7

- E

- i APPENDIX 7

- E. DETERMINATION OF FUR NACE ENERGY USE IN T HE LCC

ANALYSIS

TABLE OF CO NTENTS

7

- E.1 INTRODUCTION

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

- E

- 1

7

- E.2 DETERMINATION OF AVE RAGE ANNUAL FUEL ENE RGY CONSUMPTION (E F )

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

- E

- 1

7

- E.3 DETERMINATION OF AVE RAGE ANNUAL ELECTRIC AL ENERGY CONSUMPTION (E AE )

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

- E

- 2

7

- E.4 DETERMINATION OF NAT IONAL AVERAGE NUMBER OF BURNER OPERATING HOURS (BOH SS )

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

- E

- 3

7

- E.5 DETERMINATION OF IMPACT ON FURNACE EN ERGY USE WITH

MORE EFFICIENT FURNA CE FANS

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

- E

- 6

7

- E.6 ASSIGNING FURNACE EQ UIPMENT CHARACTERIST ICS TO SAMPLE

HOUSE HOLDS

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

- E

- 8

7

- E.6.1 Input Capacity of Existing and New Equipment

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

- E

- 8

7

- E.6.2 Airflow Size of Existing Equipment

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

- E

- 10

7

- E.6.3 AFUE of Existin g Equipment

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

- E

- 11

7

- E.6.4 AFUE of New Equipment

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

- E

- 13

LIST OF TABLES

Table 7

- E.5.1 Average V alues for Delay and Ignition Times

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

- E

- 8

Table 7

- E.6.1 Distribution of Input Capacities for Non

- Weatherized Gas

Furnaces

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

- E

- 10

Table 7

- E.6.2 Distribution of Airflow for Furnaces

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

- E

- 11

Table 7

- E.6.3 Number of Observations for Each Age Group

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

- E

- 12

Table 7

- E.6.4 Historical Fraction of Regional Non

- Weatherized Gas Furnace Shipments by AFUE Bins

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

- E

- 13

Table 7

- E.6.5 Distribution of AFUE for Non

- Weatherized Gas Furnaces

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

- E

- 147

- E

- 1 APPENDIX 7

- E. DETERMINATION OF FUR NACE ENERGY USE IN T HE LCC

ANALYSIS

7

- E.1 INTRODUCTION

DOE accounted for the fact that more efficient furnace fans will tend to contribute less heat and thereby require additional furnace operation. Since the heating load of each sample housing unit is known, it is possible to estimate what the furnace energy consumption would be if more efficient fan equipment, rather than the baseline equipment, w as used in each housing

unit.

The furnace energy consumption of non

- furnace components in the LCC analysis is determined using the 2007 ASHRAE SPC 103R “Method of T esting for Annual Fuel Efficiency

of Residential Central Furnaces and Boilers”. 1 This approach requires the calculation of the average annual fuel energy consumption ( E

F

), the average annual electrical energy consumption ( E

AE ), and the national average number of burner operating hours ( BO H

) of furnaces.

The following calculations describe the determination of E F , E AE , and BOH for gas

- and

oil

- fired furnaces.

7

- E.2 DETERMINATION OF AVE RAGE ANNUAL FUEL ENE RGY CONSUMPTION (E F )

The average annual fuel consumption is calculated in Appendix C sect ion 2 of the

ASHRAE 103/2007 test procedure: 1

E

F = BOH SS * ( Q IN - Q P ) + 8,760 * Q P , for single

- stage furnaces,

E

F = ( BOH H * Q IN

) + ( BOH R * Q IN,R ) + [8,760

- ( BOH H + BOH R )]* Q P , for two

- stage furnaces

and

E

F = ( BOH M * Q IN,M ) + ( BOH R * Q IN,R )+ [8,760

- ( BOH M + BOH R )]* Q P , for continuous modulating a 1 furnaces

where,

BOH SS = national average number of burner operating ho urs (see derivation in section 7

- E.4 ),

BOH H = nati onal average number of burner operating hours at the maximum operating

mode for two

- stage furna ces (see derivation in section 7

- E.4 ),

BOH R = national average numbe r of burner operating hours at the reduced operating mode

for two

- stage or continuous modulating furna ces (see derivation in section 7

- E.4 ),

a In this Technical Support Documentation, “continuous modulating” term is used instead of “step

- modulating”. Both terms are interchangeable used in the literature.7

- E

- 2 BOH M = national average number of burner operating hours at the modulating operating mode for continuous modulating furna ces (see derivation in section 7

- E.4 ), Q

IN = steady

- state nameplat e input rate in Btu/h for single

- stage furnaces or steady

- state nameplate maximum input rate in Btu/h for two

- stage and continuous modulating furnaces, Q

IN,R = steady

- state reduced fuel input rate, Q

IN,M = steady

- state modulating fuel input rate, and Q

P = pilot flame fuel input rate in Btu/h.

Q IN is based on the baseline value for each product class. We set Q IN,R to be 69% of Q IN for non

- condensing two

- stage equipment, 67% for condensing two

- stage equipment, and 40% for continuous modulation equipment, where this value represents the average ratio Q IN /Q IN,R as derived using manufacturer product literature and AHRI March 2012 Directory data for all listed

two

- stage furnace models. 2

From the test procedure

, 1 Q IN,M is calculated using Q OUT,M and Effy SS,M (a s defined in

section 11.4.8.10 or 11.5.8.8 in the ASHRAE SPC 103/2007 test procedure ). 1 Q P is zero for all product classes, except for the baseline manufactured

- home gas furnace and gas boiler.

7

- E.3 DETERMINATION OF AVE RAGE ANNUAL ELECTRIC AL ENERGY CONSUMPTION (E AE )

Us ing the ASHRAE SPC 103 /2007 test procedure, 1 the average annual auxiliary electrical energy consumption is calculated in Appendix C section 3:

E

AE = BOH SS (y P * PE + y IG *PE IG + y * BE) , for single

- stage furnaces,

and

E AE = BOH R (y P,R *PE R + y IG,R *PE IG,R + y R *BE R ) + BOH H or M (y P *PE H + y IG *PE IG,H + y*BE H

) b 2 , for two

- stage and continuous modulating furnaces,

where

BOHss = as defined in section 7

- E.4

, BOH H = as defined in section 7

- E.4

, BOH M = as defined in section 7

- E.4

BOH R = as defined in section 7

- E.4

y

P = ratio of induced or forced draft blower on

- time to average burner on

- time,

y

P,R = ratio of induced or forced draft blower on

- time to average burner on

- time, measured at the reduced fuel input rate,

b The ASHRAE test procedure does not deal with ignitor energy consumption. The ratio of ignitor on

- time to

burner on

- time and the ignitor power consumption variables come from the DOE test procedure. 37

- E

- 3 PE = burner (or draft inducer) electrical power input at full

- load steady

- state operation in kW,

PE R = burner (or draft inducer) electrical power input at full

- load steady

- state operation

in kW

, measured at the reduced fuel input rate,

PE H = burner (or draft inducer) electrical power input at full

- load steady

- state operation in kW, measured at the ma ximum fuel input rate,

y

IG = ratio of burner interrupted

- ignition device on

- time to average burner on

- time,

y

IG,R = ratio of burner interrupted

- ignition device on

- time to average burner on

- time, measured at the reduced fuel input rate,

PE IG = electr ical input rate to the interrupted ignition device on the burner,

PE IG,R = electrical input rate to the interrupted ignition device on the burner, measured at the reduced fuel input rate,

PE IG,H = electrical input rate to the interrupted ignition dev ice on the burner, measured at the maximum fuel input rate,

y = ratio of blower or pump on

- time to burner on

- time,

y

R = ratio of blower or pump on

- time to burner on

- time, measured at the reduced fuel input rate,

BE = circulating

- air fan or water pump electrical energy input rate in kW,

BE R = circulating

- air fan or water pump electrical energy input rate in kW, measured at the reduced fuel input rate, and

BE H = circulating

- air fan or water pump electrical energy input rate in kW

, measured at the maximum fuel input rate.

The values y P and y P,R are calculated using t P (post

- purge time). For this calculation,

DOE took t P to be 5 seconds for furnaces, which is less than or 30 seconds and is therefore set equal to 0 seconds, according to Appendix C section 1 of the ASHRAE SPC 103/ 2007

. DOE calculated the values y and y P,R using t + (blower or pump on

- delay) and t - (blower or pump off

delay). For furnaces, t + = 2 min and t - = 0.5 min, which are values obtained for the generic

furnace models . For gas furnaces, PE is equal to 75 W for non

- condensing furnaces and 90 W for condensing furnaces. For oil furnaces, PE is set to 220 W. 6 For design options which include modulating controls, we set PE R and PE H to have th e same values as PE, since it is assumed that there is no inducer modulation. For gas furnaces, PE IG , PE IG,R , and PE IG,H are set equal to 400 W. 7 For oil furnaces, PE IG is equal to 45 watts for oil equipment without interrupte d ignition

, and 25 watts with oil equipment with interrupted ignition. 8 For design options which include modulating controls, we set PE IG,R and PE IG,H to have the same values as

PE IG , since it is assumed that there is no igniti on modulation.

7

- E.4 DETERMINATION OF NATIONAL AVERAGE NUM BER OF BURNER OPERATING HOURS (BOH SS )

From the ASHRAE SPC103/2007 test procedure

, 1 the national average number of burner operating hours for furnaces and boilers is calculated in Appendix C section 1 :

BOH SS = 2080 * 0.77 * A * ( Q OU T / (1 + α ))

- 2080 * B , for single

- stage furnaces,7

- E

- 4 BOH H = X H * (2080) * (0.77) * A H * ( Q OUT / (1 + α ))

- 2080 * B H , for two

- stage furnaces at the maximum operating mode,

BOH R = X R * (2080) * (0.77) * A R * ( Q OUT / (1 + α ))

- 2080 * B R , for two

- stage and continuous modulating furnaces operating at the reduced operating mode,

and

BOH M = X H * (2080) * (0.77) * A M * ( Q OUT / (1 + α ))

- 2080 * B M

, for continuous modulating furnaces operating at the modulating operating mode,

where

2080 = national average heating load hours,

0.77 = adjustment factor to adjust the calculated design heating requirements and heating load hours to the actual heating load experienced by the heating system,

A = 100,000/ [341300(y P * PE + y IG,R *PE IG,R + y * BE) + (Q IN - Q P ) * Effy HS ] c

A H = 100,000/ [341300(y P * PE H + y IG,R *PE IG,R + y * BE H ) + (Q IN - Q P ) * Effy U,H ] a

,

3

,

A R = 100,000/ [341300(y P,R * PE R + y IG,R *PE IG,R + y R * BE R ) + (Q IN,R - Q P ) * Effy U,R ] a

, A M = 100,000/ [341300(y P * PE H + y IG,R *PE IG,R + y * BE H ) + (Q IN,M - Q P ) * Effy U,M ] a

, B = 2 * (Q P ) * (Effy HS ) * (A) / 100,000,

B H = 2 * (Q P ) * (Effy U,H ) * (A H ) / 100,000,

B R = 2 * (Q P ) * (Effy U,R ) * (A R ) / 100,000,

B

M = 2 * (Q P ) * (Effy U,M ) * (A M ) / 100,000, Q OUT = maximum fuel input rate heati ng capacity,

α = oversize factor set to 0.7

, X

H = fraction of heating load at maximum fuel input rate operating mode,

X

R = fraction of heating load at reduced fuel input rate operating mode (1

- X H ), Q

IN = as defined in above

, Q

IN,R = as defined in above

, Q

IN,M = as defined in above

, Q

P = as defined in above

, y

P = as defined in above

, y

P,R = as defined in above

, PE = as defined in above

, PE R = as defined in above

, PE H = as defined in above

, y

IG = as defined in above

, y

IG,R = as defined in above

, PE IG = as defined in above

, PE IG,R = as defined in above

, PE IG,H = as defined in above

,

c The ASHRAE test procedure does not deal with ignitor energy consumption. Th e ratio of ignitor on

- time to

burner on

- time and the ignitor power consumption variables come from the DOE test procedure. 37

- E

- 5 y = as defined in section above

, y

R = as defined in section above

, BE = as defined in section above

, BE R = as defined in section above

, BE H = as defined in section above

, Effy HS = ratio of the average length of the heating season in hours to the average heating load hours, Effy U,H = average part load efficiency at the maximum fuel input rate, Effy U,R = average part load efficiency at the redu ced fuel input rate, and Effy U,M = average part load efficiency at the modulating fuel input rate.

The modified equations used in the LCC spreadsheet are as follows (Note that the maximum value for BOH is set to 8760):

BOH SS = A * HHL

- 2080 * B , for single

- stage furnaces,

BOH H = X H * A H * HHL

- 2080 * B H , for two

- stage furnaces at the maximum operating mode,

BOH R = X R * A R * HHL

- 2080 * B R , for two

- stage and continuous modulating furnaces operating at the reduced operating mode,

and

BOH M = X H * A M * HHL

- 2080 * B M

, for continuous modulating furnaces operating at the modulating operating mode,

To calculate factors A

, A H , A R , A M , B

, B H , B R , and B M

, DOE calculated y P , y P,R , PE

, PE R , PE H

, y IG , y IG,R , PE IG , PE IG,R , PE IG,H , y , y R , BE

, BE R , BE H

, PE

, y IG , PE IG , y , BE

, Q IN

, and Q P y P , as described in section 7

- E. 3 of this appendix. For factor B , if Q P = 0, then B = 0, which is true for all cases except for the baseline manufactured

- home gas furnace and the baseline gas boiler. We

calculated Effy HS , heating seasonal efficiency, as defined in sections 11.2.11, 11.3.11.3, 11.4.11.3, and 11.5.11.3 in ASHRAE SPC 103/2 007 test procedure

. 1 For Q P = 0, Effy HS is equal to the annual fuel utilization efficiency ( AFUE ). For Q P > 0, Effy HS is calculated using Effy SS (as

defined in section 11.2.8.1 1 ). Effy SS is calculated using Q OUT (as defined below), K (factor that adjusts the jacket losses, where K = 1.7 for non

- weatherized furnaces and Lj (jacket loss, where Lj = 1 is the default value as described in section 11.2.8.1 1 )

Q OUT for all product classes is calculated using the following equations based on AHRI Directory data for Non

- Weatherized Gas Furnaces: 2

Q OUT = Q IN (0.7247 * AFUE + 0.22346), for non

- condensing equipment, and

Q OUT = Q IN (0.8127 * AFUE + 0.17557), for condensing equipment.7

- E

- 6 DOE calculated X H by using T C (balance

- point temperature as defined in section 11.4.8.4 of ASHRAE SPC 103/2007 test procedure 1 ), α (the oversize factor, as calculated in E quation 11), Q OUT , and Q OUT,R (reduced fuel input rate heating capacity). Q OUT,R is set equal to 69% Q OUT for non

- condensing equipment and 67% Q OUT for condensing equipment, as derived using manufacturer product literature and AHRI Directory data for all listed two

- stage furnace

models. 2 X R is set equal to 1

- X H

. Effy U,H = Effy U,R and therefore using the equation in section

11.5.11.3 of ASHRAE SPC 103/2007 test procedure is equal to Effy SS

. Effy U,M is calculated using the eq uation in section 11.4.9.2.3 of ASHRAE SPC 103/2007 test procedure

. 1

7

- E.5 DETERMINATION OF IMPACT ON FURNACE EN ERGY USE WITH

MORE EFFICIENT FURNA CE FANS

DOE accounted for the fact that more efficient furnace fans will tend to contribute less heat and thereby require a dditional furnace operation. Since the heating load of each sample housing unit is known, it is possible to estimate what the furnace energy consumption would be if more efficient fan equipment, rather than the baseline equipment, w as used in each housing

unit.

DOE calculated the furnace fuel consumption ( FuelUse ) for each furnace fan efficiency level using the following formula based on the current American Society of Heating, Refrigerating and Air

- Conditioning Engineers (ASHRAE) test procedure SPC 103

- 2007 section

C d :

, for single

- stage furnace, and

FuelUse = ( BOH H * Q IN

) + ( BOH R * Q IN,R ), for two

- stage furnaces

Where:

BOH = steady

- state burner operating hours (hr),

Q

IN = input capac ity of existing furnace (kBtu/h, ).

BOH H = burner operating hours at the maximum operating mode for two

- stage furnaces (see derivation in section 7

- E.4 ),

BOH R = burner operating hours at the reduced operating mode for two

- stage or continuous modulating furnaces (see derivation in section 7

- E.4 ), and

Q

IN,R = reduced f uel i nput rate.

d For natural draft equipment this formula is modified to include the pilot light consumption. IN 

### Q BOH FuelUse **× =** 7

- E

- 7 Recall from above that BOH is calculated using BE (furnace fan electrical energy input rate), which is equal to the furnace fan power during the heating operation calculated for each furnace fan efficiency level.

DOE also calculated the non

- furnace fan furnace electricity consumption (i.e., the electricity used by the induce draft blower and the electricity used by the ignitor) for each furnace fan efficiency level using the following formula:

, e

ElecUse

non

- furnac_fan = BOH R (y P,R *PE R + y IG,R *PE IG,R ) + BOH H (y P *PE H + y IG *PE IG,H ) for single

- stage furnace

, and

f 2 , for

two

- stage

Where:

BOH = steady

- state burner operating hours (hr)

,

y

P = ratio of induced

- draft blower on

- time to burner on

- time,

PE = power consumption of the draft

- inducer blower

- motor (kW),

y

IG = ratio of ignitor on

- time to burner on

- time, and

PE IG = power consumption of the ignitor (kW).

BOH H = burner operating hours at the maximum operating mode for two

- stage furnaces (see d erivation in section 7

- E.4 ),

BOH R = burner operating hours at the reduced operating mode for two

- stage or continuous modulating furnaces (see derivation in sectio n 7

- E.4 ), and

y

P

,H = ratio of induced

- draft blower on

- time to burner on

- time, measured at the maximum fuel input rate,

PE H = power consumption of the draft

- induc er blower

- motor (kW), measured at the maximum fuel input rate,

y

IG

,H = ratio of ignitor on

- time to burner on

- time, measured at the maximum fuel input rate, and

PE IG

,H = power consumption of the ignitor (kW) measured at the maximum fuel input rate.

y

P

,R = ratio of induced

- draft blower on

- time to burner on

- time, measured at the reduced fuel input rate,

PE R = power consumption of the draft

- inducer blower

- motor (kW), measured at the reduced fuel input rate,

e For two

- stage equipment this for mula includes parameters for the operation at full, modulating, and reduced load.

f The ASHRAE test procedure does not deal with ignitor energy consumption. The ratio of ignitor on

- time to burner

on

- time and the ignitor power consumption variables come from the DOE test procedure. 3 

# ( **)**

ig ig p SS fan furnace non 

### PE y PE y BE y BOH ElecUse **× +**  **× +**  **× ×**  **=**

**−**

_7

- E

- 8 y

IG

,R = ratio of ignitor on

- time to burner on

- time, measured at the reduced fuel input rate, and

PE IG

,R = power consumption of the ignitor (kW) measured at the reduced fuel input rate

.

Once the heating load of each sample housing unit is known, it is poss ible to estimate what the energy consumption would be if more efficient furnace fan equipment, rather than the baseline equipment, were used in each housing unit.

The ratio of blower on

- time to burner on

- time and the ratio of induced draft blower on

time to burner on

- time are from the current ASHRAE test procedure SPC 103

- 2007 1 using delay times (pre

- purge, post

- purge, on

- delay, and off

- delay) derived from DOE’s 2007 Furnace and

Boiler Final Rule. 4 The ratio of i gnitor on

- time to burner on

- time comes from the DOE test procedure and the ignition time derived from the 2007 final rule. The delay times are defined as follows: pre

- purge and post

- purge times are the lengths of time the draft inducer operates before

and after a firing cycle. On

- delay is the amount of time the blower waits to begin operating after the burner starts firing. Off

- delay is the time the blower keeps operating after the burner turns off. Ignition time is the length of time the hot surface ignito r is on before gas is sent to the

burner. The average values for the delay and ignition times are shown in the next table.

Table 7

- E.5.1 Average Values for Delay and Ignition Times

Pre

- Purge Post

- Purge On

- Delay Off

- Delay Ignition

15 seconds 5 seconds 30 seconds 120 seconds 37 seconds

A common value for the power consumption of the draft inducer, PE , for basic non

condensing model furnaces is 75 W, and the average value is about 75 W, so DOE selected 75 W

for all the non

- condensing models. DOE found no correlation between the PE and input capacity or between PE and airflow capacity. For condensing fu rnaces, DOE used a PE of 90 W, which closely matches the mean for that group.

7

- E.6 ASSIGNING FURNACE EQ UIPMENT CHARACTERIST ICS TO

SAMPLE HOUSEHOLDS

To estimate the heating load of each sample housing unit, DOE represented the existing furnace by assigning an input capacity, airflow capacity, and AFUE to the furnace in the RECS sample housing units.

7

- E.6.1 Input Capacity of Existing and New Equipment

DOE assigned an input capacity for the existing furnace of each housing unit based on an algorithm that correlates the housing unit size and outdoor design temperature with the distribution of input capacity of furnaces. DOE assumed that, for the new furnace installation,7

- E

- 9 the input capacity would remain the same. The following steps describe the assignment process

for furnaces:

1) DOE ranked all the RECS housing units in ascending order by size (heating square foot) multiplied by a scaling factor to account for the outdoor de sign temperature (see equation

below ) and calculated the percentile rank of each housing unit usin g the statistical weight of each of the sample records.

2) DOE constructed percentile tables by input capacity of furnaces based on the historical shipment information and number of models in AHRI Directory.

3) After selecting a housing unit from the RECS databa se during each Monte Carlo iteration, DOE noted the size of the selected housing unit and determined the percentile rank from Step 1.

4) To avoid a one

- to

- one deterministic relation between the housing unit size and input capacity, DOE added a random term to the percentile identified in Step 3 so that the correlation was not perfect. DOE used a normal distribution to characterize the random term. The random term has a mean of zero and a standard deviation of 8 percent.

5) Using the percentile from Step 4, DOE loo ked up the input capacity from the input capacity percentile table in Step 2.

DOE used ASHRAE design data to develop estimates of the average 1 percent design dry bulb temperature for each household. Using this data, DOE then developed a scaling factor to be applied to the home heating square footage and equal to:

SF design,h = (65

- T design, h ) / (65

- 42)

Where:

SF design,h = heating design scaling factor, and

T

design, h = average 1 percent ASHRAE design dry bulb temperature (°F) for heating

.

T he design scaling factor is used as a proxy to represent lower heating loads for the same

household area in cooler climates and supports the allocation of the sizes across observations, but

that the total relative allocation of sizes is unaffected. Th e end result was a distribution of sizes assigned to the weighted RECS samples that matches the distribution of sizes for shipments of

residential furnaces by input capacity

. Table 7

- E.6.1 shows the distribu tion of input capacities for the most commonly available input capacity bins for non

- weatherized gas furnaces based on the

2012 AHRI Residential Furnace Directory

. 2 See the LCC spreadsheet, worksheet “Furnace & AC Spec” for the distributions of input capacities for other product classes.7

- E

- 10 Table 7

- E.6.1 Distribution of Input Capacities for Non

- Weatherized Gas Furnaces

Non

- Condensing Condensing Input Capacity

kBtu/h 201 2 AHRI

Director y Fraction of

Models

% Cumulative

Fraction of

Models

% 201 2 AHRI Directory

Fraction of

Models

% Cumulative

Fraction of

Models

%

4 0 10.9 10.9 10.9 10.9

50 3.3 14.2 1.8 12.7

60 17.6 31.8 17.1 29.8

70 5.4 37.2 6.7 36.5

80 18.5 55.7 20.4 56.9

90 1.8 57.5 7.5 64.4

100 17.4 75.0 16.0 80.4

110 6.5 81.5 6.7 87.1

120 9.1 90.6 10.5 97.6

130 3.4 94.0 2.2 99.8

140 3.4 97.5 0.2 100.0

150 2.0 99.5 0.0 100.0

160 0.5 10.9 0.0 100.0

7

- E.6.2 Airflow Size of Existing Equipment

DOE classified furnaces by nominal maximum airflow in cfm at 0.5 in. w.g. of external static pressure. DOE assigned the airflow capacity of existing furnaces for housing units that had air conditioners in a manner similar to how it assigned furnace input capacity. Larger air conditioners go to larger housing units, according to the distribution of sizes of air conditioners sold the year the air conditioner was installed in that housing unit. DOE used the air conditioner nominal size of two, three, four, or five tons to set the airflow capaci ty with a ratio of 400 cfm per ton of cooling. The steps were:

1) DOE ranked all the RECS housing units in ascending order by size (cooling square foot) multiplied by a scaling factor to account for the outdoor design temperature (see equation

below ) and calculated the percentile rank of each housing unit using the statistical weight of each of the sample records.

2) Based on historical shipment information of residential central air conditioners by capacity, DOE constructed the airflow capacity percentiles t able for air conditioners. ( See

Table 7

- E.6.2 ). Since there are no available shipment data on the airflow capacity of furnaces, DOE used the airflo w capacity of residential central air conditioners as a proxy.

3) After selecting a housing unit from the RECS database during each Monte Carlo iteration, DOE noted the size of the selected housing unit and determined the percentile rank from Step 1.

4) To avoid a one

- to

- one deterministic relation between the housing unit size and input capacity, DOE added a random term to the percentile identified in Step 3 so that the7

- E

- 11 correlation was not perfect. DOE used a normal distribution to characterize the random

term. T he random term has a mean of zero and a standard deviation of 8 percent.

5) Using the percentile from Step 4, DOE looked up the airflow from the airflow percentile table in Step 2. DOE selected an input capacity and airflow combination with the

identified air flow capacity, based on commonly available models. If no input capacity and airflow combination with the identified airflow capacity was available, DOE selected the input capacity and airflow combination with the same input capacity and the closest

airflow capacity as a substitute.

DOE used ASHRAE design data to develop estimates of the average 1 percent design dry

bulb temperature for each household . Using these data, DOE then developed a scaling factor to be applied to the home cooling square footage and equal to:

SF design, c = ( T design, c – 65) / (95

- 65)

Where:

SF design, c = cooling design scaling factor, and

T

design, c = average 1 percent ASHRAE design dry bulb temperature (°F) for cooling

.

It is noted that the design scaling factor is used as a proxy to represent lower cooling

loads for the same household area in warmer climates and supports the allocation of the sizes across observations, but that the total relative allocation of sizes is u naffected. This end result was a distribution of sizes assigned to the weighted RECS samples that matches the distribution of sizes for shipments of residential furnaces. Table 7

- E.6.2 shows the distribution of airflow ratings for the representative product classes listed above, based on AHRI shipment data

. 5

Table 7

- E.6.2 Distribution of Airflow for Furnaces

Airflow Rating cfm 2007

- 2011 AHRI Shipments

% Cumulative Fraction

%

600 9.5 9.5

800 19.6 29.1

1000 16.5 45.6

1200 22.5 68.0

1400 8.7 76.8

1600 12.5 89.2

2000 10.8 100.0

7

- E.6.3 AFUE of Existing Equipment

DOE assigned the AFUE of existing furnaces based on the equipment age of the existing furnace as given by RECS and historical shipments by efficiency. The following steps describe

this process:7

- E

- 12 1) After DOE selected a housing unit from the RECS database during each Monte Carlo iteration, DOE randomly assigned a percentile value and extracted the furnace age information from RECS. Using the extracted furnace age, DOE assigned an installati on year from the installation year range for the applicable RECS equipment age bin (see

Table 7

- E.6.3 )

. 2) Based on the historical furnace shipment information sorted by AFUE, DOE constructed percentile tables by AFUE shipments of furnaces for 2005 and prior years. AHRI shipments data for non

- weatherized gas furnaces indicate that housing units in the northern region receive more efficient furnaces. Therefore, DOE deve loped two historical AFUE shipment distributions

— one for the northern region and one for the southern region

— for non

- weatherized gas furnaces.

3) DOE determined the AFUE by looking it up from the AFUE percentile table from Step (2) corresponding to the age of the existing equipment in the housing unit and whether the housing unit was located in the northern or southern regions (See Table 7

- E.6.4 )

. See the LCC spreadsheet, worksheet “Furnace & AC Spec” for the distributions of input capacities for other product classes.

Table 7

- E.6.3 Number of Observations for Each Age Group

RECS Bin Less than 2

Years Old 2 to 4

Years Old 5 to 9

Years Old 10 to 19

Years Old 20 Y ears or Older Total

Installation Years 2004

- 2005 2001

- 2005 1996

- 2000 1986

- 1995 1966

- 1985 Equipment Type

Non

- Weatherized

Gas Furnaces 206 229 367 477 302 1,726

13.2% 13.3% 21.3% 27.0% 17.8% 100.0%

Manufactured Home

Gas Furnaces 11 14 25 25 27 109

8.5% 12.5% 24.4% 23.5% 23.3% 100.0%

Oil

- Fired Furnaces 10 21 29 47 39 150

9.0% 14.1% 14.5% 31.7% 29.7% 100.0%7

- E

- 13 Table 7

- E.6.4 Historical Fraction of Regional Non

- Weatherized Gas Furnace Shipments by AFUE Bins

Year North Region South Region

>78 AFUE 78 to <90 >90 AFUE >78 AFUE 78 to <90 >90 AFUE

2005 0.0% 48.8% 51.2% 0.0% 81.6% 18.4%

2004 0.0% 52.2% 47.8% 0.0% 83.6% 16.4%

2003 0.0% 53.7% 46.3% 0.0% 83.6% 16.4%

2002 0.0% 59.0% 41.0% 0.0% 85.2% 14.8%

2001 0.0% 57.7% 42.3% 0.0% 86.0% 14.0%

2000 0.0% 64.6% 35.4% 0.0% 89.6% 10.4%

1999 0.0% 64.9% 35.1% 0.0% 89.5% 10.5%

1998 0.0% 64.6% 35.4% 0.0% 89.8% 10.2%

1997 0.0% 62.9% 37.1% 0.0% 87.8% 12.2%

1996 0.0% 64.8% 35.2% 0.0% 89.8% 10.2%

1995 0.0% 68.3% 31.7% 0.0% 88.9% 11.1%

1994 0.0% 66.6% 33.4% 0.0% 87.6% 12.4%

1993 0.0% 70.2% 27.4% 0.0% 86.8% 10.2%

1992 2.4% 59.3% 34.0% 3.0% 80.2% 10.7%

1991 6.7% 23.9% 29.7% 9.1% 30.9% 9.3%

1990 46.3% 22.3% 25.3% 59.8% 27.4% 7.9%

1989 52.4% 17.4% 24.3% 64.6% 21.2% 7.6%

1988 58.3% 19.6% 25.7% 71.2% 24.2% 8.1%

1987 54.8% 18.3% 23.7% 67.8% 22.2% 7.4%

1986 58.0% 18.7% 10.2% 70.4% 20.1% 3.2%

1985 71.1% 17.3% 16.2% 76.7% 19.6% 5.1%

1984 66.5% 18.2% 17.8% 75.3% 20.9% 5.6%

1983 64.0% 7.8% 22.9% 73.5% 9.4% 7.2%

1982 69.3% 8.2% 19.2% 83.4% 9.6% 6.0%

1981 72.6% 8.6% 15.6% 84.4% 9.7% 4.9%

1980 75.9% 9.0% 11.9% 85.4% 9.8% 3.7%

1979 79.1% 3.9% 5.9% 86.5% 4.1% 1.9%

1978 90.2% 1.4% 0.0% 94.1% 1.4% 0.0%

1977 98.6% 0.9% 0.0% 98.6% 0.9% 0.0%

1976 99.1% 0.5% 0.0% 99.1% 0.5% 0.0%

1975 99.5% 0.0% 0.0% 99.5% 0.0% 0.0%

1966 to 1974 100.0% 0.0% 0.0% 100.0% 0.0% 0.0%

7

- E.6.4 AFUE of New Equipment

DOE assigned the AFUE of new furnaces based on distribution of AFUE of furnaces equipment and the RECS household location standards in 2018 for furnaces (e.g. minimum efficiency of 90% AFUE for northern region households with a non

- weatherized gas furnace)

. Table 7

- E.6.5 shows the distribu tion of AFUE for the most commonly available AFUE bins for

non

- weatherized gas furnaces based on the 2012 AHRI Residential Furnac e Directory

. 2 See the LCC spreadsheet, worksheet “Furnace & AC Spec” for the distributions of AFUE for other product classes.7

- E

- 14 Table 7

- E.6.5 Distribution of AFUE for Non

- Weatherized Gas Furnaces

Non

- Condensing Condensing

AFUE

% 201 2 AHRI Directory

Fraction of

Models

% Cumulative

Fraction of

Models

% 201 2 AHRI Directory

Fraction of

Models

% Cumulative

Fraction of

Models

%

80 99.8 99.8 0.0 0.0

81 0.0 99.8 0.0 0.0

82 0.0 99.8 0.0 0.0

83 0.2 100.0 0.0 0.0

90 0.0 100.0 1.8 1.8

91 0.0 100.0 2.4 4.2

92 0.0 100.0 18.2 22.4

93 0.0 100.0 6.4 28.7

94 0.0 100.0 2.7 31.5

95 0.0 100.0 33.5 64.9

96 0.0 100.0 21.1 86.0

97 0.0 100.0 10.7 96.7

98 0.0 100.0 3.3 100.07

- E

- 15 REFERENCES

1. American Society of Heating Refrigerating and Air

- Conditioning Engineers Inc., ASHRAE Standard: Method of Testing for Annual Fuel Utilization Efficiency of

Residential Central Furnaces and Boilers , 2007. Report No. ANSI/ASHRAE 103

- 2007.

2. Air Conditioni ng Heating and Refrigeration Institute, Consumer's Directory of Certified Efficiency Ratings for Heating and Water Heating Equipment (AHRI Directory March 2012), 2012. (Last accessed March, 2012.)

< http://www.ahridirectory.org/ahridirectory/pages/home.aspx >

3. U.S. Department of Energy

- Office of Energy Efficiency and Renewable Energy, Title 10, Code of Federal Regulations, Chapter II Part 430 Appendix N, Subpart B

- Uniform Test

Metho d for Measuring the Energy Consumption of Furnaces, January 1, 2012.

4. Department Of Energy, 10 CFR Part 430 Energy Conservation Program for Consumer Products: Energy Conservation Standards for Residential Furnaces and Boilers; Final

Rule

. Federal Regis ter , 2007. 72 No.222: pp. 65132

- 65170

5. Air

- Conditioning Heating and Refrigeration Institute, AHRI Shipments Data for Air Conditioners by Capacity 2007

- 2011. < http://www.ahrinet.org/monthly+shi pments.aspx >