7

- i CHAPTER 7 . ENERGY USE ANALYSIS

TABLE OF CONTENTS

7.1 INTRODUCTION

................................ ................................ ................................ ........... 7

- 1

7.2 CONSUMER SAMPLES

................................ ................................ ................................ 7

- 2

7.2.1 Clothes Dryer Household Sample

................................ ................................ .................... 7

- 2

7.2.2 Room Air Conditioners

................................ ................................ ................................ .... 7

- 3

7.2.2.1 Residential Sample

................................ ................................ ......................... 7

- 3

7.2.2.2 Commercial Building Sample

................................ ................................ ........ 7

- 3

7.3 CLOTHES DRYERS

................................ ................................ ................................ ....... 7

- 4

7.3.1 Number of Cycles

................................ ................................ ................................ ............ 7

- 4

7.3.2 Energy Use Calculation

................................ ................................ ................................ ... 7

- 5

7.3.3 Variability of Annual Energy Consumption

................................ ................................ .... 7

- 8

7.3.4 Average Annual Energy Consumption by Efficiency Level

................................ ......... 7

- 12

7.4 ROOM AIR CONDITIONER S

................................ ................................ ..................... 7

- 14

7.4.1 General Approach

................................ ................................ ................................ .......... 7

- 14

7.4.2 Op erating Hours

................................ ................................ ................................ ............. 7

- 15

7.4.2.1 Residential

................................ ................................ ................................ .... 7

- 15

7.4.2.2 Commercial

................................ ................................ ................................ .. 7

- 18

7.4.3 Variability of Room Air Conditioner Annual Energy Consumption

............................. 7

- 20

7.4.4 Average Annual Energy Consumption by Efficiency Level

................................ ......... 7

- 27

7.4.5 Estimating Room Air Co nditioner Energy Use by Month

................................ ............. 7

- 29

LIST OF TABLES

Table 7.2.1 Selection of RECS 2005 Records for Clothes Dryer Sample

.............................. 7

- 2

Table 7.2.2 Selection of RECS 2005 Records for Residential Room Air Conditioner Samples

................................ ................................ ................................ ................ 7

- 3

Table 7.2.3 Selection of CBECS 2003 Records for Commercial Room Air Conditioner Samples

................................ ................................ ................................ ................ 7

- 4

Table 7.3.1 Number of Loads Washed per Week Based on RECS 2005 Sample

.................. 7

- 5

Table 7.3.2 RECS 2005 Sample Clothes Dryer Usage

................................ ........................... 7

- 5

Table 7.3.3 Average Clothes Dryers Utilization Derived from RECS 2005 Sample

............. 7

- 5

Table 7.3.4 Electric Standard an d Gas Clothes Dryer: Average Annual Energy Consumption by Efficiency Level

................................ ................................ ..... 7

- 13

Table 7.3.5 Electric Compact Vented Dryer: Average Annual Energy Consumption by Efficiency Level

................................ ................................ ................................ . 7

- 13

Table 7.3.6 Electric Compact Vent

- less Dryer and Combination Washer/Dryer:

Avera ge Annual Energy Consumption by Efficiency Level

............................. 7

- 14

Table 7.4.1 RECS Vintage Bins for Room Air Conditioner

................................ ................. 7

- 16

Table 7.4.2 Average Room Air Conditioner EER by Product Class and Year Sold

............ 7

- 17

Table 7.4.3 Regression Equations

................................ ................................ ......................... 7

- 19

Table 7.4.4 Room Air Conditioner, Without Reverse Cycle and with Louvers, less than 6,000 Btu/h: Average Annual Energy Use

................................ ................. 7

- 277

- ii Ta ble 7.4.5 Room Air Conditioner, Without Reverse Cycle and with Louvers, 8,000

– 13,999 Btu/h: Average Annual Energy Use

................................ ...................... 7

- 27

Table 7. 4.6 Room Air Conditioner, Without Reverse Cycle and with Louvers, 20,000

- 24,999 Btu/h: Average Annual Energy Use

................................ ...................... 7

- 28

Table 7.4.7 Room Air Conditioner, Without Reverse Cycle and with Louvers, greater than 25,000 Btu/h: Average Annual Energy Use

................................ ............... 7

- 28

Table 7.4.8 Room Air Conditioner, Without Reverse Cycle and with Louvers, greater than 25,000 Btu/h: Average Annual Energy Use

................................ ............... 7

- 28

Table 7.4.9 Room Air Conditioner, Without Reverse Cycle and with Louvers, greater than 25,000 Btu/h: Average Annual Energy Use

................................ ............... 7

- 29

LIST OF FIGURES

Figure 7.3.1 Range of Annual Energy Use for Vented Electric Standard Clothes Dryers

...... 7

- 9 Figure 7.3.2 Range of Annual Energy Use for Vented Electric Compact 120V Clothes Dryers

................................ ................................ ................................ ................... 7

- 9 Figure 7.3.3 Range of Annual Energy Use for Vented Electric Compact 240V Clothes Dryers

................................ ................................ ................................ ................. 7

- 10 Figure 7.3.4 Range of Annual Gas Use for Vented Gas Clothes Dryers

............................... 7

- 10 Figure 7.3.5 Range of Annual Electricity Use for Vented Gas Clothes Dryers

..................... 7

- 11 Figure 7.3.6 Range of Annual Energy Use for Vent

- less 240V Clothes Dryers

.................... 7

- 11 Figure 7.3.7 Range of Annual Energy Use for Vent

- less Combination Washer/Dryers

........ 7

- 12 Figure 7.4.1 Hours Above ANSI/ASHRAE Standard 55

- 2004 as a Function of Cooling Degree

- Days

................................ ................................ ................................ ...... 7

- 19 Figure 7.4.2 Range of Annual Energ y Use for Residential Room Air Conditioners without Reverse Cycle and with Louvers, less than 6,000 Btu/h

...................... 7

- 21 Figure 7.4.3 Range o f Annual Energy Use for Residential Room Air Conditioners without Reverse Cycle and with Louvers, 8,000

– 13,999 Btu/h

........................ 7

- 21 Figure 7.4 .4 Range of Annual Energy Use for Residential Room Air Conditioners without Reverse Cycle and with Louvers, 20,000

– 24,999 Btu/h

...................... 7

- 22 Figure 7.4.5 Range of Annual Energy Use for Residential Room Air Conditioners without Reverse Cycle and with Louvers, greater than 25,000 Btu/h

............... 7

- 22 Figure 7.4.6 Range of Annual Energy Use for Residential Room Air Conditioners without Reverse Cycle and without Louvers, 8,000

– 10,999 Btu/h

................... 7

- 23 Figure 7.4.7 Range of Annual Energy Use for Residential Room Air Conditioners without Reverse Cycle and without Louvers, greater than 11,000 Btu/h

.......... 7

- 23 Figure 7.4.8 Range of Annual Energy Use for Commercial Room Air Conditioners without Reverse Cycle and with Louvers, Less than 6,000 Btu/h

..................... 7

- 24 Figure 7.4.9 Range of Annual Energy Use for Commercial Room Air Conditioners without Reverse Cycle and with Louvers, 8,000

– 13,999 Btu/h

........................ 7

- 24 Figure 7.4.10 Range of Annual Energy Use for Commercial Room Air Conditioners without Reverse Cycl e and with Louvers, 20,000

– 24,999 Btu/h

...................... 7

- 25 Figure 7.4.11 Range of Annual Energy Use for Commercial Room Air Conditioners

without Reverse Cycle and with Louvers, greater than 25,000 Btu/h

............... 7

- 257

- iii Figure 7.4.12 Range of Annual Energy Use for Commercial Room Air Con ditioners without Reverse Cycle and without Louvers, 8,000

– 10,999 Btu/h

................... 7

- 26 Figure 7.4.13 Range of Annual Energy Use for Commercial Room Air Conditioners without Reverse Cycle and without Louvers, greater than 11,000 Btu/h

.......... 7

- 267-1 CHAPTER 7. ENERGY USE ANALYSIS

7.1 INTRODUCTION

To carry out the life

- cycle cost (LCC) and payback period (PBP) analys e s described in

c hapter 8, DOE must determine the operating cost savings to consumers from more efficient products

. This chapter describes how DOE determined the annual energy consumption of room air conditioners and clothes dryers for use in the LCC and PBP analys e s.

The engineering analysis described in c hapter 5 reports energy use based on the DOE test procedure. This test provides standardized results that serve as the basis for comparing the performance of different appliances used under the same conditions

. A ctual usage in the field varies depending on the conditions in which the appliances a re operated. a

T o establish a reasonable range of energy consumption in the field for room air

conditioners and clothes dryer s in residential applications

, DOE primarily use d data from the Energy Information Administration (EIA)’s 2005 Residential Energ y Consumption Survey (RECS 2005 ). 1 RECS is a national sample survey of housing units that collects statistical information on the consumption of and expenditures for energy in housing units along with data

on energy

- related characteristics of the housing units and occupants. RECS 2005 colle cted data

on 4,381 housing units and was constructed by EIA to be a national representation of the household population in the U nited States.

Room air conditioners are predom inantly used in homes, but they are also use d in some commercial buildings. To de termine the energy use patterns of room air conditioners in

commercial applications, DOE used EIA’s 2003 Commercial Building Energy Consumption Survey (CBECS ) 2 to develop a representative sample of commercial buildings using room air

conditioners

. CBECS 2003 collected energy

- related data for 5

, 215 buildings and was constructed by EIA to be a national representation of the commercial building stock in the United States.

The details of each building samp le are described in the following section

.

a DOE assembled estimates of the average annual energy use of room air conditioners from several studies and sources. Unfortunately, none of the stu dies is based on metered data. T he studies rely on power measurements and assumptions regarding usage to derive the annual energy consumption values.7-2 7.2 CONSUMER SAMPLES

7.2.1 Clothes Dryer Household Sample

The subset of RECS 2005 records used for the clothes dryer sample met all of the following criteria:

**•** The household had a clothes dryer.

**•** The household had and used a clothes washer.

**•** Clothes dryer fuel was electricity, natural gas, or LPG.

**•** Clothes dryer use was greater than zero

.

Table 7.2.1 shows ho w t he sample was divided into three sub

- samples to match to the produc t classes analyzed . For compact electric dryers, DOE developed a sub

- sample consisting of households with an electric dryer in multifamily buildings, manufactured homes, and single

fami ly homes with less than 1,000 square feet and no garage or basement, since DOE reasoned that these products are most likely to be found in these housing types.

Table 7.2.1 Selection of RECS 2005 Records for Clothes Dryer Sample

Product Class Selection Criterion No. of

Records No. of U.S.

Households Represented (million)

Electric Standard Dryer Has Dryer = Yes
Fuel Type = Electricity
Use of Dryer > 0 2655 67.0

Electric Compact Vented Dryer and

Vent

- less Dryer Has Dryer = Yes Fuel Type = Electricity
Use of Dryer > 0
Type of Housing = Mobile home, multifamily, or single family ( ≤1000 sq. ft., no attached garage ,

no basement) 570 14.4

Gas Dryer Has Dryer = Yes
Fuel Type = Natural Gas or LPG
Use of Dryer > 0 756 20.37-3 7.2.2 Room Air Conditioners

7.2.2.1 Residential Sample

The subset of RECS 2005 records used for the room air conditioner sample me t all of the following criteria:

**•** A room air conditioner was present in the household.

**•** Room air conditioner energy consumption was greater than zero.

Households were assigned to t he sub

- samples based on the average adjusted capacity of

the unit needed for the household

. The average adjusted capacity was calculated based on ENERGY STAR sizing guidelines for room air conditioners b combined with household

characteristics such as shadi ng, insulation, window and glass type, number of household members, and ceiling type. See appendix 7

- A for more details. Table 7.2. 2 shows the number of

RECS records in each sub

- sample and the selection criteria

. DOE used EIA’s weightings for

each RECS 200 5 household

. The weightings indicate how commonly each household configuration occurs in the general population

.

Table 7.2.2 Selection of RECS 200 5 Records for Residential Room Air Conditioner

S ample s

Product Class Selection Criterion No. of

Records No. of U.S.

Households Represented (million) No. of U.S.

RAC Units Represented (million)

Total sample 1222 28.2 50.6

1 Average adjusted capacity ≤ 6,000

Btu/h 266 9.2 16.9

3 and 8 Average adjusted capacity > 6,000

Btu/h and ≤ 14,000 Btu/h 890 38.9 97.1

5 Average adjusted capacity ≥ 18,000

Btu/h 66 2.5 5.4

7.2.2.2 Commercial Building Sample

The subset of CBECS 2003 records used for the commercial

- sector room air conditioner sample met all of the following criteria :

b http://www.energystar.gov/index.cfm?c=roomac.pr_properly_sized7-4 **•** A room air conditioner served as a source of air conditioning. c

**•** Building is not vacant.

**•** A room air conditioner is used as the primary equipment to cool at least a portion of the building.

The sample was divided into sub

- samples to match to the product classes analyzed. CBECS 2003 provides the total cooling square footage and the fraction of cooling by the room air conditioner for each building record, but it does not provide the number of room air conditioners used by the building, so the total room air conditioner cooling square footage is

used to determine the subsamples. Table 7.2. 3 shows the number of CBECS records in each sub

sample. DOE used EIA’s weightings for each CBECS 2003 building. The weightings indicate how commonly each building configuration occurs in the general population

.

Table 7.2.3 Selection of CBECS 2003 Records for Commercial Room Air Conditioner Sample s

Product Class Selection Criterion No. of

Records No. of U.S. Buildings Represented (million)

Total sample 440 0.4

>6

, 000 Btu/h Total RAC Cooling sq. ft.

> 0 440 0.4

8,000 to 13,999 Btu /h Total RAC Cooling sq. ft.

> 300 400 0.3

≥ 20,000 Btu /h Total RAC Cooling sq. ft.

> 900 352 0.3

7.3 CLOTHES DRYERS

DOE determined the annual energy consumption of clothes dryers by multiplying the number of cycles per year by the energy use per cycle

.

7.3.1 N umber of C ycles

DOE estimated the number of clothes dryer cycles per year for each sample household using data given by RECS 2005 on the number of laundry loads washed (clothes washer cycles) per week and the frequency of clothes dr yer use. The responses in RECS 2005 fall into one of

the bins shown in Tables 7.3.1 and 7.3 .2. For each question, DOE assumed a uniform

c PTAC systems could also be listed as room air conditioner s, so DOE tried to select buildings with only room air

conditioners. A building was selected as having a room air conditioner if it di d not have a PTAC type heating

system.7-5 distribution within the boundaries of each bin and randomly assigned a value from within the appropriate range to each s ample household.

Table 7.3.1 Number of Loads Washed per Week Based on RECS 2005 Sample

Bin Loads per Week Derived Loads per Year*

Min Max

1 1 load or less 0 78

2 2 to 4 loads 78 234

3 5 to 9 loads 234 494

4 10 to 15 loads 494 806

5 More than 15 loads 806 1118
* The ranges reflect the inclusion of values in between the given bin boundaries.

Table 7.3.2 RECS 2005 Sample Clothes Dryer Usage

Bin Description Fraction of Washer Cycles When Dryer is used

Min Max

1 Use it every time wash clothes 1 1

2 Use it for some, but not all, loads of

wash 0.50 1

3 Use it infrequently 0.00 0.50

The responses to the above questions vary among sample households using different clothes dryer products, so they yield somewhat different values for the average annual number of clothes dryer cycles for each product cl ass (see Table 7.3 .3).

Table 7.3.3 Average Clothes Dryers Utilization Derived from RECS 2005 Sample

Electric

Standard Gas Electric Compact and

Vent

- less

Washer loads

per year 301 292 268

Clothes dryer frequency* 0.95 0.93 0.94

Clothes dryer loads per year 283 274 251

* Fraction of washer loads ** Accounts for fraction of households that have a clothes washer, but no clothes dryer

7.3.2 Energy Use Calculation

For each considered efficiency level, DOE derived the field energy use by separately estimating the active mode and standby mode energy use and then adding them together. The7-6 DOE clothes dryer test procedure 3 calculates active mode energy consumption by dividing the weight (lbs) of clothes dried per cycle ( 8.45 lbs for standard and 3 lbs for compact clothes dryers) by the Combined Energy Factor ( CEF ) (lbs/kWh) and subtracting standby power

. d DOE adjusted the t est procedure energy use to reflect field conditions by making an adjustment for clothes dryer load weig ht and moisture removal factor.

For each household, DOE determined the per

- cycle test procedure clothes dryer energy use during active mode by using t he following formula:

TP TP TP TP

Active Cycles CD Stby hrs Stby Cycles CD CEF ght avgLoadWei TP

_ / 1000 *

_ _ * ** **  ** **  ** **  ** **  ** **  ** ** 

**− **  ** **  ** **  ****

**=**

Where:

avgLoadWeight TP = average load weight in the test procedure, lbs,

CEF = efficiency of the clothes dryer during active mode, lbs per kWh, CD_Cycles TP = test procedure clothes dryer cycles per y ear, Stby_hrs TP = test procedure standby hours, and, Stby = clothes dryers standby power usage, watts.

For each household, DOE determined the field adjustment for clothes dryer energy use during active mode by using the following formula:



## ( **)** Cycles CD RMC RMC RMC RMC RMC

ght avgLoadWei ght avgLoadWei RMC TP EnergyUse Adj

End TP TP Enc Field Field

TP Field adj Active Active

_

, , **∗ **  ** **  ****

** **  ** ** 

**+ **  ** **  ** **  ** **  ****

**− −**  **∗ **  ** **  ** **  ** **  ****

**∗**

**− =** 

Where:

TP Active = test procedure energy use per cycle , kWh per cycle,

RMC adj = RMC adjustment factor for the fixed energy use , kWh per cycle, avgLoadWeight TP = average load weight in the test procedure, lbs, avgLoadWeight Field = average load weight for each household, lbs,

RMC TP = remaining moisture content in the test procedure, 57.5 percent,
RMC TP,Enc = remaining moisture content at the end of the cycle in the test procedure, 5 percent,
RMC Field = remaining moisture content for the household, percent,

RMC Field,End = remaining moisture content at the end of the cycle for the household, percent, CD_Cycles = clothes dryer cycles per year

.

d See chapter 5 for more information on how to convert from CEF to EF.7-7 DOE assigned a fixed energy use adjustment ( RMC adj ) equal to 0.25 kWh/cycle to

account for energy required to heat the clothes dryer cabinet.

To assign a field average load weight ( avgLoadWeight Field ) for each household, DOE developed a distribution of load weights by matching the listed tub sizes for models in the July

2010 California En ergy Commission (CEC) directory 4 with the correlations b etween tub size and average pounds in the DOE test procedure. To account for a wider distribution of households that do not wash the average pounds in the DOE test procedure, DOE added a ±25 percent adjustment factor. The average load weights for standard

- size units range from 3.8 lbs. to 13.7
lbs., with a mean value of 8. 45 lbs , which matches DOE’s clothes dryer procedure value

. 3

To assign a field remaining moisture content (RMC Field ) valu e for each household, DOE used the 2008 shipment weighted values provided by AHAM for front loader and top lo ader

washers. 5 The shipment weighted value is 38.1 percent for front loaders and 51 percent for top loaders, with an overall shipment weighted RMC value of 47 percent . In 2008, front loader s represented 31 percent of shipments, while top loaders represented the remaining 69 percent, so the overall RMS shipment weighted value is 47

- percent . This shipment weighted averag e RMC

value in the AHAM data is based on th e clothes washer RMC which use s a correction factor to normalize testing results fr om different lots of test cloth. As a result, DOE determined that an initial clothes dryer RMC of 57.5 percent more accurately represents the moisture content of

current laundry loads after a wash cycle and therefore adjusted the shipment weighted value for front loaders and top loaders accordingly. In order to get a distribution of values, DOE used the

number of models listed at each unadjusted RMC in the July 2 010 CEC d irectory. 4 The adjusted

RMC values used in the analysis range from 3 6 percent to 6 4 percent for front loaders , with an average of 4 7 percent, and from 42 percent to 75 percent for front loaders, with an average of 62
percent. The overall average value of 57.5 percent matches DOE’s clothes dryer procedure

value

.

To assign a field remaining moisture content at the end of the cycle (RMC Field,End ) value for each household, DOE used a uniform distribution of 0 to 5 percent. In comparison, the DOE test procedure uses 5 percent.

Using the above approach, DOE calc ulated a unique value for the clothes dryer annual active mode energy consumption for each sample household with an electric clothes dryer using the number of dryer cycles specified for that household. For gas clothes dryers, DOE used a similar approach as for electric clothes dryers, but added an estimate of the energy use of the electric components. An estimate of 0.107 kWh per cycle, which was derived from tests done by DOE, was applied for all efficiency levels except for the max

- tech level. For the lat ter, which has a more efficient motor, the tests found a value of 0.091 kWh.

For each household, DOE determined the field

- adjusted clothes dryer energy use during standby mode by using the following formula:7-8 ClothesDryerEnergyUse Standby 

###  ** **  ** **  ** **  ** **  ** **  ****

**∗**

**− =**  60 _

_ 8760 Time CD Cycles CD * Standby_Power

Where:

8760 = number of hours in one year, hrs, CD_Time = clothes dryer time to complete one cycle, min/cycle,

60 = number of minutes in one hour, min/hr, Standby_Power = standby power, kW, and CD_Cycles = clothes dryer cycles per year

.

DOE assumed that clothes dryers take 60 minutes on average to complete a cycle. 6, 7, 8

Standby power varies by efficiency level as discussed in chapter 5.

DOE also considered the impact of clothes dryer operation on home heating and cooling loads. A clothes dryer releases heat to the surrounding environment. If the dryer is located indoors, its use will tend to slightly reduce the heating load during the heating season and slightly increase the cooling load during the cooling season. To calculate this impact, DOE first estimated whether the clothes dryer in a RECS sample home is located in conditioned sp ace (referred to as indoors) or in unconditioned space (such as garages, unconditioned basements, outdoor utility closets, or attics). Based on the 2005 RECS 9 and the 2009 American Housing Survey (AHS) 10 , DOE assumed that 50 percent of vented standard electric and gas dryers are located indoors, while 100 percent of compact and ventless clothes dryers are located indoors. For these installations, DOE utilized the results from a European Union study abo ut the impacts of clothes dryers on home heating and cooling loads to determine a the appropriate factor to apply to the total clothes dryer energy use. 11 This study reported that for vented dryers there is a factor of negative 3 to 9 percent (average 6 percent) and for ventless dryers there is a factor of positive 7 to 15 percent (average 11 percent). DOE believes that this effect is the sam e for all of the considered efficiency levels because the amount of air passing through the clothes dryer does
not vary

.

7.3.3 Variability of Annual Energy Consumption

F igures 7.3.1 to 7.3. 7 show the range of average annual energy consumption (active and

stan dby mode) for clothes dryers in the household sample for each product class.7-9 Figure 7.3.1 Range of Annual Energy Use for Vented Electric Standard Clothes Dryers

Figure 7.3.2 Range of Annual Energy Use for Vented Electric Compact 120V Clothes Dryers 0 200 400 600 800 1000 1200 1400 1600 1800 2000

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5 Level 6Annual Energy Use (kWh)

Efficiency Level Electric Standard Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average

0 100 200 300 400 500 600 700 800

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5 Level 6Annual Energy Use (kWh)

Efficiency Level Electric Compact 120V Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average7-10 Figure 7.3.3 Range of Annual Energy Use for Vented Electric Compact 240V Clothes Dryers

Figure 7.3.4 Range of Annual Gas Use for Vented Gas Clothes Dryers 0 100 200 300 400 500 600 700 800 900

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5 Level 6Annual Energy Use (kWh)

Efficiency Level Electric Compact 240V Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average

0 1 2 3 4 5 6 7

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Gas Use (MMBtu)

Efficiency Level Gas Average Annual Gas Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average7-11 Figure 7.3.5 Range of Annual Electricity Use for Vented Gas Clothes Dryers

Figure 7.3.6 Range of Annual Energy Use for Vent

- less 240V Clothes Dryers 0 10 20 30 40 50 60 70 80 90 100

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Energy Use (kWh)

Efficiency Level Gas Average Annual Electricity Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average

0 100 200 300 400 500 600 700 800 900 1000

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Energy Use (kWh)

Efficiency Level Ventless 240V Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average7-12 Figure 7.3.7 Range of Annual Energy Use for Vent

- less Combination Washer/Dryers

7.3.4 Average Annual Energy Consumption by Efficiency Level

Tables 7.3.4 through 7.3 .6 present the average annual energy consumption by efficiency level for each considered clothes dryer product cla ss. 0 200 400 600 800 1000 1200

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Energy Use (kWh)

Efficiency Level Ventless Combination Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average7-13 Table 7.3.4 Electric Standard and Gas Clothes Dryer: Average Annual Energy Consumption by Efficiency Level

Electric Gas

CEF (lb/kWh) kWh/year CEF (lb/kWh) MMBtu/

year kWh/year

3.55 718 3.14 2.53 42.2

3.56 716 3.16 2.53 39.0

3.61 707 3.20 2.53 29.8

3.73 684 3.30 2.45 29.8

3.81 670 3.41 2.37 29.8

4.08 627 3.61 2.25 25.5

5.42 476

-- -- --

Table 7.3.5 Electric Compact Vented Dryer: Average Annual Energy Consumption by Efficiency Level

120V 240V

CEF (lb/kWh) kWh/year CEF (lb/kWh) kWh/year

3.43 317 3.12 353

3.48 314 3.16 349

3.61 305 3.27 340

3.72 295 3.36 331

3.80 289 3.48 319

4.08 268 3.60 308

5.41 198 4.89 2237-14 Table 7.3.6 Electric Compact Vent

- less Dryer and Combination Washer / Dryer: Average Annual Energy Consumption by Efficiency Level

Compact Vent

- less Dryer (240V) Combination Washer

- Dryer

CEF (lb/kWh) kWh/year CEF (lb/kWh) kWh/year

2.55 372 2.08 463

2.59 366 2.35 399

2.69 354 2.38 394

2.71 351 2.46 383

2.80 337 2.56 365

4.03 210 3.69 226

7.4 ROOM AIR CONDITIONER S

7.4.1 General Approach

DOE calculated the annual energy consumption of a room air conditioner using the following equation:

IEER OH Capacity RAC ENERGY **∗**

**=**

W here:

RAC ENERGY = r oom air conditioner annual energy consumption (kWh/year), Capacity = r ated capacity in Btu/h,

O

H = o perating h ours per year, C

EE R = Combined Energy Efficiency Ratio in Btu/h/W.

DOE began with the data reported by RECS 2005 on the annual energy consumption ( field energy consumption ) for room air conditioning , referred to as FEC (all) RECS

. The reported

end

- use quantities were not based on metering of individual appliances ; rather, EIA used a regression technique t o estimate how much of the total annual electricity consumption for each

household can be attributed to each end

- use category. e

e 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. Fo r more information, see: h ttp://www.eia.doe.gov/pub/consumption/residential/append_c.pdf T he reported f ield energy consumption

refers to the consumption of all of the room air conditioners in a ho me

.7-15 RECS 2005 also reports the number of room air conditioners in the home. Of all homes

that use a room air conditioner

, 35 percent have two room air condition er s and 14 percent have

three or more room air conditioner s

. To estimate the energy consumption of a single room air

conditioner

, referred to as FEC RECS

, DOE divided FEC (all) RECS by the reported number of room air conditioners

. For houses with both central air conditioning and room air conditioning, DOE

scaled FEC (all) RECS using a relative use factor. For more information on the relative use factor used, see a ppendix 7

- C. Although in reality the utilization of each of the room a ir conditioners in a home may vary, DOE ha s no way to estimate such variation.

For comm ercia l

- sector room air conditioners , CBECS does not report annual energy consumption for room air conditioning

, so DOE estimated the energy consumption using variables specific to each building in the sample and data on cooling degree

- days.

In conducting the analysis of energy use by products that would meet some future

standard , DOE effectively substitute d the r oom air conditioners in the sample residential and

commercial building s with a new product of identical product class (capacity) but with different energy efficiency

. In order for the estimate of new room air conditioner energy consumption to
reflect field conditions, DOE needed to estimate the number of room air conditioner operating

hours for each household or commercial building in the samples.

7.4.2 Operating Hours

7.4.2.1 Residential

DOE calculated the annual room air conditioner active mode operating hours for each

residential sample unit using the following formula:

CDDAdj dj BldgShellA Capacity EER FEC OH RECS RECS * * **∗**

**=**

Where:

OH = o perating hours per year

, FEC RECS = field energy consumption for a room air conditioner

, EER RECS = the estimated EER of the room air conditioner in the sample home

, Ca pacity = the room air conditioner capacity in Btu/h, BldgShellAdj = adjustment to building shell efficiency in 2014, precent, CDDAdj = coolin g degree days (CDD) adjustment in Btu/h.

The derivation of FEC RECS w as discussed above. The capacit y is given by the product class; DOE used the same representative capacities for each class as it did in the engineering analysis.7-16 To ensure that the estimated operating hours are representative of future conditions, DOE used the building shell index factor from Annual Energy Outlook ( AEO ) 2010 in 2014 for space cooling in all homes of 0.96 and 115 year historical average CDD by census division. The building shell index factor decreased energy use by 4 percent, while the CDD adjustment factor decreased energy use by 10 percent on average.

DOE estimated the EER of the room air conditioner in each sample household by

matc hing the age of the room air conditioner given by RECS with the average EER for the specific product class in the year of its vintage

. In RECS, the age of a room air conditioner is given in one of the five bins shown in Table 7. 4 .1

. DOE assumed a uniform distribution within each vintage bin and assigned an age to the room air con ditioner in each sample household

.

Table 7.4.1 RECS Vintage Bins for R oom Air Conditioner

Bin Age of unit

1 Less than 2 years old

2 2 to 4 years old

3 5 to 9 years old

4 10 to 19 years old

5 20 years or older

Once the vintage year was determined, DOE assigned an EER to the unit equal to the average EER for the appropriate capacity for that year. To derive a time series of average EER by capacity , DOE began with data from AHAM on total shipment

- w eighted average EER for

197 2

– 2007

. 12 AHAM also provided average EER data by product class (capacity) for 2005

– 2007

. 12 To develop the EER values by product class (capacity) for earlier years

, DOE first assumed that all of the products shipped in each product class had the minimum efficiency required by the standard in each particular year. DOE then estimated the shares of total shipments by product class in each year us ing data for 1990

, 1993 and 2005

– 2007 , and

calculated a total shipment

- weighted EER. DOE then calculated scalars f or each year from the

ratio of the actual total shipment

- weighted EER to the calculated EER, and then applied the scalars to the minimum efficiency required for each product class in each year. Table 7. 4 .2 shows the AHAM data on total shipment

- weighted average EER and the average EER estimated

for the representative product classes

.7-17 Table 7.4.2 Average Room Air Conditioner EER by Product Class and Year Sold

Year Shipment Weighted EER Derived Average EER*

< 6000

Btu/h 8000

- 13,999

Btu/hr (PC 3) ≥ 20,000

Btu/hr 8000

- 13,999

Btu/hr (PC 8)

2007 9.81 9.80 10.10 9.10 9. 5 0

2006 10.02 9.80 10.40 9.20 9.5 0

2005 9.95 9.80 10.10 9.10 9.40

2004 9.71 9.70 9.86 8.83 9.15

2003 9.75 9.70 9.92 8.89 9.21

2002 9.75 9.70 9.92 8.88 9.21

2001 9.63 9.70 9.80 8.50 8.73

2000** 9.3 9.03 9.70 8.50 8.73

1999 9.07 8.56 9.63 8.50 8.73

1998 NA 8.56 9.63 8.50 8.73

1997 9.09 8.57 9.64 8.50 8.73

1996 9.08 8.55 9.62 8.50 8.73

1995 9.03 8.49 9.55 8.50 8.73

1994 8.97 8.42 9.47 8.50 8.73

1993 9.05 8.50 9.56 8.50 8.73

1992 8.88 8.31 9.35 8.50 8.73

1991 8.8 8.24 9.27 8.45 8.73

1990** 8.73 8.18 9.20 8.39 8.69

1989 8.48 7.95 8.95 8.15 8.45

1988 8.23 7.72 8.68 7.91 8.20

1987 8.06 7.56 8.51 7.75 8.03

1986 7.8 7.32 8.23 7.50 7.77

1985 7.7 7.22 8.13 7.40 7.67

1984 7.48 7.02 7.89 7.19 7.45

1983 7.29 6.84 7.69 7.01 7.27

1982 7.14 6.70 7.53 6.86 7.12

1981 7.06 6.62 7.45 6.79 7.04

1980 7.02 6.58 7.41 6.75 7.00

1978 6.72 6.44 7.25 6.60 6.85

1972 5.98 6.30 7.09 6.46 6.70

* Shaded area values were provided by AHAM 12

** Years in which standards became effective

The estimated mean number of operating hours for the residential room air conditioner sample is 756 h ours for the < 6

, 000 Btu/h product class, 6 11 h ou r s for 8,000 to 13,999 Btu/h product classes, and 175 h ours for the ≥ 20,000 Btu/h product class es

. For comparison, t he DOE test procedure uses 750 hours per year for all room air conditioners

. 37-18 7.4.2.2 Commercial

DOE calculated the annual operating hours for each sample commercial

- sector room air

conditioner by establishing a relationship between cooling de gree

- days and operating hours for a number of building type and building schedule combinations. DOE assumed that a room air

conditioner is operated when the outdoor air conditions are above the comfort zone described by

ANSI/ASHRAE Standard 55

- 2004 Thermal Environmental Conditions for Human Occupancy. 13

To estimate how often t his occurs, DOE us ed the following general equation:

OH 55 = (a * CDD) + b

Where:

OH 55 = a verage annual hours when the outdo or air conditions are above the

ASHRAE Standard 55 comfort zone

, CDD = the number of annual cooling d egree

- days (65 F) for a giv en location;

a and b are linear fit parameters.

DOE used data on cooling degree

- days from the National Solar Radiation Database (NSRDB)

. 14 The 1991

– 2005 NSRDB is an update of the 1961

– 1990 NSRDB. This updated NSRDB dataset is an hourly ground

- based data set of solar and meteorological fie lds for 1

, 45 4

stations. A total of 858 sites have a complete 15

- year period of record.

After removing the sites in Hawaii, Guam, and the Caribbean islands, regressions were done to predict the hours per year above Standard 55 from the number of cooling degree

- days for

each year. The data points and regression lines are shown in Figure 7. 4 .1 for all hours of the

year. The data represent 842 sites for 15 years each in the continental United States.7-19 Figure 7.4.1 Hours Above ANSI/ASHRAE Standard 55

- 2004 as a Function of Cooling Degree

- Days

As can be seen in the graph above , the data patterns are different for desert locations

, where humidity is not a present factor affecting comfort. The regression equations developed

from the data are shown in Table 7.4 .3

.

Table 7.4.3 Regression Equations Region E quation R 2 # sites

Non

- desert OH55 = 2.759 x CLDD + 127.99 0.9224 809

Desert OH55 = 1.153 x CLDD + 574.04 0.8714 33

For a given location, t he number of annual hours above the ASHR AE Standard 55

comfort zone varies by schedule , which refers to the time that a building is open

. Thus, DOE performed the regression for a number of combinations of building type and building schedule

, yielding somewhat different equations for each combination

. The building types included are : Assembly, Education, Food Service, Office, Retail, and Warehouse. For e ach building type

, DOE estimated operating hours for the following building schedule s : (1) open 24 hours a day and seven days a week (24/7); (2) open business hours Monday through Friday; (3) open business hours Monday through Saturday; (4) open business hours Monday through Friday and Sunday; (5) open business hours all week. Each of these schedules yields a variation of the

above equations

. CLDD vs #hours > ASHRAE Std55 all day, all year 1991-2005

y = 2.7592x + 127.99

R 2 = 0.9224

y = 1.153x + 574.04

R 2 = 0.8714

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

0 500 1000 1500 2000 2500 3000 3500

CLDD (base 65F)hours/year above ASHRAE Std 55

non-desert

desert

Linear (non-desert)

Linear (desert)7-20 To estimate the room air conditioner operating hours for each of the building s in the

CBECS room air conditioner sample, DOE identified the building type and the building schedule using information provided by CBECS , and used the appropriate equation (non

- desert or desert )

combined with the number of cooling degree

- days for the location of the building

. It adjusted

the result s with a scaling factor to account for the difference between the number of building operating hours assumed to derive the equations and the actual b uilding operating hours reported by CBECS

.

The above approach provide s a ‘best guess’ of the room air conditioner operating hours for a particular CBECS building

. However, o perating hours are affected by some factors not included in the analysis, such as interior heat gains from equipment or people and solar gains . To develop a range for the number of operating hours for each sample building

, DOE added an error

band to the value derived using the regression equation. The error band includes values that are ± 10% from the regression line for the appropriate building type/schedule combination.

The estimated mean number of operating hours is 1, 142 h ours for the < 6

, 000 Btu /hr product class, 1, 054 h ours for the 8,000 to 13,999 Btu /hr product classes, and 1,1 13 h ours for the greater than 20,000 Btu/hr product class es

.

The commercial sector operating hours were estimated based on the cooling climate in

2003. To match the 115 year CDD average values , DOE decreased the estimated comm ercial sector operating hours by 2 percent on average.

7.4.3 Variability of Room Air Conditioner Annual Energy Consumption

Figure s 7. 4 .2 to 7. 4

. 13 show the range of average annual energy consumption by efficiency level within the residential and commercial samples for each representative product class. The higher utilization of room air conditioners in the commercial sector is evident in the figures.7-21 Figure 7.4.2 Range of Annual Energy Use for Residential Room

Air Conditioner s w ithout Reverse Cycle and with Louvers, l ess than 6,000 Btu/h

Figure 7.4.3 Range of Annual Energy Use for Residential Room

Air Conditioner s w ithout Reverse Cycle and with Louvers, 8,000

– 13,999 Btu/h 0 200 400 600 800 1000 1200

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Energy Use (kWh)

Efficiency Level Residential <6,000 Btu/h, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Energy Use (kWh)

Efficiency Level Residential 8,000

- 13,999, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average7-22 Figure 7.4.4 Range of Annu al Energy Use for Residential Room

Air Conditioner s w ithout Reverse Cycle and with Louvers, 20,000

– 24,999 Btu/h

Figure 7.4.5 Range of Annual Energy Use for Residential Room

Air Conditioner s w ithout Reverse Cycle and with Louvers, greater than 25,000 Btu/h 0 200 400 600 800 1000 1200 1400 1600

Level 0 Level 1 Level 2 Level 3 Level 4Annual Energy Use (kWh)

Efficiency Level Residential 20,000

- 24,999 Btu/h, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average

0 200 400 600 800 1000 1200 1400 1600 1800

Level 0 Level 1 Level 2 Level 3Annual Energy Use (kWh)

Efficiency Level Residential >25,000 Btu/h, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95% median

average7-23 Figure 7.4.6 Range of Annual Energy Use for Residential Room

Air Conditioners w ithout Reverse Cycle and without Louvers, 8,000

– 10,999 Btu/h

Figure 7.4.7 Range of Annual Energy Use for Residential Room

Air Conditioners w ithout Reverse Cycle and without Louvers, greater than 11,000 Btu/h 0 200 400 600 800 1000 1200 1400 1600

Level 0 Level 1 Level 2 Level 3 Level 4Annual Energy Use (kWh)

Efficiency Level Residential 8,000

- 10,999 Btu/h, without Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average

0 500 1000 1500 2000 2500

Level 0 Level 1 Level 2 Level 3 Level 4Annual Energy Use (kWh)

Efficiency Level Residential >11,000 Btu/h, without Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average7-24 Figure 7.4.8 Range of Annual Energy Use for Commercial Room

Air Conditioners w ithout Reverse Cycle and with Louvers, Less than 6,000 Btu/h

Figure 7.4.9 Range of Annual Energy Use for Commercial Room

Air Conditioner s w ithout Reverse Cycle and with Louvers, 8,000

– 13,999 Btu/h 0 200 400 600 800 1000 1200 1400 1600 1800

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Energy Use (kWh)

Efficiency Level Commercial <6,000 Btu/h, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average

0 500 1000 1500 2000 2500 3000

Level 0 Level 1 Level 2 Level 3 Level 4 Level 5Annual Energy Use (kWh)

Efficiency Level Commercial 8,000

- 13,999 Btu/h, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average7-25 Figure 7.4.10 Range of Ann ual Energy Use for Commercial Room

Air Conditioner s w ithout Reverse Cycle and with Louvers, 20,000

– 24,999 Btu/h

Figure 7.4.11 Range of Annual Energy Use for Commercial Room

Air Conditioner s w ithout Reverse Cycle and with Louvers, greater than 25,000 Btu/h 0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Level 0 Level 1 Level 2 Level 3 Level 4Annual Energy Use (kWh)

Efficiency Level Commercial 20,000

- 24,999 Btu/h, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Level 0 Level 1 Level 2 Level 3Annual Energy Use (kWh)

Efficiency Level Commercial >25,000 Btu/h, with Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average7-26 Figure 7.4.12 Range of Annual Energy Use for Commercial Room

Air Conditioners w ithout Reverse Cycle and without Louvers, 8,000

– 10,999 Btu/h

Figure 7.4.13 Range of Annual Energy Use for Commercial Room

Air Conditioners w ithout Reverse Cycle and without Louvers, greater than 11,000 Btu/h 0 500 1000 1500 2000 2500 3000 3500

Level 0 Level 1 Level 2 Level 3 Level 4Annual Energy Use (kWh)

Efficiency Level Commercial 8,000

- 10,999 Btu/h, without Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average

0 500 1000 1500 2000 2500 3000 3500 4000

Level 0 Level 1 Level 2 Level 3 Level 4Annual Energy Use (kWh)

Efficiency Level Commercial >11,000 Btu/h, without Louvers, Average Annual Energy Use Average; Median; Box 25%

- 75%; Whisker 5%

- 95%

median

average7-27 7.4.4 Average Annual Energy Consumption by Efficiency Level

Tables 7

. 4

. 4 through 7

. 4

. 9 show the considered efficiency levels and corresponding calculated average annual energy consumption for each product class when the product is used in

the residential or commercial sector.

Table 7.4.4 Roo m Air Conditioner, Without Reverse Cycle and with Louvers, less than 6,000 Btu/h: Average Annual Energy Use
Efficiency

( CEER ) Residential (kWh) Commercial (kWh)

9.52 401 599

10.1 376 565

10.6 358 539

11.1 342 514

11. 4 334 502

11. 7 326 489

Table 7.4.5 Room Air Conditioner, Without Reverse Cycle and with Louvers, 8,000

– 13,999 Btu/h: Average Annual Energy Use
Efficiency

( CEER ) Residential (kWh) Commercial (kWh)

9.69 636 1088

10.2 604 1035

10.7 576 987

10.9 565 969

11.5 535 918

12.0 514 8837-28 Table 7.4.6 Room Air Conditioner, Without Reverse Cycle and with Louvers, 20,000

- 24,999 Btu/h: Average Annual Energy Use
Efficiency

( CEER ) Residential (kWh) Commercial (kWh)

8.47 506 3153

9.0 477 2968

9.4 452 2841

9.8 434 2726

10. 2 419 2630

Table 7.4.7 Room Air Conditioner

, Without Reverse Cycle and with Louvers, greater than 25,000 Btu/h : Average Annual Energy Use
Efficiency

( CEER ) Residential (kWh) Commercial (kWh)

8.48 589 3153

9.0 555 2969

9.4 526 2842

9.8 505 2726

Table 7.4.8 Room Air Conditioner, Without Reverse Cycle and with Louvers, greater than 25,000 Btu/h: Average Annual Energy Use
Efficiency

( CEER ) Residential (kWh) Commercial (kWh)

8.41 523 1252

9.3 474 1133

9.6 459 1098

10.0 438 1055

10. 4 423 10187-29 Table 7.4.9 Room Air Conditioner, Without Reverse Cycle and with Louvers, greater than 25,000 Btu/h: Average Annual Energy Use
Efficiency

( CEER ) Residential (kWh) Commercial (kWh)

8.44 779 1498

9.3 707 1360

9.5 693 1332

9.8 668 1291

10.0 654 1262

7.4.5 Estimating Room Air Conditioner Energy Use by Month

Room air conditioner use is concentrated in the warm parts of the year. In conducting the LCC analysis for room air conditioners (see chapter 8), DOE used monthly electricity prices because electricity tariffs show seasonal variation in many parts of the c ountry. Therefore, to properly calculate room air conditioner operating costs, DOE needed to estimate how the annual

room air conditioner ele ctricity use for each sample household is apportioned over the year.

To estimate ele ctricity use by month, DOE ut ilized data on seasonal climate variation , as measured by cooling degree

- days . RECS 2005 provides data on yearly heating and cooling degree

- days for each household in the sample, but does not break this information down by

month. To estimate monthly coolin g degree days for the households in the RECS sample, DOE developed an approach to match each household with a corresponding NOAA weather station. After matching the household to a weather station location, DOE utilized the monthly cooling

degree day data f rom the corresponding weather station to estimate the percentage of household

energy use per month. See a ppendix 7

- D for more details.7-30 REFERENCES

1. U.S. Department of Energy

- Energy Information Administration, Residential Energy Consumption Survey: 2005 Public Use Data Files, 2005.

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

2. U.S. Department of Energy

- Energy Informa tion Administration, Commercial Buildings Energy Consumption Survey, 2003. < http://www.eia.doe.gov/emeu/cbecs/ >

3. Department Of Energy, 10 CFR Part 430 Energy Conservation Program for Consumer

Products: T est Procedures for Clothes Dryers and Room Air Conditioners; Final Rule

. Federal Register , 2011. 76 No.4: pp. 972

- 1036

< http://www1.e ere.energy.gov/buildings/appliance_standards/residential/pdfs/aham2_tp_ final_rule_notice_fr.pdf >

4. California Energy Commission, California Energy Commission Appliance Efficiency Database, 2010. (Posted July) < http://www.energy.ca.gov/appliances/database/ >

5. Association of Home Appliance Manufacturers, AHAM Data on Room Air Conditioners and Clothes Dryers

. 2009

6. Pescatore, P. and P. Carbone, High Efficiency, High Performance Clothes Dryer

, March 31, 2005. TIAX. Report No. D0040. < http://www.osti.gov/bridge/servlets/purl/888669

- 2VIDn8/888669.pdf >

7. Hekmat, D. and W. J. Fisk, IMPROVING THE ENERGY PERFORMANCE OF
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< http://escholarship.org/uc/item/2f3347r8 >

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- using

- Products (EuP)

– Lot 16, June 30, 2008.

CODDE. < http://www.ecodryers.org/ >

9. U.S. Department of Energy: Energy Information Administration, Residential Energy Consumption Survey: 2005 Public Use Data Files . 2008: Washington, DC. http://www.eia.doe.gov/emeu/recs/recspubuse05/pubuse05.html

10. U.S. Census Bureau: Housing and Household Economic Statisti cs Division, American Housing Survey National Data . 2009, HUD. http://www.huduser.org/portal/datasets/ahs/ahsdata09.html

11. Rüdenauer, I. and C.

- O. Gensch, Energy demand of tumble dr yers with respect to differences in technology and ambient conditions, January 13, 2004. European Committee of Domestic Equipment Manufacturers (CECED). < http://www.aib

-7-31 deutschland.de/das_institut/mitarbeiterinnen/dok/630.php?id=40&dokid=202&anzeige=d

et&ITitel1=&IAutor1= >

12. Association of Home Appliance Manufacturers (AHAM), Trends in Energy Efficiency

2008

13. American Nat ional Standards Institute & American Society of Heating, R., and Air

Conditioning Engineers, Inc.,, ANSI/ASHRAE 55

- 2004 Thermal Environmental Conditions for Human Occupancy , 2004.

14. National Renewable Energy Laboratory, National Solar Radiation Databas e 1991

– 2005 Update: User’s Manual, 2007. < http://www.nrel.gov/docs/fy07osti/41364.pdf >