APPENDIX 5-D. ROOM AIR CONDITIONER ENGINEERING DATA 

TABLE OF CONTENTS 

5-D.1 INTRODUCTION ..................................................................................................... 5-D-1
 

5-D.2 MANUFACTURING COST MODELING DETAILS........................................... 5-D-1
 

5-D.3 ENERGY MODELING DETAILS .......................................................................... 5-D-9
 

5-D.4 DESCRIPTION OF SUPPORTING ANALYSES................................................ 5-D-16
 

5-D.4.1 Room Air Conditioner Airflow Modeling.............................................................. 5-D-16
 

5-D.4.2 Room Air Conditioner Motor Analysis .................................................................. 5-D-17
 

LIST OF TABLES 

Table 5-D.2.1 Incremental Cost Detail for 5,200 Btu/h Louvered, No Reverse Cycle 

Room Air Conditioner (Product Class 1)..................................................... 5-D-2 

Table 5-D.2.2 Incremental Cost Detail for 8,000 Btu/h Louvered, No Reverse Cycle 

Room Air Conditioner (Product Class 3)..................................................... 5-D-4 

Table 5-D.2.3 Incremental Cost Detail for 12000 Btu/h Louvered, No Reverse Cycle 

Room Air Conditioner (Product Class 3)..................................................... 5-D-5 

Table 5-D.2.4 Incremental Cost Detail for 24000 Btu/h Louvered, No Reverse Cycle 

Room Air Conditioner (Product Class 5)..................................................... 5-D-6 

Table 5-D.2.5 Incremental Cost Detail for 8000 Btu/h Non-Louvered, No Reverse 

Cycle Room Air Conditioner (Product Class 8).......................................... 5-D-7 

Table 5-D.2.6 Incremental Cost Detail for 12000 Btu/h Non-Louvered, No Reverse 

Cycle Room Air Conditioner (Product Class 8).......................................... 5-D-8 

Table 5-D.3.1 MarkN Results for 5200 Btu/h Louvered, No Reverse Cycle Room Air 

Conditioner (Product Class 1) .................................................................... 5-D-10 

Table 5-D.3.2 MarkN Results for 8000 Btu/h Louvered, No Reverse Cycle Room Air 

Conditioner (Product Class 3) .................................................................... 5-D-11 

Table 5-D.3.3 MarkN Results for 12000 Btu/h Louvered, No Reverse Cycle Room 

Air Conditioner (Product Class 3)..............................................................5-D-12 

Table 5-D.3.4 MarkN Results for 24000 Btu/h Louvered, No Reverse Cycle Room 

Air Conditioner (Product Class 5)..............................................................5-D-13 

Table 5-D.3.5 MarkN Results for 8000 Btu/h Non-Louvered, No Reverse Cycle 

Room Air Conditioner (Product Class 8)................................................... 5-D-14 

Table 5-D.3.6 MarkN Results for 12000 Btu/h Non-Louvered, No Reverse Cycle 

Room Air Conditioner (Product Class 8)................................................... 5-D-15
 

Table 5-D.4.1 Components Modeled to Calculate Room Air Conditioner Airflow ....... 5-D-17
 

5-D-i 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

 

 

 

 

 

LIST OF FIGURES 

Figure 5-D.4.1 Motor Incremental Cost Steps .................................................................... 5-D-18 

Figure 5-D.4.2 Motor Shaft Output Ratings by Capacity for Different Product Classes.5-D-18 

Figure 5-D.4.3 Motor Pricing Increase with Weight Increase ........................................... 5-D-20 

Figure 5-D.4.4 Weight-Current Curves for room air conditioner PSC motors, grouped 

by shaft output ............................................................................................. 5-D-21
 

Figure 5-D.4.5 Cost of Increased Efficiency for Different Motor Output Ratings........... 5-D-22
 

Figure 5-D.4.6 Brushless DC Motor Cost Curve by Shaft Output Rating ........................ 5-D-23
 

5-D-ii 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

APPENDIX 5-D. ENGINEERING DATA
 

5-D.1 INTRODUCTION
 

Chapter 5 presents incremental cost curves describing costs to attain each analyzed 

efficiency level for the six products analyzed in detail. The U.S. Department of Energy (DOE) 

developed the curves using design option analysis based on energy use modeling using the 

MarkN program and manufacturing cost modeling. 

The tables in section 5-D.2 show the costs associated which each of the design 

configurations analyzed. The tables identify the design options associated with each design 

configuration and show the key elements comprising the cost impacts, including materials, labor, 

overhead, and depreciation. The tables also present total manufacturing production cost (MPC), 

total manufacturer sales price (MSP), and shipping cost associated with each design 

configuration. 

Details of the energy modeling are presented in section 5-D.3. Tables in this section 

identify for each analyzed design configuration the MarkN input file name, the compressor data 

file name, the MarkN key program output (energy efficiency ratio (EER) and capacity), standby 

energy use, and integrated efficiency (integrated energy efficiency ratio (IEER)). 

Details of two aspects of the engineering analysis are presented in section 5-D.4. Section 

5-D.4.1 describes the airflow analysis that DOE used to account for changes in the airflow 

system, including changes to fans and heat exchangers. Section 5-D.4.2 describes the data 

collection and analysis used to develop the incremental cost estimates associated with increasing 

motor efficiency, both with higher-efficiency permanent split capacitor (PSC) motors and with 

brushless direct current (BLDC) motors. 

5-D.2 MANUFACTURING COST MODELING DETAILS 

The tables in this section itemize the results of the manufacturing cost analysis. The 

tables identify for each of the analyzed products the analyzed design configurations and their 

associated EER and IEER. The successive design configurations represent baseline designs with 

increasing numbers of design options. The total and incremental costs associated with each of the 

design configurations are presented in the tables as well, with separate identification of the key 

cost elements: materials, labor, overhead, depreciation, and shipping cost. The incremental 

manufacturing costs represent increases in MPC. The tables also show total MPC and MSC 

calculated for each design configuration. Chapter 5 describes the conversion of this data into 

incremental costs for specified efficiency levels (rather than by design configuration). The 

efficiency level format of the data is used in the downstream analyses (i.e., life-cycle cost (LCC), 

national impact analysis (NIA), etc.) 

5-D-1
 

EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.2.1 Incremental Cost Detail for 5,200 Btu/h Louvered, No Reverse Cycle Room Air Conditio

1) 

Design Configuration 

Description EER IEER 

Incremental Costs (MPC) 

Material Labor OH Depre­ ciation Increase Cumulative Increase MPC 

HFC-22 Baseline 9.7 9.52 - - - - - - $128.03 R-410A Conversion 8.94 8.79 $3.92 - - - $3.92 $3.92 $131.95 1 Add Subcooler 9.18 9.02 $0.57 $0.25 $0.10 $0.02 $0.94 $4.86 $132.89 2 Increase Evap Circuits 9.37 9.20 $0.75 - - - $0.75 $5.61 $133.64 3 Increase Evap Width 9.53 9.36 $0.52 $0.13 $0.06 $0.06 $0.77 $6.38 $134.41 4 Increase Chassis to 

Medium Size 10.52 10.31 $6.50 $0.57 $0.29 $0.09 $7.44 $13.82 $141.85 

5 Stand-by Reduction 10.52 10.41 $1.00 - - - $1.00 $14.82 $142.85 6 Increase Chassis to 

Large Size 11.49 11.37 $20.08 $2.46 $1.11 $0.97 $24.62 $32.00 $160.03 

7 Increase HXer Tube ODs 11.83 11.70 $4.31 $0.65 $0.26 $0.09 $5.30 $37.30 $165.33 8 Increase PSC 

Efficiency 12.20 12.06 $8.11 - - - $8.11 $45.41 $173.44 

9 DC Brushless Motor 12.32 12.18 $51.61 - - - $51.61 $88.91 $216.94 *MSP is equal to MPC times the manufacturer markup of 1.26. 

5-D-2
 

EERE-2007-BT-STD-0010 COMMENT 20.3
(1) Add subcooler with 0.25 inches (in) outer diameter (OD), 24.25 in. length, and condensate temperature of 95o F 

(2) Increase total refrigerant circuits in evaporator from 1 circuit to 2 circuits (3) Increase evaporator width by 2 in. by redesigning the unit’s user interface placement. 

(4) Increase Baseline Chassis Size by: Width 3 in., Height 0.75 in., Depth 2 in. (5) Change Main Control Board to a Switching Power Supply. 

(6) Increase Baseline Chassis Size by: Width 4.19 in., Height 1.88 in., Depth 5.72 in. Convert Condenser and Evaporator to 3-and change Condenser to Plain Fin (7) Increase tubing OD in condenser and evaporator from 5 millimeter (mm) to 7 mm 

(8) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor (9) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-3
 

EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.2.2 Incremental Cost Detail for 8,000 Btu/h Louvered, No Reverse Cycle Room Air Conditio

3) 

Design Option Step EER IEER 

Incremental Costs Tota

Material Labor OH Depre­ ciation Increase Cumulative Increase MPC M

R-410A Conversion 8.79 9.19 $5.47 - - - $5.47 $5.47 $164.65 $2071 Increase Evap Width 9.19 9.43 $0.79 $0.19 $0.09 $0.04 $1.12 $6.59 $165.77 $202 Increase Evap Tube OD 9.43 9.58 $1.24 $0.22 $0.09 $0.03 $1.58 $8.17 $167.35 $2103 Add Subcooler 9.58 9.68 $0.85 $0.36 $0.14 $0.06 $1.41 $9.58 $168.76 $2124 Increase Chassis to Medium Size 9.68 10.56 $11.36 $0.76 $0.36 $0.44 $12.92 $22.50 $181.68 $225 Stand-by Reduction 10.56 10.63 $1.00 - - - $1.00 $23.50 $182.68 $2306 Increase Chassis to Large Size 10.63 11.04 $18.43 $1.63 $1.00 $0.67 $21.73 $32.31 $191.49 $247 Increase PSC Efficiency 11.04 11.62 $13.70 - - - $13.70 $46.01 $205.19 $258 DC Brushless Motor 11.62 11.81 $76.84 - - - $76.84 $109.15 $268.33 $33

(1) Increase evaporator width by 3 in. by redesigning the unit’s user interface placement 

(2) Increase tubing OD in evaporator from 5 mm to 7 mm (3) Add subcooler with 0.25 in. OD, 24.25 in. length, and condensate temperature of 95o F 

(4) Increase baseline chassis size by: Width 0.81 in., Height 3.13 in., Depth 2.5 in. (5) Change Main Control Board to a Switching Power Supply. (6) Increase baseline chassis size by: Width 4 in., Height 2.75 in., Depth 8.1 in. (7) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (8) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-4
 

EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.2.3 Incremental Cost Detail for 12000 Btu/h Louvered, No Reverse Cycle Room Air Conditio

3) 

Design Option Step EER IEER 

Incremental Costs 

Material Labor OH Depre­ ciation Increase Cumulative Increase MPC 

HFC-22 Baseline 9.8 9.72 - - - - - - $206.92 R-410A Conversion 9.41 9.34 $7.49 - - - $7.49 $7.49 $214.41 1 Add Subcooler 9.58 9.51 $0.77 $0.36 $0.14 $0.06 $1.33 $8.82 $215.74 2 Increase Chassis Size to Medium Size 10.81 10.72 $11.26 $0.73 $0.30 $1.06 13.36 $22.18 $229.10 3 Standby Reduction 11.07 10.76 $1.00 - - - $1.00 $23.18 $230.10 4 Increase Chassis Size to Large Size 11.07 11.02 $11.51 $1.14 $0.54 $1.25 $20.63 $30.45 $237.37 5 Increase Evap Tubes OD 11.14 11.09 $2.57 $0.38 $0.15 $0.06 $3.16 $33.61 $240.53 6 Increase PSC Efficiency 11.48 11.43 $14.68 - - - $14.68 $48.29 $255.21 7 DC Brushless Motor 11.59 11.54 $80.45 - - - $80.45 $114.06 $320.98 

(1) Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F (2) Increase baseline chassis size by: Width 1 in., Height 2.5 in., Depth 0 in. (3) Change Main Control Board to a Switching Power Supply. (4) Increase baseline chassis size by: Width 2.75 in., Height 2.5 in., Depth 4.5 in. (5) Increase tubing OD in evaporator from 5 mm to 7 mm (6) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (7) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-5
 

EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.2.4 Incremental Cost Detail for 24000 Btu/h Louvered, No Reverse Cycle Room Air Conditio

5) 

Design Option Step EER IEER 

Incremental Costs T

Material Labor OH Depre­ ciation Increase Cumulative Increase MPC 

HFC-22 Baseline 8.5 8.47 - - - - - - $301.21 $R-410A Conversion 7.87 7.84 $13.70 - - - $13.70 $13.70 $314.91 $1 Add Subcooler 8.17 8.14 $1.05 $0.64 $0.26 $0.07 $2.02 $15.72 $316.93 $2 Increase Chassis size to Medium Size 8.98 8.95 $17.12 $1.45 $0.63 $0.44 $19.64 $35.36 $336.57 $3 Increase Chassis size to Large size 9.76 9.72 $37.24 $2.87 $1.23 $1.42 $50.31 $65.03 $366.24 $4 Standby Increase 8.98 9.74 $1.00 - - - $1.00 $66.03 $367.24 $5 Increase PSC Efficiency 10.06 10.04 $44.25 - - - $44.25 $110.28 $411.49 $6 Scroll Compressor 10.55 10.53 $175.00 - - - $175.00 $285.28 $586.49 $7 DC Brushless Motor 10.66 10.63 $170.58 - - - $170.58 $411.61 $712.82 $

(1) Add subcooler with 0.282 in OD, 63 in. length, and condensate temperature of 95o F (2) Increase baseline chassis size by: Width 1.75 in., Height 0.25 in., Depth 2.53 in. (3) Increase baseline chassis size by: Width 3.81 in., Height 4.69 in., Depth 2.53 in. (4) Change Main Control Board to a Switching Power Supply. (5) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (6) Replace Rotary Compressor with Scroll Compressor (7) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-6
 

EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.2.5 Incremental Cost Detail for 8000 Btu/h Non-Louvered, No Reverse Cycle Room Air Con

Class 8) 

Design Option Step EER IEER 

Incremental Costs T

Material Labor OH Depre­ ciation Increase Cumulative Increase MPC 

R-410A Conversion 8.43 8.34 $5.77 - - - $5.77 $5.77 $216.23 $ 1 Increase Evap Width 9.44 9.34 $4.69 $0.26 $0.12 $0.00 $5.08 $10.85 $221.31 $ 2 Add Subcooler 9.59 9.48 $0.77 $0.36 $0.14 $0.04 $1.32 $12.17 $222.63 $ 3 Stand by 9.59 9.53 $1.00 - - - $1.00 $13.17 $223.63 $ 4 Increase PSC Efficiency 10.05 9.99 $15.68 - - - $14.68 $27.85 $238.31 $ 5 Increase Evap Tube OD 10.17 10.11 $3.21 $0.50 $0.22 $0.04 $3.97 $31.82 $242.28 $ 6 DC Brushless Motor 10.33 10.26 $80.45 - - - $80.45 $97.59 $308.05 $ 

(1) Increase evaporator width by 4 inches by redesigning the unit’s user interface placement. (2) Add subcooler with 0.25 in. OD, 24.25 in. length, and condensate temperature of 95o F (3) Change Main Control Board to a Switching Power Supply (4) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (5) Increase tubing OD in evaporator from 5 mm to 7 mm (6) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-7
 

EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.2.6 Incremental Cost Detail for 12000 Btu/h Non-Louvered, No Reverse Cycle Room Air Co

Class 8) 

Design Option Step EER IEER 

Incremental Costs T

Material Labor OH Depre­ ciation Increase Cumulative Increase MPC 

R-410A Conversion 8.37 8.32 $7.95 - - - $7.95 $7.95 $237.28 1 Add Subcooler 8.57 8.51 $0.77 $0.36 $0.14 $0.00 $1.27 $9.22 $238.55 2 Increase Cond width w/ Coil Bend 8.87 8.80 $1.93 $0.34 $0.16 $0.00 $2.43 $11.65 $240.98 3 Increase Evap width 9.35 9.28 $7.50 $0.41 $0.20 $0.00 $8.11 $19.76 $249.09 4 Increase Evap Tube OD 9.55 9.48 $3.44 $0.45 $0.18 $0.00 $4.06 $23.82 $253.15 5 Standby Increase 9.55 9.51 $1.00 - - - $1.00 $24.82 $254.15 6 Increase Cond Tube OD 9.68 9.64 $3.95 $0.30 $0.12 $0.00 $4.38 $29.20 $258.53 7 Increase PSC Efficiency 10.01 9.97 $13.70 - - - $13.70 $42.90 $272.23 8 DC Brushless Motor 10.11 10.07 $76.93 - - - $76.93 $106.13 $335.46 

(1) Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F (2) Increase condenser width by 5 inches by bending the condenser coil to create more room. (3) Increase evaporator width by 6 inches by redesigning the unit’s user interface placement. 

(4) Increase Tubing OD in Evaporator from 5 mm to 7 mm (5) Change Main Control Board to a Switching Power Supply (6) Increase tubing OD in condenser from 5 mm to 7 mm (7) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (8) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-8
 

EERE-2007-BT-STD-0010 COMMENT 20.3
 

 

 

 

 

 

5-D.3 ENERGY MODELING DETAILS 

The tables in this section identify the analyzed design configurations for the analyzed 

products. For each design configuration, the tables present the key MarkN outputs (capacity and 

EER), the standby energy use, the IEER, and the MarkN input and compressor files used in the 

analysis. The MarkN program, a MarkN user manual, and the input and compressor files will be 

made available on the website for this rulemaking. 

5-D-9
 

EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.3.1 MarkN Results for 5200 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Prod

Design Configuration 

Description MarkN Input Filename Compressor Map (EER, Capacity) MarkN Outputs Stand-by Power 

EER Capacity 

HFC-22 Baseline In_PC1_Baseline_R22.dat 11.1 EER 5.2 kBtu/h 9.72 5375 1.4 R-410A Conversion In_PC1_Baseline_R410A.dat 9.7 EER 4.6 kBtu/h 8.94 4624 1.4 1 Add Subcooler In_PC1_Step1.dat 9.7 EER 4.6 kBtu/h 9.18 4689 1.4 2 Increase Evap Circuits In_PC1_Step2.dat 9.7 EER 4.6 kBtu/h 9.37 4834 1.4 3 Increase Evap Width In_PC1_Step3.dat 9.7 EER 4.6 kBtu/h 9.53 4927 1.4 4 Increase Chassis to Medium Size In_PC1_Step4.dat 9.7 EER 4.6 kBtu/h 10.52 5061 1.4 5 Stand-by Reduction In_PC1_Step5.dat 9.7 EER 4.6 kBtu/h - - 0.7 6 Increase Chassis to Large Size In_PC1_Step6.dat 9.7 EER 4.6 kBtu/h 11.49 5354 0.7 7 Increase HXer Tube ODs In_PC1_Step7.dat 9.7 EER 4.6 kBtu/h 11.83 5402 0.7 8 Increase PSC Efficiency In_PC1_Step8.dat 9.7 EER 4.6 kBtu/h 12.20 5404 0.7 9 DC Brushless Motor In_PC1_Step9.dat 9.7 EER 4.6 kBtu/h 12.32 5404 0.7 

(1) Add subcooler with 0.25 in. outer diameter (OD), 24.25 in. length, and condensate temperature of 95o F (2) Increase total refrigerant circuits in evaporator from 1 circuit to 2 circuits (3) Increase evaporator width by 2 in. by redesigning the unit’s user interface placement. 

(4) Increase Baseline Chassis Size by: Width 3 in., Height 0.75 in., Depth 2 in. (5) Change Main Control Board to a Switching Power Supply. 

(6) Increase Baseline Chassis Size by: Width 4.19 in., Height 1.88 in., Depth 5.72 in. Convert Condenser and Evaporator to 3-and change Condenser to Plain Fin (7) Increase tubing OD in condenser and evaporator from 5 millimeter (mm) to 7 mm 

(8) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor (9) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-10 


EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.3.2 MarkN Results for 8000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Prod

Design Option Step MarkN Filename Compressor Map (EER, Capacity) MarkN Outputs Stand-

Powe

EER Capacity 

R-410A Conversion In_PC3_12k_Baseline_R410A.dat 9.39 EER 7.6 kBtu/h 9.30 7688 1.4 1 Increase Evap Width In_PC3_8k_Step1.dat 9.39 EER 7.6 kBtu/h 9.54 7911 1.4 2 Increase Evap Tube OD In_PC3_8k_Step2.dat 9.39 EER 7.6 kBtu/h 9.69 8059 1.4 3 Add Subcooler In_PC3_8k_Step3.dat 9.39 EER 7.6 kBtu/h 9.79 8100 1.4 4 Increase Chassis to Medium Size In_PC3_8k_Step4.dat 9.39 EER 7.6 kBtu/h 10.70 8692 1.4 5 Stand-by Reduction In_PC3_8k_Step5.dat 9.39 EER 7.6 kBtu/h - - 0.7 6 Increase Chassis to Large Size In_PC3_8k_Step6.dat 9.39 EER 7.6 kBtu/h 11.12 8931 0.7 7 Increase PSC Efficiency In_PC3_8k_Step7.dat 9.39 EER 7.6 kBtu/h 11.70 8937 0.7 8 DC Brushless Motor In_PC3_8k_Step8.dat 9.39 EER 7.6 kBtu/h 11.90 8939 0.7 

(1) Increase evaporator width by 3 in. by redesigning the unit’s user interface placement 

(2) Increase tubing OD in evaporator from 5 mm to 7 mm (3) Add subcooler with 0.25 in. OD, 24.25 in. length, and condensate temperature of 95o F 

(4) Increase baseline chassis size by: Width 0.81 in., Height 3.13 in., Depth 2.5 in. (5) Change Main Control Board to a Switching Power Supply. (6) Increase baseline chassis size by: Width 4 in., Height 2.75 in., Depth 8.1 in. (7) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (8) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-11 


EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.3.3 MarkN Results for 12000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Pro

Design Option Step MarkN Filename Compressor Map (EER, Capacity) MarkN Outputs Sta

P

EER Capacity 

R-410A Conversion In_PC3_12k_Baseline_R410A.dat 9.14 EER 11.3 kBtu/h 9.41 12390 1 Add Subcooler In_PC3_12k_Step1.dat 9.14 EER 11.3 kBtu/h 9.58 12506 2 Increase Chassis Size to Medium Size In_PC3_12k_Step2.dat 9.28 EER 10.9 kBtu/h 10.81 12082 3 Standby Reduction In_PC3_12k_Step3.dat 9.28 EER 10.9 kBtu/h - - 4 Increase Chassis Size to Large Size In_PC3_12k_Step4.dat 9.28 EER 10.9 kBtu/h 11.07 12334 5 Increase Evap Tubes OD In_PC3_12k_Step5.dat 9.28 EER 10.9 kBtu/h 11.14 12455 6 Increase PSC Efficiency In_PC3_12k_Step6.dat 9.28 EER 10.9 kBtu/h 11.48 12466 7 DC Brushless Motor In_PC3_12k_Step7.dat 9.28 EER 10.9 kBtu/h 11.59 12469 

(1) Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F (2) Increase baseline chassis size by: Width 1 in., Height 2.5 in., Depth 0 in. (3) Change Main Control Board to a Switching Power Supply. (4) Increase baseline chassis size by: Width 2.75 in., Height 2.5 in., Depth 4.5 in. (5) Increase tubing OD in evaporator from 5 mm to 7 mm (6) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (7) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-12 


EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.3.4 MarkN Results for 24000 Btu/h Louvered, No Reverse Cycle Room Air Conditioner (Pro

Design Option Step MarkN Filename Compressor Map (EER, Capacity) MarkN Outputs Stand

Pow

EER Capacity 

HFC-22 Baseline In_PC5_Baseline_R22.dat 10.7 EER 24.1 kBtu/h 8.50 24286 1.R-410A Conversion In_PC5_Baseline_R410A.dat 9.79 EER 24.1 kBtu/h 7.87 22477 1.1 Add Subcooler In_PC5_Step1.dat 9.79 EER 24.1 kBtu/h 8.17 23007 1.2 Increase Chassis size to Medium Size In_PC5_Step2.dat 10.0 EER 23.1 kBtu/h 8.98 22998 1.3 Increase Chassis size to Large size In_PC5_Step3.dat 10.0 EER 23.1 kBtu/h 9.76 24372 0.4 Standby Increase In_PC5_Step4.dat 10.0 EER 23.1 kBtu/h - - 0.5 Increase PSC Efficiency In_PC5_Step5.dat 10.0 EER 23.1 kBtu/h 10.06 24394 0.6 Scroll Compressor In_PC5_Step6.dat 9.8 EER 20.0 kBtu/h 10.55 24844 0.7 DC Brushless Motor In_PC5_Step7.dat 9.8 EER 20.0 kBtu/h 10.66 24850 0.

(1) Add subcooler with 0.282 in. OD, 63 in. length, and condensate temperature of 95o F (2) Increase baseline chassis size by: Width 1.75 in., Height 0.25 in., Depth 2.53 in. (3) Increase baseline chassis size by: Width 3.81 in., Height 4.69 in., Depth 2.53 in. (4) Change Main Control Board to a Switching Power Supply. (5) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (6) Replace Rotary Compressor with Scroll Compressor (7) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-13 


EERE-2007-BT-STD-0010 COMMENT 20.3
Table 5-D.3.5 MarkN Results for 8000 Btu/h Non-Louvered, No Reverse Cycle Room Air Conditioner 

Design Option Step MarkN Filename Compressor Map (EER, Capacity) MarkN Outputs Stand-by Power 

EER Capacity 

R-410A Conversion In_PC8_8k_Baseline_R410A.dat 9.78 EER 7.2 kBtu/h 8.43 7968 1.4 1 Increase Evap Width In_PC8_8k_Step1.dat 9.78 EER 7.2 kBtu/h 9.44 8275 1.4 2 Add Subcooler In_PC8_8k_Step2.dat 9.78 EER 7.2 kBtu/h 9.59 8348 1.4 3 Stand by In_PC8_8k_Step3.dat 9.78 EER 7.2 kBtu/h - - 0.7 4 Increase PSC Efficiency In_PC8_8k_Step4.dat 9.78 EER 7.2 kBtu/h 10.05 8356 0.7 5 Increase Evap Tubes OD In_PC8_8k_Step5.dat 9.78 EER 7.2 kBtu/h 10.17 8576 0.7 6 DC Brushless Motor In_PC8_8k_Step6.dat 9.78 EER 7.2 kBtu/h 10.33 8578 0.7 

(1) Increase evaporator width by 4 in. by redesigning the unit’s user interface placement. 

(2) Add subcooler with 0.25 in. OD, 24.25 in. length, and condensate temperature of 95o F (3) Change Main Control Board to a Switching Power Supply (4) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (5) Increase tubing OD in evaporator from 5 mm to 7 mm (6) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

5-D-14 


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Table 5-D.3.6 MarkN Results for 12000 Btu/h Non-Louvered, No Reverse Cycle Room Air Conditioner 

Design Option Step MarkN Filename Compressor Map (EER, Capacity) MarkN Outputs Stan

Po

EER Capacity 

R-410A Conversion In_PC8_12k_Baseline_R410A.dat 9.03 EER 11.5 kBtu/h 8.37 11869 11 Add Subcooler In_PC8_12k_Step1.dat 9.03 EER 11.5 kBtu/h 8.57 12037 12 Increase Cond width w/ Coil Bend In_PC8_12k_Step2.dat 9.03 EER 11.5 kBtu/h 8.87 12273 13 Increase Evap width In_PC8_12k_Step3.dat 9.40 EER 11.1 kBtu/h 9.35 12442 14 Increase Evap Tube OD In_PC8_12k_Step4.dat 9.40 EER 11.1 kBtu/h 9.55 12886 15 Standby Increase In_PC8_12k_Step5.dat 9.40 EER 11.1 kBtu/h - - 06 Increase Cond Tube OD In_PC8_12k_Step6.dat 9.40 EER 11.1 kBtu/h 9.68 12820 07 Increase PSC Efficiency In_PC8_12k_Step7.dat 9.40 EER 11.1 kBtu/h 10.01 12832 08 DC Brushless Motor In_PC8_12k_Step8.dat 9.40 EER 11.1 kBtu/h 10.11 12836 0

(1) Add subcooler with 0.315 in. OD, 32 in. length, and condensate temperature of 95o F (2) Increase condenser width by 5 in. by bending the condenser coil to create more room. (3) Increase evaporator width by 6 in. by redesigning the unit’s user interface placement. 

(4) Increase Tubing OD in Evaporator from 5 mm to 7 mm (5) Change Main Control Board to a Switching Power Supply (6) Increase tubing OD in condenser from 5 mm to 7 mm (7) Replace 50 percent efficiency PSC Motor with 70 percent efficiency PSC Motor. (8) Replace PSC Motor with an 80 percent efficiency Brushless DC Motor 

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5-D.4 DESCRIPTION OF SUPPORTING ANALYSES 

This section presents additional description of two aspects of the engineering analysis for room 

air conditioners: 

Airflow modeling 

Motor pricing analysis 

5-D.4.1 Room Air Conditioner Airflow Modeling 

Many factors influence the airflow characteristics of a room air conditioner. The flow 

passages, heat exchangers, motor and fans all influence the airflow behavior within the room air 

conditioner. The MarkN model treats the heat exchanger dimensions, airflows, and motor power 

as separate, decoupled inputs, so the effect of physical changes in the airflow system on the 

airflow and motor power must be calculated separately from the model. DOE conducted an 

airflow calculation for each distinct airside design configuration. 

DOE calculated the system airflow using an iterative approach with the following steps. 

1. Select an airflow rate 

2. Calculate fan or blower pressure rise 

3. Calculate heat exchanger pressure drops using MarkN 

4. Calculate other system pressure drops using spreadsheet calculation. 

5. Add pressure drops and compare to fan or blower pressure rise. 

a.	 If fan pressure rise is higher than total pressure drop, increase is airflow rate and 

return to step 2 

b.	 If fan pressure rise is lower than total pressure drop, reduce airflow rate and return 

to step 2 

c.	 If fan pressure rise and total pressure drop are equal within reasonable tolerance, 

airflow calculation is complete. 

The airflow modeling was based on calculating the pressure drops for the separate 

components of the room air conditioner and the pressure rise associated with the condenser fan 

or the evaporator blower. The approaches for calculating the pressure characteristics of the key 

component are listed in Table 5-D.4.1 below. 

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Table 5-D.4.1 Components Modeled to Calculate Room Air Conditioner Airflow 

Component Pressure Drop Value or Calculation 

Method 

Sources 

Evaporator Blower Total Pressure Curve, adjusted using Fan 

Laws to match observed baseline unit 

performance. 

Comair Rotron Fan Company Ltd 

2008 ASHRAE Handbook: 

HVAC Systems and Equipment 

Condenser Fan Static Pressure Curve, adjusted using Fan 

Laws to match observed baseline unit 

performance. 

Sofasco International 

2008 ASHRAE Handbook: 

HVAC Systems and Equipment 

Filter 0.25 inches of water Filter vendors 

Grilles and Louvers Loss coefficient times velocity pressure 2005 ASHRAE Handbook: Fundamentals 

Ducts and Transitions Loss coefficient times velocity pressure 2005 ASHRAE Handbook: Fundamentals 

Inflow to Condenser 

(transition from fan 

outlet to condenser) 

50 percent of Condenser Pressure Drop Estimate 

Heat Exchangers MarkN Outputs MarkN Model 

Fan performance curves provided a relationship between fan static pressure rise and 

airflow delivered by the fan. DOE obtained fan performance curves for fans similar in size and 

geometry to those used in the teardown units. The fan performance curves were adjusted as 

needed to match the sizes, rotational speed, and performance of the modeled room air 

conditioner fans using the fan laws. 

On the evaporator side, DOE accounted for the airside pressure losses of the evaporator, 

the entry and exit grilles, the filter, and the impeller exit transition. On the condenser side, DOE 

accounted for the pressure losses of the condenser, the airflow path from the louvers to the fan 

inlet, and the fan exit plenum geometry. 

The evaporator and condenser pressure drops were calculated by the MarkN model based on 

assumed airflow rate. 

5-D.4.2 Room Air Conditioner Motor Analysis 

Through examination of the teardown units and interviews with room air conditioner 

manufacturers, DOE determined that PSC motors are the primary motor technology used in room 

air conditioners to power the fan and blower assemblies. DOE examined improvement in motor 

efficiency, including higher efficiency PSC motors and brushless DC motors as design options 

for improving the energy-efficiency of the room air conditioners. 

For all of the teardown units, DOE measured the power consumption of the motor at the 

available fan speeds. In accordance with the current test procedure, DOE used the data for the 

highest fan setting in its energy models, by using the energy consumption of each fan as a model 

input. Changes in the technology of the fan motor from design options are expressed in the 

model through changes in the fan motor energy consumption. 

Figure 5-D.4.1 below shows the steps taken to develop the incremental costs for the PSC 

motor efficiency increases. DOE researched motor characteristics and prices and established a 

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room air conditioner motor database. DOE developed separate correlations for price and 

efficiency as functions of motor weight and extended this analysis to develop a relationship for 

incremental costs for increases in efficiency for PSC motors. 

Figure 5-D.4.1 Motor Incremental Cost Steps 

Teardown Unit Motor Sizes 

The costs associated with increasing efficiency varied by motor shaft output rating. DOE 

examined the motor shaft output ratings associated with each of the different product classes, and 

used the baseline PSC shaft output rating as the basis of its efficiency analysis. Figure 5-D.4.2 

shows the shaft output power of the motors that were examined during the reverse engineering 

work, identified by product class and room air conditioner efficiency level (baseline or high). 

Figure 5-D.4.2 Motor Shaft Output Ratings by Capacity for
 

Different Product Classes
 

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Motor Efficiencies 

DOE obtained PSC motor efficiency data from discussions with motor vendors, review of 

motor catalogs, and discussions with room air conditioner manufacturers. Most PSC motors 

found in room air conditioners have a full-load efficiency between 45 percent and 60 percent. 

High efficiency PSC motors can reach up to 70 percent efficiency. DOE selected an efficiency of 

50 percent as the baseline for the room air conditioner PSC motors, and an efficiency of 70 

percent for high efficiency PSC motors. 

Cost as a Function of Weight 

The DOE examined motor prices for a range of power ratings from a variety of motor 

vendors. DOE examined the correlation of motor prices with weights, incoming electrical 

current, incoming electrical voltage and shaft power for both single-shafted and double-shafted 

HVAC PSC motors. 

DOE noted that, across motors of similar shaft output, motor frame size, and voltage, 

motor weight consistently increases as the efficiency increases. DOE found a strong correlation 

between motor pricing and motor weight across all motor data, and used a subset of this data to 

establish a basis for pricing PSC efficiency improvements. DOE established a statistically 

significant correlation between motor price and motor weight using data from two motor 

vendors, for motors with rated shaft output up to 0.25 horsepower (186.5 Watts (W)). Figure 5­

D.4.3 below shows the motor data used to establish this relationship. 

The correlation establishes the increased cost of a motor per increase in weight, for PSC 

motors within the range of established room air conditioner motors. It was established as 

statistically significant through statistical t-tests and DOE used the ratio of cost per weight 

increase to help calculate the cost of increasing the motor efficiency by a given amount. 

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Figure 5-D.4.3 Motor Pricing Increase with Weight Increase 

Efficiency as a Function of Weight 

Available motor data did not generally included efficiency. However, full-load current 

data was available for most motor entries. Current is an indicator of efficiency, assuming that 

power factor does not change significantly among motors that are compared. The relationships 

between current and motor weight for a range of applicable motor sizes is illustrated in Figure 5­

D.4.4 below. These relationships were developed from the available motor data. 

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Figure 5-D.4.4	 Weight-Current Curves for room air conditioner 

PSC motors, grouped by shaft output 

Cost as Function of Efficiency 

DOE combined the cost/weight and the current/weight relationships to develop a 

relationship for the cost of increasing motor efficiency from 50 percent to 70 percent as a 

function of shaft output power. DOE determined the incremental cost for this efficiency increase 

for the shaft output power levels of interest using the equation below. 

The curve shown in Figure 5-D.4.5 below illustrates the resulting cost increase as a 

function of shaft power. This relationship was developed for shaft power up to roughly 100W. 

The high end of the relationship was extrapolated linearly to 200W to represent the cost of a high 

efficiency PSC motor for a product class 5 product. DOE expects that the linear extrapolation is 

conservative, since the curve’s slope decreases as shaft power increases. 

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Figure 5-D.4.5	 Cost of Increased Efficiency for Different Motor 

Output Ratings 

Brushless DC Motors 

BLDC motors are a more efficient alternative to PSC motors, and are already in use in 

products such as in PTACs. BLDC motors provide the same output power as PSC motors at 

higher efficiencies. DOE obtained BLDC motor efficiency data from discussions with motor 

vendors, review of motor catalogs, and discussions with room air conditioner manufacturers. 

Typical BLDC motors have efficiencies between 70 percent and 90 percent. However, in 

searching for replacement motors for room air conditioners, DOE found that the average 

efficiency of these motors is approximately 80 percent; motors with 90 percent efficiency are not 

very common. DOE selected a BLDC motor efficiency of 80 percent for the analysis. 

DOE searched motor catalogs and contacted motor vendors to develop a database of 

BLDC motor characteristics. Using this data, DOE developed a representative relationship for 

the cost premium of BLDC motors as a function of shaft power. This is shown in Figure 5-D.4.6. 

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Figure 5-D.4.6 Brushless DC Motor Cost Curve by Shaft Output 

Rating 

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