Input Output Reference — EnergyPlus 22.1

Input Output Reference

This group of objects consists of tabular data which are used to characterize the performance of HVAC equipment. The use of performance tables eliminate the need to perform a regression analysis to calculate the performance curve equation coefficients. The following descriptions define the input requirements for the performance table objects.

Input for tables representing data with one or more independent variables.

A unique user-assigned name for an instance of a lookup table. When a table is used, it is referenced by this name. The name of this table object may be used anywhere a valid performance curve object is allowed.

Field: Independent Variable List Name[LINK]

The name of a Table:IndependentVariableList object that defines the independent variables that comprise the dimensions of the tabular data.

Determines if and how this output will be normalized. Choices are:

1. No: Do not normalize output.

2. DivisorOnly: Normalize the output using only the value entered into the Normalization Divisor field, below.

3. AutomaticWithDivisor: Normalize the output by dividing the output data by the value of the table at each of the independent variable normalization reference values in the associated independent variable list AND dividing by the value entered into the Normalization Divisor field, below.

Normalization applies to the Output Value fields as well as the Minimum and Maximum Output fields.

Defines a value by which output values are normalized if the Normalization Method field is set to DivisorOnly or AutomaticWithDivisor. Default is 1.0.

The (non-normalized) minimum allowable value of the evaluated table after interpolation and extrapolation. Values less than the minimum will be replaced by the minimum. If this field is left blank, no limit is imposed.

The (non-normalized) maximum allowable value of the evaluated table after interpolation and extrapolation. Values greater than the maximum will be replaced by the maximum. If this field is left blank, no limit is imposed.

Field: Output Unit Type[LINK]

This field is used to indicate the kind of units that may be associated with the output values. It is used by interfaces or input editors (e.g., IDF Editor) to display the appropriate SI and IP units for the Minimum Output and Maximum Output. If none of these options are appropriate, select Dimensionless which will have no unit conversion. Options are:

• Dimensionless

• Capacity

• Power

Field: External File Name[LINK]

The name of an external CSV file that represents the tabular data. This file should be formatted such that the data for this particular output is ordered according to the order of the corresponding independent variables. For example, for three independent variables (iv1, iv2, iv3) with 3, 2, and 4 values respectively. The output values (out[iv1][iv2][iv3]) should be ordered as:

iv1 iv2 iv3 output
iv1[1] iv2[1] iv3[1] out[1][1][1]
iv1[1] iv2[1] iv3[2] out[1][1][2]
iv1[1] iv2[1] iv3[3] out[1][1][3]
iv1[1] iv2[1] iv3[4] out[1][1][4]
iv1[1] iv2[2] iv3[1] out[1][2][1]
iv1[1] iv2[2] iv3[2] out[1][2][2]
iv1[1] iv2[2] iv3[3] out[1][2][3]
iv1[1] iv2[2] iv3[4] out[1][2][4]
iv1[2] iv2[1] iv3[1] out[2][1][1]
iv1[2] iv2[1] iv3[2] out[2][1][2]
iv1[2] iv2[1] iv3[3] out[2][1][3]
iv1[2] iv2[1] iv3[4] out[2][1][4]
iv1[2] iv2[2] iv3[1] out[2][2][1]
iv1[2] iv2[2] iv3[2] out[2][2][2]
iv1[2] iv2[2] iv3[3] out[2][2][3]
iv1[2] iv2[2] iv3[4] out[2][2][4]
iv1[3] iv2[1] iv3[1] out[3][1][1]
iv1[3] iv2[1] iv3[2] out[3][1][2]
iv1[3] iv2[1] iv3[3] out[3][1][3]
iv1[3] iv2[1] iv3[4] out[3][1][4]
iv1[3] iv2[2] iv3[1] out[3][2][1]
iv1[3] iv2[2] iv3[2] out[3][2][2]
iv1[3] iv2[2] iv3[3] out[3][2][3]
iv1[3] iv2[2] iv3[4] out[3][2][4]

Alternatively, the output may be defined using the Output Value <x> fields below.

Field: External File Column Number[LINK]

The column number (starting at 1) in the CSV file corresponding to this output.

Field: External File Starting Row Number[LINK]

The row number (starting at 1) in the CSV file where the data for this output begins. If there are not enough rows of data to fill out the full grid of data an error will be presented to the user.

If not reading from an external file, this field is repeated to capture the full set of output data in the table (if not otherwise defined in an external file). The data for this particular output is ordered according to the order of the corresponding independent variables. For example, for three independent variables (iv1, iv2, iv3) with 3, 2, and 4 values respectively. The output values (out[iv1][iv2][iv3]) should be ordered as:

iv1 iv2 iv3 output
iv1[1] iv2[1] iv3[1] out[1][1][1]
iv1[1] iv2[1] iv3[2] out[1][1][2]
iv1[1] iv2[1] iv3[3] out[1][1][3]
iv1[1] iv2[1] iv3[4] out[1][1][4]
iv1[1] iv2[2] iv3[1] out[1][2][1]
iv1[1] iv2[2] iv3[2] out[1][2][2]
iv1[1] iv2[2] iv3[3] out[1][2][3]
iv1[1] iv2[2] iv3[4] out[1][2][4]
iv1[2] iv2[1] iv3[1] out[2][1][1]
iv1[2] iv2[1] iv3[2] out[2][1][2]
iv1[2] iv2[1] iv3[3] out[2][1][3]
iv1[2] iv2[1] iv3[4] out[2][1][4]
iv1[2] iv2[2] iv3[1] out[2][2][1]
iv1[2] iv2[2] iv3[2] out[2][2][2]
iv1[2] iv2[2] iv3[3] out[2][2][3]
iv1[2] iv2[2] iv3[4] out[2][2][4]
iv1[3] iv2[1] iv3[1] out[3][1][1]
iv1[3] iv2[1] iv3[2] out[3][1][2]
iv1[3] iv2[1] iv3[3] out[3][1][3]
iv1[3] iv2[1] iv3[4] out[3][1][4]
iv1[3] iv2[2] iv3[1] out[3][2][1]
iv1[3] iv2[2] iv3[2] out[3][2][2]
iv1[3] iv2[2] iv3[3] out[3][2][3]
iv1[3] iv2[2] iv3[4] out[3][2][4]

Table:Lookup,
HPACCoolCapFT,           !- Name
HPACCoolCapFT_IndependentVariableList,  !- Independent Variable List Name
AutomaticWithDivisor,    !- Normalization Method
,                        !- Normalization Divisor
0,                       !- Minimum Output
40000,                   !- Maximum Output
Dimensionless,           !- Output Unit Type
,                        !- External File Name
,                        !- External File Column Number
,                        !- External File Starting Row Number
24421.69383, 22779.73113, 21147.21662, 19794.00525, 19524.15032, 18178.81244, 16810.36004,
25997.3589,  24352.1562,  22716.4017,  21360.49033, 21090.0954,  19742.05753, 18370.84513,
28392.31868, 26742.74198, 25102.61348, 23743.0571,  23471.93318, 22120.2503,  20745.3119,
29655.22876, 28003.546,   26361.31143, 25000,       24728.52506, 23375.08713, 21998.35468,
31094.97495, 29441.02425, 27796.52175, 26433.32038, 26161.46745, 24806.13958, 23427.47518,
33988.3473,  32330.1846,  30681.4701,  29314.75872, 29042.2038,  27683.36592, 26301.11353;

Performance Curve Output Value [][LINK]

The current value of the performance table. Performance curves and tables use the same output variable. This value is averaged over the time step being reported. Inactive or unused performance curves will show a value of -999 (e.g., equipment is off, a specific performance curve is not required for this aspect of the equipment model at this time step, etc.). This value means that the performance curve was not called during the simulation and, therefore, not evaluated. This inactive state value is only set at the beginning of each environment. When averaging over long periods of time, this inactive state value may skew results. In this case, use a detailed reporting frequency (ref. Output:Variable object) to view results at each HVAC time step.

Performance Curve Input Variable <x> Value [][LINK]

A list of Table:IndependentVariable references that define the size and dimensions of the data for one or more Table:Lookup objects. The order of this list defines the order that the tabular data must be defined. The output values in the Table:Lookup associated with this list will list the output in an order cycling through the last item in the list first, and then the second to last, and so on with the the first item cycling last. For example, for three independent variables (iv1, iv2, iv3) with 3, 2, and 4 values respectively. The output values (out[iv1][iv2][iv3]) should be ordered as:

iv1 iv2 iv3 output
iv1[1] iv2[1] iv3[1] out[1][1][1]
iv1[1] iv2[1] iv3[2] out[1][1][2]
iv1[1] iv2[1] iv3[3] out[1][1][3]
iv1[1] iv2[1] iv3[4] out[1][1][4]
iv1[1] iv2[2] iv3[1] out[1][2][1]
iv1[1] iv2[2] iv3[2] out[1][2][2]
iv1[1] iv2[2] iv3[3] out[1][2][3]
iv1[1] iv2[2] iv3[4] out[1][2][4]
iv1[2] iv2[1] iv3[1] out[2][1][1]
iv1[2] iv2[1] iv3[2] out[2][1][2]
iv1[2] iv2[1] iv3[3] out[2][1][3]
iv1[2] iv2[1] iv3[4] out[2][1][4]
iv1[2] iv2[2] iv3[1] out[2][2][1]
iv1[2] iv2[2] iv3[2] out[2][2][2]
iv1[2] iv2[2] iv3[3] out[2][2][3]
iv1[2] iv2[2] iv3[4] out[2][2][4]
iv1[3] iv2[1] iv3[1] out[3][1][1]
iv1[3] iv2[1] iv3[2] out[3][1][2]
iv1[3] iv2[1] iv3[3] out[3][1][3]
iv1[3] iv2[1] iv3[4] out[3][1][4]
iv1[3] iv2[2] iv3[1] out[3][2][1]
iv1[3] iv2[2] iv3[2] out[3][2][2]
iv1[3] iv2[2] iv3[3] out[3][2][3]
iv1[3] iv2[2] iv3[4] out[3][2][4]

A unique user-assigned name for a list of independent variables. This name is referenced by Table:Lookup objects. The name of this list object may be referenced by any number of Table:Lookup objects.

Field: Independent Variable <x> Name[LINK]

This field is repeated for the number of independent variables that define the dimensions of any corresponding Table:Lookup objects that refer to this list. Each instance provides the name of a Table:IndependentVariable object that defines the values and properties of an independent variable.

Table:IndependentVariableList,
HPACCoolCapFT_IndependentVariableList,  !- Name
HPACCoolCapFT_Tewb,                     !- Independent Variable 1 Name
HPACCoolCapFT_Todb;                     !- Independent Variable 2 Name

Independent variables are used to define the size and dimensions of a Table:Lookup object.

A unique user-assigned name for an independent variables. This name is referenced by Table:IndependentVariableList objects. The name of this object may be referenced by any number of Table:IndependentVariableList objects.

Method used to determine the value of the table within the bounds of its independent variables. The choices are:

• Linear

• Cubic

Method used to determine the value of the table beyond the bounds of its independent variables. The choices are:

• Constant: Value is the same as the interpolated value at the closest point along the table’s boundary.

• Linear: Value is linearly extrapolated in all dimensions from the interpolated value at the closest point along the table’s boundary.

The minimum allowable value. Table:Lookup output for values between this value and the lowest value provided for this independent variable will be extrapolated according to the extrapolation method. Below this value, extrapolation is held constant and a warning will be issued. If extrapolation method is “Unavailable”, the corresponding equipment will be disabled for all values less than the lowest independent variable value, regardless of the minimum value set here.

The maximum allowable value. Table:Lookup output for values between this value and the highest value provided for this independent variable will be extrapolated according to the extrapolation method. Above this value, extrapolation is held constant and a warning will be issued. If extrapolation method is “Unavailable”, the corresponding equipment will be disabled for all values greater than the highest independent variable value, regardless of the maximum value set here.

Field: Normalization Reference Value[LINK]

The value of this independent variable where nominal or rated output is defined. This will be used to normalize the data so that the outputs of any Table:Lookup at this value (and the corresponding Normalization Reference Values of the other independent variables described in the same Table:IndependentVariableList object) are equal to 1.0. If left blank, no normalization will be calculated. If this field is left blank the Normalization Reference Value of all other Table:IndependentVariable objects within the same Table:IndependentVariableList must also be left blank.

This field is used to indicate the kind of units that may be associated with this independent variable. It is used by interfaces or input editors (e.g., IDF Editor) to display the appropriate SI and IP units for the Minimum Value and Maximum Value. The available options are shown below. If none of these options are appropriate, select Dimensionless which will have no unit conversion.

• Dimensionless

• Temperature

• VolumetricFlow

• MassFlow

• Distance

• Power

Field: External File Name[LINK]

The name of an external CSV file that represents the tabular data. This file should be formatted such that the data for any output is ordered according to the order of the corresponding independent variables. For example, for three independent variables (iv1, iv2, iv3) with 3, 2, and 4 values respectively. The output values (out[iv1][iv2][iv3]) should be ordered as:

iv1 iv2 iv3 output
iv1[1] iv2[1] iv3[1] out[1][1][1]
iv1[1] iv2[1] iv3[2] out[1][1][2]
iv1[1] iv2[1] iv3[3] out[1][1][3]
iv1[1] iv2[1] iv3[4] out[1][1][4]
iv1[1] iv2[2] iv3[1] out[1][2][1]
iv1[1] iv2[2] iv3[2] out[1][2][2]
iv1[1] iv2[2] iv3[3] out[1][2][3]
iv1[1] iv2[2] iv3[4] out[1][2][4]
iv1[2] iv2[1] iv3[1] out[2][1][1]
iv1[2] iv2[1] iv3[2] out[2][1][2]
iv1[2] iv2[1] iv3[3] out[2][1][3]
iv1[2] iv2[1] iv3[4] out[2][1][4]
iv1[2] iv2[2] iv3[1] out[2][2][1]
iv1[2] iv2[2] iv3[2] out[2][2][2]
iv1[2] iv2[2] iv3[3] out[2][2][3]
iv1[2] iv2[2] iv3[4] out[2][2][4]
iv1[3] iv2[1] iv3[1] out[3][1][1]
iv1[3] iv2[1] iv3[2] out[3][1][2]
iv1[3] iv2[1] iv3[3] out[3][1][3]
iv1[3] iv2[1] iv3[4] out[3][1][4]
iv1[3] iv2[2] iv3[1] out[3][2][1]
iv1[3] iv2[2] iv3[2] out[3][2][2]
iv1[3] iv2[2] iv3[3] out[3][2][3]
iv1[3] iv2[2] iv3[4] out[3][2][4]

Independent variable values must appear in ascending order (an error will be issued if this is not the case).

Alternatively, the independent variables may be defined using the Value <x> fields below.

Field: External File Column Number[LINK]

The column number (starting at 1) in the CSV file corresponding to this independent variable. As the values of the independent variables each repeat over a defined cycle, EnergyPlus will only read unique values from this column. EnergyPlus does not validate that the cycles are repeating correctly. In fact, the same data can be read by only defining each value once as it is first encountered:

iv1 iv2 iv3 output
iv1[1] iv2[1] iv3[1] out[1][1][1]
iv3[2] out[1][1][2]
iv3[3] out[1][1][3]
iv3[4] out[1][1][4]
iv2[2] out[1][2][1]
out[1][2][2]
out[1][2][3]
out[1][2][4]
iv1[2] out[2][1][1]
out[2][1][2]
out[2][1][3]
out[2][1][4]
out[2][2][1]
out[2][2][2]
out[2][2][3]
out[2][2][4]
iv1[3] out[3][1][1]
out[3][1][2]
out[3][1][3]
out[3][1][4]
out[3][2][1]
out[3][2][2]
out[3][2][3]
out[3][2][4]

Field: External File Starting Row Number[LINK]

The row number (starting at 1) in the CSV file where the data for this independent variable begins. Any values in the same column below this row are considered part of the range.

If not reading from an external file, this field is repeated to capture the full set of values for this independent variable. These values must be defined in ascending order (an error will be issued if this is not the case).

Table:IndependentVariable,
HPACCoolCapFT_Tewb,      !- Name
Cubic,                   !- Interpolation Method
Constant,                !- Extrapolation Method
12.77778,                !- Minimum Value
23.88889,                !- Maximum Value
19.44449,                !- Normalization Reference Value
Temperature,             !- Unit Type
,                        !- External File Name
,                        !- External File Column Number
,                        !- External File Starting Row Number
12.77778,                !- Value 1
15.00000,                !- Value 2
18.00000,                !- Value 3
19.44449,                !- Value 4
21.00000,                !- Value 5
23.88889;                !- Value 6