CHAPTER 9. TRIAL STANDARD LEVELS

TABLE OF CONTENTS

9.1 INTRODUCTION .............................................................................................................. 9­1

9.2 TRIAL STANDARD LEVELS .......................................................................................... 9­1

9.3 ENERGY­EFFICIENCY EQUATIONS............................................................................ 9­3

9.3.1 Energy­Efficiency Equation for PTACs and PTHPs in the Cooling Mode......... 9­3

9.3.2 Energy­Efficiency Equation for Heating Mode................................................... 9­9

LIST OF TABLES

Table 9.2.1 PTACs Baseline Efficiency Level and TSLs........................................................... 9­2

Table 9.2.2 PTHPs Baseline Efficiency Level and TSLs........................................................... 9­2

Table 9.3.1 Existing Federal Energy Conservation Standards for PTACs and PTHPs

(Cooling Mode).................................................................................................... 9­3

Table 9.3.2 ASHRAE/IESNA Standard 90.1­1999 Energy Efficiency Levels for PTACs

and PTHPs (Cooling Mode)................................................................................. 9­4

Table 9.3.3 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by TSL

for Standards Size PTACs ................................................................................... 9­5

Table 9.3.4 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by TSL

for Standard Size PTHP....................................................................................... 9­5

Table 9.3.5 Energy­Efficiency Equations for Cooling Mode (EER as a Function of Cooling

Capacity) by TSL for Non­Standard Size PTAC................................................. 9­7

Table 9.3.6 Energy­Efficiency Equations for Cooling Mode (EER as a Function of Cooling

Capacity) by TSL for Non­Standard Size PTHP ................................................. 9­8

Table 9.3.7 Existing Federal Energy Conservation Standards for PTHPs (Heating Mode)..... 9­10

Table 9.3.8 ASHRAE/IESNA Standard 90.1­1999 Energy­Efficiency Levels for PTHPs

(Heating Mode).................................................................................................. 9­10

Table 9.3.9 Energy­Efficiency Equations for Heating Mode (COP as a Function of Cooling

Capacity) by TSL for Standard Size PTHP ....................................................... 9­11

Table 9.3.10 Energy­Efficiency Equations for Heating Mode (COP as a Function of

Cooling Capacity) by TSL for Non­Standard Size PTHP ................................. 9­11

LIST OF FIGURES

Figure 9.3.1 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by

TSL for Standards Size PTAC............................................................................. 9­6

Figure 9.3.2 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by

TSL for Standards Size PTHP ............................................................................. 9­6

Figure 9.3.3 Energy­Efficiency Equations for Cooling Mode (EER as a Function of

Cooling Capacity) by TSL for Non­Standard Size PTAC................................... 9­8

Figure 9.3.4 Energy­Efficiency Equations for Cooling Mode (EER as a Function of

Cooling Capacity) by TSL for Non­Standard Size PTHP ................................... 9­9

Figure 9.3.5 Energy­Efficiency Equations for Heating Mode (COP as a Function of

Cooling Capacity) by TSL for Standards Size PTHP........................................ 9­12

9­i

EERE-2007-BT-STD-0012 COMMENT 02
Figure 9.3.6 Energy­Efficiency Equations for Heating Mode (COP as a Function of

Cooling Capacity) by TSL for Non­Standards Size PTHP................................ 9­12

9­ii

EERE-2007-BT-STD-0012 COMMENT 02
CHAPTER 9. TRIAL STANDARD LEVELS

9.1 INTRODUCTION

The current Federal minimum energy conservation standards for packaged terminal air

conditioners (PTACs) and packaged terminal heat pumps (PTHPs) and the efficiency

requirements specified by the American Society of Heating, Refrigerating, and Air­Conditioning

Engineers (ASHRAE) and the Illuminating Engineering Society of North America (IESNA)

Standard 90.1­1999, “Energy Standard for Buildings Except Low­Rise Residential Buildings,”

(ASHRAE/IESNA Standard 90.1­1999) are expressed in terms of an energy­efficiency

equations. For the PTAC and PTHP equipment classes with a cooling capacity greater than or

equal to 7,000 British thermal units per hour (Btu/h) and less than or equal to 15,000 Btu/h, the

energy­efficiency equation characterizes the relationship between the energy efficiency ratio

(EER) of the equipment and cooling capacity (i.e., EER is a function of the cooling capacity of

the equipment). Therefore, for these equipment, the U.S. Department of Energy (DOE)

explicitly analyzed the representative cooling capacities, which allows DOE to further

investigate the slope of the energy­efficiency equation. For all cooling capacities less than 7,000

Btu/h and all cooling capacities greater than 15,000 Btu/h, the EER is calculated by substituting

either of the two capacities, 7,000 Btu/h or 15,000 Btu/h, in the energy­efficiency equation. This

chapter describes the methodology used by DOE to derive the energy­efficiency equations for

PTAC and PTHP equipment.

9.2 TRIAL STANDARD LEVELS

For the subsequent analyses, DOE refers to the grouping of efficiency levels for each

equipment class as trial standard levels (TSLs). The TSLs are identical to the efficiency levels

examined in the energy use characterization analysis and the life­cycle cost (LCC) and payback

period analyses. Table 9.2.1 and Table 9.2.2 present the analyzed efficiency levels as TSLs for

standard size and non­standard size PTACs and PTHPs for the notice of proposed notice

(NOPR).

9­1

EERE-2007-BT-STD-0012 COMMENT 02
Table 9.2.1 PTACs Baseline Efficiency Level and TSLs

Equipment

Class

(Cooling

Capacitya

)

Efficiency

Metricb

Baseline

(ASHRAE/IESNA

Standard 90.1­1999)

TSL

1

TSL

2

TSL

3

TSL

4

TSL

5

TSL

6

TSL 7

(MaxTech)

Standard Size

PTAC

(9,000 Btu/h)

EER 10.6 10.9 10.9 11.1 10.9 11.3 11.5 12.0

Standard Size

PTAC

(12,000 Btu/h)

EER 9.9 10.2 10.2 10.4 10.2 10.6 10.8 11.5

Non­Standard

Size PTAC

(11,000 Btu/h)

EER 8.6 9.4 9.4 9.7 9.4 10.0 10.7 11.2

Table 9.2.2 PTHPs Baseline Efficiency Level and TSLs

Equipment

Class

(Cooling

Capacity)

Efficiency

Metricc

Baseline

(ASHRAE/IESNA

Standard 90.1­1999)

TSL

1

TSL

2

TSL

3

TSL

4

TSL

5

TSL

6

TSL 7

MaxTech

Standard Size

PTHP

(9,000 Btu/h)

EER

COP

10.4

3.0

10.9

3.1

11.1

3.2

11.1

3.2

11.3

3.3

11.3

3.3

11.5

3.3

12.0

3.5

Standard Size

PTHP EER 9.7 10.2 10.4 10.4 10.6 10.6 10.8 11.7

(12,000 COP 2.9 3.0 3.1 3.1 3.1 3.1 3.1 3.3

Btu/h)

Non­Standard

PTHP EER 8.5 9.4 9.7 9.7 10.0 10.0 10.7 11.4

(11,000 COP 2.6 2.8 2.8 2.8 2.9 2.9 2.9 2.9

Btu/h)

The reference case or baseline is the efficiency levels specified by ASHRAE/IESNA

Standard 90.1­1999. TSLs 1, 3, 5, and 6 represent matched pairs of efficiency levels for the

three representative cooling capacities of PTACs and PTHPs. In other words, the efficiency

levels for PTACs and PTHPs with the same cooling capacity and wall sleeve dimensions are

equivalent for these four TSLs. DOE maintained the 0.7 EER decrement established by

ASHRAE/IESNA Standard 90.1­1999 between the standard size equipment with cooling

capacities of 9,000 Btu/h and 12,000 Btu/h. In addition, TSL 7 is the maximum technologically

feasible (“max tech”) level for each equipment class identified in Chapter 5 of the TSD.

a Cooling capacities are expressed in British thermal unit per hour (Btu/h).

b According to the Air­Conditioning and Refrigeration Institute (ARI) 310/380­2004 Standard for Packaged

Terminal Air­Conditioners and Heat Pumps (ARI 310/380­2004) test procedure, energy­efficiency ratio (EER) is

defined as “the ratio of the produced cooling effect of an air conditioner or heat pump to its net work input,

expressed in Btu/watt­hour.”

Coefficient of performance (COP) is defined by ARI 310/380­2004 as “the ratio of the produced cooling effect of

an air conditioner or heat pump (or its produced heating effect, depending on the mode of operation) to its net work

input, when both the cooling (or heating) effect and the net work input are expressed in identical units of

measurement.”

9­2

c

EERE-2007-BT-STD-0012 COMMENT 02
After examining preliminary results of the LCC analysis (see Chapter 8 of the TSD),

DOE developed two additional TSLs, TSL 2 and TSL 4, based on the large differences in LCC

savings results between PTACs and PTHPs. TSL 2 and TSL 4 combine different efficiency

pairings between PTACs and PTHPs. In other words, DOE examined the impacts of amended

energy conservation standards when PTACs and PTHPs are required to meet different efficiency

levels. For TSL 2, DOE combined TSL 1 for PTACs and TSL 3 for PTHPs. For TSL 4, DOE

combined TSL 1 for PTACs and TSL 5 for PTHPs. These two combination levels serve to

maximize LCC savings, while recognizing the differences in LCC results for PTACs and PTHPs.

9.3 ENERGY­EFFICIENCY EQUATIONS

The following sections describe the methodology DOE used to develop the energyefficiency equations for each TSL. To develop the energy­efficiency equation in terms of EER

and cooling capacity for each TSL, DOE used a linear regression and the existing

ASHRAE/IESNA Standard 90.1­1999 energy­efficiency equations.

9.3.1 Energy­Efficiency Equation for PTACs and PTHPs in the Cooling Mode

As stated in the engineering analysis (see Chapter 5 of this TSD), current Federal energy

conservation standards and the efficiency levels specified by ASHRAE/IESNA Standard 90.1­

1999 for PTACs and PTHPs in the cooling mode are a function of the equipment’s cooling

capacity. Both standards specify requirements in the form of energy­efficiency equations to

calculate the EER based on the equipment’s cooling capacity for PTACs and PTHPs with a

cooling capacity greater than or equal to 7,000 Btu/h and less than or equal to 15,000 Btu/h for

each equipment class. Table 9.3.1 and Table 9.3.2 show the current Federal energy conservation

standards and efficiency levels specified by ASHRAE/IESNA Standard 90.1­1999 for PTACs

and PTHPs in the cooling mode, respectively.

Table 9.3.1 Existing Federal Energy Conservation Standards for PTACs and PTHPs

(Cooling Mode)

Equipment Class Existing Federal

Equipment Cooling Capacity Energy Conservation Standards*

PTAC

<7,000 Btu/h EER = 8.88

>7,000 Btu/h and

<15,000 Btu/h EER = 10.0 – (0.16 x Cap**)

>15,000 Btu/h EER = 7.6

PTHP

<7,000 Btu/h EER = 8.88

>7,000 Btu/h and

<15,000 Btu/h EER = 10.0 – (0.16 x Cap**)

>15,000 Btu/h EER = 7.6

* For equipment rated according to the Air­Conditioning and Refrigeration Institute (ARI) standards, all EER values

must be rated at 95oF outdoor dry­bulb temperature for air­cooled products and evaporatively­cooled products and at

85oF entering water temperature for water cooled products.

** Cap means cooling capacity in kBtu/h at 95oF outdoor dry­bulb temperature.

9­3

EERE-2007-BT-STD-0012 COMMENT 02
Table 9.3.2 ASHRAE/IESNA Standard 90.1­1999 Energy Efficiency Levels for PTACs and

PTHPs (Cooling Mode)

Equipment Class Proposed Energy

Conservation Standards* Equipment Category Cooling

Capacity

PTAC

Standard Size**

<7,000 Btu/h EER = 11.0

≥7,000 Btu/h and

≤15,000 Btu/h EER = 12.5 – (0.213 x Cap††)

>15,000 Btu/h EER = 9.3

Non­Standard Size†

<7,000 Btu/h EER = 9.4

≥7,000 Btu/h and

≤15,000 Btu/h EER = 10.9 – (0.213 x Cap††)

>15,000 Btu/h EER = 7.7

PTHP

Standard Size**

<7,000 Btu/h EER = 10.8

≥7,000 Btu/h and

≤15,000 Btu/h EER = 12.3 – (0.213 x Cap††)

>15,000 Btu/h EER = 9.1

Non­Standard Size†

<7,000 Btu/h EER = 9.3

≥7,000 Btu/h and

≤15,000 Btu/h EER = 10.8 – (0.213 x Cap††)

>15,000 Btu/h EER = 7.6

* For equipment rated according to ARI standards, all EER values must be rated at 95oF outdoor dry­bulb

temperature for air­cooled products and evaporatively­cooled products and at 85oF entering water temperature for

water cooled products.

** Standard size refers to PTAC or PTHP equipment with wall sleeve dimensions greater than or equal to 16 inches

high, or greater than or equal to 42 inches wide.

† Non­standard size refers to PTAC or PTHP equipment with wall sleeve dimensions less than 16 inches high and

less than 42 inches wide. ASHRAE/IESNA Standard 90.1­1999 also includes a factory labeling requirement for

non­standard size PTAC and PTHP equipment as follows: “MANUFACTURED FOR REPLACEMENT

APPLICATIONS ONLY; NOT TO BE INSTALLED IN NEW CONSTRUCTION PROJECTS.”

†† Cap means cooling capacity in kBtu/h at 95oF outdoor dry­bulb temperature.

To derive the standards (i.e., efficiency level as a function of cooling capacity), DOE

plotted the representative cooling capacities and the corresponding efficiency levels for each

TSL. DOE then calculated the equation of the line pass through the EER values for 9,000 Btu/h

and 12,000 Btu/h for standard size PTACs and PTHPs.

For PTACs and PTHPs with cooling capacity less than 7,000 Btu/h, DOE determined the

corresponding EER value using a cooling capacity of 7,000 Btu/h in the energy­efficiency

equation. For PTACs and PTHPs with a cooling capacity greater than 15,000 Btu/h cooling

capacity, DOE determined the EER value using a cooling capacity of 15,000 Btu/h in the energyefficiency equation. This is the same method established in the Energy Policy Act of 1992 and

provided in ASHRAE/IESNA 90.1­1999 for calculating the EER and COP of equipment with

cooling capacities smaller than 7,000 Btu/h and larger than 15,000 Btu/h.

Table 9.3.3 and Table 9.3.4 list the equations for the corresponding TSL for standard size

PTAC and PTHP.

9­4

EERE-2007-BT-STD-0012 COMMENT 02
Table 9.3.3 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by TSL

for Standards Size PTACs

Standard Size** PTACs Energy­Efficiency Equation*

Baseline ASHRAE/IESNA Standard 90.1­1999 EER = 12.5 ­ (0.213 x Cap†

/1000)

TSL 1 EER = 13.0 ­ (0.233 x Cap†

/1000)

TSL 2 EER = 13.0 ­ (0.233 x Cap†

/1000)

TSL 3 EER = 13.2 ­ (0.233 x Cap†

/1000)

TSL 4 EER = 13.0 ­ (0.233 x Cap†

/1000)

TSL 5 EER = 13.4 ­ (0.233 x Cap†

/1000)

TSL 6 EER = 13.6 ­ (0.233 x Cap†

/1000)

TSL 7 EER = 13.5 ­ (0.167 x Cap†

/1000) * For equipment rated according to the DOE test procedure, all EER values must be rated at 95oF outdoor dry­bulb

temperature for air­cooled products and evaporatively­cooled products and at 85oF entering water temperature for

water cooled products. ** Standard size refers to PTAC or PTHP equipment with wall sleeve dimensions greater than or equal to 16 inches

high, or greater than or equal to 42 inches wide.

† Cap means cooling capacity in Btu/h at 95oF outdoor dry­bulb temperature.

Table 9.3.4 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by TSL

for Standard Size PTHP

Standard Size** PTHPs Energy­Efficiency Equation*

Baseline ASHRAE/IESNA Standard 90.1­1999 EER = 12.3 ­ (0.213 x Cap†

/1000)

TSL 1 EER = 13.0 ­ (0.233 x Cap†

/1000)

TSL 2 EER = 13.2 ­ (0.233 x Cap†

/1000)

TSL 3 EER = 13.2 ­ (0.233 x Cap†

/1000)

TSL 4 EER = 13.4 ­ (0.233 x Cap†

/1000)

TSL 5 EER = 13.4 ­ (0.233 x Cap†

/1000)

TSL 6 EER = 13.6 ­ (0.233 x Cap†

/1000)

TSL 7 EER = 12.9 ­ (0.100 x Cap†

/1000) * For equipment rated according to the DOE test procedure, all EER values must be rated at 95oF outdoor dry­bulb

temperature for air­cooled products and evaporatively­cooled products and at 85oF entering water temperature for

water cooled products. ** Standard size refers to PTAC or PTHP equipment with wall sleeve dimensions greater than or equal to 16 inches

high, or greater than or equal to 42 inches wide.

† Cap means cooling capacity in Btu/h at 95oF outdoor dry­bulb temperature.

Figure 9.3.1 and Figure 9.3.2 show each energy­efficiency equation plotted for the

various TSLs for standard size PTACs and PTHPs.

9­5

EERE-2007-BT-STD-0012 COMMENT 02
8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

EER

Baseline

TSL 1, TSL 2, TSL 4

TSL 3

TSL 5

TSL 6

TSL 7 (Max Tech)

5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000

Cooling Capacity, Btu/h

Figure 9.3.1 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by

TSL for Standards Size PTAC

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

EER

Baseline

TSL 1

TSL 2, TSL 3

TSL 4, TSL 5

TSL 6

TSL 7 (Max Tech)

5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000

Cooling Capacity, Btu/h

Figure 9.3.2 Energy­Efficiency Equations (EER as a Function of Cooling Capacity) by

TSL for Standards Size PTHP

9­6

EERE-2007-BT-STD-0012 COMMENT 02
The above plots show the decreasing trend observed in the engineering analysis (i.e.,

efficiency decreases with increase in cooling capacity). Energy­efficiency equations for the

TSLs above the baseline for standard size PTAC and PTHP equipment, not including TSL 7,

have a slightly steeper slope than the slope for the energy­efficiency equations in

ASHRAE/IESNA Standard 90.1­1999 (shown as baseline). Excluding the baseline energyefficiency equation and the energy­efficiency equation corresponding to TSL 7, the slopes of the

energy­efficiency equations for TSL 1 through 6 are the same for standard size PTAC and PTHP

equipment due to the efficiency pairings.

For non­standard size PTAC and PTHP equipment, DOE used the ASHRAE/IESNA

Standard 90.1­1999 energy­efficiency equation slope and the representative cooling capacity

(i.e., 11,000 Btu/h cooling capacity) to develop the energy­efficiency equations representing the

entire cooling capacity range at each TSL. For PTACs and PTHPs with cooling capacity less

than 7,000 Btu/h, DOE determined the corresponding EER value by substituting the cooling

capacity of 7,000 Btu/h in the energy­efficiency equation. For PTACs and PTHPs with a cooling

capacity greater than 15,000 Btu/h cooling capacity, DOE determined the EER value by

substituting the cooling capacity of 15,000 Btu/h in the energy­efficiency equation. This is the

same method established in the Energy Policy Act of 1992 and provided in ASHRAE/IESNA

Standard 90.1­1999 for calculating the EER and COP of equipment with cooling capacities less

than 7,000 Btu/h and greater than 15,000 Btu/h.

Table 9.3.5 and Table 9.3.6 list the equations for the corresponding TSL for non­standard

size PTAC and PTHP.

Table 9.3.5 Energy­Efficiency Equations for Cooling Mode (EER as a Function of Cooling

Capacity) by TSL for Non­Standard Size PTAC

Non­Standard Size** PTACs Energy­Efficiency Equation*

Baseline ASHRAE/IESNA Standard 90.1­1999 EER = 10.9 ­ (0.213 x Cap†

/1000)

TSL 1 EER = 11.7 ­ (0.213 x Cap†

/1000)

TSL 2 EER = 11.7 ­ (0.213 x Cap†

/1000)

TSL 3 EER = 12.0 ­ (0.213 x Cap†

/1000)

TSL 4 EER = 11.7 ­ (0.213 x Cap†

/1000)

TSL 5 EER = 12.3 ­ (0.213 x Cap†

/1000)

TSL 6 EER = 13.0 ­ (0.213 x Cap†

/1000)

TSL 7 EER = 13.5 ­ (0.213 x Cap†

/1000) * For equipment rated according to the DOE test procedure, all EER values must be rated at 95oF outdoor dry­bulb

temperature for air­cooled products and evaporatively­cooled products and at 85oF entering water temperature for

water cooled products. ** Non­standard size refers to PTAC or PTHP equipment with wall sleeve dimensions less than 16 inches high and

less than 42 inches wide.

† Cap means cooling capacity in Btu/h at 95oF outdoor dry­bulb temperature.

9­7

EERE-2007-BT-STD-0012 COMMENT 02
Table 9.3.6 Energy­Efficiency Equations for Cooling Mode (EER as a Function of Cooling

Capacity) by TSL for Non­Standard Size PTHP

Non­Standard Size** PTHPs Energy­Efficiency Equation*

Baseline ASHRAE/IESNA Standard 90.1­1999 EER = 10.8 ­ (0.213 x Cap†

/1000)

TSL 1 EER = 11.7 ­ (0.213 x Cap†

/1000)

TSL 2 EER = 12.0 ­ (0.213 x Cap†

/1000)

TSL 3 EER = 12.0 ­ (0.213 x Cap†

/1000)

TSL 4 EER = 12.3 ­ (0.213 x Cap†

/1000)

TSL 5 EER = 12.3 ­ (0.213 x Cap†

/1000)

TSL 6 EER = 13.0 ­ (0.213 x Cap†

/1000)

TSL 7 EER = 13.7 ­ (0.213 x Cap†

/1000) * For equipment rated according to the DOE test procedure, all EER values must be rated at 95oF outdoor dry­bulb

temperature for air­cooled products and evaporatively­cooled products and at 85oF entering water temperature for

water cooled products. ** Non­standard size refers to PTAC or PTHP equipment with wall sleeve dimensions less than 16 inches high and

less than 42 inches wide.

† Cap means cooling capacity in Btu/h at 95oF outdoor dry­bulb temperature.

Figure 9.3.3 and Figure 9.3.4 show each equation plotted for the various TSLs for nonstandard size PTACs and PTHPs.

7.0

8.0

9.0

10.0

11.0

12.0

13.0

EER

Baseline

TSL 1, TSL 2, TSL 4

TSL 3

TSL 5

TSL 6

TSL 7 (Max Tech)

5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000

Cooling Capacity, Btu/h

Figure 9.3.3 Energy­Efficiency Equations for Cooling Mode (EER as a Function of Cooling

Capacity) by TSL for Non­Standard Size PTAC

9­8

EERE-2007-BT-STD-0012 COMMENT 02
7.0

8.0

9.0

10.0

11.0

12.0

13.0

EER

Baseline

TSL 1

TSL 2, TSL 3

TSL 4, TSL 5

TSL 6

TSL 7 (Max Tech)

5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000

Cooling Capacity, Btu/h

Figure 9.3.4 Energy­Efficiency Equations for Cooling Mode (EER as a Function of Cooling

Capacity) by TSL for Non­Standard Size PTHP

The above plots show the decreasing trend observed in the engineering analysis (i.e.,

efficiency decreases with increase in cooling capacity). All energy­efficiency equations for the

TSLs above the baseline for non­standard size PTAC and PTHP equipment have the same slope

as the energy­efficiency equations in ASHRAE/IESNA Standard 90.1­1999. TSLs that have the

same efficiency pairing between PTACs and PTHPs have identical energy­efficiency equations

(e.g., TSL1, 3, 5, and 6).

9.3.2 Energy­Efficiency Equation for Heating Mode

The current Federal energy conservation standards for PTHPs in the heating mode is

expressed as heating coefficient of performance (COP) as a function of the PTHP’s cooling EER.

Similar to the energy­efficiency equations for PTHPs in the cooling mode, the standards specify

COP in the form of an energy­efficiency equation as a function of EER for PTHPs with a cooling

capacity greater than or equal to 7,000 Btu/h and less than or equal to 15,000 Btu/h. For PTHPs

with cooling capacity less than 7,000 Btu/h, the standard is specified by the COP value

corresponding to the EER value for equipment with cooling capacity of 7,000 Btu/h in the

energy­efficiency equation. For PTHPs with a cooling capacity greater than 15,000 Btu/h, the

standard is specified by the COP value corresponding to the EER value for equipment with

cooling capacity of 15,000 Btu/h in the energy­efficiency equation.

The current Federal minimum energy conservation standards for PTHPs in the heating

mode in terms of the COP are presented in Table 9.3.7.

9­9

EERE-2007-BT-STD-0012 COMMENT 02
Table 9.3.7 Existing Federal Energy Conservation Standards for PTHPs (Heating Mode)

Equipment Class Existing Federal

Equipment Cooling Capacity Energy Conservation Standards

PTHP

<7,000 Btu/h COP = 2.7

>7,000 Btu/h and

<15,000 Btu/h COP = 1.3 + (0.16 x EER)

>15,000 Btu/h COP = 2.5

The efficiency requirements in ASHRAE/IESNA Standard 90.1­1999 are specified by

energy­efficiency equations as a function of the equipment’s cooling capacity for PTHPs with a

cooling capacity greater than or equal to 7,000 Btu/h and less than or equal to 15,000 Btu/h for

each equipment class (i.e., COP is a function of the equipment’s cooling capacity). For PTHPs

with cooling capacity less than 7,000 Btu/h, the standard is determined by the corresponding

COP value by substituting the cooling capacity of 7,000 Btu/h in the energy­efficiency equation.

For PTHPs with a cooling capacity greater than 15,000 Btu/h, the standard is determined by the

COP value by substituting the cooling capacity of 15,000 Btu/h in the energy­efficiency

equation.

Table 9.3.8 shows the ASHRAE/IESNA Standard 90.1­1999 energy­efficiency equations

for the COP of PTHPs.

Table 9.3.8 ASHRAE/IESNA Standard 90.1­1999 Energy­Efficiency Levels for PTHPs

(Heating Mode)

Equipment Class Proposed Energy

Equipment Category Conservation Standards Cooling

Capacity

PTHP

Standard Size*

<7,000 Btu/h COP = 3.0

≥7,000 Btu/h and

≤15,000 Btu/h COP = 3.2 – (0.026 x Cap†

)

>15,000 Btu/h COP = 2.8

Non­Standard Size**

<7,000 Btu/h COP = 2.7

≥7,000 Btu/h and

≤15,000 Btu/h COP = 2.9 – (0.026 x Cap†

)

>15,000 Btu/h COP = 2.5

* Standard size refers to PTAC or PTHP equipment with wall sleeve dimensions greater than or equal to 16 inches

high, or greater than or equal to 42 inches wide.

** Non­standard size refers to PTAC or PTHP equipment with wall sleeve dimensions less than 16 inches high and

less than 42 inches wide. ASHRAE/IESNA Standard 90.1­1999 also includes a factory labeling requirement for

non­standard size PTAC and PTHP equipment as follows: “MANUFACTURED FOR REPLACEMENT

APPLICATIONS ONLY; NOT TO BE INSTALLED IN NEW CONSTRUCTION PROJECTS.”

† Cap means cooling capacity in kBtu/h at 95oF outdoor dry­bulb temperature.

To maintain consistency with ASHRAE/IESNA Standard 90.1­1999 and to develop the

energy­efficiency equations for heating COP, DOE evaluated the COP as a function of cooling

capacity. DOE applied the same methodology for deriving the energy­efficiency equations as

that for the cooling mode. To derive the standard size PTHP energy­efficiency equations (i.e.,

COP as a function of cooling capacity), DOE plotted the representative cooling capacities and

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EERE-2007-BT-STD-0012 COMMENT 02
corresponding COP levels for each TSL. For non­standard size PTHPs, DOE used the

ASHRAE/IESNA Standard 90.1­1999 equation slope and the representative cooling capacity

(i.e., 11,000 Btu/h) to develop the energy­efficiency equations for heating COP that correspond

to the entire cooling capacity range at each TSL.

Table 9.3.9 and Table 9.3.10 list the energy­efficiency equations for COP and the

corresponding TSL for standard and non­standard size PTHP, respectively.

Table 9.3.9 Energy­Efficiency Equations for Heating Mode (COP as a Function of Cooling

Capacity) by TSL for Standard Size PTHP

Standard Size** PTHPs Energy­Efficiency Equation*

Baseline ASHRAE/IESNA Standard 90.1­1999 COP = 3.2 ­ (0.026 x Cap†

/1000)

TSL 1 COP = 3.6 ­ (0.046 x Cap†

/1000)

TSL 2 COP = 3.6 ­ (0.044 x Cap†

/1000)

TSL 3 COP = 3.6 ­ (0.044 x Cap†

/1000)

TSL 4 COP = 3.7 ­ (0.053 x Cap†

/1000)

TSL 5 COP = 3.7 ­ (0.053 x Cap†

/1000)

TSL 6 COP = 3.8 ­ (0.053 x Cap†

/1000)

TSL 7 COP = 4.1 ­ (0.074 x Cap†

/1000) * For equipment rated according to the DOE test procedure, all COP values must be rated at 47oF outdoor dry­bulb

temperature for air­cooled products, and at 70oF entering water temperature for water­source heat pumps. ** Standard size refers to PTAC or PTHP equipment with wall sleeve dimensions greater than or equal to 16 inches

high, or greater than or equal to 42 inches wide.

† Cap means cooling capacity in Btu/h at 95oF outdoor dry­bulb temperature.

Table 9.3.10 Energy­Efficiency Equations for Heating Mode (COP as a Function of

Cooling Capacity) by TSL for Non­Standard Size PTHP

Non­Standard Size** PTHPs Energy­Efficiency Equation*

Baseline ASHRAE/IESNA Standard 90.1­1999 COP = 2.9 ­ (0.026 x Cap†

/1000)

TSL 1 COP = 3.1 ­ (0.026 x Cap†

/1000)

TSL 2 COP = 3.1 ­ (0.026 x Cap†

/1000)

TSL 3 COP = 3.1 ­ (0.026 x Cap†

/1000)

TSL 4 COP = 3.1 ­ (0.026 x Cap†

/1000)

TSL 5 COP = 3.1 ­ (0.026 x Cap†

/1000)

TSL 6 COP = 3.2 ­ (0.026 x Cap†

/1000)

TSL 7 COP = 3.2 ­ (0.026 x Cap†

/1000) * For equipment rated according to the DOE test procedure, all EER values must be rated at 95oF outdoor dry­bulb

temperature for air­cooled products and evaporatively­cooled products and at 85oF entering water temperature for

water cooled products. All COP values must be rated at 47oF outdoor dry­bulb temperature for air­cooled products,

and at 70oF entering water temperature for water­source heat pumps. ** Non­standard size refers to PTAC or PTHP equipment with wall sleeve dimensions less than 16 inches high and

less than 42 inches wide.

† Cap means cooling capacity in Btu/h at 95oF outdoor dry­bulb temperature.

Figure 9.3.5 and Figure 9.3.6 show each energy­efficiency equation for PTHPs in the

heating mode (i.e., COP as a function of cooling capacity) plotted for the baseline efficiency

level and each TSL for standard and non­standard size PTHPs, respectively.

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EERE-2007-BT-STD-0012 COMMENT 02
2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

COP

Baseline

TSL1

TSL 2, TSL 3

TSL 4, TSL 5

TSL 6

TSL 7 (Max Tech)

5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000

Cooling Capacity, Btu/h

Figure 9.3.5 Energy­Efficiency Equations for Heating Mode (COP as a Function of

Cooling Capacity) by TSL for Standards Size PTHP

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

COP

Baseline

TSL1

TSL 2, TSL 3

TSL 4, TSL 5

TSL 6

TSL 7 (Max Tech)

5,000 7,000 9,000 11,000 13,000 15,000 17,000 19,000

Cooling Capacity, Btu/h

Figure 9.3.6 Energy­Efficiency Equations for Heating Mode (COP as a Function of

Cooling Capacity) by TSL for Non­Standards Size PTHP

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EERE-2007-BT-STD-0012 COMMENT 02
The above plots show the decreasing trend observed in the engineering analysis (i.e.,

efficiency decreases with increase in cooling capacity). All energy­efficiency equations for the

TSLs above the baseline for the non­standard size PTHP equipment have the same slope as the

energy­efficiency equations in ASHRAE/IESNA Standard 90.1­1999.

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EERE-2007-BT-STD-0012 COMMENT 02