Reference NBS

PUBLICATIONS

NBSIR 85-3220

AlllOb 034120

A Review of Energy Use Factors

for Selected Household

Appliances

J. Greenberg

B. Reeder

S. Silberstein

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Gaithersburg, Maryland 20899

August 1985

Prepared for

U.S.

-QC

100

• U56

85-3220

1985

Department of Energy

3 of Building Energy

rch and Development

ng Equipment Division

ington, DC 20585

NATIONAL BUREAU OF STANDARDS

LIBRARY *

/jAS* Bcf

NBSIR 85-3220 ® C

»

» ' j qO

A REVIEW OF ENERGY USE FACTORS

FOR SELECTED HOUSEHOLD

APPLIANCES

J. Greenberg

B. Reeder

S. Silberstein

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Gaithersburg, Maryland 20899

August 1985

Prepared for U.S. Department of Energy

Office of Building Energy

Research and Development

Building Equipment Division

Washington, DC 20585

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Director

TART.K OF OONTENTS

Section Page

INTRCDUCTION. . V

SUMMARY OP RESUXTS vii

I WATER HEATER - INLET WATER TEMPERATURE. 1-1

II WATER HEATER - OUTLET WATER TEMPERATURE. 2-1

III WATER HEATER - AMBIENT AIR TEMPERATURE. 3-1

IV WATER HEATER - HOT WATER USAGE 4-1

V FURNACES - OUTDOOR DESIGN TEMPERATURE 5-1

VI FURNACES - AVERAGE ANNUAL HEATING HOURS 6-1

VII ROOM AIR CONDITIONERS - YEARLY HOURS OF USE 7-1

VIII CENTRAL AIR CONDITIONERS - ANNUAL FULL LOAD COMPRESSOR

OPERATING HOURS 8-1

Figure LIST OF FIGURES Page

1-

1 Median Annual Temperature of Surface Water. 1-7

2-

1 Water Heater Thermostat Dials (Typical) 2-9

7-

1 AHAM-Room Air Conditioner Average Compressor

Hours of Operation Per Year 7-8

8-

1 Compressor Hours Per Year at 75°F Set Point 8-11

8-2 Compressor Hours Saved Per Year At Day Setup of

80°F From 5:00 a.m. to 4:00 p.m. 8-12

8-3 Compressor Hours Saved Per Year at a Constant

78°F Set Point 8-13

8-4 Distribution of Cooling Load Hours Throughout the

Continental United States... 8-17

Table LIST OF TABLES Page

1-

1 Housing Population-Weighted Average Surface

Water Temperature 1-8

2-

1 Shipments of Residential Water Heaters 2-10

2-

2 Average Outlet Water Temperature By Year 2-10

3-

1 Housing Basement Data (All Year Round Heating Units) 3-7

3-2 Single Family Basement Data (Single Family Units - 1982)... 3-8

3-3 Percentage of U.S, Households by Inside Temperature - (Single Family Residences - As of November 1982) 3-9

5-

1 Housing Population-Weighted Average Outdoor Winter

Design Temperature 5-5

6-

1 Housing Population-Weighted Average Annual Degree Days 6-8

7-

1 Population-Weighted Average Hours of Operation for

Room Air Conditioner Units 7-9

8-

1 Central Air Conditioner Compressor Hours Per Year

at 75°F Set Point.. 8-14

iii
8-2 Central Air Conditioner Annual Compressor Hours of

Operation at 75°P Set Point Reduced to 80°P Prom

5:00 a.m, to 4:00 p.m 8-15

8-3 Central Air Conditioner Annual Compressor Hours of

Operation at 78°F Set Point, 8-16

8-4 Central Air Conditioner Annual Full Load Compressor

Hours of Operation at 75°F Set Point 8-18

8-5 National Average Summary of Air Conditioner Annual

Compressor Hours. 8-19

IV
INTRCDUCTION

The Energy Policy and Conservation Act (EPCA) as amended by the

National Energy Conservation Policy Act (NECPA) requires the development of

test procedures, labeling rules, and energy efficiency standards for

consumer appliances. These requirements must be established using

representative national data when establishing the various parameters for

each appliance.

During the process of establishing test procedures, labeling rules,

and energy efficiency standards, many of the parametric values used have

been questioned through written comment and public hearings. The purpose

of this report is to re-evaluate selected parametric values through

analysis of current data, and provide comment and recommendations.

Each parameter reviewed is documented in an independent section in

this report. As such, each section indicates the current value, the

historical basis for the current value, the approach used to review and

update the value, the results and conclusions, and recommendations. The

recommendations generally propose a new value for the parameter studied

based upon the information analyzed.

Although the parameters are treated separately, their relationships to

one another is noted in each section, as applicable. For example, the

delta T factor for water heaters (outlet water temperature minus inlet

water temperature) is an important parameter for water heater energy

studies, however, the outlet and inlet temperatures are evaluated in

separate sections in this report and left to the reader to relate. On the

other hand, outdoor design temperature is also addressed separately,

however, the results of this study are also included and used in the

V
section that evaluates annual heating load hours.

Where possible, the data used to determine a recommended value are

included as a table or figure in this report, This will allow the reader,

if he is so inclined, to check the values selected, especially in those

cases where there is a degree of subjectivity involved and there is roan

for individual judgement.

Finally, it should be noted that no evaluation has been made to

determine the impact of any recommended revision to the currently used

values on existing or proposed test procedures, energy savings, or

appliance economic studies.

VI
SUMMARY OF RESULTS

The results of the individual studies detailed in the following sections

are summarized below for easy reference.

SECTION PARAMETER STUDIED

CURRENT

VALUE

PROPOSED

VALUE

I Water Heater -

Inlet Water Temperature

55°F 58°F

II Water Heater -

Cutlet Water Temperature

145°F 135°F

III Water Heater - Ambient Air Temperature

55°F 65°F

IV Water Heater -

Hot Water Usage

64.3

gal/day

60

gal/day

V Furnaces -

Cutdoor Design Temperature

5°F 17°F

VI Furnaces -

Annual Heating Load Hours

2080 hrs 2080 hrs

VII Room Air Conditioners -

Yearly Hours of Use

750

hr/yr

670

hr/yr

VIII Central Air Conditioners - Annual Full Load Compressor

Operating hours

1000

hr/yr

1150

hr/yr

Vll

SECTION I

WATER HEATER

INLET WATER TEMPERATURE

CURRENT VALUE: 55°F

PROPOSED VALUE : 58°F

HISTORICAL BASIS FOR CURRENT VRUJE

Test methods were developed for water heaters in 1977 [1, 2]* in

support of Public Law 94-163 which required the Federal Energy

Administration [now the Department of Energy] to carry out energy

conservation activities related to household appliance efficiency. These

test methods were developed by the National Bureau of Standards with

cooperation from the Gas Appliance Manufacturers Association and were based

on the ANSI Standards Z21.10.1 for Gas Water Heaters and C72.1 for Electric

Water Heaters and on earlier test procedures published in the Federal

Register on August 14, 1975 (40 FR 158) for the Commerce Department

Voluntary Labeling Program.

The test procedures of Reference [1] (Section 2.1.2. 4) provide a

rationale for selecting a National average inlet water temperature of 55°F.

The average water temperature is calculated as the mean of annual median

temperatures for subdivisions of the United States and the water heater

inlet water temperature for each of these subdivisions is considered to be

equivalent to the local surface water temperature of streams, rivers, and

lakes. This average surface temperature throughout the United States is

approximately 55°F.

Numbers in brackets pertain to references listed at end of each

section.

1-1
A study of Household Appl lance Usage Data [3] also cites an inlet

water temperature of 55°P for water heaters. The report comments that this

value has a marginal empirical basis, and in view of the importance of

water heaters to the energy program, recommends independent field

verification.

Reference [1] also states that it would be inappropriate to specify an inlet water temperature of 55°P for laboratory test purposes since this

would require cooling of the tap water in the summer months when tap water

temperature can be above 55°F, Therefore, a 70°P ± 2°F feed-water

tenperature which can normally be achieved in laboratories throughout the

year is specified in the test procedures. This increase of 15°F is also

matched by a 15°F increase in outlet tenperature from 145°P to 160°F (see

SECTION II - WATER HEATERS - OUTLET WATER TEMPERATURE) to maintain a

specified at (outlet water tenperature minus inlet water tenperature).

APPROACH PQR UPDATE

The current value of 55°F is based on the average for all regions of

the United States of the median annual surface water temperature of the

streams, rivers, and lakes in those regions. No consideration, however,

is given to the specific location of the Nation's housing units. For

example, if all housing units were located in the southern parts of the

country, we might expect a higher average water heater inlet tenperature

than if all the housing units were located along the Canadian border.

Therefore, in calculating the average inlet water tenperature, the median

annual water temperature of an area should be weighted by the number of

water heaters in that area. In effect, the average water heater inlet

temperature is not an unchanging geological quantity, as the average annual

surface or ground water temperature might be, but rather changes with

population shifts. Concurrent with the continuing population migration to

1-2
the warmer regions of the United States [5, 6] , the average water heater

inlet temperature should also be increasing.

Accordingly, the approach taken was to estimate water heater inlet

temperature on a housing population-weighted basis and average surface

water teirperatures for each State as described below. Temperatures were

then weighted by the State's 1980 housing population to calculate a

National average water inlet temperature. Ibis was also done for the 1970

population to verify the upward inlet water temperature change from 1970 to

1980 in keeping with population shifts.

RESULTS AND DISCUSSION

In this study, the median annual surface-water temperatures in the

conterminous United States were used [4]. These temperatures were

determined by the U.S. Geological Survey and are reflected on a map showing

isothermal bands of median annual temperature ranges for surface water (see

Figure 1-1). The bands generally have a 5°F spread; however at the highest

and lowest ranges, the bands represent surface water teirperatures of "70°F

or higher" and "39°F or less," respectively.

Using the U.S. Geological Survey map, a single representative water

heater inlet temperature was estimated for each State (see Table 1-1).

Where a single isothermal band covers a State, the midpoint of the band was

generally used. Where more than one band covers a State, an average inlet

water temperature for the entire State was not assigned solely on the

geographical distribution of the isothermal bands within the State, but was

based on the housing population distribution. For example, if a State was

covered by two isothermal bands, a uniform housing population would lead to

selection of the boundry temperature of the two bands. If, however, the

centers of population were generally located within one of the bands, a

surface water temperature within that band was selected to represent the

1-3
average inlet water temperature for that State.

The above method is subjective in that judgment was required to select

a representative inlet water tenperature for each State, especially for

those States which lie in areas which have no fixed upper or lower limits

to the isothermal bands (bands that are defined as 70°F or higher? or bands

defined as 39°F or less). Nevertheless, it is felt that a fair assessment

has been made and that the selected temperatures shown in Table 1-1 would

vary by a small amount even in those cases where there is room for other

assessments of individual State inlet water temperatures. The overall

results, however, should not be significantly altered as a result of these

differences.

Also important to this stud/ is the location of the Nation's housing

population. This was determined by the use of 1980 census data [5] . The

1980 housing census divides housing by number of units per building:

single-family units; 2-9 units per building? and more than 9 units per

building. (The number of single family and 2 to 9 units per building, by

State, are also tabulated in Table 1-1.) Since this study is focused on

small residential water heaters it was assumed that all single-family units

would have one water heater each and that buildings having more than 9

units would not have any residential size water heaters. For buildings

having 2-9 units, calculations were made assuming that only one-eighth of

the units had individual water heaters? two-eights of the units had

individual water heaters, etc.? and finally, that all of these units had

individual water heaters. The coirputed fractions were added to the singlefamily units to arrive at State residential water heater populations for

each increment.

1-4
The above information permitted the calculation of a weighted National

average inlet water temperature for small residential water heaters by

multiplying the number of water heaters per State by the average water

surface temperature, adding the products, and dividing by the total

estimated number of water heaters. This information is presented in

Table 1-1 for single-family units and for 2-9 units incremented as

described above. As can be seen, the housing population-weighted average

water inlet temperature is 58^°F for single-family houses and varies from

58.2°F to 58.4°F if buildings having 2-9 dwelling units are included in the

estimate. This shows that neglecting multi-unit buildings has little

effect on the average inlet water temperature.

To see whether the housing population-weighted average inlet water

temperature increased from 1970 to 1980 as might be expected by population

movement to wanner climates, the same calculations were also performed for

single-family houses using 1970 census data [6]. The 1970 census divides

the population into only 2 categories: single-family and more than one

unit per dwelling. Only single-family data were used and are shown in

Table 1-1 along with the calculated average water inlet temperature of

58.2°F for 1970. The increase in housing population-weighted average inlet

water temperature for single-family units from 58.2°F for 1970 to 58.5°F

for 1980 is in the expected direction. Because any errors made in

estimating tenperatures, especially those arising from considering only

single-family houses, were probably similar for the two years studied, this

change in tenperature is probably fairly accurate.

E ENDATIQNS

Lacking field data and in view of the information presented above, a

National inlet water tenperature for residential water heaters of 58°F is

1-5
recommended, ttiis factor should be reviewed if significant field data of

actual inlet water temperatures are collected or other information

becomes available that has the potential to provide further refinement.

REFERENCES

[1] Test Procedure Review-Water Heaters; Recommendations concerning test

procedures to be proposed for use under Public Law 94-163 for Federal

Energy Administration Appliance Efficiency Program by the National

Bureau of Standards, Center for Consumer Product Technology,

March 10, 1976 Revised April 21, 1977.

[2] Federal Register; Federal Energy Administration; Energy Conservation

Program for Appliances; Test Procedures for Water Heaters; Tuesday,

October 4, 1977; Part III.

[3] Household Appliance Usage Data; NBSIR 80-1994; Alan D. Davies, et.

al. ; dated February 1980 (Final Report issued March 1980)

[4] J. F. Blakey; "Temperature of Surface Waters in the Conterminous

United States;" U.S. Geological Survey Hydrologic Investigations Atlas

HA-235; Washington, D.C., 1966.

[5] U.S. Department of Commerce,"1980 Census of Housing Volume 1,

Characteristics of Housing Units; Chapter A, General Housing

Characteristics; Part 1, United States Summary."

[6] U.S. Department of Commerce, "1970 U.S. Census of Housing; Volume 1,

Housing Characteristics for State, Cities, and Countries; Part 1,

United States Survey."

1-6
1-7

MEDIAN!

ANNUAL

TEMPERATURE.

Of

SURFACE

WATER
TABLE 1-1

HOUSING POPULATION-WEIGHTED AVERAGE SURFACE WATER TEMPERATURE

STATE

ASSUMED

AVERAGE

HOUSING POPULATION (IN THOUSANDS)

INLET 1970 CENSUS 1980 CENSUS WAlhK TEMPERATURE

°F SINGLE FAMILY

UNITS

SINGLE FAMILY

UNITS

2-9 UNITS PER BUILDING

Alabama 67 929 1,168 111 Arizona 70 426 745 87 Arkansas 65 577 725 62 California 63 4,696 6,440 1,148

Colorado 52 534 835 107 Connecticut 56 572 794 241 Delaware 55 133 170 21 District of Columbia 57 102 127 58 Florida 73 1,740 2,798 429 Georgia 64 1,107 1.525 205 Idaho 47 192 272 33 Illinois 52 2,197 2,699 1,025

Indiana 54 1,341 1,655 214 Iowa 52 783 902 117 Kansas 57 645 775 81 Kentucky 57 850 1,045 144 Louisiana 72 897 1,195 149 Maine 47 230 295 83 Maryland 57 852 1,145 202 Massachusetts 55 925 1,257 636 Michigan 46 2,162 2,721 368 Minnesota 47 895 1,128 163 Mississippi 67 598 732 65 Missouri 62 1,228 1,518 243 Montana 42 180 222 40 Nebraska 55 408 493 60 Nevada 50 105 203 39 New Hampshire 47 158 235 71 New Jersey 55 1,334 1,710 638 New Mexico 58 263 347 53 New York 55 2,487 3,096 1,758

North Carolina 62 1,341 1,761 181 North Dakota 42 149 174 38 Ohio 55 2,482 3,119 520

Oklahoma 67 798 1,010 98 Oregon 50 570 812 85 Pennsylvania 52 2,821 3,415 658

Rhode Island 57 159 221 107 South Carolina 64 669 883 89 South Dakota 47 178 200 32 Tennessee 60 1,041 1,373 163 Texas 72 3,069 4,143 450

Utah 52 234 372 54 Vermont 47 99 135 41 Virginia 60 1,112 1,554 206 Washington 47 913 1,225 154 West Virginia 55 491 577 66 Wisconsin 47 999 1,321 262 Wyoming 47 86 118 24

Population-weighted ——— . ————— National average inlet water | 58.2 | 58.5 | 58.2-58.4*

temperature (°F)

* Range is based on the calculation that one-eight of these units had individual water

heater; two-eights had individual water heaters, etc.. The individual calculations

are as follows: 1/8 - 58.4°F; 2/8 - 58.4°F; 3/8 - 58.4°F; 4/8 - 58.3°F;

5/8 - 58 . 3°F; 6/8 - 58.3°F; 7/8 - 58.3°F; 8/8 - 58.2°F.

1-8
SECTION II

OnTr.PT WATER 1 ME

CURRENT VALUE! 145°F

PROPOSED VALUE: 135°F

HISTORICAL BASIS FOR CURRENT VALUE

Test methods were developed for water heaters in 1977 [1] in support

of Public Law 94-163 which required the Federal Ehergy Administration to

carry out energy conservation activities related to household appliance

efficiency. These test methods were developed by the National Bureau of

Standards with cooperation from the Gas Appliance Manufacturers Association

and were based on ANSI Standards Z21.10.1 for Gas Water Heaters and C72.1

for Electric Water Heaters using the appropriate sections from each of

these standards and on earlier test procedures published in the Federal

Register on August 14, 1975 (40 FR 158) for the Commerce Department

Voluntary Labeling Program.

The test procedures of Reference [1] (Section 2.1.2.4) provide a

rationale for selecting a National average outlet temperature of 145°F.

The reason given is that water heater thermostats are factory set to

achieve a tank water temperature of 145°F. Reference [1] (Section 3.2.1)

further states that the setting is assumed to be 145°F because gas water

heater thermostats are normally set for 140°F and electric water heater

thermostats are set for 150°F.

A study made on Household Appliance Usage Data [2] also cites an

outlet water temperature of 145°F for water heaters. The report comments

that the empirical basis for this value is very marginal and in view of the

importance of water heaters to the energy program, independent field

verification of this factor is recommended.

2-1
It should be noted that Reference [1] specifies a thermostat setting

of 160°P when conducting water heater test procedures rather than the

National average outlet temperature of 145°F. This setting was required to

maintain a specified AT (outlet water temperature minus inlet water

temperature) and resulted from raising the inlet water temperature 15°P

(from 55°F to 70°F [±2°F]) during testing so that the tap water used in the

test procedures need not be cooled (see SECTION I - WATER HEATERS - INLET

WATER TEMPERATURE)

APPROACH FOR UPDATE

The current National average for the outlet temperature for water

heaters is derived from thermostat settings of gas and electric water

heaters and were based on practices that were used during the early and

middle 1970's. In conducting this study, it was concluded that this

approach was reasonable and that the data should be updated to reflect

current practices. Towards this end, manufacturers of gas-fired and

electrical resistance water heater control thermostats were contacted as well as water heater manufacturers and trade associations to learn the

temperatures at which units are set at the factory and/or by installers.

In addition, data regarding the number of gas and electric water heaters

manufactured was gathered to provide weighting factors in determining a

single overall value for outlet temperature. Finally, data collected

during field studies of gas and electric water heaters are included.

RESULTS AND DISCUSSION

To determine the settings of electric thermostats for residential

water heaters, representatives of two major manufacturers of water heater

thermostats [3, 4] and two major manufacturers of water heaters [5, 6] were

contacted. According to these representatives, currently-produced electric

water heaters generally have a temperature range setting from 110°F to

2-2
170°F; with index markings every ten degrees F; and a screw-type adjustment

which allows the tenperature to be infinitely set between 110°F and 170°F

(see Figure 2-1) [7]. In addition, each contacted representative stated

that electric water heaters are shipped from the factory at a setting of

140°F as required by the April 18, 1983 Standard - "Household Electric

Storage Tank Water Heaters - UL 174,"

Specifically, the provisions of UL 174 state:

21.1 A temperature-regulating thermostat shall have no marked dial

setting more than 77°C (170°F) and shall be provided with a stop

to prevent its adjustment to a higher temperature setting.

21.3 A temperature-regulating thermostat or control shall be set

before leaving the factory to a control position corresponding to

a 60°C (140°F) setting. This setting may be approximate, as in

the case of a marking that reads "Low-Medium High" or the

equivalent, instead of directly in degrees C or F.

Because the thermostat setting could be changed by the installer or

occupant, each contacted representative was asked about the likelihood of

such a change. It was the consensus that the installer would generally

have no motivation to change the setting. Also, most homeowners are not

familiar enough with the existance or location of the electric water heater

thermostats to make a change and also would generally keep away from

manipulating concealed line voltage electrical controls since most

residential electric water heaters contain two thermostats which can be

reached only after unscrewing a metal cover plate and pushing aside the

water tank insulation which covers the thermostat. It was further

postulated that those individuals who would be likely to perform such an

operation would be those persons who are generally energy conscious and who

would be inclined (and knowledgeable) to make the positive effort to lower

2-3
the thermostat from the 140°P setting. In addition to the above, no field

data were found which actually describe the thermostat settings of recently

installed electric water heaters, Therefore, a National average thermostat

setting for recently installed electric water heaters of 140°F seems

reasonable.

For gas water heaters, information was also obtained from two major

manufacturers of water heater thermostats [3, 4] and two major

manufacturers of water heaters [5, 6] as well as from the American Gas

Association [8], A summary of the responses indicates that there is no

standard, per se, on the significance of thermostat knob markings such as

"Hot", "Energy Savings", "Low", etc. A review of ANSI Z21.23 - 1980 - Gas

Appliance Thermostats [9] reveals that the only reference to temperature

dial marking for water heaters recommends a minimum marking of 100°F and a

maximum marking of 180°F with a calibration reference point of 140°F.

However, the individuals contacted indicated that on most thermostats the

following dial settings and corresponding temperatures are generally

appliable:

HOT 160°F

WARM 120°F

VACATION 110-115°F

In addition, a marking of "energy savings" would generally correspond to a

setting of 130°F (see Figure 2.1(a), (b), (c), (d) ) [10] and that gas water

heater thermostats are set at their lowest setting when the gas water

heater leaves the manufacturer and reset for 130°F during installation. As

a reference, American National Standard ANSI Z21.10.1b - 1983 was cited

[11], Specifically, the provisions state:

1.29 INSTRUCTIONS

1.29.1 Each water heater shall be acconpanied by clear, concise

2-4
printed instructions and diagrams

e. Thermostat information to the effect that:

1. The thermostat is adjusted to its lowest temperature

position when shipped from the factory.

2. The detent or marking, as applicable, on the thermostat

is the preferred starting point for setting the

temperature control (see 1.30.10).

3. Procedures for adjusting the thermostat for energy

efficient operation at the minimum water temperature

setting consistent with the consumers needs.

1.30.10 Each adjustable thermostat shall have a detent or

legible marking on Class III A material consistent with a water

tenperature of approximately 130°F (54.5°C)

The potential for thermostat setting change is greater for gas water

heaters than for electric water heaters since gas water heater thermostats

are more accessible. Older people might lower the setting to avoid

scalding as might energy concious individuals. On the other hand, people

in large households might increase the setting to accommodate a higher

demand for hot water. No field data were found which actually describe the

thermostat settings of recently installed gas water heaters, however, in

view of the above, a National average thermostat setting for recently

installed gas water heaters of 130°F seems reasonable.

With regard to the distribution of gas and electric water heaters

information received from the Gas Appliance Manufacturers Association [12]

indicates an almost even shipment distribution between gas and electric

water heaters (see Table 2-1). With this equal distribution of units and

an average setting for electric water heaters of 140°F and 130°F for gas

water heaters, a single National averge outlet water temperature for

2-5
recently installed gas and electric water heaters of 135°P seems

reasonable.

Because many older water heaters are still in service, outlet

temperatures of older water heaters were also of interest and in a field

study conducted in 1976 - 1977 data were collected for 5 electric and 5

gas-fired normally operating water heaters in new townhouses in

TVin Rivers, New Jersey [13]. In this study, outlet temperatures ranged

from 145.5°F to 163.2°F; with an average outlet water temperature of

158.2°F for gas-fired water heaters and 148.5°F for electric water heaters.

Only one water heater had an outlet temperature below 145°F. Ibis sample

may not have been representative of the National average at the time since

the sample was small, at a single location, and conducted in a test

environment. However, water heaters were generally set at a higher outlet

temperature during that time frame and the Twin Rivers study seems to

confirm this. Since the average lifetime of a water heater is 13 years

[14] , it could be expected that the National average water heater outlet

water temperature settings over a thirteen year period would tend to

approach those of current production due to the effects of energy

conservation activities, the adoption of new standards, the replacement of

older water heaters, and the installation of water heaters in new housing.

CONCLUSIONS. .ANP-Rl [QNS

It appears that the current value for a National averge outlet water

temperature of 145°F for water heaters is probably quite reasonable for the

1984 time frame. However, as the inventory of water heaters is turned over

during the 13 year average lifetime, a value approaching 135°F is more

appropriate. A suggested table of values, by year, is shown in Table 2-2.

The selection of an outlet water temperature would depend on its intended

use.

2-6
If used for test procedure development, the 135°F outlet tenperature

is recommended to reflect a single National average outlet water

temperature for currently produced gas and electric water heaters although

this value might be modified, along with the inlet water temperature, in

order to facilitate testing. If used for energy savings evaluations or

economic studies and a more time dependent value is needed to reflect the

removal of older water heaters from service, the appropriate teiperatures

should be selected from the time/temperature relationship shown in Table 2-

2. If the year in question goes beyond 1990, an update in inlet water

temperature should also be considered to reflect the effects of further

housing population shifts (see SECTION I - WATER HEATERS - INLET WATER

TEMPERATURE) .

REFERENCES

[1] Test Procedure Review-Water Heaters; Recommendations concerning test

procedures to be proposed for use under Public Law 94-163 for Federal

Energy Administration Appliance Efficiency Program by the National

Bureau of Standards, Center for Consumer Product Technology -

March 10, 1976, Revised April 21, 1977.

[2] Household Appliance Usage Data; NBSIR 80-1994; Alan D. Davies, et.

al.; dated February 1980 (Final Report Issued March 1980).

[3] Robert Shaw, Grayson Division, Long Beach, CA.

[4] White Rogers, St. Louis, MO.

[5] Reliance, Ashland City, Tennessee.

[6] Rheem, Chicago, IL.

[7] From a sample of residential electric water heaters used for a variety

of water heater projects at the National Bureau of Standards.

[8] Letter from S. L. Blackman; dated February 27, 1984; American Gas

Association Laboratories; Cleveland, Ohio.

2-7
[9] ANSI Z21.23-1980; American National Standards for Gas Appliance

Thermostats; Approved December 31, 1980; Secretariat American Gas

Association; Arlington, VA.

[10] Fran a sanple of residential gas water heaters used for a variety of

water heater projects at the National Bureau of Standards and from gas

water heaters currently being sold by Sears.

[11] ANSI Z21.10.1b-1983; Addenda to American National Standard Z2.10.l1981, Z21.10.1a-1983; for Gas Water Heaters; Volume 1 - Automatic

Storage Water Heaters With Inputs of 75,000 Btu Per Hour or Less;

Approved February 15, 1983; Secretariat-American Gas Association;

Arlington, VA.

[12] Statistical Highlights; Ten Year Summary, 1973-1982, Gas Appliance

Manufacturers Association; Arlington, VA.

[13] R. A. Grot; Field Performance of Gas and Electric Water Heaters;

Proceedings of the Conference on Major Home Appliance Technology for

Energy Conservation; February 27 - March 1, 1978; Purdue university.

West Lafayette, Indiana.

[14] U.S. Department of Energy; Consumer Product Efficiency Standards

Economic Analysis Document; Report Number DOE/CE 0029 1982;

Washington, D.C.

2-8
Figure 2-1

WATER HEATER THERMOSTAT DIALS (Typica

ELECTNG

GAS

2-9
Table 2-1

JmasE^s.gF..^iPEmftL warn.bbkeebs

(in thousands)

1979 1980 1981 1982 1983

Water Heaters, Gas 2,887 2,818 2,785 3,040 3,172

Water Heaters, Electric 2,661 2,451 2,463 2,716 3,131

Table 2-2

AVERAGE OUTLET WATER TEMPERATURE BY YEAR

Year 84 85 86 87 88 89 90 91 92 93 94 95 96 97

National Average

Outlet Water

Temperature for

Water Heaters

°F

145 144 143 143 142 141 140 140 139 138 137 137 136 135

2-10
SECTION III

WATER HEATER

AMBIENT AIR TEMPERATURE

CURRENT VALUE: 55°F

PROPOSED VALUE; 65°F

HISTORICAL BASIS FOR CURRENT, \%LUE:

Test methods were developed for water heaters in 1977 [1] in support

of Public Law 94-163 which required the Federal Ehergy Administration to

carry out energy conservation activities related to household appliance

efficiency. These test methods were developed by the National Bureau of

Standards with cooperation from the Gas Appliance Manufacturers Association

and were based on ANSI Standards Z21.10.1 for Gas Water Heaters and C72.1

for Electric Water Heaters using the appropriate sections from each of

these standards and on earlier test procedures published in the Federal

Register on August 14 r 1975 (40 FR 158) for the Commerce Department

Voluntary Labeling Program.

The Federal Register documenting proposed rules for the Energy

Conservation Program for Consumer Products [2] includes the determination

of the current value of 55°F for a national average room temperature. It

states "... the national average room ambient air temperature specification

of 55°F was derived by calculation using field data on actual gas and

electric storage water heater energy consumption in the residential sector

obtained from a survey of 50 gas and 50 electric utility companies

conducted by NBS in July 1974." Thirty-eight companies responded to this

survey, eighteen of them supplied metered data. The data obtained were

normalized to a 90°F water temperature rise and a family size of four

persons. Two of the companies responding supplied data on both water usage

3-1
and energy usage. NBS used the data supplied by these two companies to

compute an average energy efficiency factor (combination of recovery

efficiency and standby losses) for gas and electric storage water heaters.

These energy efficiency factors were then applied to the energy use data

supplied by the other companies to derive average hot water usage of

households and associated average room ambient air temperature. Following

this approach, NBS determined the average hot water usage of households to

be 450 gallons per week, or 64.3 gallons per day and the average room

ambient air temperature to be 55°F for the purposes of DOE's test

procedures for water heaters. DOE acknowledged at the time that this

average ambient room temperature specification may or may not simulate

actual ambient temperature conditions where water heaters are installed;

however, the use of this specification coupled with the daily hot water

usage specification of 64.3 gallons per day resulted in calculated values

of energy consumption that agree reasonably well with actual energy

consumption obtained from field data.

In addition, a study of Household Appliance Usage Data [3] addressing

the basis for room ambient temperature, states "no information was provided

on whether the water heaters were usually located outside the house, in

unheated cellars, or inside the heated or air conditioned volumes of

housing units." The study concludes ".... independent field verification

of each of these usage factors is recommended. It is suspected that a

value for Tr [room temperature] nearer to 70°F than to 55°F will be found,

for example."

Finally, reference [2] also states that the existing test procedures

for water heaters require the ambient air temperature to be maintained at a

temperature between 65°F and 85°F (and not vary more than ±7°F throughout

the test). It was for the convenience of testing that this temperature was

3-2
elevated 10°F to 30°F (from 55°F%

APPROACH FOR UPDATE

The ambient water heater temperature is, of course, based on the

location of the water heater which in turn is a function of the house

configuration, climate, and in sane cases fuel type. House configuration

determines the possible location of the water heater in that houses built

with basements would normally have their water heaters located in those

basements. Houses built solely with crawl spaces, however, would have

their water heaters placed elsewhere since most crawl spaces usually are

too low to accommodate water heaters. In addition, crawl spaces generally

provide an unreasonable access for setting, servicing, maintaining or

replacing water heaters. In houses built on grade (concrete slab), water

heaters are generally placed within the conditioned square footage such as

closets or laundry rooms. Water heaters may also be placed in garages or,

in milder climates, in spaces outside of the heated or air conditioned

volumes of the house.

Fuel type also affects the placement of water heaters. If a water

heater is fueled by gas, the furnace generally would also be gas fueled and

the water heater placed near the furnace to avoid running extra lengths of

gas pipe. This placement of water heaters in proximity to furnaces would

generally prevail for all types of installation; basement, closet, garage,

etc. Electric water heaters on the other hand, may be located, in

principle, anywhere in or near the houses. From a practical point,

however, if a basement exists, the electric water heater would also be

placed near the furnace to keep all utility type equipment together to

allow for more flexible use of the remaining basement space.

The approach for update of this factor is based on a search for data

involving the most likely location for the water heater and the ambient

3-3
temperature at that location. Very little data in this regard were

identified, however, some census data did provide an insight into

determining a representative value for this factor.

RESULTS AND DISCUSSION

In addressing the determination of a water heater ambient temperature.

Census Data were reviewed to determine the national population for housing

with and without basements [4]. A summary of Housing Basement Data is

presented for 1977 and 1970 in Table 3-1. These data indicate that for all

year round housing units, 47.4% of the total U.S. Housing in 1977 had

basements - a reduction from 54.3% in 1970. This trend to fewer basements

is not surprising as the cost of housing increases and affordability

decreases. The greatest number of basements in 1977 were in the colder

climates with 85.5% of the housing in the North East having basements and

70.4% for the North Central region. Housing in the South and West having

basements were 18.2% and 22.0% respectively. These data were for all types

of residential units from apartment buildings to single family detached

houses.

Another source of data which concentrates solely on single family

units was derived from the Energy Information Administration of the

Department of Energy [5] and is shown in Table 3-2. For single family

units the data combine basements and crawl spaces and do not present

information separating the two. Again, the number of basement/crawl space

single family units are greatest in the North East and North Central

regions (87.5% and 90.8% respectively) and lowest in the South and West

(69.5% and 65.1%).

Unfortunately, no definitive numerical conclusions can be drawn from

the above data. However, one can observe that there are a large number of

basements in the colder climates of the North East and North Central parts

3-4
of the country with many of the basements directly heated. Residences in

the South and West, with their wanner climates, have fewer basements with a

smaller percentage directly heated. If it can be assumed that (1) the

water heater will be generally located in the basement when a basement is

available and (2) the number and distribution of residential basements are

geographically wide ranging as described above, than it is hard to imagine

the surrounding ambient temperature of the water heater being as low as

55°F, the current value. In the wintertime, directly heated basements

might range in the order of 65°F to 70°F while unheated basements might

range in the 60°F to 65°F region due to heat being radiated from a nearby

furnace or boiler. Also in the summertime, the basement temperature would

generally be higher than 55°F when the outside temperature fluctuates

between 70°F and 90°F, as might be expected.

Regarding the ambient temperature for water heaters not located in

basements, a strong argument can be made for assuming that the water heater

ambient temperature would generally be the same as the prevailing ambient

temperature in the residence. To determine this temperature, data showing

the percentage of U.S. Households by inside temperatures were identified.

These data, shown in Table 3-3, were developed by the Energy Information

Administration of the Department of Energy [5] and show (1) Daytime

Temperature When Someone Is At Hone; (2) Daytime Temperature When No Che Is

At Home? and, (3) Nightime (Sleeping Hours) Temperatures. The information

is for winter indoor temperatures and is classified by heating degree days

and residence square footage. An inspection of the data reveals that the

percentage of indoor winter temperatures less than 63°F is relatively

small. In the summertime, of course, the indoor ambient temperature would

be much higher, even with air conditioning.

3-5
RECOMMENDATIONS

It would be difficult to justify the current value of 55°P as a

National average ambient water heater temperature based on a critical

review of the data presented above. Although inpossible to quantify with

the data available, a value of 65°F to 70°F seems more supportable. In view

of the above, it is recommended that a value of 65°F be used until a better

approach can be developed or actual field data collected.

REFERENCES

[1] Test Procedure Review - Water Heaters; Recommendations concerning test

procedures to be proposed for use under Public Law 94-163 for Federal

Energy Administration Appliance Efficiency Program by the National

Bureau of Standards, Center for Consumer Product Technology; March 10,

1976, Revised April 21, 1977.

[2] Federal Register; Department of Energy; Part II; Office of

Conservation and Renewable Energy; 10 CFR Part 430; Energy

Conservation Program for Consumer Products; Test Procedures for Water

Heaters; Public Heating; Proposed Rule; Wednesday, February 8, 1984.

[3] Household Appliance Usage Data; NBSIR 80-1994; Alan D. Davies, et.

al.; dated February 1980 (Final Report issued March 1980).

[4] Annual Housing Survey: 1977; General Housing Characteristics; Part A

- United States and Regions; U.S. Department of Commerce; Bureau of

the Census/U.S. Department of Housing and Urban Development; Office of

Policy Development of Research.

[51 Residential Energy Consumption Survey: Housing Characteristics 1982;

DOE/EIA-0314 (82) ; Published August 1984; Energy Information

Administration, Washington, DC 20585.

3-6
TABLE 3-1

HOUSING BASEMENT DATA

(all year round housing units)

1977

Total

US

North

East

North

Central South West

Housing

With

Number

(Thousand)

38253 15141 14920 4797 3395

Basement % 47.4 85.5 70.4 18.2 22.0

Housing

Without

Number

(Thousand)

42463 2566 6261 21625 12011

Basement % 52.6 14.5 29.6 81.8 78.0

1970

Total

US

North

East

North

Central South West

Housing

With

Basement

Number

(Thousand)

34467 13843 13452 4180 2992

% 54.3 89.4 76.7 21.7 26.8

Housing

Without

Basement

Number

(Thousand)

28978 1640 4084 15077 8177

% 45.7 10.6 23.3 78.3 73.2

Source

Annual Housing Survey: 1977

General Housing Characteristics

3-7
TABLE 3-2

SINGLE-FAMILY BASEMENT DATA

(SINGLE-FAMILY UNITS - 1982)

TOTAL

u.s. NORTH

EAST

NORTH

CENTRAL SOUTH WEST

Have Basement/

Crawl Space

Number

(Millions)

44.7 9.3 13.6 14.5 7.3

% 77.5 87.5 90.8 69.5 65.1

Heated

Number

(Millions)

12.7 3.6 6.5 1.5 1.1

cv

/o 22.0 33.6 43.2 7.2 9.9

No Basement/

Crawl Space

Number

(Millions)

13.0 1.3 1.4 6.4 3.9

i %

* 22.5 12.5 9.2 30.5 34.9

Source

Energy Information Administration

Office of Energy Markets and End Use

The 1982 Residential Energy Consumption Survey

3-8
w

4-3 cqC

H

QJ C ON H vrnmNOONONN M cd on p

O £ a • vocMcNinmaNCMO S 4J —1 CT* on rH CM CM CM Q

§

CO oo

o •

•* O ON 4J OONOOr^vOONrH O O ON

-U ON • MCMCOntnMMH

c 4—1 r-1 CT ON CM CM CO

cd CO 4=H

CD u 05 O 0) • O r-1 CD C O 4-1 r^r-HmOHCOul-3-O

0-. CO Cd O Cn

05 CD 33 • omomNMrnn -I 4-J —

cr oh t-h t—( csi ri M CO d

3

CO

x) .

4J

05 CD G On -u inonMnnHvT M cd On Pli /-v cd O 42 On . OH-3-sjrHvOOOO

a <u S U rH tr ON H n CM CM

C/D Q 33 Q CO w P 02 '-v P £ ^ S

H 00 05 ON < ON >h co ON « rH <d oo MJ- • w Q ON »> O OH HJ oomcoi—icorHmr^

Pi Ctf- rH m O O ON Pm S W 05 O U on • COnCMHOWNOO 05 33 o rH rH CT1 ON rH CO CM CM H 2 g a 4-1 CO

00 Vi w >- a) cd o

H 2. o CO oo 32 Z [H C oo • HH O •H 3 C/5 G O 4-1 HcOCMinONCMHOO 4J O CO cd o H C/D cd g 05 42 O . oou-immoou-iOtH cQ <3. 0) 33 J 4 H cr OH H (N N N 33 4-i CO

CO 1 Q CM —1 CO 00 o w ON

33 CJ w z • CO W rH «) C o> i) NvOCM^OONhJHCM

2 9 *H d (d ON ti Q h Vi O 33 ON • ONf^oOrHuOMDOO a SUH cr ON rH CO CM H w < Q CO

CO @ • >*

ZD -! ON

t—1 ON H S • O < * O ON 4-» Oh O PI O CO 00 H m O 0 ON Cm U 4J ON . ON ON vO sf H 00 o 1 o w c rH r| a* ON c—i ro CM r-| < 4-J cd CO H O 32 2 2 E-i W i—

CJ CO 05

OZ, ' rjj u W g o o Ph o s CO c O 4J comovocMinvOvo 33 CO Cd O Pm

<1> -C O ° vonmcoooHON H t—3 4-» rH cr ON rH CM CO rH

<3 CO

COM

W

z rH o cd COONhJNNN^h w 4-1 2 o r'-9nNvO-?HH oCO H ON ri CM CM CM 2

wg

CO CO w co ai 03 01 01 X 01 33 C -I v u u u H O CD CD 00 05 H h h h 01 4-H 3 05 TJ O to 00 Q <4-4 CO 05 <D 0) o G 0-4 C IBQQ « « <J s M 01 0) l-i T3 W 3 UiOOi HI O » o H HI-ihOhOI-iSCZ

to to u \

H !oo)ooo)>-i3c:

H

H

HH Q 4_j 4J Q OH 5o

4-1 CO MT N O rH 4-1 C >* (!) vD \0 N N Cd Jti <3 0) 0) c O K 35 O

ONvrroOfHOoom

<JOMnOOOCO moMHHdno nO (N rH i-H rH i—| CO

csiOON<rror^cNvO

srrvooooc^oncN

LO t—

|

r—i Mf

HOOO'*JOOvO<f

vOOOCOO-vTONCOO

ON CM CSI CM rH

<rooMooHino>N

O^HfOsTHCOO a\ <N CM H H H

NON>J\OOvOCO

ooor^cM<roNOOcM

ONMtmOOr^OO OV n M CN H

nO On VO O rH Os

NONnOOvOHH

HOmMnoMnn O'* CO CM i—| i—

|

'COCON^NCOH

H H £ -*

NNfO>i)MinvON

vOHO'OHiAO'iA

vOO'JO'HHCNO

f'''» CM rH r—I rH r—| CM

ON 00 t—i—I <J N CO O rH rH T—I r-H rH CM

coin<rmcMCMON<f

vOvOOHvOONCMO

ON CM CM CM rH

inrOvOOi^M'CON

<M^vJ(^fOH*sfO

ON CM CM H i—I i—

COCOHNNHl/NCsJ

MM-romooNincM

ONONS^CMiAOO ON CM CM CM rH

H'JCOOfO'CNM

COOmdHONHO ON CO CM CM rH

HHinONCNiOvTsT

fOHvDONSCOfOCO

ON CM CM H rH

sOONCMLOCMOOCOrH DfOCMONfOONOH

30 (N CM H H rH

CO 05 o CO CD

05 CO CO 05 z 05 CO CO 05

*-4 05 05 Vi Vi! HH G H 05 05 Vi Vi

05 05 00 05 Oh D 05 05 00

Vi V4 V4 05 urn 3 W Vi Vi Vi 05 U-l o 00 00 Q *4H CO w O O 00 oo Q 4-4 CO

05 ai o c 05 05 CD o c CO

05 Q Q CO 05 c C/D C CO Q Q CD 05 < 05 G X V—

Vi 05 05 Vi

05 vO ON Q5 O 05 o 3 05 NO ON Q5 o 05 o Vi vO VO Vi 2 C 2 H Vi vO ON Vi 2 C z 00 Vi 2 00 to u

05 o O 05 V4 G G hH CO 05 O O 05 Vi 3 o 4-1 4J CD o H 5 H -1 Q 4-1 4J Q o H 5

O H CO <r O rH 4-1 c. 33 4-1 co r- O c vO vO VO n- C- cd O cd vO NO no r>. r>- 03

05 c HH 05 05 c

33 =1 z 35 33 3)

05U

ViG

O

C/D

3-9

Energy

Information

Administration;

Office

of

Energy

Markets

and

End

Use;

The

1982

Residential

Energy

Consumption

Survey

SECTION IV

WATER HEATERS,

HOT WATER USAGE

CURRENT VALUE: 64.3 gal/day

PROPOSED VALUE; 60 gal/day

HISTORICAL BASIS FOR CURRENT VALUE

The current value for hot water usage was estimated by the National

Bureau of Standards [1] not from direct measurements, but from hot-water

heater energy usage metered data obtained by several electric and gas

utilities and from general service efficiency factors obtained from

laboratory tests. The following equation was used to calculate hot water

usage by the indirect analysis:

Average hot water usage in gallons =

(average total energy consumed) x (average service efficiency)

energy required per gallon heated

Using the above equation, the national average hot water usage was

calculated to be 64.3 gallons per day, 365 days per year with a nominal

tank temperature of 145°F; input water temperature of 55°F; and an ambient

air temperature of 55°F. A National Bureau of Standards report. Household

Appliance Usage Data [2], describes the basis for the estimate and includes

the origin for the data used as follows:

The energy consumed was treated independently for gas and for electric

water heaters. 'Hie average gas energy of 378 therms per year was taken as

the average of the average annual energy consumptions reported for regional

usage by five gas utility companies. The average gas heater service

efficiency of 47 percent was taken as the average of results of laboratory

studies on one gas heater tested by the Institute of Gas Technology and on

two gas heaters tested by the Houston Lighting and Power Company. The

4-1
average annual energy consumption for the electric heaters of 6012 kWh per

year was taken as the average of the average annual regional energy

consumptions reported by 13 electric utility companies. The average

service efficiency for the electric heater of 75 percent was taken as the

average of results of (a) laboratory tests conducted on one heater by the

Institute of Gas Technology and on three heaters by the Houston Lighting

and Power Company, and (b) field tests on 54 metered units by Detroit

Edison over two weeks in the summer and two weeks in the winter.

In each separate case--gas and electric—reported results were

combined into unweighted averages without regard to sampling methods,

locality, manufacturer, size, or specific operating conditions. The data

collected in the field were those offered voluntarily by the utility

companies and varied widely in format, detail, and estimated reliability.

In most instances, the thermostat setting was unknown; and no information

was provided on whether the water heaters were usually located outside the

house, in unheated cellars, or inside the heated or air-conditioned volumes

of housing units. Most of the data were for individual houses, but some

were for apartments.

The annual median water surface temperature (as reported by the U.S.

Geological Survey) was taken to be the annual average tank water- input

temperature for the specific location involved.

In addition, the NBS report states that no direct data are available

to support an estimate of uncertainty in national average hot water usage

and the magnitude of systematic errors cannot be reasonably estimated

because of the diversity of the reported observations. The report

correctly addresses the point that the mathematical relationship used

(shown at the beginning of this section) is in error on the high side

(i.e., gives too large a value of average water use) because it includes an

4-2
additional average of cross-product terms of energy and service efficiency

and that the magnitude of the cross-product contribution is unknown.

APPROACH FOR UPDATE

The current value of 64.3 gal/day for a national hot water usage

factor is a derived value determined indirectly from average energy usage

and average service efficiencies, as explained above. In order to revise

this value, this update incorporates information developed subsequent to

the establishment of the 64.3 gal/day value and evaluates a number of

reports that address this topic. Each report is reviewed for methodology,

data presented, and conclusions reached and an overall assessment made

regarding the adequacy of the current value.

RESULTS AND DISCUSSION

A report by R. D. Clear and D. B. Goldstein [3] addresses those

factors iirportant in estimating hot water consumption and energy use. The

report analyzes the National Bureau of Standards approach and establishes a

methodology for determining hot water usage based upon a home inhabited by

an average size family with an average appliance usage.

The focus for the Clear and Goldstein report lies with the following

algorithm: W = (P + ScC + Sd

D) x FS.

W = Daily water usage (gal/day)

P = Per-capita water use for personal services (showers, hand washing,

bathing (gal/day)

C = Per-capita increase in water use caused by the presence of a clotheswasher (gal/day)

D = Per-capita increase in water use (compared to hand dishwashing)

caused by the presence of an automatic dishwasher (gal/day)

Sc = Saturation of clothes washers (percentage of families owning a clothes washer)

Sd

= Saturation of dishwashers (percentage of families owning a dishwasher)

FS = Family size (number of members)

4-3
The above equation assumes a relationship of a simple linear

combination of coefficients, all of which are proportional to family size.

The authors state that this equation is intuitively plausible and that sane

data exists to support its accuracy. The authors derive numerical values

for each of the parameters and state that for some of the parameters good

agreement is achieved when compared to some direct or indirect measurement.

The following results are presented:

WATER USAGE PARAMETERS

Auto Clotheswasher

Wringer Washer

Dishwasher

Personal Use

Family Size

C = 5.6 ± 1

WW = 3 ± 2

D = 3 ± 1.5

P (gas) = 10.3t 3

FS (avg) =2.8

Sc

= .7 (estimate)

S^ = .1 (estimate)

S^ = .4 (estimate)

P (electric) = 6 ± 1 P (avg) = 8 ± 2

FS (single family) =3.2

Water Use: W

Electric; W = (6+5.6x.7+3x.l+3x.4) x 2.8 = 11.4x2.8 = 32gpd +4

Gas; W = (10.3+5.6x.7+3x.l+3x.4) x 2.8 = 15.7x2.8 = 44 gpd +9

Average;* W = (8+5.6x.7+3x.lxl+3x.4) x 2.8 = 13.4x2.8 = 38 gpd ±5

Average Single Family; W = 13.4x3.2 = 42 gpd ±7

* This is not a weighted average of gas and electric households.

P (electric) is far more accurately known than P (gas) and a sinple

average was used for the estimate of average water use.

In effect, it is concluded that for a family of 3.2 persons, the daily

hot water usage would be 42 gpd ±7.

Although the above is presented with detailed back-up, the accuracy of

the results are questionable. The assumption of a simple linear

combination of coefficients, all of which are proportional to family size,

is unjustified (see Ontario Hydro, below). Small variations in

nonlinearity and non-proportionality could change the results

4-4
significantly. In addition, the authors question their own values for P,

the personal use parameter, which provides the largest input to the

equation. The report states that the water use for gas water heaters is

only supported by two studies, one of them small and the other small and

non-random, and concludes that more study is clearly needed to evaluate P

more accurately.

The results, however, are considered as another useful data point

developed through a different premise from that by v&ich the current 64.3

gal/day was developed. However, neither is based on actual metered water

use. A second report evaluated was prepared by M. Perlman of Ontario Hydro

for the American Society of Heating, Refrigerating, and Air Conditioning

Engineers, Inc. [4]. The report uses data derived from actual measurements

conducted in residences and contains the results of consumer surveys

regarding water usage. The field measurements include two years of data

for five residences in the Toronto area and one year of data for fifty more

residences located throughout the Province of Ontario. The report

addresses such items as the overall and peak average hot water usage; the

average daily and peak hourly hot water use by family size, average age of

adults, presence of children, seasonal variations, etc. The results

indicate an overall average hot water use of 62.4 gal/day for all families

and a 63.1 gal/day for a "typical family" defined as a family size of 4

(two adults and two children) owning a clothes washer and dishwasher.

In reviewing the data which are thoroughly presented in graphic and

tabular form, the non-linearity of the various parameters are manifest.

Some of the variables are reported as follows:

4-5
Average Daily Hot Water By Family Size

Family Size

Average Daily Use

gal/person

2

3

4

5

18.1

22.6

16.6

12.3

Average Daily Hot Water Use By Average Age of Adults

Average Age

of Adults

Average Daily Use

gal/person

30

30-35

35-40

40-45

45-50

59

14.6

20.4

19.1

17.6

17.1

15.8

This representation, in effect, is counter to the Clear and Goldstein

basis that assumes a simple linear combination of coefficients, all of

which are proportional to family size.

Regarding the Ontario Hydro value of 63.1 gal/day for the "typical"

family, the assumption of a 4 member family is coupled with the demographic

survey of the residences which revealed that 98% of the households in

Ontario had automatic clothes washers and 79% automatic dishwashers. This

must be compared to the average United States household numbering 2.7

persons in 1980 [5] and the saturation levels of clothes washers and

dishwashers for 1983 as 73.6% and 45.0% respectively [6], It should be

noted that the term "family" refers to a group of two or more persons

related by blood, marriage, or adoption and residing together in a

household. A "household", however, includes all persons who occupy a

"housing unit." (For complete definitions see Statistical Abstract of the

United States, National Data Book and Guide Sources, Bureau of the Census.)

In addition to the above, another factor which must be addressed in

the average cold water temperature differences between Canada and the

United States. Section I of this report, (WATER HEATERS - INLET WATER

4-6
TEMPERATURE), recommends a national average temperature of 58°F. Using the

same source data [7], the average inlet water temperature for the Ontario

area is at least 10°F colder. If it can be assumed that this inlet water

temperature also represents the temperature flowing from the cold water

tap, a higher hot water use rate will result if this colder inlet vater is

blended with hot water for showering or other personal use.

In summary, the detailed data and analysis presented by Ontario Hydro

lends high credibility for the 63J. gal/day water usage for the "typical"

family in the Ontario area. Comparable data for the United States,

however, showing a smaller number of persons in the average household,

fewer clothes washers and dishwashers, and a higher average cold water tap

temperature, leads us to conclude that the Canadian data can be viewed as a

reasonable upper bound for water temperature usage extrapolated to the

United States.

A third report evaluated that contains field data was provided by a

study prepared by the Lawrence Berkeley Laboratory [8], The paper

describes and analyzes both laboratory and field test data on water heaters

from more than 75 published and unpublished sources. The report contains a

table showing per capita hot water usage from occupied households in

various locations in the United States, Denmark, and Canada. The pertinent

data only for the United States are shown below:

4-7
PER CAPITA HOT WMER USflGE (GAL/DMf)

Averaoe No. Number of.

Daily. Dot Water

Use Ssl .Capita Building fuel Pifiiest.

qL Ctewpants Units (Gallons) Tvoe Type. Location

2.8 8 12.2 SF E Tacoma, WA

4.0 1 13.0 SF E Chico, CA

4.0 1 15.5 SF E Chico, CA

4.0 13 17.1 SF G San Diego, CA

3.3 18 17.7 SF E Portland, OR

4.7 23 17.7 SF S San Diego, CA

4.0 85 18.3 SF E USA

3.6 10 28.7 SF E Portland, OR

2.9 15 19.7 SF S USA

2.9 32 21.7 SF E MD, VA, WV

3.7 10 22.7 SF E PA

2.9 12 22.9 SF S San Diego, CA

3.7 23 23.9 SF E Seattle, WA

3.6 251 18.54

In reviewing the above table, a number of observations can be made. If

the daily water use per capita (18*54 gal/day) is multiplied by the average

number of occupants (3.6), the daily usage is 66.7 gal/day. If the daily

water use per capita (18*54 gal/day), however, is multiplied by the average

number of persons per household in the United States (2.7), the daily water

use falls to 50.1 gal/day. In addition, if the number of occupants is

weighted by number of units and per capita use (since the high daily water

use per capita also corresponds to the larger number of units) a per capita

use of 19.6 gal/day is derived and when multiplied by the average number of

persons per household (2.7) a total consumption of 53.0 gal/day results.

Finally, assuming that the average family size in a single-family dwelling

is 3.2 people [3], the daily usage is either 59.3 or 62.7 gallons if the

daily water use per capita is 18.54 or 19.6 gallons per day, respectively.

Of course, it should be noted that the 251 units sampled are still small in

number and not geographically dispersed to give very special meaning to the

results. On the other hand, the data and results cannot be ignored.

4-8
£1 £

A review of the information presented above shows that both the

analytical approach and the limited field data available suffer from lack

of definitive data on a nationwide basis. The analytical approach of Clear

and Goldstein offers a daily water usage of 42 gallons; the Qitario Hydro

studies show results of 63.1 gallons for a Canadian scenerio; and the

Usbelli study varies between 66.7 and 50JL gallons. The daily usage rate,

based on the Usibelli study, varies between 59.3 and 62.7 gallons, if the

average family size of 3.2 in a single-family dwelling is used. Further,

in weighing all of the studies together it could be reasonably concluded

that the current 64.3 gallons per day factor for a national hot water usage

may be an upper limit and a lower value may be more representative. In

this regard, a proposed value of 60 gallons per day may be more desirable

as it would move the value closer to an "integrated assessment" and also

not imply the measure of accuracy that the current 64.3 gallon per day

value suggests. It is, therefore, recommended that the current value for

hot water usage be changed from 64.3 to 60 gallons per day until a better

body of field data is gathered and a more definitive usage factor

determined

REFERENCES

[1] National Bureau of Standards; "Test Procedure Review - Water Heaters";

Washington, D.C.; April 21, 1977.

[2] Alan D. Davies, et. al; "Household Appliance Usage Data"; NBSIR 80-

1994; National Bureau of Standards; Washington, D.C.; dated February

1980 (Final Report issued March 1980)

[3] R. D. Clear and D. B. Goldstein; "A Model for Water Heater Energy

Consumption and Hot Water Use: Analysis of Survey and Test Data on

Residential Hot Water Heating"; Lawrence Berkeley Laboratory Report

10797; Berkeley, CA; Revised May 2, 1980.

4-9
[4] M. Perlman; B. E. Mills; and B. T. Barber; "Development of Residential

Hot Water Use Patterns"; RP-430; Prepared for American Society of

Heating, Refrigerating, and Air-Condition Engineers, Inc. by Qitario

Hydro; Toronto, Ontario; December 1984.

[5] General Housing Characteristics; United States Summary; 1980 Census of

Housing; HC80-1-A1; Bureau of the Census; U.S. Department of Commerce;

Issued May 1983.

[6] Appliance Magazine; A Dana Chase Publication; "The Saturation

Picture"; September 1984.

[7] J. F. Blakey; "Temperature of Surface Waters in the Conterminous

United States"; U.S. Geological Survey Hydologic Investigations Atlas

HA-235; Washington, D.C.; 1966.

[8] A. Usibelli; "Monitored Energy Use of Residential Water Heaters -

Buildings Energy - Use Compilation and Analysis: Part D"; Report No.

LBL-17873; Buildings Energy Data Group; Lawrence Berkeley Laboratory;

Berkeley, CA; dated May 1984.

4-10
SECTION V

furnaces

OUTDOOR DESIGN TEMPERATURE

CURRENT VALUE: 5°F

PROPOSED VALUE : 17°F

HISTORICAL BASIS FOR CURRENT Wm

Test methods were developed for furnaces in 1978 [1, 2] in support of

Public Law 94-163 which required the Federal Ehergy Administration to carry

out energy conservation activities related to the efficiencies of household

appliances. As part of the development of test procedures for furnaces, a

national average value for heating load hours per year was needed which

included the value of a National outdoor design temperature (see SECTION IV

- FURNACES - HEATING LOAD HOURS).

As reported in the Household Appliance Usage Data [3] , the current

outdoor design temperature of 5°F was calculated as a weighted average of

long-term "97.5%-design dry-bulb temperatures" at weather stations in the

lower 48 states supplied by the Armed Forces [4], The "97.5% winter design

dry-bulb temperature" is defined as temperatures which have been equaled or

exceeded by 97.5% of the total hours in the months of December, January,

and February (a total of 2160 hours). In a normal winter, there would be

approximately 54 hours at or below the 97.5% value [5]. The weighting was

by the number of housing units using gas or oil as their primary heating

fuel as reported by the 1970 census, but it is unknown how the regions were

delineated or how much of the population was not included in the

calculation.

This factor is primarily used in the equation to compute heating load

hours (see SECTION IV - FURNACES - HEATING LOAD HOURS). The factor is

5-1
discussed herein separately to present, in detail, the methodology and data

used to confirm the current value or develop a new proposed value.

Further, by including this factor as a separate section of this report, the

value is highlighted for use in other building related energy studies

requiring a National average outdoor design temperature.

approach for update

The approach taken here for estimating the National average outdoor

design temperature is similar to that for estimating annual average water

heater inlet temperature (see SECTION I - WATER HEATERS - INLET WATER

TEMPERATURE). This means that the average outdoor design temperature will

be weighted for each State by its housing population. Specifically,

average "97.5%-design temperatures" were estimated for each State using

data for climatic conditions for the United States as tabulated in the

ASHRAE Handbook of Fundamentals [5]. This information was weighted by the

number of single-family housing units for that State derived from 1980

census data [6] and an overall National average outdoor design temperature

determed.

Estimating average state oiitdoor design temperatures was subjective.

An alternative would have been to weight the temperature reported for each

locale by the population of that locale. However, this would have

frequently meant neglecting populous regions. For example, no weather

station is listed for Montgomery County, Maryland, which is one of the most

populous counties of the state and contains the state's second largest

city. In the method used here, Montgomery County, which is a suburb of

Washington, DC, was assigned a design temperature equal to that of

Washington, DC, and was considered in calculating the average state outdoor

design temperature.

5-2
RESULTS AND DISCUSSION

Table 5-1 shows the results of the outdoor design temperature

calculation. The resulting housing population-weighted average outdoor

design temperature was 16.7°F, considerably higher than the presently used

5°F value. Although a certain amount of subjectivity is involved in

estimating state average outdoor design temperatures, the National average

outdoor design temperature should change little even allowing for

differences in individual assessments. As indicated above, all populous

areas were included even if they were not represented by a weather station

in the ASHRAE Fundamentals [5],

We cannot fully explain the large difference between our result,

16.7°F, and the current value of 5°F. Part of this could be due to the

shift of population to warmer climates between 1970 and 1980. Further

differences could be attributed to the different methodologies used since

the current value is weighted by housing units having gas- or oil-fired

heating systems, while the proposed value uses single-family houses. In

addition, the current value and the proposed value are based on different

weather-station data and different regions over which temperatures were

averaged. It is quite possible that temperatures simply cannot be

meaningfully estimated for areas located between two weather stations, and

large population areas are necessarily neglected no matter how much one

tries to include them.

The replacement of the current 5°F value with a 17°F value for a

National average outdoor design temperature seems justified. Hie basis for

the justification is the relatively high confidence placed in the

methodology and the data used. It is again noted that this new value is

used in the equation to compute heating load hours (see SECTION VI -

5-3
FURNACES - HEATING LOAD HOURS) and may also be used in other building

related energy studies requiring a National average outdoor design

temperature.

RFFRRRNfTRS

[1] "Test Procedures for Conventional Ranges, Conventional Cooking Tops,

Conventional Ovens, Microwave Ovens and Microwave/Conventional Ranges,

Furnaces and Vented and Unvented Home Heating Equipment"; Federal

Register 43, 91; 20108-20205 (May 10, 1978).

[2] "Proposed Test Procedures for Furnaces; Public Hearing"; Federal

Register 42, 155; 40826-40845 (August 11, 1977)

[3] Davis, AJ)., et al.; "Household Appliance Usage Data"; NBSIR 80-1994,

National Bureau of Standards, Washington, DC; February 1980.

[4] Departments of the Air Force, Army, and Navy, "Engineering Weather

Data," AFM-99-8, June 15,1967.

[5] American Society of Heating, Refrigerating and Air-Conditioning

Engineers, Inc., "ASHRAE Handbook, 1981 Fundamentals," Atlanta, 1981.

[6] U.S. Department of Commerce; "1980 Census of Housing Volume 1,

Characteristics of Housing Units; Chapter A, General Housing

Characteristics; Part 1, United States Summary"; Bureau of the Census;

Issued May 1983.

5-4
TABLE 5-1

LOUSING PCEULATTON^MBIGETED AVERAGE OUTDOOR WINTER DESIGN TEMPERATURE

STATE

ASSUMED

97.5% WINTER

DESIGN DRY BULB

TEMPERATURE °F

BOOSING POPULATION

(IN THOUSANDS)

1980 CENSUS

SINGLE FAMILY UNITS

Alabama 21 1,168

Alaska 21 86 Arizona 33 745

Arkansas 20 725

California 41 6.440

Colorado 1 835

Connecticut 7 794

Delaware 14 170

District of Columbia 17 127

Florida 42 2,798

Georgia 22 17525

Hawaii 63 198

Idaho 10 272

Illinois 2 2,699

Indiana 2 1,655

Iowa - 5 502 Kansas 5 775

Kentucky 10 1,045

Louisiana 33 1,195

Maine - 2 295

Maryland 17 1,145

Massachusetts 9 1,257

Michigan 6 2,721

Minnesota -12 1,128

Mississippi 25 732

Missouri 7 1,518 Montana -16 222

Nebraska - 3 493

Nevada 20 203

New Hampshire - 1 235

New Jersey 14 1,710

New Mexico 13 347

New York 12 3,096

North Carolina 21 1,761

North Dakota -19 174

Ohio 5 3,119

Oklahoma 13 1,010

Oregon 24 812

Pennsylvania 11 3,415

Rhode Island 9 221

South Carolina 26 883

South Dakota -10 200 Tennessee 18 1,373 Texas 30 4,143

Utah 8 372 Vermont - 8 135

Virginia 18 1,554

Washington 26 1,225

West Virginia 10 577

Wisconsin - 5 1,321

Wyoming - 7 118

Population-weighted National Average Winter 16.7

Design Temperature (°F)

* Not included in calculation.

5-5

SECTION VI

ElffiNflCES

ANNUAL HEATING LQMLHgffiS

CURRENT VALUE; 2080 Hours Per Year

PROPOSED VALUE : 2080 Hours Per Year

HISTORICAL BASIS FOR CURRENT VALUE

Test methods were developed for furnaces in 1978 [1, 2], in support of

Public Law 94-163 which required the Federal Energy Administration to carry

out energy conservation activities related to the efficiencies of household

appliances. As part of the development of test procedures for furnaces, a

national average value for heating load hours per year was needed [2]. A

study made on Household Appliance Usage Data [3] describes the analytical

approach used to determine the current value for furnace annual heating

load hours and is based upon the following equation:

Annual Heating Load Hours =

Degree-days per year x 24 hr. per dav x SHL

(Balance Point Temp.- Outdoor Design Temp.) x SHL

where: SHL = heat loss rate of the structure in Btu per hour

per degree Fahrenheit

The current value was derived as follows:

Annual Heating Load Hours = 2080 =

52QPDegree-davs per year x 24 hr. per day

(65°F - 5°F)

The calculation that produced the current value of 2080 heating load

hours per year used 5200 degree-days; a balance point of 65°F; and a 5°F

outdoor air design temperature. These were based on weighted averages

using long-term weather data and 1970 census data. The 65°F temperature

used as the balance point (zero heat point) is the traditional reference

6-1
temperature for computing degree-days, and marks the outdoor dry bulb

temperature boundary between a load and no load on the heating system.

The Household Appliance Usage Data Study [3] further states that the rate

of conduction and infiltration is, for practical purposes, considered

proportional to the difference between indoor and outdoor temperatures.

The number of degree-days in a day at a given location is computed by

finding the arithmetic average of the high and low temperatures for the day

and subtracting the result from the balance point (65°F). No heating

degree-days are counted if the average is above the balance point. When

summed over the heating season, the total degree-days for a year is

proportional to the annual heating load. In addition, the conductive heat

loss characteristics of a given structure may also be included in the

annual heating load hour calculation, but since these characteristics

appear in the numerator and denominator of the equation (see above), they

cancel out and may be dropped for brevity.

APPROACH FOR UPDATE

As a first stq?, this update addresses the 65°F balance point and its

use in deriving the current value for annual heating load hours. A review

was made of currently marketed heating equipment [4], systems design

practices [5]

,

and housing construction practices [6] in order to reveal

any appropriate changes to the original assumptions used in the calculation

of the current value. The second step in the update addresses the

calculation of average degree-days based upon a housing population

weighting. This information, along with the revised outdoor design data,

which is also based upon a housing population weighting, (see SECTION V -

FURNACES - OUTDOOR DESIGN TEMPERATURE) is incorporated into the Annual

Heating Load Hour equation and a new value determined.

RESULTS AND DISCUSSION

The function of the heating load hours parameter is to combine certain

climate and indoor factors into a form that is concise and convenient for

6-2
analytical uses, while meeting the requirement for a representative

national value. The 65°F balance point, a reference used in the analytical

equation to combine climate and indoor factors, has been of concern to the

furnace manufacturing community, [1], This community has at times stated

that this balance point is no longer representative of current home

construction and heating practices and leads to serious overestimates.

An analysis by NBS [3] also revealed areas of uncertainty with regard

to the use of 65°F as a balance point. Historically, the 65° balance point

temperature was proposed [7] in the 1920's as a result of study by a gas

utility company. In their analysis [3], NBS pointed out that several

changes since that date indicate that a re-examination of that balance

point would be in order. Residential construction is considerably tighter,

reducing heat losses from air infiltration; much more insulation is being

used, reducing heat losses by conduction through the walls and ceilings?

and there are many more heat releasing appliances in homes, reducing the

additional heat requirements from furnaces. NBS also states in this

analysis that higher fuel costs are encouraging the use of lower thermostat

settings during the heating season. Further, because of heat storage

characteristics of house structures and contents, transient excursions of

outdoor air temperatures below 65°F may result in no call for heat from the

central heating system for as long as 6 to 12 hours.

DOE has recognized the general nature and effects of the factors

listed above, but has deferred any change from the 65°F balance point until

deeper study reveals a better alternative [3], However, the lack of

precision with regard to the assumptions used to determine furnace energy

use can have a major impact on the resulting heating load hours per year

value. NBS has estimated [3] that the effect of a change of one degree

fahrenheit in either the indoor temperatures (an indoor design temperature

of 70°F was used in determining the present value) , or the balance point

tarperature (65°F) at 5200 degree-days is approximately 900/5 = 180 degree6-3
days. The corresponding effect on the heating load hours per year would be

approximately 72 hours per degree P, After reviewing related heating and

weather data [5, 8], NBS recommended and DOE accepted an adjustment factor,

C, of 0.77 as a multiplier for changing the burner operating hours to the

approximate heating load experienced by the system.

A survey of data compiled by industry [9, 10] and professional

research communities [11, 12, 13] revealed that there is as yet no field

data comprehensive enough to replace analytical data in areas of: indoor

control temperatures, including any setback temperatures and durations; and

design point temperatures, including local variations relative to the

reference weather station. Because of the above, along with the

realization that there is a large accumulation of data based on a long

institutionalized 65°F balance point, no recommendation is made here to

change this value. Requirements for the determination of burner operating

hours (not studied here) should be based on a reassessment of the C = 0.77

(adjustment) factor rather than a recomputation of degree-days using a

different balance point.

In addition to reviewing the degree-day basis, as noted above, the

methodology for determining a national average degree-day value was also

evaluated. Instead of using the data for degree-days at the weather

stations selected to represent the various states, a housing population

weighted degree-day average was calculated.

The study used data of yearly heating degree days as distributed in

the conterminous United States which was found in the 1980 U.S. Climatic

Atlas produced by NOAA [14], Degree day values were given for at least

four population centers in every State. A degree-day value for each State

was determined by averaging the values of these centers, giving weight to

housing population distribution.

Although the above method is subjective in that judgement was required

to select a representative value for average degree days by State,
nevertheless, it is felt that a fair assessment has been made and that the

selected values would vary by a small amount even in those cases where

there is room for other assessments. Such differences should not,

therefore, significantly alter the overall results.

Also important to this study is the location of the Nation's

population of single-family housing units. This was determined by the use

of the 1980 census data [15]. The census divides single-family housing

units by State. These are the same housing population values used to

determine the updated outdoor design temperature value. (See SECTION V -

FURNACES - OUTDOOR DESIGN TEMPERATURE.) The above information resulted in

a weighted national average yearly value of 4232 degree-days (see Table 6-

1 ).

The annual heating load hours may now be recalculated using the

following values in the equation: 4232 annual degree-days (as derived

above) ; 65°F as the balance point (no change) ; and 17°F as the average

outdoor design temperature (as determined in SECTION VI - FURNACES -

OUTDOOR DESIGN TEMPERATURE).

Annual Heating Load Hours = 2116 =

4232 Degree-days per Year x 24 hr. per dav

(65°F “ I?°F)

It should be noted again that the annual average degree-day value (4232)

and the average outdoor design temperature (17°F) are both derived using

housing population weighted data and consequently, will shift with

population migrations.

RECOMMENDATIONS

In viewing the annual heating load hours (2116) derived through the

methodology using housing population weighted data, and comparing this

value with the current value of 2080 heating load hours per year, little

change is noted. This may indicate that a consistent approach in

determining the annual degree-days and average outdoor design temperature

6-5
will result in little change in determining annual heating load hours. In

view of the small difference between the two values (approximately 1.7%),

it is recommended that the current value of 2080 heating load hours be

retained.

REFERENCES

[1] "Test Procedures for Conventional Ranges, Conventional Cooking Tops,

Conventional Ovens, Microwave Ovens and Microwave/Conventional Ranges,

Furances and Vented and Unvented Home Heating Equipment"; Federal

Register 43, 91? 20108-20205 (May 10, 1978).

[2] "Proposed Test Procedures for Furnaces? Public Hearing"? Federal

Register 42, 155? 40826-40845 (August 11, 1977).

[3] Davis, AJ}., et al.? "Household Appliance Usage Data"? NBSIR 80-1994,

National Bureau of Standards, Washington, DC? February 1980.

[4] 1984 Sweets Catalog? Heating Equipment? McGraw Hill? New York.

[5] ASHRAE Handbook of Fundamentals, 1980.

[6] National Association of Homebuilders; Washington, DC.

[7] American Gas Association? House Heating? 1930.

[8] Departments of the Air Force, Army, Navy? Engineering Weather Data?

(AFM-88-8) ; June 15, 1967.

[9] Mr. J. Griffin; Edison Electric Institute? Washington, DC.

[10] Mr. J. Langmead? GAMA.

[11] Nelson, L.W.? "Reducing Fuel Consumption with Night Setback"? ASHRAE

Journal? August 1973.

[12] The Code for Energy Conservation in New Building Construction?

National Conference of States on Building Codes and Standards?

December 1977.

[13] Energy Conservation in New Building Design? Standard 90A-80? ASHRAE?

1980.

[14] U.S. Climatic Atlas? NQAA? 1980.
[15] U.S. Department of Commerce; 1980 Census of Housing; Volume 1;

Detailed Housing Characteristics; Equipment Numbing Facilities

for States; Part 1; United States Summary.
TABLE 6-1

Housing Population Weighted Average Annual Degree Days

SXATE

BOUSING POPULATION

(IN TBOUSAIOS) 1980

CENSUS SINGLE FAMILY UNITS

DEGREE DAYS

(AVERAGE PER YEAR)

Alabama 1168 2400

Arizona 748 3300

Arkansas 725 3300

California 6440 2800

Colorado 835 6300

Connecticut 794 5900

Delaware 170 4900

District of C. 127 4200

Florida 2798 2100

Georgia 1525 2400

Idaho 272 6100

Illinois 2699 5800

Indiana 1655 5700

Iowa 902 6800 Kansas 755 5300

Kentucky 1045 4900

Louisianna 1195 3300

Maine 295 8600

Maryland 1145 4700

Massachusetts 1257 6500

Michigan 2721 7400

Minnesota 1128 8900

Mississippi 732 2200

Missouri 1518 4900 Montana 222 8000

Nebraska 493 6600

Nevada 203 6100 New Hanpshire 235 10600 New Jersey 1710 4800 New Mexico 347 4600 _ . . New York 3096 6200

North Carolina 1761 3300

North Dakota 174 9300

Chio 3119 5800

Oklahoma 1010 3800

Oregon 812 5300

Pennsylvania 3415 5500

Rhode Island 221 5900

South Carolina 883 2300

South Dakota 200 7800 Tennessee 1373 4000 Texas 4143 1900

Utah 372 6100 Vermont 135 8200

Virqinia 1554 2SQQ

Washington 1225 5400 West Virginia 577 4800

Wisconsin 1321 7800

Wyoming 118 7600

National Average Yearly Degree Days 4232

6-8
SECTION VII

TOM ME .CCMjm

YEARLY HOURS OF USE

CURRENT VALUE: 750 Hours Per Year

PROPOSED VALUE: 670 Hours Per Year

HISTORICAL BASIS FOR CURRENT VALUE

Test methods were developed for room air conditioners in 1976 [1 ]

,

[2], in support of Public Law 94-163 which required the Federal Energy

Administration to carry out energy conservation activities related to

household appliance efficiency. These test methods were developed at the

National Bureau of Standards (MBS) with cooperation from the Association of

Home Appliance Manufacturers (AHAM) and in conjunction with the ANSI

Standard Z234.1--1972 (AHAM-RAC-1) for Room Air Conditioners. The methods

NBS developed were based upon an analytical approach which was used to

calculate the estimated national average hours of use for room air

conditioners

NBS [3] used a report by David A. Pilati of Oak Ridge National

Laboratory as a starting point. This Pilati report [4], estimates the

annual compressor operating hours for ten cities using selected weather

years. The author modified the National Bureau of Standards' Load

Determination (NBSLB) computer program to calculate compressor operating

hours while also accounting for the ability of natural ventilation to

provide cooling. The assumptions were that a house rocm air conditioner

was set at 78°F and the windows were opened if the outdoor conditions could

maintain the inside temperature between 75°F and 78°F. Compressor hours

for ten cities were averaged using census data and market saturation data

[5] as weighting factors. Average air conditioning demand hours were also

calculated using the same data (demand hours being defined in this study as

7-1
the larger of two numbers: hours of dry bulb temperature above 80°F, or

wet bulb temperature above 67°F.) The required weather data were obtained

from the Engineering Weather Data Manual AFM 88-8 [6], The ratio of

compressor hours to demand hours then gave the percent of time that the

room air conditioner compressor was operating per demand hour.

The National Bureau of Standards used this modified program to then

compute the annual national average air conditioning demand hours value.

This average was weighted for population and market saturation using the

same weather [6] and market saturation data [5] used in the Pilati study

[4]. Average hours of air conditioner operation were computed for 138

Standard Metropolitan Statistical Areas (SMSA's). From this work, the

estimated national average of 730 hours of compressor operating time was

computed and rounded up to the 750 value.

The study. Household Appliance Usage Data [7], describes this

analytical approach and also cites 750 hours as the national average number

of hours of compressor operation per year for room air conditioner units.

This same study also states that the usage factor of 750 hours per year is

based entirely on analyses and assumptions and that field surveys are

advisable in order to verify the factor. Such field survey data would

account for the impact of thermostat settings, the oversizing or

undersizing of air conditioner units and also account for ventilation use

patterns. It is assumed that users of room air conditioners, unlike

consumers who cool with central air conditioners, are more Inclined to open

windows when the outdoor air speed and temperature are adequate to maintain

comfortable indoor temperature. Ventilation can make a substantial

difference in the cooling required by air conditioners, thus affecting

hours of use. Also, the great differences in hours of roan air conditioner

usage from one locality of the country to another would impact a national

7-2
average usage factor if field data were used to determine regional values.

Early progress reports of field tests by AHAM [8] were mentioned in

the Household appliance Usage Data report [7], but at that time testing was

considered too incomplete to be useful input. Since the AHAM study is new

complete [9], it appears that field survey data is available that is

sufficient to check against the calculation method which established the

initial factor.

APPROACH FOR UPDATE

The approach for this update focused upon field data available with

regard to annual hours of operation for room air conditioners since the

establishment of the current value of 750 hours. Two manufacturers of room

air conditioners, York and Carrier, were contacted as well as various trade

and professional associations including: the Air Conditioning Contractors

of America (ACCA) , The Association of Home Appliance Manufacturers (AHAM),

The Air Conditioning and Refrigeration Institute (ARI), and the Edison

Electric Institute (EEI) . In addition, The American Society of Heating,

Refrigerating and Air Conditioning Engineers (ASHRAE), Oak Ridge National

Laboratory (ORNL) , and Lawrence Berkeley Laboratories (LBL) were contacted

in an attempt to obtain field data. It was found through discussion with

room air conditioning manufacturers [10] , and trade and professional

associations [11], [12], [13], that the final AHAM Report [9] was used as a basis for recent research done by these organizations [14], [15]. This

AHAM report is also the basis for this current study. In effect, data from

the AHAM study which shows yearly hours of use of room air conditioners as distributed in the conterminous United States, is adjusted by room air

conditioner saturation, by state, to arrive at a national average.

7-3
Beams - imjascassiCH

The AHAM report was the result of an extensive field survey whose

major objective was to provide sufficient room air conditioner field test

data on compressor operating hours per year for correlation with a

calculation method also developed by AHAM. Data were taken from AHAM field

testing sites, throughout the United States, in over 30 locations with

major emphasis on New York City, Chicago, St. Louis, and Dallas. Data for

a total of over 290 units were collected. Another source of data for the

AHAM Report was the field testing results collected and published by other

organizations [16, 17, and 18],

As part of the AHAM report a map was developed which shows yearly

hours of operation for room air conditioners as distributed in the

conterminous United States [19]. This map shows bands of operating hours

for room air conditioners with each band spread generally representing a

change of 250 yearly hours of operation.

Using the AHAM map (Fig. 7-1), a single representative number of hours

of operation was estimated for each State (Table 7-1). Where a single band

covers a State, the midpoint of the band was used. Where more than one

band covers a State, an average number of hours of operation for the State

was not assigned solely on the geographic distribution of the bands within

the State, but was based on the room air conditioners saturation within the

state. For example, if a State was covered by two bands, a uniform room

air conditioners saturation would lead to selection of the boundary value

of the two bands. If, however, the centers of population were generally

located within one of the two bands, the number of hours within that band

was selected to represent the average number of hours of room air

conditioner operation for that State.

7-4
The above method is subjective in that judgement was required to

select a representative value for hours of operation for each State.

Nevertheless, it is felt that a fair assessment has been made and that the

selected values would vary by a small amount even in those cases where

there is room for other assessments of individual State hours of operation

of room air conditioners. Such differences, therefore, should not

significantly alter the overall results.

Also important to this study is the location of the Nation's

population of room air conditioning units. This was determined by the use

of the 1980 census data [20] (Table 7-1) in that the census survey of

equipment and plumbing facilities also includes individual room air

conditioning units by State. It should be noted that no information is

provided regarding the number of room air conditioners per dwelling unit or

air conditioner size.

The above information permitted the calculation of a weighted National

average for the number of hours of operation of room air conditioning

units. The average number of operation hours for room air conditioners by

State was multiplied by the number of units in that State; the products

added; and then divided by the total number of room air conditioning units.

From these calculations, the average room air conditioning hours of

operation, weighted by roan air conditioner saturation, is 668.

RECOMMENDATIONS

In consideration of the information presented above, a National

average number of annual hours of operation for room air conditioning units

of 670 hours is recommended. Although this recommended figure varies to

some degree from the current value of 750 hours, the variance is less when

viewed from the perspective that the original computat.j on for the current

value was calculated at 730 hours and later rounded up to 750 hours. This

7-5
factor should be reviewed if significant changes in field data or census

data occur or if other information is developed that has the potential to

provide further refinement.

REFERENT

[1] Federal Agency Administration; "Test Procedures for the Energy

Conservation Program for Appliances (Room Air Conditioners)"; Federal

Register 41, 145; 31237-31239 (July 27, 1976).

[2] "Test Procedures for Room Air Conditioners" (Final); Federal Register

42, 105; 27896-27899 (June 1, 1977).

[3] Hung, H.K.; Estimating Annual Hours of Use of Room Air Conditioners, a memorandum to S. Fischler of the Product Systems Analysis Division,

National Bureau of Standards; Washington, DC; February 20, 1976.

[4] Pilati, D.A.; Room Air-Conditioner Lifetime Cost Considerations;

Annual Operating-Hours and Efficiency; ORNL-NSF-EP-85; Oak Ridge

National Laboratory; Oak Ridge, Tennessee.

[5] Billboard Publications, Inc.; Merchandising Week; February 24, 1975.

[6] Departments of the Air Force, Army, Navy; Engineering Weather Data;

(AFM 88-8); June 15, 1967.

[7] Household Appliance Usage Data; NBSIR 80-1994; Alan D. Davies, et.

al.; February 1980 (Final Report Issued March 1980).

[8] Weizeorick, J.T.; A letter to S. Fischler; NBS; Progress Report On The

AHAM Room Air Conditioner Hours of Operation Program; Association of

Heme Appliance Manufacturers; (AHAM); August 16, 1976.

[9] Beard, W.J.; Hours of Operation for Room Air Conditioners; Association

of Home Appliance Manufacturers, (AHAM); September 1978.

[10] Larry Rathensburger; York Air Conditioners; Harrisburg, PA.

[11] J. Griffin; Edison Electric Institute; Washington, DC.

7-6
[12] J.T. Weizeorick, Paul Growman? Association of Home Appliance

Manufacturers; Chicago, IL.

[13] Dick Denny; Air Conditioning and Refrigeration Institute; Arlington,

Virginia.

[14] York; 1982; Publication #2041.

[15] Edison Electric Institute; 1978; "Air Conditioning Usage Study"; #78-

2 .

[16] "Energy Efficiency Program for Room Air Conditioners, Central Air

Conditioners, Dehumidifiers, and Heat Pumps"; Science Applications,

Inc.; Prepared for DOE under Contract No. CR-04-60724-00; La Jolla,

CA; March 1978.

[17] "Manual J: Load Calculation for Residential Winter and Summer Air

Conditioning"; National Environmental Systems Contractors

Association; Arlington, Virginia, 1975.

[18] "Application Guide: Weatherton (R) Heat Pump Seasonal Performance

Factor (SPF) Calculation Guide"; Publication No. 22-3050-1; General

Electric; Louisville, Kentucky; April, 1975.

[19] "AHAM Room Air Conditioner HOURS OF OPERATION"; Association of Home

Appliance Manufacturers, (AHAM); June 1980.

[20] U.S. Department of Commerce; "1980 Census of Housing Volume 1,

Detailed Housing Characteristics, Equipment and Plumbing Facilities

for States, Part 1, United States Summary."

7-7
Figure 7-1

AHAM

FCOM AIN CONDITIONER

AVERAGE CDMfEEESOI\ HOURS Cf OPERATION!

PEN YEAN

7-8
TABLE 7-1

POPULATION-WEIGHTED AVERAGE HOURS OF OPERATION

FOR ROOM AIR CONDITIONER UNITS

STATE

ASSUMED AVERAGE ANNUAL

HOURS OF OPERATION

FOR ROOM AIR

CONDITIONERS*

NUMBER OF ROOM AIR CONDITIONER UNITS (IN

THOUSANDS) 0

Alabama 1050 488

Arizona 1275 88 Arkansas 1000 288

California 800 1613

Colorado 550 180

Connecticut 250 446

Delaware 550 78 District of Columbia 550 94 Florida 1750 1194

Georgia 1000 524

Idaho 425 56 Illinois 550 1503

Indiana 500 585 Iowa 400 368 Kansas 730 315

Kentucky 625 441

Louisiana 1250 559

Maine 150 42 Maryland 550 419

Massachusetts 275 .681 Michigan 250 698

Minnesota 275 460

Mississippi 1125 325

Missouri 750 568 Montana 350 37 Nebraska 500 181

Nevada 1000 50 New Hampshire 250 76 New Jersey 450 1230 New Mexico 750 87 New York 275 2275

North Carolina 750 646

North Dakota 200 67 Ohio 450 1041

Oklahoma 900 443

Oregon 350 117 Pennsylvania 400 1328

Rhode Island 250 102 South Carolina 875 357 South Dakota 425 91 Tennessee 750 711 Texas 1250 1550

Utah 750 85 Vermont 200 17 Virginia 550 530

Washington 275 133 West Virginia 450 181 Wisconsin 350 441 Wyoming 350 23

Population-weighted National average hours | 668 | of operation for Room Air Conditioning Units.

* Association of Home Appliance Manufacturers, 1984.

0 U.S. Housing Census, 1980

7-9

SECTION VIII

CENTRAL AIR CONDITIONERS*

ANNUAL FULL LOAD COMPRESSOR OPERATING HOURS

CURRENT VALUE: 1000 Hours Per Year

PROPOSED VALUE: 1150 Hours Per Year

HISTORICAL BASIS FOR CURRENT VALUE

Test methods were developed for central air conditioners in 1977 [1]

and 1978 [2] in support of Public Law 94-163 which required the Federal

Energy Administration to carry out energy conservation activities related

to household appliance efficiency.

In order to develop the current value for central air conditioner

annual hours of operation (full load compressor operating hours), three

approaches were compared. The first involved a study by Pilati [3] who

used a value of 750 annual operating hours for room air conditioners (see

SECTION VII - ROOM AIR CONDITIONERS - YEARLY HOURS OF USE) to derive a value for central air conditioners. He assumed that users of room air

conditioners will tend to use natural ventilation to achieve their cooling

objectives when outdoor conditions permit, while users of central air

conditioners will tend to avoid natural ventilation during the cooling

season. Data from the "ASHRAE Handbook of Fundamentals," American Society

of Heating, Refrigerating and Air Conditioning Engineers, 1972, were used

in a multi-variable regression analysis to extend the results over the

country and to produce "predictions" for ten cities and the results were

cross-plotted. The calculations using this method yielded a result of

approximately 1100 hours per year. A second study was made by Honeywell

[4] who reported the results of compressor-hours analysis for 26 cities

(six of which coincided with Pilati's selections) using weather data from

* Including heat pumps operating in the cooling node.

8-1
the Departments of the Air Force, Army, and Navy. These data included the

mean number of hours per year for which the dry bulb temperature was

observed in each of a succession of five-degree bins. Compressor operating

hours for an unventilated house were estimated for three temperature

control methods. Averages among the six cities coinciding with Pilati's

selection show a value of 1518 annual hours.

The third method, developed by the National Bureau of Standards, is

based upon the same weather data used in the Honeywell study. The results

from this approach are considered to be more approximate than the previous

two because of the methods of data aggregation. The average number of

hours in each temperature bin were first combined by state and then

weighted by the number of housing units with central air conditioning by

State (derived from the 1970 U.S. Census of Housing Summary HC(1)B1.), to

develop nationally averaged bin-hours. The compressor was assumed to be

off for outdoor temperatures below the balance point and to operate

continuously for temperatures at and above a temperature determined by the

design point and any system oversizing. A linear relationship with respect

to outdoor temperature was used to estimate the fraction of operating time

for conditions between these two temperatures. Assuming a 78°F set point,

a 68°F balance point, a 95°F design point and a ten percent oversizing

factor, a value of 1238 compressor operating hours per year results. Use

of a 65°F balance point yields 1373 hours.

Statistical information provided by industry on usage patterns in

specific locations of the country showed evidence that no single value for

usage could be usefully regarded as "representative" even within a limited

climate area over more than one cooling season. It was also concluded by

MBS [5] that the effects of climate variation across the nation contribute

further to usage variation, weather variations from season to season were

also stated to contribute uncertainties. NBS, therefore, recommended that

8-2
the annual usage factor be heavily rounded to avoid undue impression of

applicability in all situations. Hie value of 1000 compressor hours per

year was recommended because it was believed to be reasonably close to

analytical results and because it would provide a convenient basis for

calculations if a form of regional treatment is considered in the future.

The study. Household Appliance Usage Data, [6] commented that this

usage factor was based entirely upon analyses and assumptions. It was

stated that field data, oversizing practices, consumer practices regarding

ventilation, temperature objectives, and shutoff periods should be

investigated.

APPROACH FOR UPDATE

The general approach for this update is to review the most current

information available on central air conditioner hours of use [7] and a

National average determined by weighing the available data by central air

conditioner saturation as published by the Census Bureau [8] for 1980.

Data are presented and analyzed using a set point temperature at a constant

75°F; a normal set point of 75°F with an adjustment to the set point to

80°F from 5:00 a.m. to 4:00 p.m.; and a constant thermostat set point of

78°F. In addition, the current value of 1000 annual full load compressor

hours is reevaluated using 1980 Census Bureau data [8] to determine central

air conditioner saturation on a state-by-state basis in order to establish

a single National value. Heat pumps operating in the cooling mode have

also been included to reflect their increasing popularity as a combination

heating and cooling appliance.

Bssaa&im. di mtssKM

Three approaches were used in developing a value for annual conpressor

operating hours. Two assumed an indoor thermostat constant set point of

78°F; the third approach assumed a constant 75°F set point. All of the

approaches assumed that there was no natural ventilation. It was assumed

8-3
that users of central air conditioning will tend to avoid natural

ventilation during the cooling season. In these approaches, the compressor

was assumed to be off for outdoor temperatures below the balance point and

to cycle, as appropriate, for temperatures at and above a temperature

determined by the design point and any system oversizing. In the NBS

document, Test Procedure Review - Central Air Conditioners [5], it was

determined that one characteristic of the bin calculation methods used in

this analysis concerns all outdoor temperature excursions into the cooling

demand region. These contribute to the total compressor hours, however

brief they may be or whenever they may occur during the year. However,

there are practical reasons for adjusting these theoretical results.

Because of the thermal masses of walls and building contents, indoor

temperatures do not respond immediately or fully to short-term outdoor

temperature fluctuations. Operating hours would also be reduced by any

tendencies to confine system usage to the main cooling season. Also, no

allowance is made in the analyses for conservation-motivated setbacks

during vacations or other periods of absence. Thus, it was recommended in

this review, that some downward adjustment of theoretical results was

warranted.

Of the three approaches used, the Honeywell study [4] found that a

one-degree increase in indoor tenpereture decreases the operating hours by

an estimated 3%. A study published in the ASHRAE Journal [7]

,

reveals a

savings in compressor hours of operation of 8-20% by setting the thermostat

to 80°F during the day and 75°F at night as compared to a constant 75°F set

point. This reflects a practice employed by those households in which all

family members are absent from the house during the day. The study also

showed a 16-33% savings in compressor hours of use with a thermostat

setting of 78°F constant setpoint versus the 75°F set point. This practice

is the one most appropriate to a majority of households in which family

8-4
members are at home during the day. Both energy conserving setback

practices are becoming increasingly popular in homes with central air

conditioning and should be taken into consideration if the average annual

number of compressor operating hours is to reflect realistic conditions.

These accepted set point practices, along with the concern expressed

earlier for response to regional differences, led to the methodology for

this update study. It was decided that an air conditioner saturationweighted average of yearly hours of use be determined for each of the set

point practices described above. Sources of data for these studies were

the ASHRAE Journal 1976 study previously cited [7] and the 1980 census data

[8], which lists the number of central air conditioners for single family

residences by State.

The first map used (see Fig. 8-1) shows yearly hours of operation for

central air conditioners in single family housing in the conterminous

United States when the set point temperature is a constant 75°F. This map

shows bands of operating hours for central air conditioners. From 1000

hours to 3000 hours, the bands have a 200 hour spread; from 1000 hours to

300 hours the bands have a 100 hour spread. The second and third maps

(Fig. 8-2; 8-3) show yearly hours of savings from the hours shown on the

first map for central air conditioners (Fig. 8-1) when two different

temperature settings are used. Figure. 8-2 indicates the compressor

operating hours saved per year when the thermostat is increased to 80°F

from 5:00 a.m. to 4:00 p.m. and set back to 75°F the rest of the time.

Figure 8-3 shows the compressor operating hours saved per year when the

thermostat is set up to a constant 78°F. Both of these maps (Fig. 8-2; 8-

3) show bands of saved operating hours for central air conditioners; the

bands having a 25 hour spread in the lower range and a 50 hour spread in

the upper range.

8-5
For each map, a single representative number of hours of operation was

estimated for each State. In Figure 8-2 and 8-3, these hours were yearly

hours of operation saved over those hours in Figure 8-1. For each map,

where a single band covers a State, the midpoint of the band was generally

used. Where more than one band covers a State, an average number of hours

of operation, or saved hours of operation, for that State was not assigned

solely on the geographic distribution of the bands within the State, but

was based on the central air conditioner saturation distribution. For

example, if a State was covered by two bands, a uniform central air

conditioner saturation would lead to a selection of the boundary value of

the two bands. If, however, the central air conditioner saturation favored

one of the two bands, the number of hours within that band was selected to

represent the average yearly number of hours of operation or hours of

operation saved for central air conditioners for that State.

The above method is subjective in that judgement was required to

select a representative value for hours of operation for each State.

Nevertheless, it is felt that a fair assessment has been made and that the

selected values would vary by a small amount even in those cases where

there is room for other assessments of individual State hours of operation

of central air conditioners. Such differences should, therefore, not

significantly alter the overall results.

The hours of operation saved in each State as a result of moving the

thermostat to the 80°F set point and the constant 78°F set point were then

subtracted from the yearly average hours of operation for central air

conditioners at the 75°F set point for each State. Average yearly hours of

operation were then listed for each set point by State. (See Tables 8-1;

8-2; and 8-3.)

8—6
Using this information and the 1980 census data [8] in which the

census of equipment and plumbing facilities includes the saturation of

individual central air conditioning systems and heat pumps by State, a

calculation was performed which derived a weighted National average number

of hours of operation of central air conditioners, heat pumps, and total

units for each of the accepted set points. For each set point, the average

number of hours of central air conditioning operation per State was

multiplied by the number of units in that State; the products were added;

and divided by the total number of central air conditioning units. (See

Tables 8-1; 8-2; and 8-3.)

From these calculations, the central air conditioning unit populationweighted average number of hours of operation at a 75°F constant set point

is 1548 hours; at 75°F varying the set point to 80°F from 5:00 a.m. to

4:00 p.m. is 1383 hours; and at a 78°F constant set point is 1286 hours.

(See Table 8-5.)

In further reviewing the basis for the current value, it appears that

the value is based on "equivalent annual full load compressor hours."

Unfortunately, the documentation covering this subject has been found to be

inconsistent in usage and nomenclature. Terms such as "hours of full load

compressor operation per year" and "hours/year" are used. As such, it

should be pointed out that the information presented above is based on the

ASHRAE Journal, June 1976 [7] data and is clearly compressor operating

hours. The results have been included in this study for completeness,

further reference, and later use in extrapolating full load compressor

hours.

A conversion from annual compressor operating hours to equivalent

annual full load hours was made by the York Division, Borg-Warner

Corporation and was based on the annual compressor operating hour

information published in the ASHPAE Journal, June 1976 [7], The results.

8-7
which are mapped as iso-annual full load hours, are contained in the NBS

report Method of Testing, Rating, and Estimating the Seasonal Performance

of Central M^Conditioners and Heat Pumps Operating in the Cooling Mode

[93, and effectively reduce the AfiTOAE annual compressor operating hours by

ten percent* The cooling load hour map contained in the MBS report is

reproduced here as Figure 8-4,

Utilising the same methodology as described above for annual

compressor operating hours, and using 1980 Census Bureau Data, a State-byState analysis was made and a single National value determined for annual

full load operating hours based on a 75°F set point. In addition, annual

full load operating hours for a 75°F set point (increased to 80°F from

5:00 a.m. to 4:00 p.m.) and a constant 78°F set-point were also determined

by interpolation using the ASHRAE Journal computations for annual

compressor operating hours. The resulting annual full load operating hours

at a 75°F constant set point is 1319 hours? at 75°F varying the set point

to 80°F from 5:00 a.m. to 4:00 pjm. is 1178 hours; and at a 78°F constant

set point is 1286 hours. (See Table 8-5.)

RECOMMENDATIONS

In viewing the summary data presented in Table 8-5, attention is

directed to the full load compressor operating hours shown for the 75°F set

point; the 75°F set point (80°F from 5:00 a.m. to 4:00 p.m.); and the 78°F

set point. The highest number of annual full load operating hours is 1319

at the 75°F set point. However, under energy and cost savings conditions,

raising the set point for the day, or part of a day, lowers the annual full

3oad compressor operating hours. If it can be reasonably assumed that the

reduced set point temperature is a widely accepted practice throughout the

nation and more representative of current usage, the National average for

annual full load compressor operation operating hours should reflect this

condition. As such, it is recommended that a new value of 1150 hours be

8-8
accepted as the current National average for the annual full load

compressor operating hours? this figure not being refined further to

suggest a degree of accuracy not warranted by the data and methodology

used. This value should be reviewed if significant field data are

obtained, if major changes occur in central air condtioner saturation, if

the 1976 ASHRAE data are updated, or if other information is developed that

has the potential to provide further refinement.

REFERENCES

1. Federal Energy Administration, "Test Procedures for Central Air

Conditioners" (Final); Federal Register 42, 227; 60250-60257?

(November 25, 1977).

2. Federal Energy Administration; "Test Procedures for Central Air

Conditioners? Corrections"? Federal Register 43, 108? 24268-24269?

(June 5, 1978).

3. "Roan Air Conditioner Lifetime Cost Consideration: Annual Operating

Hours and Efficiencies?" Pilati, David A.? Oak Ridge National

Laboratory? October 1975.

4. "Reducing Energy Consumption During the Cooling Season - an Analog

Computer Study?" Honeywell Corporation Report 70-6245? September 1974.

5. National Bureau of Standards? Test Procedure Review - Central Air

Conditioners? July 12, 1977.

6. National Bureau of Standards? "Household Appliance Usage Data"; NBSIR

80-1994? Davies, A. D., et al.? February 1979.

7. McConnell, Tobias, and Nelson? "Reducing Energy Consumption During the

Cooling Season"? ASHRAE Journal? June 1976.

8. U.S. Department of Commerce? "1980 Census of Housing, Volume ],

Detailed Housing Characteristics, Equipment and Plumbing Facilities

for States, Part 1? United States Summary."

8-9
9. Method of Testing, Rating and Estimating the Seasonal Performance of

Central Air-Conditioners and Heat Purrps Operating in the Cooling Mode;

NBSIR 77-1271? G.E. Kelly and W.H. Parken, Jr.; April 1978? National

Bureau of Standards? Washington, DC 20234.

8-10
Figure 8-1

COMPRESSOR HOURS PER YEAR

AT 75°F SET POINT *

# ASHPAE JOURNAL, JUNE ITO-
Figure 8-2

COMPRESSOR HOURS SAVED PER

AT DAY SETUP OF SOT FROM 5A.M. TO

YEAR

4PM. *

* ASWAI JOOPMM , JUNE 11%.
Figure 8-3

COMPRESSOR HOURS SAVED PER YEAR

AT A CONSTANT 78° F SET POINT

*

r *

ASttPAE vJOUmAL , JUNE TO.

8-13
Table 8-1

CENTRAL AIR OCNDITICNER ANNUAL COMPRESSOR HOURS OF OPERATION AT 75°F SET POINT

State

Mousing

Population

(in thousands)

Having Central

Air Conditioners

(1980 Census)

Bousing

Population

(In thousands)

Having Heat

Punps

(1980 Census)

Average Number of

Compressor Hours Per Year at 75°F

Set Point (ASHRAE

Journal, June 1976)

Alabama 531 103 1875

Arizona 674 160 1975

Arkansas 346 29 1575

California 2084 169 975

Colorado 179 17 750

Connecticut 87 19 800

Delaware 71 6 1000

District of Columbia 92 7 1100

Florida 2399 648 3125

Georgia 805 88 1750

Idaho 60 19 725

Illinois 1351 65 950

Indiana 625 66 1075

Iowa 372 22 875 Kansas 430 14 1225

Kentucky 396 80 1175

Louisianna 704 35 2250

Maine 3 5 500

Maryland 667 70 1100

Massachusestts * 109 31 750

Michigan 484 25 450

Minnesota 286 17 550

Mississippi 307 33 1900

Missouri 808 36 1300 Montana 25 5 550

Nebraska 296 11 950

Nevada 186 34 1825 New Hanpshire 8 5 650 New Jersey 511 40 900 New Mexico 209 6 1100 New York 481 51 750

North Carolina 680 199 1300

North Dakota 34 7 550

Ohio 891 151 1000

Oklahoma 559 26 1500

Oregon 65 45 500

Pennsylvania 539 84 950

Rhode Island 13 3 700

South Carolina 407 128 1625

South Dakota 65 9 725 Tennessee 574 141 1525 Texas 3016 158 2225

Utah 150 8 950 Vermont 1 2 600

Virginia 766 153 1100

Washington m 62 625 West Virginia 103 21 1075

Wisconsin 216 20 725

Wyoming 13 M

8-14
Table 8-2

CENTRAL AIR CttDITTONER ANNUAL COMPRESSOR BOORS OP OPERATION AT 75° SET POINT

REDUCED TO 80°F FROM 5:00 a.m. to 4:00 p.m.

State

Housing

Population

(in thousands)

Having Central

Air Conditioners

(1980 Census)

Bousing

Population

(in thousands)

Having Beat

Pumps

(1980 Census)

Average Number of

Compressor Hours Per Year at 75°F

Set Point Reduced

to 80°F from

5:00am to 4:00pm

(ASHRAE Journal,

June 1976)

Alabama 531 103 1675

Arizona 674 160 1845

Arkansas 346 29 1415

California 2084 169 900

Colorado 179 17 665

Connecticut 87 19 700

Delaware 71 6 865

District of Columbia 92 7 960

Florida 2399 648 2775

Georqia 805 88 1550

Idaho 66 19 645

Illinois 1351 65 880

Indiana 625 66 970 Iowa 372 22 780 Kansas 430 14 1075

Kentucky 396 80 1045

Louisiana 704 35 2050

Maine 3 5 425

Maryland 667 70 965

Massachusetts 109 31 650

Michigan 484 25 375

Minnesota 286 17 475

Mississippi 307 33 1705

Missouri 808 36 1165 Montana 25 5 520

Nebraska 296 11 845

Nevada 186 34 1725 New Hampshire 8 5 525 New Jersey 511 40 775 New Mexico 209 6 1000 New York 481 51 620

North Carolina 680 199 1150

North Dakota 34 7 515

Ohio 891 151 820

Oklahoma 559 26 1350

Oregon 85 45 445

Pennsylvania 539 84 840

Rhode Island 13 3 600

South Carolina 407 128 1400

South Dakota 65 9 610 Tennessee 574 141 1535

Texas 3016 158 2000

Utah 150 8 880

Vermont 1 2 535

Virginia 766 153 980

Washington 111 62 560 West Virginia 103 21 980

Wisconsin 216 20 640

Wyoming 13 3

'iUilAL 25,809 3,136

8-15
Table 8-3

CENTRAL AIR QONDITTQNER ANNUAL COMPRESSOR HOURS OF OPERATION AT 78°P SET POINT

State

Housing

Population

(in thousands)

Having Central

Air Conditioners

(1980 Census)

Housing

Population

(in thousands)

Having Heat Pumps

(1980 Census)

Average Number of

Compressor Hours Per Year at 75°F

Set Point (ASHRAE

Journal, JUne 1976)

Alabama 531 103 1610

Arizona 674 160 1800

Arkansas 346 29 1365

California 2084 169 1535

Colorado 179 17 750

Connecticut 87 19 625

Delaware 71 6 785

District of Columbia 92 7 885

Florida 2399 648 2375

Georaia 805 88 1615

Idaho 60 19 575

Illinois 1351 65 815 Indiana 625 66 920 Iowa 372 22 725 Kansas 430 14 1040

Kentucky < 396 80 1085

Louisianna 704 35 1985

Maine 3 5 375

Maryland 667 70 890

Massachusetts 109 31 540

Michigan 484 25 265

Minnesota '286 17 465

Mississippi 307 33 1625

Missouri 808 36 1110 Montana 25 5 1390

Nebraska 296 11 655

Nevada 186 34 1075 New Hampshire 8 5 465 New Jersey 511 40 700 New Mexico 209 6 1300 New York 51 550

North Carolina 680 199 1250

North Dakota 34 7 585

Ohio 891 151 715

Oklahoma 559 26 1290

Oregon 85 45 415

Pennsylvania 539 84 525

Rhode Island 13 3 325

South Carolina 407 128 1225

South Dakota 65 9 460 Tennessee 574 141 1265 Texas 3016 158 1620

Utah 150 8 865 Vermont 1 2 460

Virginia 766 153 885

Washington in 62 485 West Virginia 103 21 900

Wisconsin 216 20 370

Wyoming 13 3 675

tt/cW, 23,809 57^57

8-16
Figure 8-4 *co

•H

CO •H>

•H 2 Q <u <U CO 2 c« •u

S-< 2 O (C rH 2 C •H CO O 0

CO •H 2 0 H 2 4J 0) P H CO 2 o C 2 CO 2 H <U o •H

CO

u a. i—

2

03 j-> 2 <3

Q

a o P 02 2 <y a a 2 H CO M 2 u r-4 <3 2 a) CO 2 c •H • • 5-i S-< 2 0) co dJ CT> C a rs 4-1 1“

2 0 i CO 2 a) 00 B Q) 2 !-i C 2 a) O C zz M 4-4 CQ o H d) 2 pi ouw2HH2o

PCo

toO

Pi

PCH

CO

pi

PCo

PC3o2o2I—

2ooo2o2o

t—

H

PP> CQM

PiH

CO

I—

Q

8-17
Table 8-4

CENTRAL AIR CONDITIONER ANNUAL FULL LOAD COMPRESSOR BOORS

OP OPERATION AT 75°F SET POINT

Skate

Housing

Population

(in thousands)

Having Central

Air Conditioners

(1980 Census)

Bousing

Population

(in thousands)

Having Heat

Punps

(1980 Census)

Average Number of

Full Load

Conpressor Hours Per Year at 75°F

Set Point (York

Load Curve)

Alabama 531 103 1475

Arizona 674 160 1600

Arkansas 346 29 1400

California 2084 169 900

Colorado 179 17 600

Connecticut 87 19 650

Delaware 71 6 800

District of Columbia 92 7 900

Florida 2399 648 2775

Georqia 805 88 1400

Idaho 60 19 575 Illinois 1351 65 725

Indiana 625 66 875 Iowa 372 22 800 Kansas 430 14 1000

Kentucky 396 80 950

Louisianna 704 35 2000

Maine 3 5 400

Maryland 667 70 850

Massachusetts 109 31 550

Michigan *484 25 600

Minnesota 286 17 500

Mississippi 307 33 1650

Missouri 808 36 1100 Montana 25 5 450

Nebraska 296 11 750

Nevada 186 34 1475 New Hanpshire 8 5 450 New Jersey 511 40 750 New Mexico 209 6 1000 New York 481 51 650

North Carolina 680 199 1200

North Dakota 34 7 400

Ohio 891 151 800

Oklahoma 559 26 1300

Oregon 85 45 450

Pennsylvania 539 84 750

Rhode Island 13 3 600

South Carolina 407 128 1325

South Dakota 65 9 525 Tennessee 574 141 1225 Texas 3016 158 1900

Utah 150 8 800 Vermont 1 2 500

Virqinia 766 153 900

Washington 111 62 375 west Virginia 103 21 975

Wisconsin 216 20 550

Wyoming 13 3 , m

TOTAL 557855 5713?

8-18
Table 8-5

SUMMARY OF NATIONAL AVERAGE AIR CONDITIONER

ANNUAL COMPRESSOR HOURS

Annual Hours

Air

Conditioner

Only

Heat

Pump

Only

Total

for Air

Conditioner

and

Heat Pump

Operating Hours

based on

ASHRAE Journal

June 1976

and 1980

Census Data

75°F Set Point 1530 1684 1548

75°F Set Point

(80° from 5:00 am

to 4:00 pm)

1363 1499 1383

78°F Set Point 1271 1396 1286

Full Load

Operating

Hours Based

on York

Load Curve

and 1980

Census Data

75°F Set Point 1304 1437 1319

75°F Set Point

(80°F from 5:00 am

to 4:00 pm)

1161 1279 1178

78°F Set Point 1083 1196 1095

8-19
NBS-114A (REV. 2-80) U.S. DEPT. OF COMM. 1. PUBLICATION OR 2. Performing Organ. Report No. 3. Publication Date BIBLIOGRAPHIC DATA

REPORT NO.

August 19, 1985 SHEET (See Instructions) NBSIR 85-3220

4. TITLE AND SUBTITLE

A Review of Energy Use Factors for Selected Household Appliances

5. AUTHOR(S)

J. Greenberg, B. Reeder, S. Silberstein

6. PERFORMING ORGANIZATION (If joint or other than NBS, see Instructions)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No. DE-AIO 1- 7 6PR0 6010

8. Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, State, ZIP)

U.S. Department of Energy

Office of Building Energy Research & Development

Building Equipment Division

Washington, D.C. 20585

10. SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, Is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information. If document Includes a significant

bibliography or literature survey, mention it here) The Energy Policy and Conservation Act (EPCA) as amended by the National Energy

Conservation Policy Act (NECPA) requires the development of test procedures, labeling

rules, and energy efficiency standards for consumer appliances. These requirements

must be established using representative national data when establishing the various

parameters for each appliance. During the process of establishing tests procedures,

labeling rules, and energy efficiency standards, many of the parametric values used

have been questioned through written comment and public hearings. The purpose of this

report is to re-evaluate selective parametric values through analysis of current data,

and provide comment and recommendations. The parameters reviewed are: For water

heaters - inlet water temperature, outlet water temperature, ambient air temperature,

and hot water usage; for furnaces - outdoor design temperature and average annual

heating hours; for room and central air conditioners - yearly hours of use. Each

parameter reviewed is documented in an independent section in this report and indicates

the current value, the historical basis for the current value, the approach used to

review and update the value, the results and conclusions, and recommendations. The

recommendations generally propose a new value for the parameter studied based upon the

information analyzed.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Central Air Conditioner; Furnaces; Hours of Operation; Household Appliance;

Hot Water Usage; Outdoor Design Temperature; Water Heater; Water Temperature

13. AVAILABILITY

[X] Unl imited

| | For Official Distribution. Do Not Release to NTIS

Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

[X] Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

86

15. Price

$11.50

USCOMM-DC S043-P80