5-i

CHAPTER 5. ENGINEERING ANALYSIS

TABLE OF CONTENTS

5.1 INTRODUCTION ........................................................................................................... 5-1

5.2 METHODOLOGY OVERVIEW.................................................................................... 5-1

5.3 PRODUCT CLASSES..................................................................................................... 5-3

5.4 EFFICIENCY LEVELS ANALYZED............................................................................ 5-5

5.4.1 Baseline................................................................................................................ 5-5

5.4.2 Intermediate Efficiency Levels............................................................................ 5-6

5.4.3 Max-tech Efficiency Levels............................................................................... 5-10

5.5 TEARDOWN ANALYSIS............................................................................................ 5-11

5.5.1 Selection of Units............................................................................................... 5-11

5.5.2 Generation of Bill of Materials.......................................................................... 5-13

5.6 COST MODEL.............................................................................................................. 5-14

5.6.1 Cost Model Overview........................................................................................ 5-15

5.6.2 Cost Model Assumptions................................................................................... 5-16

5.7 MANUFACTURER SELLING PRICE ........................................................................ 5-19

5.7.1 Manufacturer Markup ........................................................................................ 5-20

5.7.2 MSP in the Downstream Analyses .................................................................... 5-21

5.8 INDUSTRY COST-EFFICIENCY RELATIONSHIPS................................................ 5-21

5.9 RESULTS ...................................................................................................................... 5-21

LIST OF TABLES

Table 5.3.1: Product Classes........................................................................................................ 5-4

Table 5.4.1: Baseline Unit FER and IFER for Residential Furnace Fans.................................... 5-6

Table 5.4.2: Intermediate Efficiency Level Correlation between Technologies, Technology 

Status, and Analysis Approach ............................................................................... 5-7

Table 5.4.3: Reduction in FER or Standby Power for Each Efficiency Level ............................ 5-8

Table 5.4.4: Efficiency Levels for Furnace Fans Used in Non-Hydronic HVAC Products........ 5-9

Table 5.4.5: Efficiency Levels for Hydronic Air Handler Fans (Heat/Cool) .............................. 5-9

Table 5.4.6: Max-Tech Efficiency Levels for Furnace Fans..................................................... 5-10

Table 5.5.1: Characteristics of Representative Residential Furnaces........................................ 5-12

Table 5.6.1: Cost Model Categories and Descriptions .............................................................. 5-15

Table 5.6.2: Purchased Furnace Fan Components..................................................................... 5-17

Table 5.6.3: Factory Parameter Assumptions............................................................................ 5-19

Table 5.9.1: MPC Estimates for Design Option Approach Efficiency Level Components ...... 5-22

Table 5.9.2: Cost-Efficiency Results for High-Volume Product Classes.................................. 5-23

Table 5.9.3: Cost-Efficiency Results for Low-Volume Product Classes................................... 5-23
5-ii

LIST OF FIGURES

Figure 5.2.1: Engineering Analysis Methodology ....................................................................... 5-3

Figure 5.5.1: Example of BOM Spreadsheet ............................................................................. 5-14

Figure 5.6.1: Cost Model Methodology ..................................................................................... 5-16

Figure 5.7.1: Components of Manufacturer Selling Price ......................................................... 5-20
5-1

CHAPTER 5. ENGINEERING ANALYSIS

5.1 INTRODUCTION

The engineering analysis establishes the relationship between manufacturer selling price 

(MSP) and energy-efficiency (i.e., fan efficiency rating (FER)) for the products covered in this 

rulemaking. The cost-efficiency relationship serves as the basis for subsequent cost/benefit 

calculations for individual customers, manufacturers, and the Nation. In determining this 

relationship, the U.S. Department of Energy (DOE) estimates the increase in the manufacturer 

selling price (MSP) associated with technological changes that reduce the energy consumption of 

the baseline models.

The primary inputs to the engineering analysis are data from the market and technology 

assessment (chapter 3 in the TSD), energy performance data from testing and publicly available 

product literature and research reports, input from manufacturers, baseline specifications, and 

production cost estimates developed using a cost model. The primary output of the engineering 

analysis is a set of cost-efficiency relationships that represent the average incremental cost of 

increasing product efficiency above the baseline levels. In the subsequent markups analysis 

(chapter 6 in the TSD), DOE determines customer prices by applying distribution markups, sales 

tax, and contractor markups to the manufacturer sales prices (MSPs) developed in the 

engineering analysis. After applying these markups, the data serve as inputs to the energy use 

characterization (chapter 7 in the TSD) and the life-cycle cost and payback period analyses 

(chapter 8 in the TSD). 

In this chapter, DOE discusses: (1) the identification of representative baseline units for 

each product class, (2) the methodology used to develop bills of materials (BOMs) and MSPs, 

(3) the process for constructing the industry cost-efficiency relationships, and (4) the costefficiency relationship outputs.

5.2 METHODOLOGY OVERVIEW

This section describes the analytical methodology used in the engineering analysis. In 

this rulemaking, DOE used an efficiency-level approach in conjunction with a design option 

approach to identify incremental improvements in efficiency for each product class. An 

efficiency level approach enabled DOE to identify incremental improvements in efficiency for 

efficiency-improving technologies that furnace fan manufactures already incorporate in 

commercially-available models. A design option approach enabled DOE to model incremental 

improvements in efficiency for technologies that are not commercially available in residential 

furnace fan applications. In combination with these approaches, DOE used a cost-assessment 

approach to determine the manufacturing production cost (MPC) at each efficiency level 
5-2

identified for analysis. This methodology estimates the incremental cost of increasing product 

efficiency. 

The cost-assessment is based on reverse engineering data and was validated by 

manufacturer input. First, DOE used information gathered from manufacturers and/or data from 

the market and technology assessment to identify baseline units and representative models. DOE

selected a set of units at the baseline and higher efficiencies for teardown analysis based on this 

information. The baseline unit serves as a starting point for the analysis, and the units selected 

for teardown analysis span a range of manufacturers, functionality, and efficiencies for 

commercially available products. DOE developed estimates of MPC for the each of the units 

selected for teardown by disassembling each unit, developing a bill of materials, and using this 

information as input for a manufacturing cost model. 

To determine the MSP of a unit at each efficiency level, DOE applied manufacturer 

markups to the MPC. DOE used the same markups for this preliminary analysis as it did for 

furnaces in the direct final rule for HVAC products. 76 FR 37453 DOE derived the manufacturer 

markup for that rulemaking by evaluating publicly available industry financial data and through 

manufacturer feedback. The results of the engineering analysis are a set of cost-efficiency 

relationships, in the form of MSP as a function of energy-efficiency, for each product class. The 

methodology for the engineering analysis is a logical, concise, and reproducible process, as 

illustrated in Figure 5.2.1.
5-3

Figure 5.2.1: Engineering Analysis Methodology

5.3 PRODUCT CLASSES

DOE identified nine key product classes and 12 additional product classes that DOE 

differentiated by product application and internal structure. Key product classes are those 

representing most of the energy use associated with furnace fans. DOE directly analyzed the nine 

key product classes. The 12 additional product classes represent significantly fewer shipments 

and significantly less energy use. DOE identified two approaches to generating results for the 

additional product classes. One approach is for DOE to generate unique results for each 

additional product class by extrapolating from key product class results. Alternatively, DOE 

decided to group each non-key product class with a key product class to which it is closely 

related in application and internal structure for the preliminary analysis. DOE assigned the 

engineering results of each key product class to the non-key product classes with which it is 

grouped. Table 5.3.1 presents the 21 product classes and maps the additional product classes to 

the nine key product classes.

Cost Model

Manufacturer

Markup

Analysis

Cost-Efficiency 

Relationship

(Efficiency vs 

MPC)

Engineering 

Manufacturer 

Interviews

Physical

Teardown

Analysis

Bills of 

Material 

(BOM)

Selling PriceEfficiency 

Relationship

(Efficiency vs 

Baseline unit, MSP)

Efficiency levels, 

Representative 

Products

Market and Tech 

Assessment

(chapter 3)

Screening Analysis

(chapter 4)

Virtual

Teardown

Analysis
5-4

Table 5.3.1: Product Classes

Key Product Class Additional Product Classes

Non-Weatherized, Non-Condensing Gas Furnace 

Fan (NWG-NC)

Non-weatherized, Condensing Gas Furnace Fan 

(NWG-C)

Weatherized, Non-condensing Gas Furnace Fan 

(WG-NC)

• Weatherized, Non-Condensing Oil Furnace Fan 

(WO-NC)

• Weatherized Electric Furnace/Modular Blower Fan 

(WEF/WMB)

• Manufactured Home Weatherized Gas Furnace Fan 

(MH-WG)

• Manufactured Home Weatherized Oil Furnace Fan 

(MH-WO)

• Manufactured Home Weatherized Electric 

Furnace/Modular Blower Fan (MH-WEF/WMB)

Non-weatherized, Non-condensing Oil Furnace Fan 

(NWO-NC)

• Non-Weatherized, Condensing Oil Furnace Fan 

(NWO-C)

• Manufactured Home Non-Weatherized Oil Furnace 

Fan (MH-NWO)

Electric Furnace / Modular Blower Fan (EF/MB)

Heat/Cool Hydronic Air Handler Fan (HAH-HC)

• Heat-Only Hydronic Air Handler Fan (HAH-H)

• Hydronic Air Handler Fan with Coil (HAH-C)

• Manufactured Home Heat/Cool Hydronic Air 

Handler Fan (MH-HAH-HC)

• Manufactured Home Heat-Only Hydronic Air 

Handler Fan (MH-HAH-H)

• Manufactured Home Hydronic Air Handler Fan 

with Coil (MH-HAH-C)

Manufactured Home Non-Weatherized, Noncondensing Gas Furnace Fan (MH-NWG-NC)

Manufactured Home Non-Weatherized, Condensing 

Gas Furnace Fan (MH-NWG-C)

Manufactured Home Electric Furnace/ Modular 

Blower Fan (MH-EF/MB)

DOE developed new candidate standard levels for the key product classes based on the

fan efficiency rating (FER), a new energy use metric proposed in the furnace fan test procedure 

NOPR that DOE published on May 15, 2012. 77 FR 28674 FER represents normalized annual 

energy use. For furnace fans used in non-hydronic HVAC products, FER only accounts for 

active-mode energy use because standby and off mode energy use for furnace fans used in 

these products is accounted for in other DOE rulemaking activities. For furnace fans used in 

hydronic air handlers, the NOPR proposed to use the integrated fan efficiency rating (IFER), a 

variation of FER that integrates active mode and standby mode energy use. Chapter 3 of this 

TSD describes these rating metrics in greater detail.
5-5

5.4 EFFICIENCY LEVELS ANALYZED

DOE analyzed multiple efficiency levels for each product class presented in section 5.3

and estimated the manufacturer production cost (MPC) at those levels. The following 

subsections discuss efficiency levels from the baseline to maximum technologically feasible 

(“max-tech”) efficiency for each product class. DOE identified the highest efficiency level by 

reviewing product literature for commercially available products and research reports that 

included energy performance data of prototype furnace fans.

5.4.1 Baseline

DOE selected baseline units as reference points for each product class, against which 

changes resulting from potential new energy conservation standards could be measured. The 

baseline unit in each product class possesses the basic characteristics of products in that class. 

Typically, a baseline unit is a unit that just meets, but does not exceed current Federal energy 

conservation standards and provides basic consumer utility. However, energy conservation 

standards for furnace fans do not exist. As a result, DOE selected baseline models typical of the 

least-efficient furnace fans used in commercially available residential HVAC models.

DOE used the baseline units for comparison in several analyses, including the 

engineering analysis, life-cycle cost (LCC) analysis, payback period (PBP) analysis, and national 

impacts analysis (NIA). To determine energy savings that will result from a new energy 

conservation standard, DOE compared energy use at each of the higher energy efficiency levels 

to the energy consumption of the baseline unit. Similarly, to determine the changes in price to the 

consumer that will result from a new energy conservation standard, DOE compared the price of a 

baseline unit to the price of a unit at each higher efficiency level.

DOE reviewed FER values that it calculated using test data and performance information 

from publicly-available product literature to determine baseline FER ratings. Table 5.4.1 presents 

the baseline FER for each non-hydronic air handler product class, and the baseline IFER for the 

key hydronic air handler product class. As discussed above, IFER integrates standby mode and 

off mode energy consumption with active mode energy consumption for those products. Note 

that the baseline IFER for hydronic heating/cooling air handlers is significantly lower than the 

baseline FER values for the other product classes. This is because standby mode consumption is 

much lower than active mode consumption. In addition, IFER is normalized by total annual 

hours (8,760 hours) whereas FER is normalized by total annual active mode operating hours 

(1,870 hours for single stage products).
5-6

Table 5.4.1: Baseline Unit FER and IFER for Residential Furnace Fans

Product Class

FER 

(W/1000 cfm)

IFER

(W/1000 cfm)

Non-weatherized, Non-condensing Gas Furnace Fan 380

Non-weatherized, Condensing Gas Furnace Fan 393

Weatherized Gas Furnace Fan 333

Non-Weatherized Oil Furnace Fan 333

Electric Furnace / Modular Blower Fan 312

Manufactured Home Non-weatherized, Noncondensing Gas Furnace Fan 295

Manufactured Home Non-weatherized, Condensing 

Gas Furnace Fan 319

Manufactured Home Electric Furnace / Modular 

Blower Fan 243

Hydronic Air Handler Fan (Heat/Cool) 107

Incremental MPCs for intermediate efficiency levels are the MPCs for products 

representative of these levels minus the MPC of baseline products. The baseline MPCs are based 

on products representative of the baseline efficiency level. These incremental MPCs represent 

the added costs of efficiency-improving design features incorporated into intermediate-efficiency

products that are not present in baseline efficiency units. Throughout the analyses, the 

intermediate-efficiency products are compared with baseline products, including evaluation of 

differences in MPC, installation cost, and operating costs (chapter 8).

5.4.2 Intermediate Efficiency Levels

DOE determined FER and IFER values representing the intermediate efficiency levels 

based on tests conducted for selected products according to the proposed DOE test procedure and 

on information obtained in AHRI’s product certification directories,

1

5.9

manufacturer catalogs, and 

other publicly available literature. The intermediate efficiency levels are all defined by specific 

design options used to attain them. For each key product class, DOE analyzed multiple efficiency 

levels and estimated MPCs at each efficiency level. Section contains cost efficiency data for 

the full efficiency level range that DOE analyzed from the baseline efficiency level to the max 

tech efficiency level for each key product class. 

DOE used a combination of an efficiency level approach and a design option approach to 

determine MPCs for intermediate efficiency levels for each product class. DOE used the 

efficiency level approach for intermediate efficiency levels that products can achieve by using

commercially available technologies. MPCs were determined based on reverse engineering of 

purchased products representing these efficiency levels. However, some of the efficiency levels, 

particularly the higher efficiency levels, are based on use of prototype technologies that are not 

commercially available or technologies that are commercially available but not in residential 
5-7

furnace fan applications. For assessment of these efficiency levels, DOE used the design option 

approach, determining the additional cost and the additional energy savings associated with 

adoption of the particular technologies. Table 5.4.2 lists the efficiency levels DOE considered, 

showing the technologies and analysis approach used for each. Chapter 3 of this TSD includes a 

detailed discussion of each technology option.

Table 5.4.2: Intermediate Efficiency Level Correlation between Technologies, Technology 

Status, and Analysis Approach 

Efficiency Level Design Option Technology Status

Analysis 

Approach

1 Improved PSC Commercialized Efficiency Level

2 Inverter-Driven PSC Prototype* Design Option

3 X13 Commercialized Efficiency Level

4 ECM and MultiStaging Commercialized Efficiency Level

5

(non-hydronic 

max-tech)

Premium ECM and 

Multi-Staging + 

Backward-Curved 

Impeller

Prototype Design Option

Hydronic 6 Switching Mode Power 

Supply

Commercialized, but not 

in Furnace Fan Products Design Option

Hydronic 7

(hydronic max-tech) Toroidal Transformer Commercialized, but not in Furnace Fan Products Design Option

*DOE is aware that a furnace model using an inverter-driven PSC motor was once commercially available, but no 

longer.

DOE finds from manufacturer feedback and its review of publically available product 

literature that manufacturers use similar furnace fan components and follow a similar technology 

path to improving efficiency across all product classes. DOE does not expect the percent 

reduction in FER associated with each design option, whether commercially available or 

prototype, to differ across product classes as a result. Therefore, DOE determined average FER 

reductions for each efficiency level for a subset of key product classes and applied these 

reductions to all product classes. DOE based the reductions in FER associated with 

commercialized technologies on measurements or publicly available performance information. 

DOE based the FER reductions associated with prototype technologies on research reports that 

included performance data. DOE then applied these FER reductions to each product class. 

Table 5.4.3 presents the percent FER reductions and reductions in standby power input 

that DOE determined each design option and efficiency level. DOE used these reductions to 

calculate all of the nominal FER values for the intermediate efficiency levels of all the key 

product classes. The FER reductions for efficiency levels 1 through 4 are expressed in relation to 

the baseline. DOE determined these percent reductions based on averaging the calculated 

reductions associated with all products for which information was available, including both 
5-8

tested products and products for which sufficient information was available in public literature. 

The reduction in FER for the backward-inclined blower design option used for efficiency level 5 

is in relation to the previous efficiency level. Note that this design option is described in more 

detail in chapter 3. Finally, the impact of standby mode efficiency improvements for efficiency 

levels 6 and 7 for hydronic air handler furnace fans are expressed in terms of standby mode 

power reduction.

Table 5.4.3: Reduction in FER or Standby Power for Each Efficiency Level

Efficiency Level

(EL) Design Option

Percent 

Reduction in 

FER from 

Baseline

Percent 

Reduction in 

FER from 

Previous EL

Reduction in 

Standby Power

from Baseline

(Watts)

1 Improved PSC 2% - NA

2 Inverter-Driven 

PSC 10% - NA

3 X13 45% - NA

4 ECM 59% - NA

5

(non-hydronic 

max-tech)

ECM + BackwardCurved Impeller - 10% NA

Hydronic 6 Switching Mode 

Power Supply - - 1

Hydronic 7 

(hydronic maxtech)

Toroidal 

Transformer - - 1

5.4.2.1 Intermediate Efficiency Levels for Non-Hydronic Air Handler Fans

For all product classes except hydronic air handler fans, DOE analyzed four efficiency 

levels in addition to the baseline and the max-tech. Table 5.4.4 shows the FER for each 

efficiency level within each non-hydronic air handler fan product class.
5-9

Table 5.4.4: Efficiency Levels for Furnace Fans Used in Non-Hydronic HVAC Products

Efficiency 

Level

NWGNCNWGC

MHNWGNCMHNWGC

NWONC WG EF/MBMHEF/MB

Baseline 380 393 295 319 333 333 312 243

1 371 384 288 312 326 326 305 238

2 344 356 267 289 301 301 282 220

3 209 216 162 175 183 183 171 133

4 158 163 122 132 138 138 129 101

5 142 147 110 119 124 124 116 90.8

5.4.2.2 Intermediate Efficiency Levels for Furnace Fans used in Hydronic Air 

Handler Fans

For furnace fans used in hydronic air handlers, DOE added two additional efficiency 

levels associated with design options that reduce standby and off mode energy consumption. To 

analyze these efficiency levels, DOE used cost and efficiency information developed in the 

recent HVAC products rulemaking—see chapter 5 of the HVAC products direct final rule TSD.a

Table 

5.4.5

 

Based on detailed investigation of wiring diagrams, control schematics, and images of control 

boards of both gas furnaces and hydronic air handlers DOE determined that standby/off mode 

power consumption and the potential for its reduction, are equivalent for these products. 

shows the IFER for each hydronic air handler fan efficiency level.

Table 5.4.5: Efficiency Levels for Hydronic Air Handler Fans (Heat/Cool)

Efficiency Level IFER (W/1000 cfm)

Baseline 107

1 105

2 97.1

3 58.9

4 40.2

5 36.2

6 35.5

7 – Max-tech 34.8

a The TSD for the direct final rule for HVAC products is accessible at the following website: 

http://www1.eere.energy.gov/buildings/appliance_standards/residential/residential_furnaces_central_ac_hp_direct_f

inal_rule_tsd.html
5-10

5.4.3 Max-tech Efficiency Levels

As part of the engineering analysis, DOE determined the maximum technologically 

feasible improvement in energy efficiency for the covered products, as required by section 

325(o) of EPCA. (42 U.S.C. 6295(o)) In the market and technology assessment (chapter 3 of this 

TSD), DOE conducted a survey of the markets for the covered products and their supporting 

research areas. The max-tech efficiency level in each product class is based on a combination of 

design options that is not used in any known product on the market. Some of the included design 

options are based on prototype designs. Consequently, the max-tech level designs identified are 

more efficient than the maximum technology that is commercially available.

The max-tech levels identified for the key furnace fan product classes are shown in Table 

5.4.6. The max tech efficiency level designs for all of these product classes use a premium ECM 

motor and backward-inclined impeller. The premium ECM motor operates at a higher RPM than 

a typical ECM, which is required for desirable operation when paired with a backward-inclined 

impeller. In addition, the premium ECM was a smaller diameter, resulting in a less-restricted 

furnace fan inlet and improved efficiency. For hydronic air handler fans, the max tech efficiency 

level design also includes a switching mode power supply (from efficiency level 6) and toroidal 

transformer in addition to a premium ECM and backward-inclined impeller (efficiency level 5). 

Table 5.4.6: Max-Tech Efficiency Levels for Furnace Fans

Product Class

Max-Tech

Efficiency Level 

FER, W/1000 cfm

FER

(W/1000 cfm)

IFER

(W/1000 cfm)

Non-weatherized, Non-condensing Gas Furnace Fan 142

Non-weatherized, Condensing Gas Furnace Fan 147

Weatherized Gas Furnace Fan 110

Non-weatherized Oil Furnace Fan 119

Electric Furnace / Modular Blower Fan 124

Manufactured Home Non-weatherized, Noncondensing Gas Furnace Fan 124

Manufactured Home Non-weatherized, Condensing 

Gas Furnace Fan 116

Manufactured Home Electric Furnace / Modular 

Blower Fan 90.8

Hydronic Air Handler Fan (Heat/Cool) 34.8
5-11

5.5 TEARDOWN ANALYSIS

Other than obtaining detailed manufacturing costs directly from a manufacturer, the most 

accurate method for determining the production cost of a product is to disassemble it piece-bypiece, compile a bill of materials (BOM), and estimate the material and labor cost of each 

component. DOE refers to this practice as a physical teardown. A supplementary method, called 

a catalog teardown (or “virtual teardown”), uses published manufacturer product literature and 

supplementary component data to estimate the major physical differences between the catalog 

teardown unit and a similar physical teardown unit. One alternative to the teardown method is to 

conduct price surveys to determine the production cost, but this approach only provides insight 

into total MPC under current market conditions. The teardown approach provides insight into 

MPC by component and cost category, which enables DOE to estimate product costs and prices 

as new energy conservation standards change the affected market. 

Units selected for physical teardowns were dismantled, and each part was characterized 

according to weight, manufacturing processes, dimensions, material, and quantity, in order to 

facilitate the creation of a complete BOM and manufacturing cost estimate for the product. 

BOMs for catalog teardowns leverage existing BOMs from teardowns by substituting 

components that are different between models based on product literature. These modifications 

are based on data taken from manufacturer specification sheets and supplementary component 

data.

5.5.1 Selection of Units

For the teardown analysis of furnace fans, DOE included 26 physical teardowns and two

additional virtual teardowns. DOE identified and selected representative units across the entire 

range of efficiencies that are currently available to consumers. To the extent possible, all major 

efficiency levels and technologies were captured in the selection of models for teardown 

analysis. Each product class was considered separately. 

Teardown units must be representative of their product class; hence their characteristics 

should be representative of typical characteristics of the products sold in the market. The

characteristics of the key product classes are shown in Table 5.5.1. DOE also required that 

teardown units be manufactured in considerable volume, be commonly available, and have the 

most popular features. 
5-12

Table 5.5.1: Characteristics of Representative Residential Furnaces

Product Class

Input 

Heat 

Capacity 

kBtu/h

Airflow

Capacity

cfm

Heat 

Exchanger 

Type

Number of Heat 

Exchangers

Non-weatherized, Non-condensing 

Gas Furnace Fan 70 1200 Clamshell/Tubular 1

Non-weatherized, Condensing Gas 

Furnace Fan 70 1200 Clamshell/Tubular 2

Weatherized Gas Furnace Fan 70 1200 Clamshell/

Tubular 1

Non-weatherized Oil Furnace Fan 120 1200 Drum 1

Electric Furnace / Modular Blower 

Fan 70 1200

Electrical 

Resistance 

Heat 

Elements

1

Manufactured Home Nonweatherized, Non-condensing Gas 

Furnace Fan

70 1200 Clamshell/

Tubular 1

Manufactured Home Nonweatherized, Condensing Gas 

Furnace Fan

70 1200 Clamshell/

Tubular 2

Manufactured Home Electric 

Furnace / Modular Blower Fan 70 1200

Electrical 

Resistance

Heat 

Elements

1

Hydronic Air Handler Fan 

(Heat/Cool) 70 1200 Hydronic 1

DOE also adopted more specific criteria to guide the selection process. In order to 

understand incremental manufacturing costs associated with design options that improve

efficiency, products chosen for teardowns included models of various efficiency levels taken 

from the same manufacturer and product series to the extent possible. This approach minimized 

the cost effects of non-efficiency-related design differences between models. The manufacturers 

that were chosen have large market shares of the particular product class. DOE made an 

exception to this criterion for the highest efficiency product (or max-tech product) in each 

product class; as such, the max-tech products for teardown were chosen irrespective of 

manufacturer. DOE selected products to represent max-tech efficiency that include design 

options that have the highest potential for energy savings according to interested party feedback 

on the framework document. This approach was necessary because FER ratings were not 

available. DOE also selected products that minimized the occurrence of non-efficiency-related 

premium features, which could inflate the incremental manufacturing cost of achieving higherefficiency levels. 
5-13

DOE surveyed the residential furnace fan industry and identified products available to 

consumers as well as prototypes developed by research efforts. DOE then applied the 

aforementioned criteria and selected baseline, intermediate, and max-tech units that were as close 

to the representative characteristics as possible and included the most prevalent technologies on 

the market. 

Because the large majority of residential furnace fan shipments fall into the nonweatherized gas product class, DOE focused its teardown analysis heavily on non-weatherized

gas furnace fans. As a result, DOE selected units for teardown that include nine non-weatherized, 

non-condensing gas furnace fans and three non-weatherized, condensing gas furnace fans. DOE 

selected the remainder of the units for teardown from the remaining key product classes. The 

furnace fans selected spanned the range of efficiency levels from baseline to max-tech. DOE also 

selected units for teardown with airflow capacities above and below the representative 1,200 

cfm. DOE did not identify the model number or manufacturer of the units examined during the 

teardown analysis because this could expose sensitive information about individual 

manufacturers’ products.

5.5.2 Generation of Bill of Materials

The end result of each teardown is a structured BOM, describing each product component 

and its relationship to the other parts in the estimated order in which manufacturers assembled 

them. The BOMs describe each fabrication and assembly operation in detail, including the type 

of equipment needed for fabrication (e.g., presses, drills) and the process cycle times. The result 

is a thorough and explicit model of the production process. The BOMs incorporate all materials, 

components, and fasteners classified as either raw materials or purchased parts and assemblies. 

The classification into raw materials or purchased parts is based on DOE’s previous industry 

experience, recent information in trade publications, and discussions with high- and low-volume 

original equipment manufacturers (OEMs). DOE also visited several manufacturing plants (for 

this rulemaking and other rulemakings that cover the HVAC products in which furnace fans are 

used) to reinforce its understanding of the industry’s current manufacturing practices. For 

purchased parts, the purchase price is an estimate based on high-volume price quotations and 

detailed discussions with suppliers and manufacturers. For fabricated parts, the price of 

intermediate materials (e.g., tube, sheet metal) and the cost of transforming them into finished 

parts is an estimate based on current industry pricing. For a continued discussion of the cost 

details and assumptions, refer to section 5.6.2.

The BOM for a catalog teardown is identically structured and provides a description in 

equal detail to the BOM of a physical teardown. However, it is generated using a slightly 

different methodology. BOMs for catalog teardowns are generated by modifying the BOM of a 

similar unit that has been physically torn down. These modifications reflect the major physical 

differences between the units. Specific to this engineering analysis, the catalog teardown 

methodology was employed to generate bills of materials for fans with inverter-driven PSC 
5-14

motors and fans with backward-inclined impellers. DOE physically tore down five fans with 

improved PSC motors and nine fans with ECM motors. Based on these physical teardowns, DOE 

executed one supplementary PSC with inverter catalog teardown and one supplementary ECM 

with a backward-inclined impeller catalog teardowns. 

Figure 5.5.1 below shows an example of a section of a BOM spreadsheet. Each row of 

the spreadsheet represents a single part of the unit assembly and includes a description of the 

part, a material type, initial and final dimensions, and weight. These rows also include 

placeholders for the type and number or duration of fabrication processes (stamping, drilling, 

etc.) required to create that part. From this information, a part cost is generated, and the part 

costs are summed across the sheet to create a cost estimate for the entire unit.

Figure 5.5.1: Example of BOM Spreadsheet

5.6 COST MODEL

The cost model is a detailed, component-focused, activity-based tool for estimating the 

manufacturing cost of a product. Once teardowns were completed, DOE implemented a cost 

model that could translate the physical information from the BOMs into manufacturing costs. 

The cost model is based on production activities and divides factory costs into materials, labor, 

depreciation, and overhead. DOE defines the cost inputs of these broader categories in Table 

5.6.1.
5-15

Table 5.6.1: Cost Model Categories and Descriptions

Major Category Sub-Category Description

Material Costs

Direct Raw materials (e.g., coils of sheet metal) and 

purchased parts (e.g., fan motors, compressors)

Indirect Material used during manufacturing (e.g., welding 

rods, die oil, release media)

Manufacturing 

Labor

Assembly Part/unit assembly on manufacturing line

Fabrication Conversion of raw material into parts ready for 

assembly

Indirect

Fraction of overall labor not associated directly with 

product manufacturing (e.g., forklift drivers, quality 

control)

Supervisory Fraction of indirect labor that is paid a higher wage 

Depreciation

Equipment, 

Conveyor, Building

Straight line depreciation over expected life

Tooling Cost is allocated on a per-use basis or obsolescence, 

whichever is shorter

Other Overhead

Utilities A fixed fraction of all material costs meant to cover 

electricity and other utility costs

Maintenance Based on installed equipment and tooling investment

Property Tax and 

Insurance

A fixed fraction based on total unit costs

DOE entered the cost data from all the BOMs—whether they were obtained through 

physical teardowns or catalog teardowns—into the cost model. The cost model analysis created 

cost estimates for each of the products analyzed in the teardown analysis. The cost model uses 

specific assumptions to provide cost estimates; the following sections describe these 

assumptions.

5.6.1 Cost Model Overview

This section provides a general overview of the process by which the cost model converts 

the physical information in each product’s BOM into cost information. After gathering 

component information through physical teardowns and organizing it into BOMs, the resulting 

data were used as inputs for the cost model spreadsheet. To determine the costs, DOE followed 

one of two different paths, depending on whether a subassembly was purchased (out-sourced) or 

produced in-house. For purchased parts, DOE gathered price quotations from major suppliers at 

different production volumes. For parts produced in-house, DOE reconstructed manufacturing 

processes for each part using modeling software based on internal expertise. For example, for an 

access panel, DOE deduced the time required for setup, handling, changeover, and punching 

holes, as well as the number of holes and hits. By repeating this process, DOE was able to assign 

labor time, equipment utilization, and other important factors to each subassembly in each of the 
5-16

units considered for this analysis. The last step was to convert the information into dollar values. 

To perform this task, DOE collected information on such factors as labor rates, tooling 

depreciation, and costs of purchased raw materials. DOE assumed values for these parameters 

using internal expertise and confidential information available to its contractors. Figure 5.6.1

provides an illustration of the cost model methodology.

Figure 5.6.1: Cost Model Methodology

In sum, DOE assigned costs of labor, materials, and overhead to each part, including coils, 

whether purchased or produced in-house. DOE then aggregated single-part costs into major 

assemblies. Furnace fans are a component of HVAC products that include other products not 

associated with the cost or efficiency of the furnace fan. Therefore, DOE limited the scope of its 

engineering analysis to the components that comprise the furnace fan assembly, including:

• fan motor and integrated controls;

• primary control board;

• impeller;

• fan housing; and

• components used to direct or guide airflow.

DOE summarized these costs in a spreadsheet. DOE repeated this same process for each unit in 

the engineering analysis, representing a specific efficiency level at the chosen capacity and 

mapped the resulting cost-efficiency points to use as a basis for developing the cost-efficiency 

relationships.

5.6.2 Cost Model Assumptions

Assumptions about manufacturer practices and cost structure play an important role in 

estimating the final cost of the products. DOE used assumptions regarding the manufacturing 

process parameters, (e.g., equipment use, labor rates, tooling depreciation, and cost of purchased 

raw materials) to determine the value of each component. It then summed the values of the 

components into assembly costs and, finally, the total MPC for the product. The MPC includes 

Purchased Parts

Bill of

Materials

Fabrication

Processes Assembly

Processes

Teardown 

Observation

Production 

 Cost

Raw

Materials

Finished

Materials
5-17

the material, labor, depreciation, and overhead costs associated with the manufacturing facility. 

The material costs include both raw materials and purchased part costs. The labor costs include 

fabrication, assembly, and indirect and overhead (burdened) labor rates. The depreciation costs 

include equipment depreciation, tooling depreciation, and building depreciation. The overhead 

costs include indirect process costs, utilities, equipment and building maintenance, and rework. 

The following sections describe the cost model assumptions related to material prices, purchased 

parts and factory parameters.

5.6.2.1 Material Prices

DOE determined the cost of raw materials by using prices for copper, steel, and 

aluminum from the American Metals Market.2

 DOE noted that there have been drastic 

fluctuations in metal prices over the last few years. To account for these large fluctuations, DOE 

used prices of metals that reflect a five-year average of the Bureau of Labor Statistics Producer 

Price Indices (PPIs) spanning 2006 to 2011.

3

5.6.2.2 Fabricated Parts and Purchased Parts

 

DOE characterized parts based on whether manufacturers fabricated them in-house or 

purchased them from outside suppliers. For fabricated parts, DOE estimated the price of 

intermediate materials (e.g., tube, sheet metal) and the cost of forming them into finished parts. 

For purchased parts, DOE estimated the purchase price for OEMs based on discussions with the 

manufacturers. Whenever possible, DOE obtained price quotes directly from suppliers of the 

manufacturers of the units being analyzed. DOE assumed that the components in Table 5.6.2

were purchased from outside suppliers.

Table 5.6.2: Purchased Furnace Fan Components

Assembly Purchased Sub-Assemblies

Fan Assembly

Fan Motor

Motor Capacitor

Impeller

Controls Transformer

PCB 

Variability in the costs of purchased parts can account for large changes in the overall 

MPC values calculated. The purchased part prices utilized in this study were typical values based 

on estimated production volumes and other factors. In actuality, purchased part costs can vary 

significantly based on the quantities desired and the component suppliers chosen. The role of 

purchase part prices in the MPC calculation is further magnified because these parts comprise 

significant portions of these systems by cost. Additionally, some parts, such as molded plastic 

components, may be produced in-house by some manufacturers and purchased by others. The 

choice between these options would result in changes to the calculated overall system costs.
5-18

The market for HVAC products is highly segmented, as described in chapter 3. Some 

products like non-weatherized gas furnaces are produced at volumes significantly larger than

other products under review. In addition, some manufacturers offer most types of the HVAC 

products included in this rule, while other manufacturers focus on niches. DOE separated furnace 

fan product classes into high-volume product classes and low-volume product classes to account 

for these factors, which contribute to manufacturers’ purchasing power and ultimately, purchased 

part prices. DOE categorized furnace fans used in oil furnaces and hydronic air handlers as lowvolume products. DOE categorized all other product classes as high-volume products. Based on 

feedback from manufacturers, DOE has made estimates regarding the cost of acquiring 

purchased parts as a function of the manufacturing volume. High-volume manufacturers

operating also in lower-volume adjacent markets are expected to have purchased part price 

efficiencies consistent with their higher overall purchasing volume from their suppliers. 

5.6.2.3 Factory Parameters

Certain factory parameters, such as fabrication rates, labor rates, and wages, also affect 

the cost of each unit produced. DOE factory parameter estimates were based on internal 

expertise and manufacturer feedback. Table 5.6.3 below lists the factory parameter assumptions 

used in the cost model. These factory parameters are independent of the efficiency level of the 

unit produced. DOE recognizes that the current production levels of high-efficiency units may be 

a small fraction of the current total production, but under a standard, the production levels of 

these units could rise to baseline levels. As stated in the previous section, DOE divided furnace 

fan manufacturers into high-volume manufacturers and low-volume manufacturers. The factory 

parameters shown below are only representative of high-volume manufacturing. Low-volume 

operations (i.e., oil furnace and hydronic air handler production) would show much lower 

manufacturing volumes and fewer shifts per day, among other factors. 
5-19

Table 5.6.3: Factory Parameter Assumptions

Parameter

Furnace Fan 

Estimate

Actual Annual Production Volume 

(units/year) 1,250,000

Work Days Per Year (days) 250

Assembly Shifts Per Day (shifts) 2

Fabrication Shifts Per Day (shifts) 2

Fabrication Labor Wages ($/h) 16

Assembly Labor Wages ($/h) 16

Length of Shift (hrs) 8

Average Equipment Installation Cost (% 

of purchase price) 10%

Fringe Benefits Ratio 50%

Indirect to Direct Labor Ratio 33%

Average Scrap Recovery Value 30%

Building Cost ($/ft2) 202

Worker Downtime 10%

Building Life (in years) 25

Burdened Assembly Labor Wage ($/h) 24

Burdened Fabrication Labor Wage ($/h) 24

Supervisor Span (workers/supervisor) 25

Supervisor Wage Premium (over 

fabrication and assembly wage) 30%

*Includes non-weatherized mobile home furnaces.

5.7 MANUFACTURER SELLING PRICE

The output of the cost model is the MPC, which includes all direct costs including 

production-related labor, materials, depreciation, and overhead costs (as defined in section 5.6). 

To obtain the MSP, DOE multiplies the MPC by the manufacturer markup. The MSP includes all

production and non-production costs as well as profit. The markup includes sales, general and 

administrative, research and development, other corporate expenses, and profit. The components 

of MSP are shown in Figure 5.7.1. The MPCs are obtained as an output of the cost model, and 

the manufacturer markup costs were derived as described in section 5.7.1 below. 
5-20

Figure 5.7.1: Components of Manufacturer Selling Price

5.7.1 Manufacturer Markup

In the preliminary analysis, DOE used the manufacturer markups that DOE developed for 

the HVAC products final rule. The methodology DOE used to determine manufacturer markup 

for the HVAC products final rule is included in chapter 5 of the HVAC products direct final rule 

TSD.4

In the engineering analyses for residential furnaces and CAC and heat pump products, 

DOE also included shipping costs in the MSP. DOE included shipping costs in the CAC 

engineering analysis because implementation of certain design options involved increasing the 

size and weight of the product, which increases shipping costs. DOE also included shipping costs 

in the furnace rulemaking to be consistent with the CAC rulemaking, even though no size 

increases were considered for furnaces. DOE did not include shipping costs in the MSP for its 

engineering analysis of furnace fans because, as discussed in detail in chapter 4 of this TSD, 

DOE did not consider design options that would impact the size of the HVAC product. 

The manufacturer markup varied by product class. DOE used a markup of 1.35 for 

product classes including HVAC products designed for site-built homes and 1.30 for product 

classes including HVAC products designed for manufactured homes. These values are equivalent 

to those used by DOE in the recent direct final rule analysis for HVAC products.

Manufacturer 

Selling Price

Full Cost of 

Product

Manufacturer 

Production Cost

Direct 

Labor

Direct 

Material Overhead

Indirect Labor

Indirect Material

Maintenance

Depreciation

Taxes

Insurance related 

to assets

Non-Production 

Cost

Selling

Market 

Research

Advertising

POS Promotion

Salesperson 

Comp & Travel

Logistics 

(Warehousing, 

Delivery, RecordKeeping, Order 

Processing)

General & 

Admin.

Costs of 

Service & 

Staff Units

General 

Corporate 

Costs 

(Comp, etc)

R & D

Costs associated 

with finding new 

and improved 

products or 

processes

Code 

Compliance

Modernization

Interest

Cost of 

borrowing 

funds

Profit
5-21

Consequently, DOE does not expect use of the design options identified in this rulemaking to 

impact shipping costs. 

5.7.2 MSP in the Downstream Analyses

The MSPs derived in the engineering analysis are important inputs to the life-cycle cost 

analysis (LCC) and the manufacturer impact analysis (MIA). In the LCC, the MSPs are 

necessary to calculate the total installed cost of each unit. In the MIA, DOE constructs a number 

of scenarios that analyze how different pricing schemes impact manufacturers financially. In the 

MIA, both MSP and the direct production cost components of MSP are important drivers of 

results. DOE discusses how the engineering analysis is used in the other analyses in chapters 8 

and 12 of the TSD. 

5.8 INDUSTRY COST-EFFICIENCY RELATIONSHIPS

For residential furnace fans, DOE used the cost model to estimate the MPC of various 

products across the full range of efficiencies and for many manufacturers with significant market 

share. DOE used these results as the basis for its cost-efficiency relationship for all furnace fan

product classes.

DOE began its construction of the cost efficiency relationship at the baseline efficiency 

level. To create an industry average cost at the baseline efficiency, DOE calculated a marketweighted average of the cost modeling results for each product that was torn down at the baseline 

efficiency level. DOE then calculated the market weighted average incremental increase in cost 

to achieve each efficiency level above the baseline for each level analyzed up to max-tech. 

DOE developed one cost-efficiency relationship for high-volume product classes and 

another for low-volume product classes. DOE found that MPC did not differ significantly across 

product classes at a given efficiency level and production volume because manufacturers use

similar components. Therefore, DOE assigned on set of MPCs across each efficiency level for all 

high-volume product classes and another set of MPCs across each efficiency level for all lowvolume product classes.

5.9 RESULTS

The final result of the engineering analysis is a set of cost-efficiency relationships. DOE 

developed relationships for the nine key product classes of furnace fans using the analysis 

methodology described above. The cost-efficiency results are shown in Table 5.9.2 and Table 

5.9.3 in the form of FER or IFER versus MPC for high-volume product classes and low-volume 

product classes, respectively. The MPC presented is not for the entire HVAC product because 

furnace fans are a component of the HVAC product in which they are integrated. The presented 
5-22

MPC includes costs only for the components of the HVAC product that impact FER or IFER, 

which DOE considered to be the:

• fan motor and integrated controls;

• primary control board;

• impeller;

• fan housing; and

• components used to direct or guide airflow.

Table 5.9.1 presents MPC estimates of the design option components for efficiency levels 

established using the catalog teardown / design option approach. As stated previously, DOE used 

the design option approach to estimate the cost and efficiency impacts for technologies that are 

not commercially available in furnace fan applications.

Table 5.9.1: MPC Estimates for Design Option Approach Efficiency Level Components

Efficiency 

Level Design Option

High Volume 

MPC Low Volume MPC

2 Inverter Controls for InverterDriven PSC $11.52 $16.24

5 Premium ECM and Multi-Staging 

+ Backward-Curved Impeller $107.02 $122.01

6 Switching Mode Power Supply NA* $7.25

7 Toroidal Transformer NA* $10.95

* Standby mode consumption is not covered in this rulemaking for high volume products; therefore the standby 

design options are not applicable to high volume product classes.

For efficiency level 2, the MPC represents the cost of an inverter, $11.52 and $16.24 for high 

volume and low volume products, respectively. DOE estimated this cost by reverse engineering

an inverter that is suitable for use in furnace fan applications. The MPC for efficiency level 5 

includes the cost for a premium ECM motor and the cost of a backward-curved impeller. DOE 

used a 10% markup on the estimated MPC for an ECM as the added cost for a premium ECM 

motor. DOE found that prototype designs using backward-curved impellers require ECM motors 

with premium characteristics that increase the cost of the motor, such as higher RPM capabilities 

and a smaller outer diameter. DOE used photographs and specifications found in research reports 

to determined cost model inputs, such as weight and fabrication processes, to estimate the MPC

of the backward-curved impeller to be $12.00 and $12.32 for high volume and low volume 

products, respectively. The MPC estimates for efficiency levels 6 and 7 are the same as those 

used in the direct final rule engineering analysis for HVAC products.

As stated above, DOE used the cost-efficiency curves from the engineering analysis as an 

input to the life-cycle cost (LCC) analysis to determine the added price of the more efficient 

furnace fan components in HVAC equipment sold to the customer (see chapter 8 of the TSD).
5-23

Table 5.9.2 and Table 5.9.3 present the MPC and efficiency metric (FER or IFER) for 

each of the key product classes. As discussed in section 5.3, DOE assigned the engineering 

analysis results of each key product class to the additional product classes with which it is 

grouped (see Table 5.3.1).

Table 5.9.2: Cost-Efficiency Results for High-Volume Product Classes

Efficiency Level Baseline EL1 EL2 EL3 EL4 EL5

Design Option Improved 

PSC

PSC + 

Inverter X13 ECM +Multi-Stage

Premium 

ECM + 

Multi-Stage + 

BI Impeller

MPC $68.98 $70.98 $80.50 $91.71 $160.93 $176.00

NWG-NC 380 371 344 209 158 142

NWG-C 393 384 356 216 163 147

MH-NWG-NC 295 288 267 162 122 110

MH-NWG-C 319 312 289 175 132 119

WG 333 326 301 183 138 124

EF/MB 312 305 282 171 129 116

MH-EF/MB 243 238 220 133 101 90.8

Table 5.9.3: Cost-Efficiency Results for Low-Volume Product Classes

Efficiency 

Level Baseline EL1 EL2 EL3 EL4 EL5 EL6 EL7

Design Option Improved 

PSC

PSC + 

Inverter X13

ECM 

+MultiStage

Premium 

ECM + 

MultiStage + 

BI 

Impeller

Switch 

Mode PS

Toroidal 

XFMR

MPC $84.34 $91.32 $100.58 $121.59 $190.96 $206.35 $213.60 $224.55

O-NC 333 326 301 183 138 124 NA NA

HAH-HC 107 105 97.1 58.9 40.2 36.2 35.5 34.8
5-24

REFERENCES

1 AHRI. Directory of Certified Product Performance, Performance Data Updated June 7, 2010. 

Last accessed June 7, 2010. <http://www.ahridirectory.org/ahridirectory/pages/home.aspx>

2 American Metals Market, (Last accessed December 8, 2010.) <http://www.amm.com/.>

3 U.S. Department of Labor, Bureau of Labor Statistics, Producer Price Indices. (Last accessed 

December 8, 2010.) <http://www.bls.gov/ppi/>

4 U.S. Department of Energy, Building Technologies Program, Residential Furnaces and Central 

Air Conditioners and Heat Pumps Direct Final Rule Technical Support Document. 

<http://www1.eere.energy.gov/buildings/appliance_standards/residential/residential_furnaces_

central_ac_hp_direct_final_rule_tsd.html>