4

- i CHAPTER 4. SCREENING ANALYSIS

TABLE OF CONTENTS

4.1 INTRODUCTION

................................ ................................ ............................... 4

- 1 4.2 SCREENED

- OUT TECHNOLOGIES

................................ ................................ 4

- 2 4. 2.1 Furnace Fan Energy Efficiency (FER) Standards

................................ .... 4

- 2 4.3 REMAINING TECHNOLOGI ES

................................ ................................ ....... 4

- 4 4.3.1 Furnace Fan Energy Efficiency Standards

................................ ............... 4

- 4 4.3.2 Standby Mode and Off Mode Power Consumption Standards

................ 4

- 4

LIST OF TABLES

Table 4.3.1 Screened

- In Standby Mode and Off Mode Design Options

......................... 4

- 44

- 1 4.1 INTRODUCTION

This chapter details the screening analysis that the U.S. Department of Energy (DOE) conducted in support of the direct final rule for energy conservation standards for residential furnace fans

.

In the market a nd technology assessment (MTA; c hapter 3), DOE presents an initial list of technologies that manufacturers can use to improve the energy efficiency of residential furnace fans and standby and off mode electrical power consumption for hydronic air handlers

. The purpose of the screening analysis is to evaluate the technologies that improve product energy efficiency or reduce standby and off mode energy consumption to determine which technologies DOE should consider further in the rulemaking analyses. DOE con sulted a range of parties, including industry and technical experts and others, to develop a list of technologies for consideration in the market assessment (see chapter 3 of the TSD)

. Some of these technologies can reduce annual energy consumption of prod ucts in actual applications but may not improve the annual fan efficiency ratio (FER) or reduce standby and off mode electrical power consumption

. Th is rating metric is measured according to DOE regulations at XXX

. DOE removed from consideration those tech nologies that do not improve FER or reduce standby and off mode electrical power consumption per the DOE test procedures. DOE evaluated t he remaining technologies pursuant to the criteria in t he Energy Policy and Conservation Act (EPCA), as amended. (42 U. S.C. 6311

- 6317)

Section 325(o) of EPCA establishes criteria for prescribing new or amended standards designed to achieve the maximum improvement in energy efficiency

. Furthermore, EPCA directs the Secretary of Energy to determine whether a standard is tech nologically feasible and economically justified. (42 U.S.C. 6295(o)(2)(A)(B)) In view of this requirement, 10 CFR Part 430 Subpart C, Appendix A

, Procedures, Interpretations and Policies for Consideration of New or Revised Energy Conservation Standards for Consumer Products (the Process Rule), guides DOE in its consideration and promulgation of new or revised product efficiency standards. These procedures elaborate on the statutory criteria provided in 42 U.S.C. 6295(o) and, in part, eliminate problematic technologies early in the process of prescribing or amending an energy efficiency standard. In particular, DOE determines whether to eliminate from consideration any technology that presents unacceptable problems with respect to the following criteria:

Technological feasibility. Technologies that are not incorporated in commercial products or in working prototypes will not be considered further

. Practicability to manufacture, install, and service. If it is determined that mass production of a technology in commercial products and reliable installation and servicing of the technology could not be achieved on the scale necessary to serve the relevant market at the time of the effective date of the standard, then that technology will not be consid ered further.4

- 2 I mpacts on product utility to consumers. If a technology is determined to have significant adverse impact on the utility of the product to significant subgroups of consumers or result s in the unavailability of any covered product type with pe rformance characteristics (including reliability), features, sizes, capacities, and volumes that are substantially the same as products generally available in the U.S. at the time, it will not be considered further.

S afety of technologies

. If it is determi ned that a technology will have significant adverse impacts on health or safety, it will not be considered further. In sum, if DOE determine s that a technology, or a combination of technologies, has unacceptable impacts on the policies stated in section 5(b) of the Process Rule, it will be eliminated from consideration. If a particular technology fails to meet one or more of the four criteria, it will be screened out from further consideration in the engineering analysis

. 61 FR 36974

- 36987 ; 10 CFR part 430, subpart C, ap pendix A, section (5)(b)

. The reasons for eliminating any technology are documented in section 4.2

.

4.2 SCREENED

- OUT TECHNOLOGIES

This section describes the technologies that DOE eliminated based on consideration of the following four factors: 1) technological feasibility; 2) p racticability to manufacture, install, and service; 3) adverse impacts on product utility or product availability ; and 4) adverse impacts on health or safety

.

4.2.1 Furnace Fan Energy Efficiency ( FER ) Standards

DOE eliminated the following technology options fo r residential furnace fans from further consideration: housing design modifications; and airflow path design

.

4.2.1.1 Housing Design Modifications

DOE investigated housing design modifications during its teardown analysis

. DOE found that housing design s did not vary dramatically between baseline and higher

efficiency models or across manufacturers

. In addition, DOE found no quantitative data correlating specific housing design modifications with efficiency improvements

. M anufacturers also estimated that housing i mprovements would have very little effect on fan efficiency during manufacturer interviews

. For these reasons, DOE is not including improved housing designs as a technology option.

4.2.1.2 Airflow Path Design

DOE recognizes that the airflow path design of the HVAC product in which the furnace fan is used impacts efficiency

. DOE anticipates that modifying the size of the cabinet and the geometry of the heat exchanger(s) would be the primary considerations for improving airflow path design

. A lterations to the design and configuration of internal components, such as the heat exchanger, could impact the thermal performance of the HVAC product

. For the preliminary analysis, DOE was unable to confirm that heat exchanger modifications would not reduce thermal performance a nd result in reduced4

- 3 system efficiency

. In addition, HVAC products that use furnace fans have space constraints. Any increase in overall size of the product could reduce utility to the consumer by potentially reducing or eliminating product availability fo r certain applications. While DOE did account for the impacts of airflow path design in the proposed test procedure and other aspects of the preliminary analyses (e.g., product class selection), DOE did not consider airflow path design as a technology opti on for these

reasons

.

4.2.2 Standby Mode and Off Mode Power Consumption Standards

DOE eliminated the following standby mode and off mode technology options for residential furnace fans from further consideration: ECM control relay.

4.2.2.1 ECM Control Relay

While PSC b lower motors do not draw any power w hen off , ECM blower motor s and their associated controls consume an average of 3 watts in order to provide power to

an integral control board for modulat ing the fan speed. To reduce standby power consumption of a furnace and off mode consumption of a central air conditioner or heat
pump equipped with an ECM blower, DOE considered adding a relay to the circuit to disconnect the blower motor ’s control circuit when not in use. A typical relay activates a switch when current runs through it

, and a spring holds the switch open when there is no
current flow

. Manufacturer fee dback provided during the interview process (see chapter 12 of this TSD) indicated that ECMs are subject to an inrush of current upon start up . The
p ower supply on the ECM’s control board, which is typically a switching mode power supply

, cannot withstand the repeated surge of current that occurs at ECM startup and, therefore, completely depowering and reactivating the motor by use of a control relay

w ould shorten the motor’s lifetime significantly

. DOE considers a premature failure of the blower to be a reliability issue that has an adverse impact on product utility to the

consumer. Therefore, DOE believes that disconnection of an ECM fan motor when th e blower is not in use should not be consider ed in the engineering analysis. In addition, DOE has not found any HVAC products that utilize a control relay or other mechanism to disconnect the ECM fan when the product in standby or off mode

. Therefore, DOE did not consider this technology option for this rulemaking.4

- 4 4.3 REMAINING TECHNOLOGI ES

After eliminating those technologies that have no effect or do not increase energy efficiency and screening out those technologies that that do not meet the requirements o f sections 4(a)(4) and 5(b) of the Process Rule, DOE considered the technologies in the following sections.

4.3.1 Furnace Fan Energy Efficiency Standards

For its FER standards rulemaking analysis, DOE considered the following technology options:

**•** H igher efficienc y fan motors

**•** H igher efficiency fan blades (backward

- curved impellers)

**•** Inverter technology

4.3.2 Standby Mode and Off Mode Power Consumption Standards

Because DOE is required by EPCA, as amended by EISA 2007, to include a descriptor for standby mode and off mode energy consumption for residential furnaces and a descriptor for off mode energy consumption for central air conditioners and heat pumps, a separate screening analysis was conducted for standby and off mode design options. (42 U.S.C. 6295(gg)(2)(A))

DOE id entified the following design options that are capable of reducing the standby and off mode electrical power consumption of hydronic air handlers :

Table 4.3

. 1 Screened

- In Standby Mode and Off Mode Design Options
Design Option Hydronic Air Handlers Toroidal transformer X Switching mode power supply X