7

- i CHAPTER 7. ENERGY USE ANALYSIS

TABLE OF CONTENTS

7.1 INTRODUCTION

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

- 1 7.2 GENERAL APPROACH TO THE ENERGY USE ANALY SIS

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

- 1 7.3 HOUSEHOLD SAMPLE

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

- 2 7.4 FURNACE FAN POWER CO NSUMPTION

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

- 4 7.4.1 System Curves

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

- 4 7.4.2 Furnace Fan Curves

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

- 6 7.4.3 Fan Power

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

- 7 7.4.4 Determinat ion of Fan Performance by Product Class and Efficiency Level

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

- 9 7.5 OPERATING HOURS

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

- 17 7.5.1 Heating Mode

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

- 17 7.5.2 Coolin g Mode

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

- 23 7.5.3 Constant Circulation Mode

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

- 28 7.6 FURNACE FAN STANDBY ENERGY USE

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

- 30 7.7 CHANGES IN HEATING A ND AIR

- CONDITIONING ENERGY USE WITH MORE

- EFFICIENT FURNACE FA NS

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

- 31 7.7.1 Impact on Furnace Fuel Use with More Efficient Furnace Fans

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

- 31 7.7.2 Impact on Central Air Conditioner Energy Use with More Efficient Furnace Fans

..... 7

- 32 7.8 SUMMARY OF ENERGY US E RESULTS

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

- 33

LIST OF TABLES

Table 7.1.1 Furnace Fan Product Classes Analyzed

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

- 1 Table 7.3.1 Household Samples for Furnace Fan Products

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

- 3 Table 7.4.1 Values Used for External Static Pressure

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

- 5 Table 7.4.2 Coefficients for CFM equation for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton

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

- 10 Table 7.4.3 Coefficients for Watts/CFM Equation for Non

- Weatherize d (Non

Condensing) Gas Furnaces, 3

- Ton

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

- 12 Table 7.5.1 Heating Degree

- Day Adjustment Factors

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

- 21 Table 7.5.2 Range of Adjusted Heating Load for Each Furnace Fan Product Class, million Btu/h

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

- 22 Table 7.5.3 Range of Baseline Furnace Fan Heating Operating Hours for Each Furnace Fan Product Class, hours

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

- 23 Table 7.5.4 Cooling Degree Day Adjustment Factors

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

- 26 Table 7.5.5 Range of Annual Cooling Load for Each Furnace Fan Product Class, million Btu/h

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

- 27 Table 7.5.6 Rang e of Baseline Furnace Fan Cooling Operating Hours for Each Furnace Fan Product Class, hours

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

- 28 Table 7.5.7 Results from Constant

- Circulation Use Studies and Estimated National Constant

- Circulation Hours

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

- 297

- ii Table 7.5.8 Average Baseline Constant Circulation Furnace Fan Operating Hours for Each Furnace Fan Product Class, hours

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

- 30 Table 7.8.1 Average Annual Energy Consumption and Savings for Furnace Fans Used in Non

- Weatherized Gas Furnaces

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

- 33 Table 7.8.2 Average Annual Energy Consumption and Savings for Furnace Fans Used in Weatherized Gas Furnace Fans and Oil

- Fired Furnaces

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

- 34 Table 7.8.3 Average Annual Energy Consumption and Savings for Furnace Fans Used in Manufactured Home Gas Furnaces

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

- 34 Table 7.8.4 Average Annual Energy Consumption and Savings for Furnace Fans Used in Electric Furnaces and Manufactured Home Electric Furnaces

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

- 35 Table 7.8.5 Average Annual Energy Consumption and Savings for Furnace Fans Used in Hydronic Air Handlers

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

- 35

LIST OF FIGURES

Figure 7.4.1 Sample of System Curves with a Typical Fan Curve

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

- 6 Figure 7.4.2 Example Fit of CFM for 3

- Ton PSC Furnace in Heating Mode

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

- 7 Figure 7.4.3 Example Fit of Watts/CFM for 3

- Ton Single

- Stage Furnace

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

- 9 Figure 7.4.4 CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Heating Mode)

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

- 11 Figure 7.4.5 CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Cooling Mode)

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

- 11 Figure 7.4.6 CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Constant Circulation Mode)

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

- 12 Figure 7.4.7 Watt/CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- T on (Heating Mode)

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

- 13 Figure 7.4.8 Watt/CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Cooling Mode)

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

- 13 Figure 7.4.9 Watt/CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Constant Circulation Mode)

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

- 14 Figure 7.4.10 Resulting Watt vs. Pressure Curves for Non

- Weatherized (Non

Condensing) Gas Furnace Fan, 3

- Ton (Heating Mode)

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

- 15 Figure 7.4.11 Resulting Watt vs. Pressure Curves for Non

- Weatherized (Non

Condensing) Gas Furnace Fan, 3

- Ton (Cooling Mode)

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

- 16 Figure 7.4.12 Resulting Watt vs. Pressure Curves for Non

- Weatherized (Non

Condensing) Gas Furnace Fan, 3

- Ton (Constant Circulation Mode)

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

- 177

- 1 CHAPTER 7. ENERGY USE ANALYSIS

7.1 INTRODUCTION
The purp ose of the energy use analysis is to determine the annual energy consumption of furnace fans in representative U.S. homes and to assess the energy savings potential of increased fan efficiency. I n contrast to the DOE test procedure , which uses typical operating conditions in a laboratory setting, the energy use analysis seeks to estimate the range of energy consumption of the products in the field

. DOE estimated the annual energy consumption of furnace fans at specified energy efficiency levels across a range of climate zones and household characteristics. T he energy use analysis provides estimates of the distribution of annual energy consumption for furnace fans at the efficiency standard levels considered.

DOE developed energy consumption estimates fo r the key product classes analyzed in the engineering analysis (chapt er 5 of the technical support document ( TSD ) )

. These are listed in Table 7.1.1

.

Table 7.1.1 Furnace Fan P roduct Classes Analyzed Non

- W eatherized, Non

- C ondensing Gas Furnace Fan Non

- W eatherized, Condensing Gas Furnace Fan Weatherized Gas Furnace Fan Oil Furnace Fan Electric Furnace / Modular Blower Fan Manufactured Home Non

- W eatherized, Non

- C ondensing Gas Furnace Fan Manufactured Home Non

- W eatherized, Condensing Gas Furnace Fan Manufactured Home Electric Furnace / Modular Blower Fan Hydronic Air Handler Fan (Heat/Cool)

7.2 GENERAL APPROACH TO THE ENERGY USE AN ALYSIS

E stimating annual energy consumption of furnace fans requires calculating the energy

use at different operating modes: heating, cooling, constant circulation , and standby

. DOE estimated the total annual energy consumption of furnace fans for each household sampled using the following equation:

FFEU total = FFOH h eating × FFP h eating + FFOH cooling × FFP cooling + FFOH cont fan
× FFP cont fan + FFOH standby × FFP standby

W here:

FFEU total = Total annual energy consumption by furnace fan, kW/yr,

FFOH heating = furnace fan operating hours during the heating season, h,

FF P heat ing = furnace fan power during the heating operation, kW,7

- 2 FFOH cool ing = furnace fan operating hours during the coo ling season

, h,

FF P cooli ng = furnace fan power during the cooling operation, kW,

FFOH cont fan = furnace fan operating hours during constant circulation fan operation , h,

FF P cont fan = furnace fan power during the constant circulation fan operation , k W,

FFOH standby = furnace fan operating hours during standby, h, and

FF P

standby = furnace fan power during the standby operation, kW

.

7.3 HOUSEHOLD SAMPLE
DOE’s calculation of the annual energy use of residential furnace fan s relied on data from Energy Information Administration’s 2005 Residential Energy Consumption Survey ( RECS 2005 )

. 1 RECS collects energy

- related data for occupied primary housing units in the United States. The RECS 2005 included data from 4,381 housing units that represent alm ost 111.1 million households. The subset of RECS 200 5 records used to study furnace fans met all of the following criteria:

**•** used a furnace as the main or secondary source of heat;

**•** used a heating fuel that is natural gas, liquefied petroleum gas (LPG), ele ctricity

, or fuel oil;

**•** heated only one housing unit; and

**•** had a heating energy consumption greater than zero.

DOE divided the furnace subset into further subsets designed to include households that use one of the furnace fan product classes ( Table 7.3.1 ). Appendix 7

- A presents the variables included and their definitions.

The RECS 2005 weighting indicates how commonly each household configuration

occ urs in the general population in 2005. DOE made some adjustments to EIA’s weightings for each RECS 2005 household in order to create a furnace fan population weight for 2018 . The first adjustment was to compensate for the fact that the RECS 2005 sample doe s not distinguish between weatherized and non

- weatherized gas furnaces. DOE also took into account the growth in population by region from 2005 to 2018 based on U.S. census population projections. Finally, DOE adjusted the weightings to account for househo lds with multiple furnaces. A ppendix 7

- A provides further details on these adjustments

.7

- 3 Table 7.3.1 Household Samples for Furnace Fan Products

Product Class Criteria No. of Records RECS 2005 2018 Estimate

Number of Houses million Number of Furnaces

million

Non

- Weatherized, Non

- Condensing Gas Furnace Fan Primary or Secondary Heating Equipment = Gas Furnace a Region = South Housing Type = non

- mobile home 736 19.6 14.5

Non

- Weatherized, Condensing Gas Furnace Fan Primary or Secondary Heating Equipment = Gas Furnace Housing Type = non

- mobile home 1726 45.5 35.6

Weatherized Gas Furnace Fan Primary or Secondary Heating Equipment = Gas Furnace Region = South Housing Type = non

- mobile home Primary or Secondary Cooling Equipment = Central Air Conditioner 576 15.4 17.9

Oil Furnace Fan Primary or Secondary Heating Equipment = Oil Furnace Housing Type = non

- mobile home 150 2.9 3.3

Electric Furnace / Modular Blower Fan Primary or Secondary Heating Equipment = Electric Furnace Housing Type = non

- mobile home 40 1.3 0.8

Manufactured Home Non

- Weatherized, Non

- Condensing Gas Furnace Fan Primary or Secondary Heating Equipment = Gas Furnace Region = South Housing Type = mobile home 565 15.6 3.6

Manufactured Home Non

- Weatherized, Condensing Gas Furnace Fan Primary or Secondary Heating Equipment = Gas Furnace Housing Type = mobile home 51 1.2 1.2

Manufactured Home Electric Furnace / Modular Blower Fan Primary or Secondary Heating Equipment = Electric Furnace Housing Type = mobile home 109 2.5 1.6

Hydronic Air Handler Fan (Heat/Cool) Primary or Secondary Heating Equipment = Gas Furnace Region = South Housing Type = non

- mobile home Primary or Secondary Cooling Equipment = Central Air Conditioner
Water Heater Equipment = Gas Water Heater Household Square Footage <2000 sq ft 68 1.9 2.1

a Natural Gas or LPG Furnace.7

- 4 7.4 FURNACE FAN POWER CONSUMPTION
The electricity consumption (and overall efficiency) of a furnace fan depends on the speed at which the motor operates, the external static pressure difference across the blower, and the airflow through the blower. The power consumption of the furnace fan is determine d using the individual sample housing unit operating conditions (the pressure and airflow) at which a particular furnace fan will operate when performing heating, cooling, and constant circulation functions

. These operating conditions can be graphically displayed as the intersection of a system curve of the air

- distribution system in the housing unit (which plots the airflow across the supply and return air ducts as a function of static pressure) with the fan curve of the furnace (which plots the airflow through the furnace as a function of static pressure). 2 The intersection of these two curves is the airflow and the static pressure at which the furnace will operate in that housing unit.

Furnace fan c urves, reported as tables of airflow rise versus static pressure through the furnace, are available from manufacturers in the product literature for most furnace models

. Some of the manufacturers also supply blower

- motor input power as a function of static pressure across the furnace.

Air power is calculated from the air speed through the furnace and the pressure rise across the furnace. The overall air

- moving efficiency is air power divided by the electric power to the blower motor.

All of the e lectric power of the blower motor eventually is converted in to heat that contributes heat to the building’s interior

. DOE takes this into account by increasing the heating load and/or decreasing the cooling load for more efficient furnace fans.

7.4.1 System Cu rves DOE modeled system curves as quadratic curves, which is standard in heating, ventilation, and air conditioning (HVAC) design and fan selection handbooks. 3 The curves are based on Bernoulli’s equations for fluid flow and are expressed as the following equation:

Q = � P

α

W here:

Q = airflow ( CFM ),

P = external static pressure (in.w.g.), and

α = a constant coefficient.7

- 5 DOE selected the external static pressure (ESP) in the system curve equation for each sample housing unit. DOE identified four installation types with unique ESP considerations:

u nits paired with an evaporator coil; h eating

- only units or u ni ts with an internal evaporator coil;

m anufactured home units paired with an evaporator coil ; and m anufactured home heating

- only units . To develop distributions of ESP values for each of these types, DOE gathered field data from available studies and research reports to determine an appropriate distribution of ESP value s . DOE compiled over 1

, 300 field ESP measurements from several studies that included furnace fans i n single

- family and manufactured hom es in different regions of the country. The data and sources are described in a ppendix 7

- B

. Table 7.4.1 gives the weighted average ESP values for each type. DOE de signed each distribution as a normal distribution based on the field studies. DOE randomly sampled a static pressure value at the nominal maximum airflow from one of the four distributions, depending on the type of equipment installed in the housing unit.

Table 7.4.1 Values Used for External Static Pressure

Installation Type Associated Product Class Weighted Average ESP (in. w.c.) Standard Deviation (in. w.c.) Units paired with an evaporator coil Furnaces paired with a CAC unit 0. 73 0.12

Heating

- only units or Units with an internal evaporator coil Furnaces not paired with a CAC unit or Weatherized gas furnaces 0.5 2 0.12

Manufacture d h ome paired with an evaporator coil Manufacture d h ome furnaces paired with a CAC unit 0. 37 0.6

Manufacture d h ome heating

- only

u nits Manufacture d h ome furnaces
not paired with a CAC unit 0. 17 0.6

Figure 7.4.1 show s an example of a plot of system curves intersecting a furnace fan

curve.7

- 6 Figure 7.4.1 Sample of System Curves with a Typical Fan Curve

7.4.2 Furnace Fan Curves
Depending on the resistance (measured as static pressure) of the supply and return air ducts, a furna ce will move more or less air. When these airflow values are plotted graphically against pressure, they are referred to as fan curves.

DOE developed fan curves for PSC, PSC with controls, X13 , and ECM furnace models by fitting airflow and pressure data points from manufacturer product literature and measurements conducted during the engineering analysis to a second

- order polynomial. DOE did this separately for each of the four main nominal ai r handler sizes (2

- ton, 3

- ton, 4

- ton, and 5

- ton) . The cubic feet per minute ( CFM ) is given by the following equation:

CFM = m 0 + m 1 × ( P ) + m 2 × ( P 2 )

W here :

CFM = airflow in CFM reported by manufacturer,

m 0,1,2,and 3 = coefficients derived from 2 nd degree polynom ial approximation, and

P = external static pressure (in. w.g.). 0 400 800 1200 1600

0.00 0.25 0.50 0.75 1.00 External Static Pressure (in. w.g.) Airflow (CFM)

Highest 1%

median

Lowest 10%

1200 CFM Generic Single-Stage Furnace Model (Heating Tap)7

- 7 Figure 7.4.2 shows an example of a CFM curve for a 3

- ton non

- condensing PSC gas furn ace fitted with the manufacturer ’ s raw data.

Figure 7.4.2 Example Fit of CFM for 3

- T on PSC Furnace in Heating Mode

7.4.3 Fan Power
Once the operating point of air flow and static pressure is determined

, by finding the intersection of the fan performance curve and the system curve, the watts per cubic feet per minute ( CFM ) of airflow are determined from the equations developed by DOE using manufacturer product literature and measurements conducted during the engineering analysis

. The power consumption of the fan at this operating point , BE, is calculated by multiplying the
watt s/ CFM by the CFM at the operating point:

BE = � Watts
CFM � × Q

W here :

BE = circulating air fan electrical energy consumption (watts),

Watts/CF M = blower electricity consumption in watts reported by manufacturer divided by the airflow in CFM at the same static pressure (watts/ CFM ) , and 0 500 1000 1500 2000 2500

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Pressure (in.w.g.) Air Flow (CFM) L1RA072*12B L1RA090*12B M1BB-086-*** M1GB-090-*** M1GH-077-*** M1GH-090-*** M1MB-056-*** M1MB-090-*** RGPN-10(E,N)AMER GUIC070**30 TUD060C936K* TUE060A936L* RGPN-07(E,N)AMER G40DF-36A-070-* G50DF-36A-070-* TDD060C936F* TDE060A936M* DPGB075A3* MPGA075B3* RGPJ-07EAUER M1BB-086-*** M1GB-090-*** M1GH-077-*** M1GH-090-*** M1MB-056-*** M1MB-090-*** P4HUA12N03201 P4HUA12N04801 P4HUA12N06401 ABA080NH3R N8MPL050B12 N8MPN050B12 P4DNA12N03201 P4DNA12N04801 P4DNA12N06401 T8MPL050B12 T8MPN050B12 58DLA045-12 58DLX045-12* 58STA045-12 58STX045-12* G40DF-36C-110-** G50DF-36C-110-** 58DLA070-12 58DLX070-12* 58STA070-12 58STX070-12* RGLJ-07EAUER G40DF-36B-090-*7

- 8 Q = airflow ( CFM ).

Some manufacturer s of furnace fan s report watts across a range of external static
pressures

. Furthermore, DOE conducted measurements on several furnace fan models during the engineering analysis. For these models, DOE divided watts at these pressures by air flow in CFM at these same pressures. These values of watts per CFM across a range of pre ssures were fit to a second

- order polynomial for the basic furnace models made by the manufacturer. DOE did this separately for each of the f our nominal air handler sizes. The watts per CFM is given by the following equation:

Watts

CFM = m 0 + m 1 × ( P ) + m 2 × ( P 2 )

W here :

Watts/CFM = blower electricity consumption in watts reported by manufacturer divided by the airflow in CFM at the same static pressure,

m 0,1, and 2 = coefficients derived from second

- degree polynomial approximation, and

P = external static pressure (in. w.g.).

Figure 7.4.3 shows the watt s per CFM curve for 3

- ton condensing single

- stage furnace fitted to the manufacturers’ data. A s imilar process of fitting curves to data was done for each nominal blower size.7

- 9 Figure 7.4.3 Example Fit of Watts/CFM for 3

- T on Single

- Stage Furnace

7.4.4 D etermination of Fan Performance by Product Class and Efficiency Level
In order to generate the fan performance data used in the analysis DOE applied the following procedure ( the 3

- ton baseline PSC motor for non

- weatherized

, non

- condensing gas furnace s is used as an example):

STEP 1: Using the airflow and power curves at each airflow speed (heating, cooling, and constant circulation), DOE found the airflow and power at DOE’s proposed furnace fan test procedure conditions. For example, DOE’s reference system curve external static pressure is 0.65 in. wc at the maximum cooling airflow speed for non

weatherized gas furnaces. For the 3

- ton baseline PSC motor for non

- weatherized (non

- condensing) gas furnaces the maximum airflow CFM was calculate d to be 1158 cubic feet per minute

.

STEP 2: DOE used the equation above to calculate the BE at each airflow speed (heating, cooling, and constant circulation ) with DOE’s proposed furnace fan test procedure conditions. For example, for the 3

- ton baseline PSC motor for non

- weatherized (non

condensing) gas furnaces BE was calculate d to be 382 watts at heating, 495 watts at cooling, and 382 watts at constant circulation

.

STEP 3: Using the calculated maximum airflow CFM and BE values at the external static pressure prescribed by DOE’s reference system curve , Furnace E fficiency Rating 0 0.1 0.2 0.3 0.4 0.5 0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Pressure (in.w.g.) Watt/CFM G51MP-36B-045-**

G43UF-36B-070-**

G51MP-36B-070-**

G43UF-36C-090-**

G43UF-36C-090H-**

G51MP-36C-090-**

data fit7

- 10 (FER) values were e valuated

. For example, for the 3

- ton baseline PSC motor for non

weatherized (non

- condensing) gas furnaces FER was calculate d to be 363

.

STEP 4: The constant curve fit parameter m 0 , that is derived from plotting the watts/CFM vs. the ESP , is then used to adjust the airflow and power curve in order to match the FER values derived from the engineering analysis (for all product classes and efficiency levels). For example, for the 3

- ton baseline PSC motor for non

- weatherized (non

condensing) gas furnaces the F ER value derived in the engineering analysis was 380, so the adjustment multiplier to convert the FER value calculated in step 3 was calculate d to be 1.04

.

Table 7.4.2 shows the airflow ( CFM ) vs. pressure coefficients determined for non

weatherized (non

- condensing) gas furnaces (3

- t on) at each efficiency level (EL)

. Figure 7.4.4 to Figure 7.4.6 shows the resulting curves at various pressures and operating modes

. See appendix 7

- C for further details.

Table 7.4.2 Coefficients for CFM equation for Non

- Weatheriz ed (Non

- Condensing) Gas Furnace Fan , 3

- Ton

E L Heating Cooling Constant Circulation

m 0 m 1 m 2 m 0 m 1 m 2 m 0 m 1 m 2 0 1158

- 12

- 507 1523

- 280

- 432 1158

- 12

- 507

1 1158

- 12

- 507 1523

- 280

- 432 931 99

- 527

2 1059 269

- 405 1277 198

- 516 667

- 117

- 44

3 1139

- 403

- 62 1427

- 323

- 15 1001

- 880 214

4 1043 24

- 101 1203 8

- 26 679 3

- 64

5 1043 24

- 101 1203 8

- 26 679 3

- 647

- 11 Figure 7.4.4 CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Heating Mode)

Figure 7.4.5 CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Cooling Mode) 600 700 800 900 1000 1100 1200

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Airflow (CFM)

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller

600 700 800 900 1000 1100 1200 1300 1400 1500 1600

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Airflow (CFM)

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller7

- 12 Figure 7.4.6 CFM Curves for Non

- Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton ( Constant Circulation Mode)

Table 7.4.3 shows the watts/ CFM vs. pressure curves coefficients determined for non

weatherized (non

- condensing) gas furnaces (3

- t on) at eac h efficiency level. Figure 7.4.7 to Figure 7.4.9 shows the resulting curves at various pressures. Figure 7.4. 10 to Figure 7.4.12 show the resulting Watts vs. pressure curves. See appendix 7

- C for further details.

Table 7.4.3 Coefficients for Watts/CFM E quation for Non

- Weatherized (Non

Condensing) Gas Furnaces , 3

- Ton

E L Heating Cooling Constant Circulation

m 0 m 1 m 2 m 0 m 1 m 2 m 0 m 1 m 2 0 0.45

- 0.21 0.19 0.46

- 0.12 0.15 0.45

- 0.21 0.19

1 0.45

- 0.21 0.19 0.46

- 0.12 0.15 0.44

- 0.20 0.21

2 0.30 0.16 0.02 0.35 0.16

- 0.03 0.22 0.15 0.14

3 0.15 0.10 0.10 0.24 0.12 0.04 0.13 0.01 0.42

4 0.12 0.24

- 0.03 0.13 0.29

- 0.04 0.07 0.24 0.00

5 0.09 0.24

- 0.03 0.10 0.29

- 0.04 0.06 0.24 0.00 0 200 400 600 800 1000 1200 1400

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Airflow (CFM)

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller7

- 13 Figure 7.4.7 Watt/ CFM Curves for Non

- Weatherized (Non

Condensing) Gas Furnace Fan, 3

- Ton (Heating Mode)

Figure 7.4.8 Watt/ CFM Curves for Non

- Weatherized (Non

Condensing) Gas Furnace Fan, 3

- Ton (Cooling Mode) 0.00 0.10 0.20 0.30 0.40 0.50 0.60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Watts/CFM

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller

0.00 0.10 0.20 0.30 0.40 0.50 0.60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Watss/CFM

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller7

- 14 Figure 7.4.9 Watt/ CFM Curves for Non

- Weatherized (Non

Condensing) Gas Furnace Fan, 3

- Ton ( Constant Circulation Mode) 0.00 0.10 0.20 0.30 0.40 0.50 0.60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Watts/CFM

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls X13 ECM (Variable Speed) ECM + BC Impeller7

- 15 Figure 7.4.10 Resulting Watt vs. Pressure Curves for Non

Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Heating Mode) 0 100 200 300 400 500 600

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Watts

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller7

- 16 Figure 7.4.11 Resulting Watt vs. Pressure Curves for Non

Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton (Cooling Mode) 0 100 200 300 400 500 600 700 800

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Watss

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller7

- 17 Figure 7.4.12 Resulting Watt vs. Pressure Curves for Non

Weatherized (Non

- Condensing) Gas Furnace Fan, 3

- Ton ( Constant Circulation Mode)

7.5 OPERATING HOURS

The DOE test procedures for furnaces and air conditioners were used to estimate heating and cooling mode operating hours for the furnace fan.

7.5.1 Heating M ode

DOE use d the furnace test procedure 4 to determine furnace fan operating hours b during the heating season using the following formula:

FFOH h eating = y × BOH , for single stage furnaces

.

W here:

FFOH heating = furnace fan operating hours during the heating season, h

,

y = ratio of blower on

- time to average burner on

- time

, and

BOH = burner operating hours, h.

b Approach described for single stage operation only; see Appendix 7

- E for multistage details 0 100 200 300 400 500 600

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Watts

External Static Pressure (in w.c.) Baseline (PSC) Improved PSC PSC w/ Controls

X13 ECM (Variable Speed) ECM + BC Impeller7

- 18 Using DOE’s furnace test procedure, the ratio of blower on

- time to average burner on

time ( y ) is calcu lated using the following formula:

y = 1 + t +

− t −

t ON

W here:

t + = off

- period (blower off delay) between burner shutdown and blower shutdown in min utes,

t - = on

- period (blower on delay) between burner shutdown and blower shutdown in min utes, and

t ON = average burner on

- time in min utes

.
The blower off

- delay ( t + ) and blower on

- delay ( t - ) values are derived from manufacturer default blower delay settings for non

- weatherized gas furnace models in the 2007 Furnace Database from DOE’s 2007 Furnace and Boiler Final Rule. 5 The median values using th e s e data

a re 120 seconds (or 2 minutes) for blower off

- delay ( t + ) and 30 seconds (or 0.5 minutes) for blower on

- delay ( t - ). The average burner on

- time ( t ON ) is equal to 3.87 minutes for single

- stage furnaces with a fan delay based on DOE’s furnace test procedure. T herefore, the ratio of blower

on

- time to average burner on

- time ( y ) is estimated to be 1.39 using the median values

. The burner operating hours are calculated using the following formula c :

BOH = A * HHL , for single

- stage furnaces

.

W here:

A = 100,000/ [341300( y

P * PE + y IG *PE IG + y * BE ) + Q IN * Effy HS ]

,

y

P = ratio of induced or forced draft blower on

- time to average burner on

- time,

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

- load steady

- state operation in kW,

y

IG = ratio of burner i nterrupted

- ignition device on

- time to average burner on

time,

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

y = ratio of blower or pump on

- time to burner on

- time,

BE = furnace fan electrical energy input rate in kW,

Q

IN = steady

- state nameplate input rate in Btu/h

,

c Approach described for single stage operation and a furnace without pilot ignition only; see Appendix 7

- E for multistage operation details and derivation of the formula.7

- 19 Effy HS = ratio of the average length of the heating season in hours to the average heating load hours,

HHL = house heating load in MMBtu/h

.

Details about the calculation of the parameters used to calculate the value A ( such as y P , PE, y IG, PE IG

, y, BE

, Q IN

, and Effy HS ) are provided in a ppendix 7

- E.

The annual house

- heating load ( HHL ) is the total amount of heat output from the furnace that the house needs during the heating season. This includes heat from the burner and heat from the blower and the blower motor. DOE determined HHL for each sampled housing unit, based on the burner operating hours ( BOH ) and the characteristics of the assigned existing furnace, using the following calculations:

Where:

Q YR ,RECS = annual fuel consumption for heating based on RECS 2005 (kBtu /yr),

AFUE ex = AFUE of the existing furnace (see appendix 7

- E ),

3.412 = constant to convert kW to kBtu/hr,

BE ex = power consumption of the blower motor of the existing furnace (kW),

BOH e x = burner operating hours of existing household (hr/yr),

N = number of cycles per hour (set equal to 5 for furnaces),

t + = off delay (seconds),

t - = on delay (seconds), and

Adj_Factor = adjustment factor s (discussed below)

.

DOE calculated BOH ex for the existing furnace as:

Where:

BOH ex = burner operating hours of existing household (hr/yr), 

### Factor Adj t t N BOH BE AFUE Q HHL

ex ex RECS YR



### _ 3600 412

. 3

, 

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

**− ×**  **+ ×**  **× +**  **× =**  **− +** 

ex IN

RECS YR

ex 

### Q Q BOH

, , 

### =7

- 20 Q YR,RECS = as defined above (kBtu/yr), and

Q

IN

, ex = input capacity of the existing furnace (see appendix 7

- E) (kBtu/hr).

DOE made adjustments to the house heating load to reflect the expectation that newly built housing units in 2018 will have a somewhat different house heating load than the housing units in the RECS 2005 sub

- sample. The adjustment involves multiplying the calculated HHL for each RECS 2005 h ousing unit by a building shell efficiency index derived from the National Energy Modeling System ( NEMS ) simulation performed for EIA’s AEO 201 2

. 6 The building shell efficiency index sets the heating load value at 1.00 for an average home in 2005 (by type) in each census division. The values listed represent the change in heating load based on the difference in physical size and shell attributes for homes in the future (which takes into account physical size difference and efficiency gains from better insulation and windows). This factor differs for new construction and replacement households. The value for households in 201 8 is 0.8 6 for replacements and 0.8 7 for new construction, which means that the average new home in 2018 will require less heat energy to maintain indoor comfort. To add variability, the factor is varied by plus o r minus 15 percent.

DOE also made adjustments to the HHL calculated using RECS 2005 data to reflect historical average climate conditions. Table 7.5.1 shows the 2002

- 2011 average heating degree days (HDD) as well as the 2005 average HDD for the 29 geographical areas . The adjustment factors are calculated using the equation below

.

Where:

HDD res_stock _2005 = HDD in 2005 for the specific region where the housing unit is located, and

HDD 10

_ yr_avg = 10

- year average HD D (2002

– 20 11 ) based on NOAA data 7 for the specific region where the housing unit is located. d

d The last 10

- year average is used to normalize the HDD values, which is similar to what is done in AEO 2012. 2005

_ _ _

_ 10
lim

_ _ stock res avg yr
ate c average HDD HDD Factor Adj **=**7

- 21 Table 7.5.1 Heating Degree

- Day Adjustment Factors Geographical Area Average HDD Adjustment Factor

2002

- 2011 2005
1 CT, ME, NH, RI, VT 6576 6746 0.97 2 MA 6184 6467 0.96 3 NY 5770 5912 0.98 4 NJ 5105 5311 0.96 5 PA 5656 5806 0.97 6 IL 6047 5800 1.04 7 IN, OH 5687 5759 0.99 8 MI 6655 6608 1.01 9 WI 7365 6975 1.06 10 IA, MN, ND, SD 7857 7326 1.07 11 KS, NE 5455 4988 1.09 12 MO 4943 4622 1.07 13 VA 4224 4328 0.98 14 DE, DC, MD, WV 4500 4621 0.97 15 GA 2807 2709 1.04 16 NC, SC 3171 3180 1.00 17 FL 692 647 1.07 18 AL, KY, MS 3251 3153 1.03 19 TN 3757 3625 1.04 20 AR, LA, OK 2727 2434 1.12 21 TX 1855 1686 1.10 22 CO 7109 6949 1.02 23 ID, MT, UT, WY 6964 6744 1.03 24 AZ 1946 1788 1.09 25 NV, NM 3908 3581 1.09 26 CA 2575 2450 1.05 27 OR, WA 5267 5132 1.03 28 AK NA NA 1.03 29 HI NA NA 1.05 Note: Data for Alaska and Hawaii w as not available. The region 27 adjustment factor was used for Alaska, while region 26 adjustment factor was used for Hawaii.

For households in which it is clear that the fuel use for heating is associated solely with the use of furnace equipment as the primary or secondary heating equipment, DOE used the annual fuel consumption for heating the housing uni t from RECS 2005. DOE adjusted the house heating load for households that used both a furnace (either as the primary or secondary heating equipment) and other heating equipment using the same fuel. RECS 2005 reports the percentage of heating energy consump tion attributable to secondary products. DOE derived the house heating load applicable to the furnace by subtracting the estimated amount of heat provided by the other heating system

. In the case when it was determined that a household had multiple furnace s, the house heating load was divided by the number of furnaces. Details are presented in appendix 7

- D

.

Table 7.5.2 shows the results for the range in adjusted heating load among sample households.7

- 22 Table 7.5.2 Range of Adjusted Heating Load for Each Furnace Fan Product Class , million Btu/h

Product Class Min Max Average Percentiles

5% 25% 50% 75% 95%
Non

- Weatherized, Non

- Condensing Gas Furnace Fan 0.31 143.44 20.25 3.99 9.40 16.29 26.78 49.08

Non

- Weatherized, Condensing Gas Furnace Fan 0.36 215.43 37.94 9.57 23.21 34.74 48.37 77.91

Weatherized Gas Furnace Fan 0.36 156.88 20.34 3.85 9.50 16.42 26.55 49.57

Oil Furnace Fan 2.37 140.24 55.49 24.19 35.86 56.14 71.50 94.55 Electric Furnace / Modular Blower Fan 0.29 31.08 6.61 1.73 3.54 5.86 8.46 14.27

Manufactured Home Non

- Weatherized, Non

- Condensing Gas Furnace Fan 3.89 78.73 22.82 6.38 12.68 21.37 28.03 47.98

Manufactured Home Non

- Weatherized, Condensing Gas Furnace Fan 3.65 101.59 33.15 9.86 21.51 31.58 42.58 66.16

Manufactured Home Electric Furnace / Modular Blower Fan 0.30 29.41 7.90 1.80 4.10 6.77 10.51 19.17

Hydronic Air Handler Fan (Heat/Cool) 0.62 69.61 12.60 2.50 3.74 9.11 16.10 35.70

Table 7.5.3 shows the results for the baseline heating furnace fan operating hours among sample households.7

- 23 Table 7.5.3 Range of Baseline Furnace Fan Heating Operating Hours for Each Furnace Fan Product Class, hours

Product Class Min Max Average Percentiles

5% 25% 50% 75% 95%
Non

- Weatherized, Non

- Condensing Gas Furnace Fan 8 4826 434 93 207 355 560 1040

Non

- Weatherized, Condensing Gas Furnace Fan 9 3749 591 159 336 508 746 1313

Weatherized Gas Furnace Fan 9 4835 393 87 188 321 505 916

Oil Furnace Fan 24 2448 716 230 438 680 945 1336 Electric Furnace / Modular Blower Fan 8 3322 274 68 138 211 336 696

Manufactured Home Non

- Weatherized, Non

- Condensing Gas Furnace Fan 100 2478 661 183 371 613 816 1396

Manufactured Home Non

- Weatherized, Condensing Gas Furnace Fan 77 2644 797 263 486 734 1018 1593

Manufactured Home Electric Furnace / Modular Blower Fan 9 1545 370 69 205 316 478 892

Hydronic Air Handler Fan (Heat/Cool) 15 2252 339 70 112 254 405 913

7.5.2 C ooling M ode

F urnace fan operating hours during the cooling season are calculated using the following formula:

FFOH cooling = y C × COH

W here:

FFOH cooling = furnace fan operating hours during the cooling season ;

y C = ratio of blower on

- time to average compressor on

- time; and

C OH = c ooling o perating h ours.
Some furnace fans come with a cooling blower off delay feature. To account for this DOE estimated the ratio of blower on

- time to average compressor on

- time ( y C ) using the following formula:7

- 24 y C = 1 + t C +

− t C −

t ON

, C

W here:

t C + = off

- period (blower off delay in cooling mode ) between compressor shutdown and blower shutdown in minutes,

t C

− = on

- period (blower on delay in cooling mode) between compressor start

- up and blower start

- up in minutes, and

t ON ,C = average compressor on

- time in minutes.

The blower off

- delay ( t C + ) and blower on

- delay ( t C − ) values are derived from manufacturer default blower delay settings. The median values using these data are 45 seconds for blower off

- de lay ( t C + ) and 2 seconds for blower on

- delay ( t C − ). The average burner on

- time ( t ON,C ) is equal to 6 minutes for single

- stage central air conditioners based on DOE’s central air conditioner test procedure. Using these assumptions , the ratio of blower o n

- time to average burner on

- time ( y C ) is estimated to be 1.12.

The cooling operating hours are calculated using the following formula:

COH = HCL CoolingCapacity × Adj

_ Factor motor

W here:

COH = c ooling o perating h ours, hour/year

,
HCL = house cooling load

, MMBtu /year,

CoolingCap acity = cooling capacity of air conditioner , B tu/h (see appendix 7

- F)

, and
Adj

_ Factor motor = adjustment factor to account for impact of motor heat on cooling operating hours.

The house cooling load ( HCL ) assumes that the household has a default furnace fan motor power output of 365 watts per 1000 CFM ( used in the CAC test procedure ) . To properly account for increased or decreased cooling operating hours due to the higher or lower motor power output for different furnace fan efficiencies, DOE used the following equation to determine the adjustment factor :

Adj

_ Factor motor = 1

( 1 + 3

. 412 × 365 1000 ∗ CFM

− FFPcooling CoolingCapacity )7

- 25 W here:

365

1000 ∗ CFM = default central air conditioner blower output used for calculating SEER, watts,

CFM = nominal cooling load CFM measured at 400 CFM per AC ton, cu. ft. per min,

FF P cooli ng = furnace fan power during the cooling operation, kW, and

CoolingCap acity = cooling capacity of air conditioner, Btu/h.

The house cooling load is derived using the EIA’s RECS 2005 8 cooling energy use data for the sample households as follows:

HCL = CoolingEnergyUseRECS × SEER ex CoolingCapacity ex × Adj

_ Factor

W here:

HCL = house cooling load

, MMbtu /year

, CoolingEnergyUseRECS = annual electricity consumption for cooling based on RECS 2005 (kBtu /yr),

SEER ex = SEER of the existing central air conditioner (see appendix 7

- F),

CoolingCap acity = cooling capacity of existing central air conditioner, Btu/h (see appendix 7

- F), and

Adj_Factor = adjustment factors (discussed below).

DOE made adjustments to the house cooling load to reflect the expectation that newly built housing units in 2018 will have a somewhat different house cooling load than the housing units in the RECS 2005 sub

- sample. Similar to furnace fan energy use calculatio n above, t he building shell efficiency index sets the cooling load value at 1.00 for an average home in 2005 (by type) in each census division. DOE developed adjustment factors to represent the change in cooling load based on the difference in physical siz e and shell attributes for homes in the future (which takes into account physical size difference and efficiency gains from better insulation and windows). This factor differs for new construction and replacement households. The value for households in 201 8 is 0. 94 for replacements and 1.01 for new construction . To add variability, the factor is varied by plus or minus 15 percent.

DOE also made adjustm ents to the HC L calculated using RECS 2005 data to reflect historical average climate conditions. Table 7.5.4 shows the 2002

- 2011 average heating degree days (HD D) as well as the 2005 average C DD for the 29 geographical areas . The adjustment factors are calculated us ing the equation below

.7

- 26 Where:

CDD res_stock _2005 = CDD in 2005 for the specific region where the housing unit is located, and

CDD 10

_ yr_avg = 10

- year average CDD (2002

– 201 1) based on NOAA data 7 for the specific region where the housing unit is located.

Table 7.5.4 Cooling Degree Day Adjustment Factors Geographical Areas Average C DD Adjustment Factor

2002

- 2011 2005
1 CT, ME, NH, RI, VT 485 562 0.86 2 MA 522 576 0.91 3 NY 737 943 0.78 4 NJ 932 1121 0.83 5 PA 765 901 0.85 6 IL 924 1151 0.80 7 IN, OH 879 1027 0.86 8 MI 622 828 0.75 9 WI 552 747 0.74 10 IA, MN, ND, SD 637 792 0.81 11 KS, NE 1327 1491 0.89 12 MO 1325 1534 0.86 13 VA 1206 1250 0.97 14 DE, DC, MD, WV 1004 1034 0.97 15 GA 1832 1804 1.02 16 NC, SC 1654 1644 1.01 17 FL 3558 3436 1.04 18 AL, KY, MS 1813 1832 0.99 19 TN 1517 1576 0.96 20 AR, LA, OK 2266 2392 0.95 21 TX 2841 2908 0.98 22 CO 352 345 1.02 23 ID, MT, UT, WY 575 533 1.08 24 AZ 3171 3130 1.01 25 NV, NM 1753 1740 1.01 26 CA 923 837 1.10 27 OR, WA 235 227 1.04 28 AK NA NA 1.04 29 HI NA NA 1.10 Note: Data for Alaska and Hawaii w as not available. The region 27 adjustment factor was used for Alaska, while region 26 adjustment factor was used for Hawaii.

DOE is calculating multi

- stage cooling the same way as single

- stage equipment ( i. e. , at the highest cooling mode only) and therefore used the same number of operating hours, since: 2005

_ _ _

_ 10
lim

_ _ stock res avg yr
ate c average CDD CDD Factor Adj **=**7

- 27 1) Multi

- stage heating is not necessarily ass ociated with multi

- stage cooling equipment (e.g. multi

- stage cooling is much less common than multi

- stage furnace equipment); and

2) SEER already captures cases when multi

- stage heating and cooling equipment are matched

.
For households in which it is clear that the electricity use for cooling is associated solely with the use of central air conditioning equipment, DOE used the annual electricity consumption for cooling the household from RECS 2005. DOE adjusted the house cooling load for households that used both a central air conditioner and a room air conditioner . RECS 2005 reports the percentage of cooling energy consumption attributable to room air conditioners

. DOE derived the house cooli ng load applicable to the central air conditioner by subtracting the estimated amount of cooling provided by the other cooling system

.

Table 7.5.5 shows the range in cooling load among sample households for each furnace fan product class

. The table also provides the fraction of households that have central air conditioning.

Table 7.5.5 Range of Annual Cooling Load for Each Furnace Fan Product Class, million Btu/h

P roduct Class Frac tion with Central AC Min Max Avg. Percentiles

5% 25% 50% 75% 95%
Non

- Weatherized, Non

- Condensing Gas Furnace Fan 76.0% 0.11 107.34 14.55 1.97 6.31 11.84 18.94 37.02

Non

- Weatherized, Condensing Gas Furnace Fan 72.1 % 0.25 107.34 8.49 1.51 3.81 6.37 10.61 21.91

Weatherized Gas Furnace Fan 100.0% 0.11 107.34 14.16 1.97 5.95 11.61 18.77 34.63

Oil Furnace Fan 34. 0 % 1.30 15.57 7.60 2.23 3.76 6.32 11.43 15.57 Electric Furnace / Modular Blower Fan 85.1 % 0.76 101.14 14.41 2.72 7.03 12.42 19.42 31.97

Manufactured Home Non

- Weatherized, Non

- Condensing Gas Furnace Fan 54. 5 % 1.27 22.87 9.72 1.90 4.62 8.40 15.63 21.88

Manufactured Home Non

- Weatherized, Condensing Gas Furnace Fan 41.1 % 0.24 22.87 5.74 2.16 3.28 4.29 5.73 15.80

Manufactured Home Electric Furnace / Modular Blower Fan 78.3 % 1.22 29.17 13.33 2.86 9.23 12.87 18.30 26.27

Hydronic Air Handler Fan (Heat/Cool) 100.0% 0.78 31.14 9.87 0.78 3.31 6.31 17.15 24.667

- 28 Table 7.5.6 shows the results fo r the baseline furnace fan cooling operating hours among sample households.

Table 7.5.6 Range of Baseline Furnace Fan Cooling Operating Hours for Each Furnace Fan Product Class, hours

Product Class Min Max Average Percentiles

5% 25% 50% 75% 95%
Non

- Weatherized, Non

- Condensing Gas Furnace Fan 0 7879 902 0 136 729 1332 2563

Non

- Weatherized, Condensing Gas Furnace Fan 0 7127 420 0 0 290 591 1379

Weatherized Gas Furnace Fan 0 8240 1162 174 552 970 1532 2877

Oil Furnace Fan 0 1035 139 0 0 0 214 663 Electric Furnace / Modular Blower Fan 0 8760 1240 0 455 1100 1760 3178

Manufactured Home Non

- Weatherized, Non

- Condensing Gas Furnace Fan 0 3633 625 0 0 302 1052 2331

Manufactured Home Non

- Weatherized, Condensing Gas Furnace Fan 0 3506 240 0 0 0 359 1078

Manufactured Home Electric Furnace / Modular Blower Fan 0 4330 1323 0 322 1367 2017 3028

Hydronic Air Handler Fan (Heat/Cool) 0 5885 1157 0 423 962 1527 3113

7.5.3 Constant Circulation Mode

The amount of constant

- circulation hours are based on data from surveys . One survey

was conducted by researchers in Wisconsin in 2003. 9 The second survey was conducted by the Center for En ergy and the Environment (CEE) in Minne sota, the results of which were provided by CEE in a written comment that is included in the docket for the furnace fan test procedure. e

Table 7.5.5 DOE combined both studies and derived average annual furnace fan constant

- circul ation operating hours for each survey

, as shown in

. DOE assumed a value for average number of fan constant

- circulation hours for each survey response. F or “no constant circulation” responses, DOE assumed zero constant

circulation hours. For “year

- round” responses, DOE assumed 100 percent of non

- heating or cooling furnace fan operating hours, which DOE calculated by subtracting furnace fan heating and coo ling operating hours from the total annual hours (8,760). For “during heating season”

e Docket Number EERE

- 2010

- BT

- STD

- 0011. ( CEE, No. 22 at p p . 1

- 3)7

- 29 responses, DOE assumed 15 percent of non

- heating or cooling furnace fan operating hours . For “d uring cooling season ” responses, DOE assumed 15 percent of non

- heating or cooling furnace fan operating hours . For other or “some constant circulation” responses, DOE assumed 5 percent of non

- heating or cooling furnace fan operating hours

.

DOE did not use these data dir ectly , because it believes they are not representative of consumer practices for the U.S. as a whole. In Wisconsin and Minnesota, many homes have low air infiltration, and there is a high awareness of indoor air quality issues, which leads to significant use of constant circulation . To account for this

, DOE d evelop ed separate regional fractions that took into account information from manufacturer product literature and regional climate conditions. Furnace fan manufacturer literature states that constant circulation fan operation is not recommended for humid climates. Therefore, DOE assumed that the fraction using constant circulation would only be 10 percent in the South Hot Humid region f

Table 7.5.7 Results from Constant

- Circulation Use Studies and Estimated National Constant

- Circulation Hours of what was reported in the Wisconsin and Minnesota studies (i. e. 3.1 percent compared to 31 percent in the studies). For the rest of the country (North and South Hot Dry regions), DOE assumed that the fraction using constant circulation would be 50 percent of what was reported in the Wisconsin and Minnesota studies (i. e. 15.5 perc ent compared to 31 percent in the studies).

Table 7.5.8 shows the results for the average baseline constant circulation furnace fan operating hours among sample households.

f Regions as defined in the Furnace and Central Air Conditioner Final Rule. 10

How Often is Constant Circulation Fan Used? Combined Data from Studies

Estimated North and South

- Hot Dry

Region Fractions for LCC Analysis Estimated South

Hot Humid Region Fractions for LCC Analysis Number of Household s Percentage ( % ) No constant f an 69 68% 84 % 97 % Year

- round 14 14% 7 % 1 % During heating

season 4 4% 2 % 0.4 %

During cooling

season 4 4% 2 % 0.4 %

Other (some

con stant fan) 10 10% 5 % 1 %

Total 101 100% 100% 100%7

- 30 Table 7.5.8 Average Baseline Constant Circulation Furnace Fan Operating Hours for Eac h Furnace Fan Product Class, hours

Product Class Average

Non

- Weatherized, Non

- Condensing Gas Furnace Fan 316 Non

- Weatherized, Condensing Gas Furnace Fan 558 Weatherized Gas Furnace Fan 249 Oil Furnace Fan 552 Electric Furnace / Modular Blower Fan 257 Manufactured Home Non

- Weatherized, Non

Condensing Gas Furnace Fan 342 Manufactured Home Non

- Weatherized, Condensing Gas Furnace Fan 567 Manufactured Home Electric Furnace / Modular Blower Fan 213 Hydronic Air Handler Fan (Heat/Cool) 412

7.6 FURNACE FAN STANDBY ENERGY USE

Furnaces with h igher efficiency furnace fan s tend to have higher standby energy use. To account for this effect

, for all products other than hydronic air handlers, DOE first estimated the difference in power consumption betw een the baseline efficiency level (EL 0) and the higher furnace fan efficiencies. g This difference in power consumption was estimated to be 0 watts for EL1 and EL2 and 3 watts for EL 3 and above

, based on test data from the 2011 Furnace rulemaking. 10 The power consumption is then multiplied by the standby hours calculated for each sampled house hold

.

H ydronic air handlers are the only product in this rulemaking that have no standby and off

- mode power included in existing test procedures. The proposed furnace fan test procedure incorporate s test methods to measure the standby mode and off mode energy of hydronic air handlers . In this rulemaking

, an integrated metric was developed that combines the steady

- state standby mode and off mode elec trical energy consumption measurements for hydronic air handlers with the active mode en ergy use for this product (see chapter 5 for additional details)

. The LCC analysis uses the integrated metric for hydronic air handlers and thus account s for the standb y use associated with this product

.

g EISA 2007 requires t hat standby energy consumption be considered in energy consumption unless the test procedure already accounts for standby mode and off mode energy use. Furnace fans are integrated in the electrical systems of the HVAC products in which they are used and c ontrolled by the main control board. Therefore, there is no standby mode and off mode energy use associated with furnace fans used in these products that would not already be measured by the established test procedures.7

- 31 7.7 CHANGES IN HEATING A ND AIR

- CONDITIONING ENERGY USE WITH
MORE

- EFFICIENT FURNACE FA NS
DOE accounted for the effect of improved furnace fan efficiency on the heating and cooling load of the sample homes. With improved furnace fan efficiency there is less heat from the motor, which means that the heating system needs to operate more and the cooling system needs to operate less.

7.7.1 Impact on Furnace Fuel Use with More Efficient Furnace Fans

DOE account ed for the fact that m ore 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.

DOE calculated the furnace fuel consumption ( FuelUse ) for each furn ace fan efficiency level using the following formula h :

, for single

- stage furnace

Where: BOH = steady

- state burner operating hours (hr), and Q

IN = input capacity of existing furnace (kBtu/hr).

Recall from section 7.5.1 that BOH is calculated using BE (furnace fan electrical energy input rate) , which is equal to the FF P heat ing (furnace fan power during the heating operation) variable calculated for each furnace fan efficiency level

. The differential in fuel use between the baseline equipment (EL 0) and more efficient design options (EL 1 and above) for each efficiency level is shown in the results tables in section 7.8.

DOE also calculated the non

- furnace fan furnace electricity c onsumption (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:

, i for single

- stage furnace ,

Where:

BOH = as defined above,

h For natural draft equipment this f ormula is modified to include the pilot light consumption.
i For two

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

### Q BOH FuelUse **× =** 



# ( **)**
ig ig p SS fan furnace non 

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

**−**

_7

- 32 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).

The differential in non

- fur nace fan furnace electricity consumption between the baseline equipment (EL 0) and more efficient design options (EL 1 and above) for each efficiency level is included in the total electricity use shown in the results tables in section 7.8.

The details for calculating furnace energy consumption at each considered fan efficiency level appear in appendix 7

- E.

7.7.2 Impact on Central Air C onditioner Energy Use with More Efficient Furnace Fans

DOE accounted for the fact that more efficient furnace fans will tend to contribute less heat and thereby require less cooling operation by the central air conditioner

. Since the cooling load of each sample housing unit is known, it is possible to estimate what the air conditioner energy consumption would be if more efficient fan equipment, rather than the baseline equipment, were used in each housing unit.

DOE calculated the non

- furnace fan cooling energy using the following formula:

CoolingEne rgyUs e non

− furnace

_ fan = COH × Power non

− furnace

_ fan

Where:

C OH = as defined above in section 7.5.2,

Power non

- furnace_fan = power consumption of all non

- furnace fan components of the central air conditioner (kW).

DOE calculated the non

- furnace fan cooling power consumption as follows:

Power non

− furnace

_ fan = ( CoolingCapacity
SEER − 365
1000 ∗ CFM )

Where:

365

1000 ∗ CFM = default central air conditioner blower output, watts,

CFM = nominal cooling load CFM measured at 400 CFM per AC ton, CFM

,
SEER = SEER of central air conditioner , Btu/ ( W .h) , and7

- 33 CoolingCap acity = cooling capacity of air conditioner, Btu/h.

The differential in non

- furnace fan furnace electricity consumption between the baseline equipment (EL 0) and more efficient design options (EL 1 and above) for each efficiency level is included in the total electricity use shown in the results tables in section 7.8.

The details for calculating the central air conditioner energ y consumption at each considered fan efficiency level appear in appendix 7

- F.

7.8 SUMMARY OF ENERGY USE RESULTS

This section presents the average annual energy use and the average energy savings for each considered energy efficiency level compared to the base line energy efficiency for each furnace fan product class

. For the efficiency levels above the baseline the electricity use includes the difference from the baseline in the non

- fur nace fan cooling energy use, non

- furnace fan furnace electricity consumption , and furnace standby energy use . Thus

, the electricity savings account for these indirect impacts on the higher furnace fan efficiency levels.

For the LCC and PBP analyses, DOE used the full distribution of energy use values calculated for the sample ho useholds.

Table 7.8.1 Average Annual Energy Consumption and Savings for Furnace Fans Used in Non

- Weatherized Gas Furnaces Efficiency Level Non

- Condensing Furnace Condensing Furnace Annual Electricity Use (kWh) Electricity Use Savings (kWh) Additional Fuel Use ( MMBtu) Annual Electricity Use (kWh) Electricity Use Savings (kWh) Additional Fuel Use (MMBtu)

Baseline (PSC) 798 NA NA 768 NA NA

Improved PSC 784 13 0.00 736 32 0.00

PSC w/ Controls 779 19

- 0.04 643 125

- 0.03

X13 508 290 0.28 421 347 0.39 ECM + Multi

- Stage 532 265 0.33 410 357 0.44

ECM + Backward

curved Impeller 478 319 0.36 372 396 0.487

- 34 Table 7.8.2 Average Annual Energy Consumption and Savings for Furnace Fans Used in Weatherized Gas Furnace Fans and Oil

- Fired Furnaces Efficiency Level Weatherized Gas Furnace Oil

- Fired Furnace Annual Electricity Use (kWh) Electricity Use Savings (kWh) Additional Fuel Use (MMBtu) Annual Electricity Use (kWh) Electricity Use Savings (kWh) Additional Fuel Use (MMBtu)

Baseline (PSC) 886 NA NA 639 NA NA

Improved PSC 879 7 0.00 606 32

- 0.01

PSC w/ Controls 833 54 0.03 471 168 0.07

X13 516 370 0.29 310 329 0.56 ECM + Multi

- Stage 476 411 0.34 282 357 0.65

ECM + Backward

curved Impeller 420 466 0.37 255 384 0.71

Table 7.8.3 Average Annual Energy Consumption and Savings for Furnace Fans Used in Manufactured Home Gas Furnaces Efficiency Level Non

- Condensing Furnace Condensing Furnace Annual Electricity Use (kWh) Electricity Use Savings (kWh) Additional Fuel Use (MMBtu) Annual Electricity Use (kWh) Electricity Use Savings (kWh) Additional Fuel Use (MMBtu)

Baseline (PSC) 545 NA NA 572 NA NA

Improved PSC 533 12 0.00 545 27

- 0.01

PSC w/ Controls 431 114 0.15 399 172 0.22

X13 297 247 0.46 267 304 0.61 ECM + Multi

- Stage 236 309 0.50 211 360 0.68

ECM + Backward

curved Impeller 211 333 0.53 192 380 0.717

- 35 Table 7.8.4 Average Annual Energy Consumption and Savings for Furnace Fans Used in Electric Furnaces and Manufactured Home Electric Furnaces Efficiency Level Electric Furnace Manufactured Home Electric Furnace Annual Electricity Use (kWh) Net Electricity Use Savings * (kWh) Annual Electricity Use (kWh) Net Electricity Use Savings * (kWh) Baseline (PSC) 594 NA 529 NA Improved PSC 585 9 526 4 PSC w/ Controls 591 2 446 83 X13 440 154 365 164 ECM + Multi

Stage 455 139 295 234

ECM + Backward

curved Impeller 416 178 268 261

* Accounts for additional energy used for heating.

Table 7.8.5 Average Annual Energy Consumption and Savings for Furnace Fans Used in Hydronic Air Handlers Efficiency Level Annual Electricity Use (kWh) Net Electricity Use Savings (kWh) Additional Fuel Use (MMBtu)

Baseline (PSC) 838 NA NA Improved PSC 827 11 0.00 PSC w/ Controls 844

- 6

- 0.04

X13 533 305 0.25 ECM + Multi

Stage 367 471 0.31

ECM + Backward

curved Impeller 329 509 0.32

Switching Mode Power Supply 309 529 0.32

Toroidal Transformer 296 543 0.327

- 36 REFERENCES

1. U.S. Department of Energy

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

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

2. Michael R. Lindeburg, P., Fans and Ductwork . In Mechanical Engineering Reference Manual for the PE Exam , P. Michael R. Lindeburg, Editor. Tenth ed. 1997. Professional Publications, Inc.: Belmont, CA. p. 20

- 1, 20

- 26

3. American Society of Heating Refrigeration and Air

- Conditioning Engineers, ASHRAE 1997 Handbook

- Fundamentals . 1997. Atlanta, GA.p. 3.12.

4. 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 Method for Measuring the Energy Consumption of Furnaces, January 1, 2012.

5. U.S. De partment of Energy

- Energy Efficiency & Renewable Energy, Technical Support Document: Energy Efficiency Standards for Consumer Products: Residential Furnaces and Boilers , 2007. Washington, DC.

6. Energy Information Administration, Annual Energy Outlook 2010 with Projections to 2035 , 2010. Washington, DC. Report No. DOE/EIA

- 0383(2010).

< http://www.eia.doe.gov/oiaf/aeo/ >

7. National Oceanic and Atmospheric Administration, NNDC Climate Data Online, (Last

acce ssed February 2009.) <www7.ncdc.noaa.gov/CDO/CDODivisionalSelect.jsp>

8. U.S. Department of Energy: Energy Information Administration, Residential Energy Consumption Survey (RECS), 2005. (Last accessed September, 2011.) Public use data files. < http://www.eia.doe.gov/emeu/recs/recspubuse05/pubuse05.html >

9. Pigg, S., Electricity Use by New Furnaces: A Wisconsin Field Study, October, 2003. Energy Center of Wisconsin. Madison. Repor t No. 230

- 1. prepared for Focus on Energy.

< http://www.ecw.org/ecw/productdetail.jsp?productId=499&numPerPage=1000&sortAtt ribu te=initiative.title&sortOrder=ASC >

10. U.S. Department of Energy

- Energy Efficiency & Renewable Energy, Technical Support Document: Energy Efficiency Standards for Consumer Products: Residential Furnaces, Central Air Conditioners, and Heat Pumps , 2011. W ashington, DC.