln⎜ ⎟⎟

⎟ +θ Eq. 7.13 ⎝ ⎝ SP ⎠⎠

Where: 

SP = randomly selected survival value, 

α = Weibull scale parameter, 

β = Weibull shape parameter, and 

θ = Weibull delay parameter. 

After an age was assigned to the refrigerator or freezer, it was clear what efficiency 

standards and (if applicable) ENERGY STAR specifications were in effect when it was sold. 

7.3.3 Energy Use of Second Refrigerators 

When a household purchases a new refrigerator, some first units become second units. 

See chapter 8 for a discussion of how DOE modeled the conversion of refrigerators from first to 

second units. A second refrigerator, generally located in a basement or garage, enters a new 

operating environment and may be used less than year-round. For those units that become a 

second refrigerator, therefore, the annual energy consumption changes, presumably remaining at 

the new level for the rest of its lifetime. 

Field energy consumption for the first (FEC1) and second (FEC2) phases of a 

refrigerator’s lifetime can be expressed as: 

FEC1 = (UAF1 ×TECstd) Eq. 7.14 

Mon FEC2 = ( ×UAF ×TECstd) Eq. 7.15 12 2 

7-18
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

Where: 

UAF1 = usage adjustment factor for first phase of the unit’s lifetime, 

UAF2 = usage adjustment factor for second phase,d 

TEC = test energy consumption, and 

Mon = number of months per year refrigerator is on. 

7.3.4 Estimated Number of ENERGY STAR Refrigerators 

As stated earlier, DOE used Eq. 7.2 to derive the UAF for RECS households likely to 

own an ENERGY STAR appliance. Although RECS 2005 provides information on ownership of 

ENERGY STAR refrigerators purchased between 2001 and 2005, the data seem to greatly 

overestimate the stock of ENERGY STAR refrigerators compared to data regarding shipments 

made during those years. DOE therefore developed a method that predicts ENERGY STAR 

ownership in the RECS sample based on annual average market shares of ENERGY STAR 

refrigerators and on household income. 

DOE based its approach on a study from Natural Resources Canada8

 that reported 

ENERGY STAR buyers based on three income categories. DOE assumed that the relative 

behavior of each income category is the same in the United States as for Canadian consumers. 

After matching the three income categories to RECS income bins, DOE assigned a probability of 

owning an ENERGY STAR unit to each household record as a function of its income. This 

probability was then scaled to reflect income levels in the RECS sample and national ENERGY 

STAR sales. The following equation was used. 

Estaryear = scaleyear × (Flow × P _ Estarlow + Fmid × P _ Estarmid + Fhigh × P _ Estarhigh) Eq. 7.16 

Where: 

Estaryear = percent of annual national refrigerator sales that were ENERGY STAR 

qualified; 

Flow|mid|high = percent of weighted number of RECS 2005 households in low, medium, 

and high income bins; 

P_Estar low|mid|high = probability of households in an income bin buying an ENERGY STAR 

appliance; and 

scaleyear = scaling factor to obtain the appropriate percent of ENERGY STAR 

refrigerators for each vintage. 

Table 7.3.7 shows the market shares of ENERGY STAR refrigerators (Estaryear), which 

were obtained from the ENERGY STAR program.9

 The market shares of ENERGY STAR 

freezers are estimates. 

d

 This UAF accounts for the changed operating environment during the second phase. 

7-19
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

Table 7.3.7 Market Share of ENERGY STAR Products 

Year 1997 1998 1999 2000 2001 2002 2003 2004 2005 

Refrigerators 25.3% 19.0% 25.0% 27.0% 17.3% 20.1% 25.7% 33.2% 32.9% 

Freezers - - - - - - 10% 10% 10% 

The scaling factor for each year was calculated as: 

Estaryear scaleyear = Eq. 7.17 (Flow×P_ Estarlow+Fmid×P_ Estarmid+Fhigh×P_Estarhigh) 

A household in the low-income bin that purchased a refrigerator in a given year was a 

assigned a probability Scaleyear times P_Estar low for having an ENERGY STAR refrigerator. A 

similar approach was taken for households in the mid- and-high income bins. 

7.3.5 Validating Field Energy Consumption 

The values for refrigerator energy consumption reported in RECS 2005 ranged from 6 

kWh to more than 10,000 kWh for households having one refrigerator. DOE developed an 

approach that utilized the UAFs calculated for each household to confirm whether the reported 

values for refrigerators (and freezers) were reasonable. This approach required calculating 

maximum and minimum plausible UAFs for various refrigeration products. 

A range of possible UAFs can apply to a given refrigerator, based on the range of 

possible refrigerator sizes and ages consistent with the household’s RECS response. If the range 

of UAFs for a given household was entirely outside the boundaries of what DOE considered to 

be plausible, DOE excluded the household from the LCC analysis. Such outliers occur if the 

maximum possible UAF for a record is lower than the minimum plausible UAF or if the 

minimum UAF is higher than the maximum plausible UAF. 

If the range of UAFs for a given household intersected the range of plausible UAFs, the 

UAFs outside the boundaries were brought to the minimum or maximum plausible value. Thus, a 

household was not excluded from the sample if it had a plausible UAF. 

7.3.6 Maximum Usage Adjustment Factor 

To evaluate the maximum plausible UAF, DOE estimated the maximum plausible energy 

consumption of a refrigerator if it were running continuously. DOE’s calculation of the 

maximum electricity consumption assumes that the compressor runs constantly, comparable to 

leaving the door open 24 hours a day for 365 days a year. The evaporator and condenser fans, the 

interior lights, and the gasket heater (found only on refrigerators built before 1993) also were 

assumed to run continuously. DOE assumed that both the refrigerator and freezer compartment 

have a 20-W light bulb. The defrost cycle is often initiated based on the compressor run time. 

7-20
 

EERE-2008-BT-STD-0012 COMMENT 20
DOE assumed the defrost cycle runs for 10 minutes every 10 hours, which is the default input to 

the EPA’s refrigerator analysis (ERA) model.10 

Table 7.3.8 shows the power consumption and times DOE estimated for various 

components of each cycle for the ice maker. In real-world operation the compressor must run 

longer than indicated in Table 7.3.8 in order to extract the heat from the ice maker components, 

along with the latent heat of freezing from freezing water to make ice. To calculate the maximum 

theoretical electricity consumption, DOE assumed that the compressor already runs 

continuously, so there is no additional compressor run time. The components consume a total of 

6.3 Watt-hours per ice-making cycle.11 The value used for maximum ice-making cycles per day 

was nine.12 

Table 7.3.8 Power Consumption for Ice Maker Components 

Component Watts Length of Cycle 

Mold heater 185 2 minutes 

Solenoid valve 20 8 seconds 

Motorized ejector 3 2 minutes 

The formula for calculating the maximum plausible UAF is: 

(WComp +WFans +WLights +WGasket +WDefrost ×1.7%)×365× 24 /1000 + kWhIce MaxUAFpl = , TECSTD-EXIST-TP × ESAF 

Eq. 7.18 

Where: 

WComp = the power (in Watts) used by the compressor; 

WFans = the power (in Watts) used by the fans; 

WLights = the power (in Watts) used by the light; 

WGasket = the power (in Watts) used by the gasket heater; 

WDefrost = the power (in Watts) used by the defrost cycle, which is active 1.7 percent of 

the time 

kWhIce = the energy (in kWh) used to complete nine ice-making cycles per day 

(including mold heater, solenoid, and ejector) in one year; 

TECSTD-EXIST-TP = the test energy consumption; and 

ESAF = the efficiency standard adjustment factor. 

DOE collected the wattage for most components for the baseline models in several 

product classes from the Technical Support Documents (TSDs) developed in the analyses 

leading to the 2001 standard, the July 1995 notice of proposed rulemaking,13 and the November 

1989 final rule.14 The earlier TSDs (March 198215 and June 198016) did not report baseline 

energy use for the compressor. The documents, however, do report the amount of time the 

7-21
 

EERE-2008-BT-STD-0012 COMMENT 20
refrigerator was running during the test procedure. DOE calculated the maximum plausible 

annual energy consumption by (1) increasing the test procedure output to what it would be if the 

refrigerator were running continuously and (2) adding a continuously burning 40-W light bulb. 

The equation given above was used to calculate the maximum theoretical UEC and UAF 

for each baseline model in the TSDs. The theoretical maximum UAFs based on past TSDs for all 

of the analyzed product classes are shown in Tables 7.3.9 through 7.3.13. 

7-22
 

EERE-2008-BT-STD-0012 COMMENT 20
Table 7.3.9 Theoretical Maximum Energy Consumption for Baseline Product Class 3 Refrigerator-Freeze

Baseline 

(TSD) Compressor 

W 

Evaporator 

Fan 

W 

Condenser 

Fan 

W 

Lights 

W 

Gasket Heater 

W 

Defrost 

W 

Defrost % 

Time On 

% 

Ice 

Making 

kWh 

Test 

Procedure 

kWh 

Ti

o

2001 124 4.5 4.5 40 0 450 1.7% 20.6 544 

Jul-95 145 9.1 12 40 0 450 1.7% 20.6 788 

Nov-89 186 10 13.5 40 19 450 1.7% 20.6 1,073 

Mar-82 - - - 40 - - - - 1,518 65

Jun-80 - - - 40 - - - - 1,805 53

* Unit Energy Consumption. † Usage adjustment factor. 

Table 7.3.10 Theoretical Maximum Energy Consumption for Baseline Product Class 5 Refrigerator-Freez

Baseline 

(TSD) Compressor 

W 

Evaporator 

Fan 

W 

Condenser 

Fan 

W 

Lights 

W 

Gasket 

Heater 

W 

Defrost 

W 

Defrost % 

Time On 

% 

Ice 

Making 

kWh 

Test 

Procedure 

kWh 

Tim

o

% 

2001 133 4.5 4.5 40 0 450 1.7% 20.6 573 

Jul-95 143 10.5 10.0 40 0 450 1.7% 20.6 845 - 

Nov-89 187 10.0 13.5 40 12 450 1.7% 20.6 1,324 - 

Mar-82 - - - 40 - - - - 2,209 63

* Unit Energy Consumption. † Usage adjustment factor 

7-23
 

EERE-2008-BT-STD-0012 COMMENT 20
Table 7.3.11 Theoretical Maximum Energy Consumption for Baseline Product Class 7 Refrigerator-Freez

Baseline 

(TSD) 

Compressor 

W 

Evaporator 

Fan 

W 

Condenser 

Fan 

W 

Lights 

W 

Gasket 

Heater 

W 

Defrost 

W 

Defrost % 

Time On 

% 

Ice 

Making 

kWh 

Test 

Procedure 

kWh 

Tim

on 

% 

2001 141 8.0 4.5 40 0.0 450 1.7% 20.6 764 

Jul-95 150 8.0 11.6 40 0.0 450 1.7% 20.6 912 

Nov-89 186 10 14 40 - 0 1.7% 20.6 1,756 

Mar-82 - - - 40 - - - - 2,517 52

Jun-80 - - - 40 - - - - 2,422 53

Note: The Max UAF derived from the 1989 TSD does not agree with the rest of the sample, making the R2 drop from 0.99 to 0.41; 

thus it has been excluded from the regression. * Unit Energy Consumption. † Usage adjustment factor 

Table 7.3.12 Theoretical Maximum Energy Consumption for Baseline Product Class 9 Freezers 

Baseline 

(TSD) Compressor 

W 

Evaporator 

Fan 

W 

Condenser 

Fan 

W 

Lights 

W 

Gasket 

Heater 

W 

Defrost 

W 

Defrost % 

Time On 

% 

Test 

Procedure 

kWh 

Time 

on 

% 

Max 

UEC* 

kWh 

2001 119 4.5 0.0 20 0 450 1.7% 663 - 1,260 

Jul-95 126 9.0 0.0 20 0 450 1.7% 759 - 1,357 

Nov-89 169 10.0 0.0 20 9 450 1.7% 1,088 - 1,822 

Mar-82 - - - 20 - - - 1,303 81% 1,784 

Jun-80 - - - 20 - - - 1,332 87% 2,194 

* Unit Energy Consumption. † Usage adjustment factor 

7-24
 

EERE-2008-BT-STD-0012 COMMENT 20
Table 7.3.13 Theoretical Maximum Energy Consumption for Baseline Product Class 10 Freezers 

Baseline 

(TSD) Compressor 

W 

Evaporator 

Fan 

W 

Condenser 

Fan 

W 

Lights 

W 

Gasket 

Heater 

W 

Defrost 

W 

Defrost % 

Time On 

% 

Test 

Procedure 

kWh 

Time 

on 

% 

Max 

UEC 

kWh 

2001 85 0 0 20 0 0 0.0% 394 - 916 

Jul-95 101 0 0 20 0 0 0.0% 472 - 1,059 

Nov-89 187 0 0 20 0 0 0.0% 557 - 1,813 

Mar-82 - - - 20 - - - 1,215 80% 1,695 

Jun-80 - - - 20 - - - 1150 69% 1842 

Note: The Baseline model from the 1989 TSD was excluded because its compressor power was 100 W higher than to be expected if it fthe trend in W/cu ft between 1995 and 2001. 

7-25
 

EERE-2008-BT-STD-0012 COMMENT 20
0

0.5

1

1.5

2

2.5

3

3.5

0 5 10 15 20 25

M

a

x

U

A

F

Age

PC3

PC5

PC7

PC9

PC10

The maximum annual energy consumption allowed by a given standard scales linearly 

with volume. DOE assumed that in the extreme case used to determine the maximum plausible 

energy consumption, annual energy consumption also scales linearly with volume. Therefore, the 

maximum theoretically possible UAF is constant for each production year and product class, 

regardless of volume. 

Older refrigerators generally had low maximum plausible UAFs. As the minimum 

efficiency allowed by standards increased, compartments became better insulated and the 

refrigeration cycle more efficient. The compressor therefore uses less energy to maintain 

conditions inside the cabinet and so runs for less time. Ordinary test procedure operation thus 

represents a smaller and smaller fraction of the extreme, all-out energy consumption used in the 

calculations described in this section. Thus, the test procedure energy use (TEC) for older 

refrigerators is closer to their maximum theoretically possible field energy consumption than it is 

for newer refrigerators. 

The maximum theoretically possible UAF (MaxUAF) scales linearly with age, as shown 

in Figure 7.3.5. 

Figure 7.3.5 Maximum Usage Adjustment Factor by Product Age in 2005 

7-26
 

EERE-2008-BT-STD-0012 COMMENT 20
DOE performed a linear regression to fit MaxUAF by vintage, thus providing a value of 

MaxUAF for a unit of any age. Table 7.3.14 shows the intercept and slope of the regression line 

for MaxUAF for each product class. The quality of the linear fit from the regression for each 

product class is shown by the R2

 value. 

Table 7.3.14	 Regression Parameters by Product Class for Maximum Usage Adjustment 

Factor 

Product 

Class Description Slope Intercept R2 

3 Top-mount refrigerator-freezer -0.0554 3.0796 0.9033 

5 Bottom-mount refrigerator-freezer -0.0733 3.0835 0.9298 

7 Side-by-side refrigerator-freezer with 

TTD ice service -0.0307 2.4140 0.9033 

9 Upright freezer -0.0187 1.9671 0.6832 

10 Chest freezer -0.0434 2.5638 0.9034 

DOE compared the MaxUAF value to the smallest possible UAF for the refrigerator for 

each RECS record to determine whether the household’s refrigerator energy use was plausible 

and the RECS record should be retained in the analysis. 

7.3.7 Minimum Usage Adjustment Factor 

To estimate the least plausible UAF, DOE used EPA’s refrigerator analysis (ERA) 

model.10 DOE used the default models in ERA for product classes 3 and 10. Values for the other 

product classes were derived from the default models for those product classes. DOE assumed 

that product classes 3 and 5 have identical minimum UAFs. 

For each year a TSD was published, DOE modified the ERA input file to better match the 

characteristics of the baseline model described in the TSD. Then the ERA model was run under 

test procedure conditions and under very favorable conditions (such as in an air-conditioned 

kitchen or a basement). The temperature settings for the compartments were assumed to be the 

maximum allowed by the ERA model. DOE also assumed that any gasket heater was turned off. 

Tables 7.3.15 and 7.3.16 show the temperature settings used to model both these “ideal” 

conditions and test conditions. 

Table 7.3.15 Temperature Settings for Refrigerators Under Test and Ideal Conditions 

Ambient 

Temp. 

Air Entering 

Condenser 

Air Under 

Cabinet 

Fresh Food 

Compartment 

Freezer 

Compartment 

Test 

Conditions 

32.2 °C 

(90.0 °F) 

37.8 °C 

(100.0 °F) 

35 °C 

(95.0 °F) 

7.22 °C 

(45.0 °F) 

-15 °C 

(5.0 °F) 

Ideal 

Conditions 

17 °C 

(62.6 °F) 

19 °C 

(66.2 °F) 

19 °C 

(66.2 °F) 

10 °C 

(50.0 °F) 

-2 °C 

(28.4 °F) 

7-27
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

Table 7.3.16 Temperature Settings for Freezers Under Test and Ideal Conditions 

Ambient 

Temp. 

Air Entering 

Condenser 

Air Under 

Cabinet 

Freezer 

Compartment 

Test 

Conditions 32.2 °C (90.0 °F) 37.8 °C (100.0 °F) 35 °C (95.0 °F) -17.8 °C (0.0 °F) 

Ideal 

Conditions 12 °C (53.6 °F) 14 °C (57.2 °F) 14 °C (57.2 °F) -9.99 °C (14.0 °F) 

In order to validate the model, DOE compared the ERA simulation model under test 

procedure conditions to the results of the test procedure reported in each TSD. In addition to the 

temperatures listed in Tables 7.3.15 and 7.3.16, the other control settings during the test were: 

• Defrost controls were not operative during the test procedure. 

• Anti-sweat heater switch was set to the position that consumes the maximum energy. 

The 1995 TSD also mentions a correction factor to adjust the ERA model results based 

on the tested consumption. Correction factors for DOE’s modeling for this analysis, as well as 

the values cited in the 1995 TSD, are listed in Table 7.3.17. If the error percentage is greater than 

0, it means that the ERA model overestimated the energy use in the test procedure, and the value 

of CAL in Eq. 7.19 is greater than 1. 

Table 7.3.17 Model Errors by Product Class and Vintage 

Product Class DOE % Error Estimate from 1995 

1989 1995 2001 TSD %

Top-Mount 5.93 4.14 22.29 5.93 

Side-by-Side 12.15 5.16 8.54 12.15 

Upright Freezer 19.67 15.54 17.74 19.67 

Chest Freezer 0.64 12.11 11.84 0.64 

The simulation models produced the same range of error as those specified in the 1995 

TSD. When calculating the minimum UAF, this calibration factor cancels out, as shown in the 

following equation, because the ERA model also over-estimates the energy use in the ideal 

conditions by the same factor. DOE defined the minimum plausible UAF as: 

FEC Ideal RECS FECERA CAL MinUAF = = Eq. 7.19 TEC × ESAF TEC × ESAF ERA RECS 

CAL 

Where: 

FECIdeal_ERA = minimum field energy consumption modeled in ERA under ideal conditions, 

TECERA = test energy consumption modeled in ERA under existing test procedure 

conditions, 

FECRECS = field energy consumption of the RECS record, 

7-28
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

TECRECS = test consumption calculated based on the volume and age designated for the 

UAF calculation, 

CAL = calibration factor defined by the ratio between the results from the ERA model 

and the test procedure, 

ESAF = efficiency standard adjustment factor. 

Figure 7.3.6 shows the results of calculating the minimum plausible UAF as a function of 

vintage. 

0.00 

0.05 

0.10 

0.15 

0.20 

0.25 

0.30 

0.35 

0.40 

0 5 10 15 20 

M 

i

n 

U

A

F 

Age 

Top Mount 

Side by Side 

Chest Freezer 

Upright Freezer 

Figure 7.3.6 Minimum Plausible Usage Adjustment Factor as a Function of 

Product Age in 2005
 

DOE performed a linear regression for each product class in order to model the relation 

between the minimum UAF and the vintage of a unit. The following table shows the resulting 

parameters. 

7-29
 

EERE-2008-BT-STD-0012 COMMENT 20
 

Table 7.3.18 Regression Results Based on Unit Vintage 

Product Class Slope Intercept R2 

Top-Mount -0.0048 0.2496 0.909 

Side-by-Side -0.0033 0.2356 0.8022 

Upright Freezer -0.0025 0.3000 0.8107 

Chest Freezer -0.0055 0.3325 0.6448 

DOE assumed that minimum UAFs are constant across volumes, that bottom-mount and 

top-mount products have the same minimum UAF, and that through-the-door ice service does 

not affect the minimum UAF. 

7.3.8 Results by Product Class 

Figures 7.3.7 through 7.3.16 show the distribution of UAFs for the RECS households in 

the subsample that represents each standard-sized product class. Each figure shows the 

distribution of UAFs before and after the truncation produced by applying the minimum and 

maximum UAFs. The distribution used for LCC analysis is the distribution after removing 

households having implausible UAFs. 

7-30
 

EERE-2008-BT-STD-0012 COMMENT 20
 

Frequency Chart 

.000 

.006 

.013 

.019 

.025 

0 

62.5 

125 

187.5 

250 

0. 117 0. 754 1. 391 2. 027 2. 664 

10,000 Trials 9, 800 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.7 Initial UAF Distribution for Standard-Size Top-Mount 

Refrigerator-Freezers (Product Class 3) 

Frequency Chart 

.000 

.007 

.013 

.020 

.027 

0 

66.5 

133 

199.5 

266 

0. 181 0. 804 1. 427 2. 050 2. 673 

10,000 Trials 9, 858 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.8 Final UAF Distribution for Standard-Size Top-Mount 

Refrigerator-Freezers (Product Class 3) 

7-31
 

EERE-2008-BT-STD-0012 COMMENT 20
 

Frequency Chart 

.000 

.007 

.014 

.020 

.027 

0 

68.25 

136.5 

204.7 

273 

0. 153 0. 708 1. 263 1. 818 2. 373 

10,000 Trials 9, 853 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.9 Initial UAF Distribution for Standard-Size Bottom-Mount 

Refrigerator-Freezers (Product Class 5) 

Frequency Chart 

.000 

.006 

.013 

.019 

.025 

0 

63 

126 

189 

252 

0. 137 0. 698 1. 258 1. 818 2. 379 

10,000 Trials 9, 899 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.10 Final UAF Distribution for Standard-Size Bottom-Mount 

Refrigerator-Freezers (Product Class 5) 

7-32
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

Frequency Chart 

.000 

.006 

.012 

.019 

.025 

0 

62 

124 

186 

248 

0. 199 0. 833 1. 467 2. 100 2. 734 

10,000 Trials 9, 889 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.11 Initial UAF Distribution for Standard-Size Side-by-side 

Refrigerator-Freezers (Product Class 7) 

Frequency Chart 

.000 

.005 

.011 

.016 

.021 

0 

53 

106 

159 

212 

0. 233 0. 778 1. 323 1. 869 2. 414 

10,000 Trials 9, 997 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.12 Final UAF Distribution for Standard-Size Side-by-side 

Refrigerator-Freezers (Product Class 7) 

7-33
 

EERE-2008-BT-STD-0012 COMMENT 20
 

Frequency Chart 

.000 

.006 

.012 

.018 

.024 

0 

60.5 

121 

181.5 

242 

0. 372 1. 234 2. 096 2. 958 3. 820 

10,000 Trials 9, 825 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.13 Initial UAF Distribution for Standard-Size Upright Freezers 

(Product Class 9) 

Frequency Chart 

.000 

.010 

.020 

.030 

.040 

0 

99.25 

198.5 

297.7 

397 

0. 331 0. 736 1. 140 1. 544 1. 948 

10,000 Trials 9, 919 Displ ayed 

Forecast : UAF (1) 

Figure 7.3.14 Final UAF Distribution for Standard-Size Upright Freezers 

(Product Class 9) 

7-34
 

EERE-2008-BT-STD-0012 COMMENT 20
 

Frequency Chart 

.000 

.006 

.012 

.018 

.024 

0 

59.25 

118.5 

177.7 

237 

10,000 Trials 9, 885 Displ ayed 

Forecast : UAF (1) 

0.103 1.416 2.729 4.042 5.356 

Figure 7.3.15 Initial UAF Distribution for Standard-Size Chest Freezers 

(Product Class 10) 

Frequency Chart 

.000 

.008 

.017 

.025 

.034 

0 

84 

168 

252 

336 

0. 343 0. 898 1. 453 2. 008 2. 564 

10,000 Trials 10,000 Di spl ayed 

Forecast : UAF (1) 

Figure 7.3.16 Final UAF Distribution for Standard-Size Chest Freezers 

(Product Class 10) 

The maximum plausible UAF limits the freezer sample more than the refrigerator-freezer 

sample. The maximum is more restrictive for freezers because their compressors are assumed to 

run more than 80 percent of the time in normal operation, as opposed to 52 percent to 65 percent 

of the time for refrigerators. As a result, increasing appliance energy use to its theoretical 

maximum, to reflect a compressor that runs 100 percent of the time, has a smaller effect for 

freezers. RECS also has a simpler model for estimating household energy use for freezers than it 

does for refrigerator-freezers, which may contribute to the wide range of energy consumption 

assigned to freezers across the household sample. The minimum and maximum UAF thresholds 

enabled DOE to remove from the sample households having unrealistic freezer energy 

consumption. 

7-35 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

Table 7.3.19 summarizes the characteristics of the UAFs before and after the final sample 

was selected. 

Table 7.3.19 Usage Adjustment Factors Before and After Excluding Minimums and 

Maximums 

Product Class 

Complete RECS Sample 

After Selecting Sample Based On 

Min and Max Plausible UAF 

Mean 

UAF 

Min 

UAF 

Max 

UAF 

Sample 

Size 

Mean 

UAF 

Min 

UAF 

Max 

UAF 

Sample 

Size 

Top-mount 

refrigerator-freezer 1.254 0.115 4.203 2,303 1.227 0.134 3.08 2,231 

Bottom-mount 

refrigerator- freezer 1.079 0.097 3.155 2,303 1.077 0.134 2.888 2,242 

Side-by-side 

refrigerator-freezer 1.46 0.17 4.219 1,026 1.437 0.201 2.414 871 

Upright freezer 1.7988 0.324 5.367 248 1.37 0.316 1.967 170 

Chest freezer 2.248 0.103 7.795 369 1.479 0.343 2.564 243 

7.3.9 Distributions: Comparison with Other Studies 

The variation in UAFs within the national RECS sample has several causes, including 

indoor temperature, appliance age, and varying usage patterns. Meier et al.17 and Miller and 

Pratt18 indicate that refrigerator energy use varies significantly in response to ambient 

temperature, which implies that climate contributes to variation in household energy use. In 

addition, refrigerators generally use more energy as they age, 19 and the RECS sample includes 

appliances having a wide range of ages. Household choices regarding the frequency of door 

opening and how often and how much warm food is loaded into the unit, along with the ambient 

temperature in the kitchen, likely add to variability. In addition, the DOE test procedure does not 

measure energy consumed by ice making, so it is not reflected in the labeled energy 

consumption. The presence or absence of an automatic ice maker, as well as variation in the 

amount of ice made, also contribute to the variation in UAF within and between product classes. 

In addition to their significant width, the UAF distributions shown in Figures 7.3.7 

through 7.3.16 do not have a mean value of 1, indicating that the average energy use for a 

refrigerator drawn from the American residential stock differs from the labeled energy use of that 

same refrigerator when it was new. This result is consistent with reports in the literature. A full 

literature survey, available in appendix 7-A, is summarized here. Refrigerator energy use may be 

characterized by three measures: 

(A) the label on the product when new, derived from the DOE test procedure; 

7-36 

EERE-2008-BT-STD-0012 COMMENT 20
(B) the results of the DOE test procedure on a particular appliance after it has been used 

in the field; and 

(C) the in situ (ideally directly measured) energy consumption in a user’s home. 

The UAF for a given refrigerator is the ratio of (C) to (A). Studies described in the 

literature examined two classes of refrigerators: new or likely new (installed in new homes), for 

which the usual comparison is (C) to (A); and recycled/disposed refrigerators, for which all 

possible pairs of measures have been compared. 

Studies of new (or likely new) refrigerators in consumers’ homes reveal a wide variation 

in energy use among consumers. The mean energy consumption cited in those studies lies within 

40 percent of the appliance label.20 The literature indicates that refrigerators in cooler climates 

tend to use less energy than their labeled energy consumption,19 whereas those in warmer 

locations tend to use more energy than labeled. This difference contributes to the width of the 

national UAF distributions. 

Studies of non-new refrigerators generally examine refrigerators collected as part of early 

replacement programs operated by electric utilities. Such studies are used to measure the effect 

of the utility program and to obtain credit for the energy reductions resulting from replacing old 

appliances. The non-new refrigerators described in the literature, which must be in use by their 

owners, commonly are relatively old. Measurements, both in situ and from the DOE test 

procedure, show these refrigerators use significantly more energy than the labeled consumption. 

KEMA21 used the DOE procedure to test 136 such refrigerators. This comparison of (B) to (A) 

isolates the effect of age from those of user behavior or environment. KEMA found that the 

median increase in energy consumption relative to labeled use was 46 percent, and that roughly 

15 percent of the sample used more than twice the labeled energy. Only 7 percent of the sample 

used less than labeled. When Peterson et al.22 combined the data from several studies (of a total 

of 193 recycled refrigerators), they found that the average increase in energy consumption, as 

measured by the DOE test procedure, was 50 percent, with 25 percent of refrigerators using more 

than 1.7 times their labeled energy. Miller and Pratt18 performed a regression analysis on in-use 

refrigerators in New York public housing [a (C) to (A) comparison], deducing an average 1.4­

percent increase in energy use per year. These studies indicate that the UAF distribution for old 

refrigerators is expected to be wide and to have a mean significantly higher than 1. 

Several aspects of in-use refrigerator operation are not reflected in the DOE test 

procedure and therefore affect the UAF. In particular, the DOE test does not measure the energy 

used by ice makers. Estimates of the effect of this omission range from 5 percent to 26 percent,11 

with a rough estimate of 10 percent being common and consistent with published direct 

measurements. Through-the-door (TTD) ice making may consume more energy than non-TTD 

ice making. DOE therefore expects the UAF distribution from product classes that include TTD 

ice makers to have a somewhat higher mean than classes that do not. The size of the difference 

depends on the fraction of non-TTD refrigerators that use ice makers, and the possible difference 

in ice-making behavior among users of various product classes. Meier and Martinez11 also report 

that ice-making energy may increase over time, compounding the increased energy use with age. 

7-37
 

EERE-2008-BT-STD-0012 COMMENT 20
A national sample of refrigerators, such as RECS, covers refrigerators in various climate 

zones and of various ages. As such, DOE expects those two factors (as well as behavioral 

differences among users) to produce significant scatter in the UAF. If new refrigerators use 

energy at close to their labeled rate as determined by the DOE test, and refrigerators at retirement 

use significantly more energy when tested using the same procedure, the national mean UAF is 

expected to be greater than 1. DOE could not conclude from the literature that a particular value 

or distribution should be assigned to the UAF, Therefore, DOE cannot justify further adjusting 

the UAF distribution derived from RECS. 

7.4 ENERGY USE OF COMPACT REFRIGERATION PRODUCTS 

As mentioned in the introduction to this chapter, compact refrigerators and freezers are 

used in homes, college dormitories, hotels and motels, and some commercial buildings. DOE 

found no data on the typical field energy consumption of compact refrigeration products. It 

therefore assumed that the average field energy use of compact refrigerators and freezers of a 

given size is the same as the maximum energy use allowed by the DOE standard, as measured in 

the DOE test procedure. In effect, DOE assumed that variation in field energy use of compact 

products is a function solely of volume. To represent the distribution of volumes in the field, 

DOE used data from the 2008 CEC appliance model database.2 Figures in appendix 7-B show 

the distribution of appliance sizes represented within the database. 

DOE used the CEC database to develop a linear equation relating listed total volume to 

adjusted volume for product class 11. The parameters of the equation are listed in Table 7.4.1. 

For compact freezers, the adjusted volume is equal to 1.73 times the volume.3

 DOE then used the 

relation between adjusted volume and energy use described by the DOE test procedure to relate 

the distribution of volumes in the CEC database to a distribution of energy use values. 

Table 7.4.1 Parameters for Calculating Adjusted Volume from Total Volume for Compact 

Refrigerators 

Product Category Slope Intercept R2 Count 

Compact Refrigerators 1.0458 -0.0905 0.9822 187 

7.5 ANNUAL ENERGY CONSUMPTION BY EFFICIENCY LEVEL 

This section reports the annual field energy consumption calculated for refrigeration 

products that meet new efficiency standards if they were used in RECS 2005 homes. As 

described in section 7.2, DOE calculated field-adjusted annual energy consumption for each 

home’s refrigeration product by multiplying the tested energy consumption of a new 

refrigeration product, measured using the existing test procedures, by the efficiency standard 

adjustment factor (ESAF), which is a constant for each product class, and by the UAF for that 

household. 

7-38
 

EERE-2008-BT-STD-0012 COMMENT 20
As discussed in chapter 5, DOE analyzed specific efficiency levels for the considered 

product classes. Tables 7.5.1 through 7.5.6 show the considered efficiency levels and 

corresponding annual energy consumption for each product class. The tables for standard-sized 

products show the average annual energy consumption according to the proposed DOE test 

procedure (“proposed test”) and in the average energy use based on the corresponding RECS 

2005 household subsamples (“field”). The tables for compact appliances (product classes 11 and 

18) show the average annual energy consumption according to the proposed DOE test procedure, 

using a distribution of product volumes based on the CEC appliance database. 

Table 7.5.1 Product Class 3, Top-Mount Refrigerator-Freezers Without Through-theDoor Ice Service: Average Annual Energy Use by Efficiency Level 

Efficiency Level 

(percent less than baseline 

energy use) 

Proposed Test Field 

kWh/year kWh/year 

Baseline 534 657 

1 (10%) 481 591 

2 (15%) 454 558 

3 (20%) 428 526 

4 (25%) 401 493 

5 (30%) 374 460 

6 (35%) 347 427 

7 (40%) 321 394 

8 (45%) 294 361 

7-39
 

EERE-2008-BT-STD-0012 COMMENT 20
Table 7.5.2 Product Class 5, Bottom-Mount Refrigerator-Freezers Without Through-theDoor Ice Service: Average Annual Energy Use by Efficiency Level 

Efficiency Level 

(percent less than baseline 

energy use) 

Proposed Test Field 

kWh/year kWh/year 

Baseline 652 699 

1 (10%) 587 629 

2 (15%) 554 594 

3 (20%) 522 559 

4 (25%) 489 524 

5 (30%) 456 489 

6 (35%) 424 454 

7 (40%) 391 419 

8 (45%) 359 384 

Table 7.5.3 Product Class 7, Side-by-side Refrigerator-Freezers with Through-the-Door 

Ice Service: Average Annual Energy Use by Efficiency Level 

Efficiency Level 

(percent less than baseline 

energy use) 

Proposed Test Field 

kWh/year kWh/year 

Baseline 756 1087 

1 (10%) 680 979 

2 (15%) 643 924 

3 (20%) 605 870 

4 (25%) 567 815 

5 (30%) 529 761 

6 (35%) 491 707 

7 (40%) 454 652 

7-40
 

EERE-2008-BT-STD-0012 COMMENT 20
Table 7.5.4 Product Class 9, Upright Freezers: Average Annual Energy Use by Efficiency 

Level 

Efficiency Level 

(percent less than baseline 

energy use) 

Proposed Test Field 

kWh/year kWh/year 

Baseline 717 980 

1 (10%) 646 882 

2 (15%) 610 833 

3 (20%) 574 784 

4 (25%) 538 735 

5 (30%) 502 686 

6 (35%) 466 637 

7 (40%) 430 588 

8 (45%) 394 539 

Table 7.5.5 Product Class 10, Chest Freezers: Average Annual Energy Use by Efficiency 

Level 

Efficiency Level 

(percent less than baseline 

energy use) 

Proposed Test Field 

kWh/year kWh/year 

Baseline 428 623 

1 (10%) 385 561 

2 (15%) 364 530 

3 (20%) 342 498 

4 (25%) 321 467 

5 (30%) 300 436 

6 (35%) 278 405 

7 (40%) 257 374 

8 (45%) 235 343 

7-41
 

EERE-2008-BT-STD-0012 COMMENT 20
Table 7.5.6 Compact Refrigerators and Freezers: Average Annual Energy Use by 

Efficiency Level 

Efficiency Level 

(percent less than 

baseline energy use) 

Product Class 

11: Compact refrigerators and 

refrigerator-freezers with manual defrost 

(kWh) 

18: Compact chest freezers 

(kWh) 

Baseline 325 313 

10% 292 282 

15% 276 266 

20% 260 250 

25% 244 235 

30% 227 219 

35% 211 203 

40% 195 188 

45% 179 172 

7-42
 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

 

 

 

 

 

 

 

REFERENCES 

1	 U.S. Department of Energy–Energy Information Administration. Residential Energy 

Consumption Survey, 2005 Public Use Data Files. 2009. U.S. Department of Energy: 

Washington, D.C. <www.eia.doe.gov/emeu/recs/recspubuse05/pubuse05.html> 

2	 California Energy Commission. Appliances Database—Refrigeration. 

<www.energy.ca.gov/appliances/database/excel_based_files/Refrigeration/> (Last accessed April 25, 

2009.) 

3	 Title 10—Energy, Chapter II—Department of Energy, Part 430—Energy Conservation 

Program for Consumer Products, Subpart B—Test Procedures, Appendix A1 and B1. 

4	 U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy. Energy 

Conservation Program for Consumer Products: Proposed Rulemaking Regarding Energy 

Conservation Standards for Refrigerators, Refrigerator-Freezers, and Freezers. Federal 

Register. July 20, 1995. 60 FR 37388. 

5	 U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy. Energy 

Conservation Program for Consumer Products: Energy Conservation Standards for 

Refrigerators, Refrigerator-Freezers, and Freezers; Final Rule. Finding of No Significant 

Impact; Notice. Federal Register. April 28, 1997. 62 FR 23102. 

<www.eere.energy.gov/buildings/appliance_standards/residential/pdfs/refrig_final.pdf> 

6	 U.S. Environmental Protection Agency and U.S. Department of Energy. Revision of the 

ENERGY STAR Criteria for Residential Refrigerators and Freezers. (Last accessed April 25, 

2009.) <www.energystar.gov/index.cfm?c=revisions.res_refrig_spec> 

7	 U.S. Environmental Protection Agency. Maintaining the Value of ENERGY STAR: 2006 

Report. [U.S. EPA: Washington, D.C.] 

8	 Ipsos-Reid Corporation. Tracking Study: Awareness of ENERGY STAR/EnerGuide Symbols 

Final Report. Natural Resources Canada. September 2006 

9	 Karney, R. ENERGY STAR Criteria for Refrigerators: Overview of ENERGY STAR Criteria 

Setting Process and History of Refrigerator Criteria. June 4, 2007. (Last accessed April 15, 

2009.) 

<www.energystar.gov/ia/partners/prod_development/revisions/downloads/refrig/Karney_Ref 

rigeratorCriteriaRevision_6.4.07.pdf> 

10	 Merriam R., Verone A., Feng H. EPA Refrigerator Analysis (ERA) Program: User's Manual 

Version 1.0, Cambridge, MA: Arthur D. Little Inc. March 1993. 

7-43 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

 

 

 

 

 

 

 

 

 

 

11	 Meier, A. and M. Martinez. Energy Use of Icemaking in Domestic Refrigerators. ASHRAE 

Transactions: Symposia. 1996. AT-96-19-2. 

12	 Parker, D. and T. Stedman. Measured Electricity Savings of Refrigerator Replacement: Case 

Study and Analysis. ACEEE 1992 Summer Study on Energy Efficiency in Buildings, 

Proceedings—Commercial Performance: Analysis and Measurement Panel 3. 1992. 

American Council for an Energy-Efficient Economy. 

13	 U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy. Energy 

Conservation Program for Consumer Products: Technical Support Document: Energy 

Efficiency Standards for Consumer Products: Refrigerators, Refrigerator-Freezers, and 

Freezers. July 1995. Washington, D.C. 

14	 U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy. Energy 

Conservation Program for Consumer Products: Technical Support Document: Energy 

Efficiency Standards for Consumer Products: Refrigerators and Furnaces. November 1989. 

Washington, D.C. 

15	 U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy. Consumer 

Products Efficiency Standards: Engineering Analysis Document. March 1982. Washington, 

D.C. DOE/CE-0030. 

16	 U.S. Department of Energy–Office of Energy Efficiency and Renewable Energy. Consumer 

Products Efficiency Standards: Engineering Analysis. June 1980. Washington, D.C. 

DOE/CE-0166. 

17	 Meier. A., A. Megowan, B. Litt, and B. Pon. The New York State Residential Refrigerator 

Electrical Energy Monitoring Project: Final Report. 1993. Lawrence Berkeley National 

Laboratory: Berkeley, CA. Report No. LBL-33708. 

18	 Miller, J.D. and R.G. Pratt. Estimates of Refrigerator Loads in Public Housing Based on 

Metered Consumption Data. 1998. Pacific Northwest National Laboratory. Report No. 

PNNL-11991. 

19	 Meier, A.. and R. Jansky. Field Performance of Residential Refrigerators: A Comparison 

with the Laboratory Test. 1991. Lawrence Berkeley Laboratory: Berkeley, CA. Report No. 

LBL-31795. 

20	 Meier, A. “Refrigerator Energy Use in the Laboratory and in the Field.” Energy and 

Buildings. 1995. 22: pp. 233–243. 

21	 KEMA. 2004. 2003 EM&V RARP Study:Degradation and Market Potential Analysis. 

Prepared for Southern California Edison, Rosemead, CA. Prepared by KEMA Inc., Madison, 

7-44 

EERE-2008-BT-STD-0012 COMMENT 20
 

 

WI. December 23, 2004. CALMAC STUDY ID SCE0205 ma:project:scee0015 rarp 03 

evaluation:report:title. 

22	 Peterson, J., D. Dohrmann, T. Alereza, S. Samiullah, S. Westberg, and J.H. Redd. Gross 

Savings Estimation for Appliance Recycling Programs: the Lab Versus in situ Measurement 

Imbroglio and Related Issues. Proceedings of the 2007 International Energy Performance 

Evaluation Conference (IEPEC). 2007. Chicago, IL. August. Report 653. 17 pp. 

7-45 

EERE-2008-BT-STD-0012 COMMENT 20
APPENDIX 7-A. LITERATURE SURVEY OF ENERYG CONSUMPTION BY 

RESIDENTIAL REFRIGERATOR-FREEZERS 

TABLE OF CONTENTS 

7-A.1 INTRODUCTION .................................................................................................7-A-1 

7-A.2 TEST PROCEDURE AND FIELD STUDIES......................................................7-A-2 

7A.2.1 DOE Test Procedure ..............................................................................................7-A-2 

7A.2.2 Field Studies...........................................................................................................7-A-3 

7A.2.2.1 KEMA-Xenergy Findings....................................................................7-A-3 

7-A.3 LITERATURE ANALYSIS ..................................................................................7-A-5 

7-A.4 SUMMARY...........................................................................................................7-A-6 

7-A.5 BIBLIOGRAPHY..................................................................................................7-A-6 

LIST OF TABLES 

Table 7-A.2.1 Refrigerator Energy Consumption Data by Year.......................................7-A-3 

Table 7-A.2.2 Literature summary....................................................................................7-A-4 

7A-i 

EERE-2008-BT-STD-0012 COMMENT 20
APPENDIX 7-A. LITERATURE SURVEY OF ENERGY CONSUMPTION BY 

RESIDENTIAL REFRIGERATOR-FREEZERS 

7-A.1 INTRODUCTION 

Efficient refrigerator-freezers reduce peak energy consumption as well as total household 

energy use. As a result, electric utilities regard replacement programs for these appliances as an 

attractive and effective way to reduce residential energy consumption. To estimate the amount of 

electricity savings attributable to an energy-efficient refrigerator-freezer program, utilities must 

evaluate the difference between the pre- and post-program energy consumption of the appliance 

stock. The challenge to accurately estimate the electricity savings of a refrigerator-freezer 

replacement program lies in estimating the real-life consumption of the original and replacement 

units. 

Estimation of appliance energy consumption may be undertaken in three ways, all of 

which are represented in the literature: 

A) The labeled energy consumption on a new appliance, based on the U.S. Department 

of Energy (DOE) test procedure undertaken on a sample of several identical 

appliances, and reported by the appliance manufacturer 

B) The DOE test procedure applied to a particular appliance (often not a new appliance), 

and 

C) Measurement for some period of time in situ in a household. 

Most studies compare two of these measurements in order to evaluate energy use. For example, 

a study might compare the results of the DOE test procedure on an old refrigerator with the 

labeled energy consumption when new to isolate the effect of appliance age, while eliminating 

possible effects due to user behavior. This appendix refers to such a study as comparing (B) to 

(A). 

Researchers have conducted studies that measure the field consumption of refrigeratorfreezers to compare in situ measurements to the DOE test results, represented either by the 

labeled results ((C) to (A)), or through direct testing under DOE conditions ((C) to (B)). When 

such field studies are evaluated, the lack of consistency among study conditions (such as 

geographic location, housing type, and the number and type of units), limited time of direct 

measurements, and the degradation of efficiency throughout the lifetime of a refrigerator-freezer 

contribute to the challenge of estimating potential energy consumption savings from new units. 

This appendix summarizes available literature regarding the comparison of different 

measurement methods for refrigerator-freezers in order to evaluate reasonable possible values for 

the ‘usage adjustment factor’ (UAF), which is an estimate of the ratio of (C) to (A). There are 

very few published measurements of freezers or compact appliances, so DOE addresses only 

refrigerator-freezers in this summary. Section 2 summarizes the DOE test procedure and lists and 

characterizes the field studies which DOE used in its analyses. Section 3 discusses these studies 

and their implications for the UAF parameter used in Chapter 6, particularly regarding variation 

with season and climate, and efficiency degradation with unit age. 

7-A-1 

EERE-2008-BT-STD-0012 COMMENT 20