VRF Performance Curve, os:table input

asked 2025-09-23 16:45:11 -0500

KLim
41 ●1

updated 2025-09-24 09:37:55 -0500

14460 ●91 ●25 http://bigladdersoftware.com/

Hi. I am trying to build the cooling performance curve for VRF condensing unit. Following specific excel template which is this (https://docs.google.com/spreadsheets/...).

Based on my input, I got ended up having this curve (table) for the temperature-capacity curve.

OS:Table:Lookup,
  {5532089b-8c9b-4aff-9371-984933646b1a}, !- Handle
  Table Lookup EP120TNU/YNU CLG_CCR_fn_T-Output,!- Name
  {98862933-0764-43a3-aa10-ad8a7a159775}, !- Independent Variable List Name
  DivisorOnly,                            !- Normalization Method
  1,                                      !- Normalization Divisor
  0.35703950257726, !- Minimum Output {BasedOnField A5}
  1.30663523102881, !- Maximum Output {BasedOnField A5}
  Dimensionless,                          !- Output Unit Type
  ,                                       !- External File Name
  ,                                       !- External File Column Number
  ,                                       !- External File Starting Row Number
  1.00288776398616,!- Output Value 1 {BasedOnField A5}
  1.00418987741641,!- Output Value 2 {BasedOnField A5}
  0.808872862877439,!- Output Value 3 {BasedOnField A5}
  0.35703950257726,!- Output Value 4 {BasedOnField A5}
  1.08774749786191,!- Output Value 5 {BasedOnField A5}
  1.08915979012088,!- Output Value 6 {BasedOnField A5}
  0.87731595127476,!- Output Value 7 {BasedOnField A5}
  0.38725053741072,!- Output Value 8 {BasedOnField A5}
  1.15599133978996,!- Output Value 9 {BasedOnField A5}
  1.15749223740069,!- Output Value 10 {BasedOnField A5}
  0.93235759579009,!- Output Value 11 {BasedOnField A5}
  0.411546124864202,!- Output Value 12 {BasedOnField A5}
  1.30494094260684,!- Output Value 13 {BasedOnField A5}
  1.30663523102881,!- Output Value 14 {BasedOnField A5}
  1.05249196773224,!- Output Value 15 {BasedOnField A5}
  0.46457388530615;!- Output Value 16 {BasedOnField A5}

OS:ModelObjectList,
  {98862933-0764-43a3-aa10-ad8a7a159775}, !- Handle
   Table Lookup EP120TNU/YNU CLG_CCR_fn_T-Output_List, !- Name
  {35c0814c-9d56-4515-b377-2fd91c445712}, !- Model Object 1
  {7bf540c0-cc77-4615-9b59-9ed9c499cff6}; !- Model Object 2

OS:Table:IndependentVariable,
  {35c0814c-9d56-4515-b377-2fd91c445711}, !- Handle
  Table Lookup EP120TNU/YNU CLG_CCR_fn_T-Input_0,!- Name
  Linear,                                 !- Interpolation Method
  Constant,                               !- Extrapolation Method
  59.0106312292358,!- Minimum Value {BasedOnField A5}
  74.9893687707641,!- Maximum Value {BasedOnField A5}
  ,                                       !- Normalization Reference Value {BasedOnField A5}
  Temperature,                            !- Unit Type
  ,                                       !- External File Name
  ,                                       !- External File Column Number
  ,                                       !- External File Starting Row Number
  59.0106312292358,!- Value 1
  64.0179401993355,!- Value 2
  68.9401993355481,!- Value 3
  74.9893687707641;!- Value 4

OS:Table:IndependentVariable,
  {7bf540c0-cc77-4615-9b59-9ed9c499cff6}, !- Handle
  Table Lookup EP120TNU/YNU CLG_CCR_fn_T-Input_1,!- Name
  Linear,                                 !- Interpolation Method
  Constant,                               !- Extrapolation Method
  22.8771804062126,!- Minimum Value {BasedOnField A5}
  115.053285543608,!- Maximum Value {BasedOnField A5}
  ,                                       !- Normalization Reference Value {BasedOnField A5}
  Temperature,                            !- Unit Type
  ,                                       !- External File Name
  ,                                       !- External File Column Number
  ,                                       !- External File Starting Row Number
  22.8771804062126,!- Value 1
  67.8905615292712,!- Value 2
  115.053285543608,!- Value 3
  125.738590203106;!- Value 4

Within the openstudio, I could not see the inputs within the openstudio interface starting the line with "OS:Table:IndependentVariable," in the middle of script.

For trouble shooting, I would like to confirm this table is really working correctly or no.

Is there any method that I can see these independent variable tables are connected with output curve above?

Thank you.

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answered 2025-09-25 05:21:23 -0500

Julien Marrec

30271 ●112 ●80 http://www.effibem.com/

Your Independent variables are definitely wrong. You seem to have entered temperatures in Farenheit, you need to use Celsius.

Looking at your spreadsheet, the output values of the curve above does not match what was in the table.

Your Independent Variable list (OS:ModelObjectList) has a wrong handle with respect to your first Table Independent Variable (one ends with 12 the other with 11)

OS:ModelObjectList,
   {35c0814c-9d56-4515-b377-2fd91c445712}, !- Model Object 1

OS:Table:IndependentVariable,
  {35c0814c-9d56-4515-b377-2fd91c445711}, !- Handle

Here is a python script you can use to format your Table to a csv

import openstudio
from itertools import product
import pandas as pd

m = openstudio.model.Model.load('model.osm').get()
table = m.getTableLookups()[0]

xs = list(product(*[i.values() for i in table.independentVariables()]))
ys = table.outputValues()

assert len(xs) == len(ys), f"Product of independant variables is size {len(xs)} when dependent variable has {len(ys)} elements"
df = pd.DataFrame(xs, columns=["Indoor T WB (C)", "Condenser Entering T DB (C)"])
df["Cooling Capacity"] = ys
df.to_csv('table.csv')

If you don't have python installed, you can use the OpenStudio CLI to run it. Place it next to your model.osm, save it as curve.py and call openstudio curve.py. You'll have a table.csv as a result

Currently your curve looks like this:

image description

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VRF Performance Curve, os:table input

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