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## Investigation of the Relationship between IEER and EER for Commercial Air-cooled Air Conditioners and Air-source Heat Pumps with Rated Cooling Capacities Greater than or Equal to 65,000 Btu/h and Less than 760,000 Btu/h

January 25 , 2013

Executive Summary This document provides the methodology for, and the results of, the investigation of the relationship between Integrated Energy Efficiency Ratio (IEER ) and Energy Efficiency Ratio ( EER ) for the purpose of evaluating the relationship between the current Federal minimum

standa rds in EER and baseline IEER values for commercial, a ir

- cooled air conditioners (AC) and heat pumps (HP) with rated cooling capacities greater than and equal to 65,000 British thermal units per hour (Btu/hr) and less than 760,000 Btu/hr (i.e., 5 to 63 tons).

For the analysis shown in Table E.1., DOE considered only those models that are rated at the

c urrent Federal minimum energy conservation standard level by equipment class. DOE then analyzed the distribution of corresponding IEER values based on manufacturer ratings for each

of the six equipment classes and two heating-types. Table E.1. summarizes various IEER baseline values and the current COP Federal minimum energy conservation standards for each

he at pump equipment class. Additional details about the methodology and analysis is described

in detail below.

Table E.1. IEERs at various cut-offs

Equipment

Class Class 1: AC

≥ 65 to < 135

kBTU/h Class 2: AC

≥ 135 to < 240

kBTU/h Class 3: AC

≥ 240 to < 760

kBTU/h Class 4: HP

≥ 65 to < 135

kBTU/h Class 5: HP

≥ 135 to < 240

kBTU/h Class 6: HP

≥ 240 to < 760 kBTU/h‡

Supplemental heating

- type Electric

resistance heating/no heating Other

heating † Electric

resistance heating/no heating Other

heating † Electric

resistance heating/no heating † Other

heating † Electric

resistance heating/no heating Other

heating

** Electric

resistance heating/no heating † Other

heating † ** Electric

resistance heating/no heating Other

heating

**IEER Cut-offs Min 11.2 11.2 10.8 10.8 10.1 9.9 11.0 10.8 10.7 10.5 9.5 9.3

10% 11.4 11.2 11.1 10.8 10.1 9.9 11.3 11.1 10.7 10.5 9.5 9.3

25% 11.7 11.2 11.2 10.8 10.5 9.9 11.5 11.3 10.7 10.5 9.5 9.3

50% 12.2 11.2 11.8 10.8 11.9 9.9 11.8 11.6 11.0 10.8 9.5 9.3

Mean 12.4 11.4 11.9 11.1 11.4 10.1 12.0 11.8 11.2 11.0 9.5 9.3

Max 20.8 20.2 18.7 18.4 18.7 14.3 20.2 20.2 18.4 18.2 9.5 9.3

EER* 11.2 11.0 11.0 10.8 10.0 9.8 11.0 10.8 10.6 10.4 9.5 9.3

IEER # 11.4 11.2 11.2 11.0 10.1 9.9 11.2 11.0 10.7 10.5 9.6 9.4

COP (47°F) *

- - - 3.3 3.2 3.2
* Current Federal energy conservation standard (10 CFR Part 431.97).

# Efficiency levels in ANSI/ASHRAE Standard 90.1-2010. ** Italicized values realize a 0.2 Btu/W-h credit given to heat pumps with no supplemental electric resistance heating. †Data overlap prevents the identification of different IEER values for the 10% and 25% cut-offs. ‡ Cut-offs based on the efficiency levels in ANSI/ASHRAE Standard 90.1-2010 were used due to insufficient data for this class in the AHRI

Database.

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## Purpose This document provides the methodology and results of DOE’s investigation of the relationship between IEER and EER of current equipment available on the market for commercial, a ir -cooled

AC s and H Ps with rated cooling capacities greater than or equal to 65,000 Btu/hr and less than 760,000 Btu/hr (i.e., 5 and 63 tons). This analysis also examines the impact of such a relationship on current product models.

Methodology The methodology consisted of a search on the Air-Conditioning, Heating, and Refrigeration

I nstitute (AHRI) Certification Database with the following constraints:

• Commercial,

• Air-cooled,

• AC or HP , and

• ≥ 6 5 to < 760 kBTU/h.

Individual model data for equipment meeting the above criteria w as downloaded from the AHRI

Certification Database on August 20, 2012. DOE further narrowed the sample by only considering models that:

• Have “Active Status” in the AHRI Certification Database, and

• Have capacity, EER, and IEER ratings corresponding to a li ne- to -line voltage of 208 V (120 V line- to -neutral, for U.S. products)

.

Data was separated into six equipment classes consistent with the equipment classes reflected by the current Federal energy conservation standards in Title 10 of the Code of Federal Regulations

Section 431.97:

• Class 1: AC ≥ 65 to < 135 kBTU/h;

• Class 2: AC ≥ 135 to < 240 kBTU/h;

• Class 3: AC ≥ 240 to < 760 kBTU/h;

• Class 4 : HP ≥ 65 to < 135 kBTU/h;

• Class 5 : HP ≥ 135 to < 240 kBTU/h; and

• Class 6: HP ≥ 240 to < 760 kBTU/h.

Figure 1 shows a scatter plot of the resulting data. DOE removed any models from consideration that were showing efficiency ratings below the Federal energy conservation standards. Afte r removal of the outliers, the final data set contained 6600 product models.

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## Figure 1. A Scatter Plot of the IEER and EER Data for Equipment Class 1

The current Federal energy conservation standards for commercial, air-cooled AC and HP

e quipment are also differentiated based on the type of heating associated with the unit. Specifically, the heating-types are differentiated by their heating energy source for air conditioners (or their supplemental heating energy source for heat pumps). The “Electric resistance heating/no heating” category consists of air conditioning (heat pump) equipment that

have (supplemental) electric resistance heating or no (supplemental) heating, whereas the “Other

he ating” category consists of air conditioning (heat pump) equipment that have (supplemental) hydronic heating or (supplemental) heating via combustion of natural gas.

W hile the AHRI Certification Database does not specify the heating-type, the California Energy

C ommission’s (CEC) Database does. Therefore, the two databases were cross-referenced to

de termine the heating-type for the models listed in the AHRI Certification Database. However,

e xamining the data for the heat pump equipment classes revealed that only two product models

have a heating-type of “Other heating.” Being such a small sample size, the data set pertaining to heat pumps was not disaggregated by heating-type and those product models with a heating-type

of “o ther heating” were not included in any datasets.

The dataset for each equipment class was split into two groups based on whether the units were baseline equipment or n on -baseline equipment. Baseline equipment groups are defined as

e quipment rated at the current Federal minimum energy conservation standards. In Figure 2 (pr esented at the end of this document), data from the non-baseline equipment group are exhibited in a scatter plot (with each data point represented by a solid circle), while data for the

ba seline equipment group are plotted in a vertical line (with each data point represented by an

‘x ’).

DOE then calculated various statistics on the dataset including the minimum, mean, and maximum IEER levels. In addition, DOE established IEER bins for each equipment class and heating type. The bins represent the IEER value that eliminates a given percentage of the models

that ha ve an EER equal to the DOE minimum efficiency standard. The minimum (0%), median (50%), mean, and maximum IEER value, as well as the IEER values that eliminate 10% and 25%

of the market were determined, depending on data availability, and plotted in Figure 2.

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## For each cut-off in equipment classes 4, 5 , and 6 with the “Other heating” heating-type, the IEERs were estimated using a 0.2 Btu/W-h credit given to heat pumps with no supplemental electric resistance heating because of the lack of commercially available data. Similarly, since

li mited data were available in the AHRI Certification Database for equipment class 6 and

ove rlapped to make up only three points on the scatter plot, the IEER cut-offs for this class could

not be determined; instead the IEER cut-offs were based on the IEER efficiency levels in

AN SI/ASHRAE Standard 90.1-2010.

T able 1

. IEERs at Various C ut -offs

Equipment

Class Class 1: AC

≥ 65 to < 135

kBTU/h Class 2: AC

≥ 135 to < 240

kBTU/h Class 3: AC

≥ 240 to < 760

kBTU/h Class 4: HP

≥ 65 to < 135

kBTU/h Class 5: HP

≥ 135 to < 240

kBTU/h Class 6: HP

≥ 240 to < 760 kBTU/h‡

Supplemental heating

- type Electric

resistance heating/no heating Other

heating † Electric

resistance heating/no heating Other

heating † Electric

resistance heating/no heating † Other

heating † Electric

resistance heating/no heating Other

heating

** Electric

resistance heating/no heating † Other

heating † ** Electric

resistance heating/no heating Other

heating

**IEER Cut-offs Min 11.2 11.2 10.8 10.8 10.1 9.9 11.0 10.8 10.7 10.5 9.5 9.3

10% 11.4 11.2 11.1 10.8 10.1 9.9 11.3 11.1 10.7 10.5 9.5 9.3

25% 11.7 11.2 11.2 10.8 10.5 9.9 11.5 11.3 10.7 10.5 9.5 9.3

50% 12.2 11.2 11.8 10.8 11.9 9.9 11.8 11.6 11.0 10.8 9.5 9.3

Mean 12.4 11.4 11.9 11.1 11.4 10.1 12.0 11.8 11.2 11.0 9.5 9.3

Max 20.8 20.2 18.7 18.4 18.7 14.3 20.2 20.2 18.4 18.2 9.5 9.3

EER* 11.2 11.0 11.0 10.8 10.0 9.8 11.0 10.8 10.6 10.4 9.5 9.3

IEER # 11.4 11.2 11.2 11.0 10.1 9.9 11.2 11.0 10.7 10.5 9.6 9.4

COP (47°F) *

- - - 3.3 3.2 3.2
* Current Federal energy conservation standard (10 CFR Part 431.97).

# Efficiency levels in ANSI/ASHRAE Standard 90.1-2010. ** Italicized values realize a 0.2 Btu/W-h credit given to heat pumps with no supplemental electric resistance heating. †Data overlap prevents the identification of different IEER values for the 10% and 25% cut-offs. ‡ Cut-offs based on the efficiency levels in ANSI/ASHRAE Standard 90.1-2010 were used due to insufficient data for this class in the AHRI

Database.

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## Figure 2. Scatter plots for Equipment Class 1: AC ≥ 65 to < 135 kBtu/h, Electric Heat/No

Heating with C ut

- off L ines ( D otted)

Figure 3. Scatter Plots for Equipment Class 1: AC ≥ 65 to < 135 kBtu/h, Other Heating

w ith Cut-off Lines (Dotted) 8 10 12 14 16 18 20 22

8 9 10 11 12 13 14 15 16IEER



### EER Mean: 53% cut

- off

50% cut

- off

25% cut

- off

10% cut

- off

Minimum

8 10 12 14 16 18 20 22

8 9 10 11 12 13 14 15 16IEER



### EER Mean: 65% cut

- off

Minimum

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## Figure 4. Scatter Plots for Equipment Class 2: AC ≥ 135 to < 240 kBtu/h, Electric Heat/No

H eating with Cut-off Lines (Dotted)

Figure 5. Scatter Plots for Equipment Class 2: AC ≥ 135 to < 240 kBtu/h, Other H eating

C ut -off Lines (Dotted) 8 10 12 14 16 18 20 22

8 9 10 11 12 13 14 15 16IEER



### EER Mean: 52% cut

- off

50% cut

- off

25% cut

- off

10% cut

- off

Minimum

8 10 12 14 16 18 20 22

8 9 10 11 12 13 14 15 16IEER



### EER Mean: 80% cut

- off

Minimum

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## Figure 6. Scatter Plots for Equipment Class 3: AC ≥ 240 to < 760 kBtu/h, Electric Heat/No Heating with Cut-off Lines (Dotted)

Figure 7 . Scatter Plots for Equipment Class 3: AC ≥ 240 to < 760 kBtu/h, Other H eating

with C ut

- off L ines ( D otted ) 8 10 12 14 16 18 20 22

8 9 10 11 12 13 14 15 16IEER



### EER 50% cut

- off

Mean: 41% cut

- off

25% cut

- off

Minimum

8 10 12 14 16 18 20 22

8 9 10 11 12 13 14 15 16IEER



### EER Mean: 82% cut

- off

Minimum

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## Figure 8 . Scatter Plots for Equipment Class 4: HP ≥ 65 to < 135 kBtu/h, Electric Heat/No Heating with Cut-off Lines (Dotted)

Figure 9. Scatter Plots for Equipment Class 5: HP ≥ 135 to < 240kBtu/h, Electric H eat/ N o

H eating with C ut

- off L ines ( D otted ) 8 10 12 14 16 18 20 22

9 10 11 12 13 14IEER



### EER

Mean

50% cut

- off

25% cut

- off

10% cut

- off

Minimum

8 10 12 14 16 18 20 22

9 10 11 12 13 14IEER



### EER Mean: 75% cut

- off

50% cut

- off

Minimum

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## Figure 10. Scatter Plots for Equipment Class 6: HP ≥ 240 to < 760 kBtu/h, Electric H eat/ N o

H eating with C ut

- off L ines ( D otted ) 8 10 12 14 16 18 20 22

9 10 11 12 13 14IEER



### EER