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+--- Thread: setting Window to Wall Ratio (WWR) (/showthread.php?tid=34)
setting Window to Wall Ratio (WWR) - Rose - 01-11-2015
Hi everyone
I have a simple zone with a window on the northern wall.I would be appreciated if there is any one to explain me how I can set Window to Wall Ratio (WWR) and also Window length and width in jEPlus IDF editor to analyse and find my outputs via an example please?I mean,I don’t know how to put Search strings in jEPlus IDF editor and put my parameters in CSV file?
Thanks in advance
Rose
RE: setting Window to Wall Ratio (WWR) - oddovalspin - 01-12-2015
Hi,
I edit my idf files using Notepad++ (freeware) outside from IDF editor. You are just changin a text fiel so it doesn' tmatter to much what sort of text editor you use. There are some people who write scripts in Python or Matlab to automate the process but this is beyond my skill level at moment.
Adding parameters one at a time to the Parameter Tree using the Parameter Item fields works well for small numbers of parameters but is likely to become cumbersome and laborious if the number of parameter items becomes large.
However, jEPlus has the facility to export and import parameter trees. jEPlus exports a Comma Separated Variable (CSV) file. This means that the external file can be independently created and used to import parameter descriptions into jEPlus. The export function is useful to confirm the format or to save a parameter tree.
The technique applies equally to jEPlus+NET.
The import and export function is limited in that only the first branch of the parameter tree can be exported or imported. This means that multiple parameter values cannot be included for evaluation by this method. However the Parameter Tree need only serve to inform jEPlus of the parameters to be assessed. The values of the parameters can be defined in a job file which is added in the “Job list in file” field under the Execution tab. Since this is the method that I use to define the values for the parametric assessment, this is sufficient.
The format of the columns in the CSV file are shown in the table below. The header shows the order of the parameters and the first line is an example of the definition of a parameter. These data were copied from an early test file.
# ID Name Parameter Type Description Search String Value Type Value String Selected Value Index
L1 Lights 1 0 Lights 1 @@lights1@@ 1 {3} 0
The parameter tree allows for the definition of huge numbers of simulations. For example even a modest parametric analysis of 12 parameters (p=12), each of which could be defined by say 5 values (v=5) yields vp = 244,140,625 simulations. This large number of combinations would require vast processing power and would not necessarily be useful. To limit the number of simulations that are actually executed, jEPlus provides options for selected a limited number of jobs.
The Actions pane under the Execution tab allows for various subsets of analysis to be executed.
Once the parameters have been defined and described in a parameter CSV file, jEPlus needs to be directed as to which values are to be used in simulations. Under the Execution tab, a pre-constructed list of parameters and the values for which the simulation is to be executed can be included. This is done by selecting the “Job list in file” radio dial and browsing to the text file.
The figure below shows the format for the job file is shown below. The header describes the data in each column and the first row gives an example taken from one of the early test files. The indices for the weather and IDF files start at 0.
Job name Weather file index IDF file index Value of 1st parameter in tree Value of 2nd parameter in tree Value of 3rd parameter in tree etc
LHS-000000 0 0 3.040027 3.976158 5.076852 6.357665
I create my csv files in in Excel but there are a few tricks.
The standard tag used in jEPlus search strings is “@@”, however Excel reads this as a function and will highlight any entry starting with “@@” as an error. One work-around for this is to start the cell with an apostrophe (‘) however this would interfere with the operation of jEPlus. One solution to this is to enter the search tags in an Excel spreadsheet and then save the file as a CSV file. When the file is re-opened, Excel ignores the apostrophe which allows the CSV file to be assembled correctly.
The format for the string value for an imported parameter tree is {value}. Excel is convenient for manipulating large columns of values, but it would be laborious to add the curly brackets to each value. One option is to use the =concatenate() function. For example; a value of 80% of cell A1 containing say the value 1.0, could be expressed as {0.8} by using =concatenate(“{“,A1*0.8,”}”). The cell will display {0.8} but will still contain the formula string. To convert this to an entry of {0.8} the cell can be copied and then pasted-special as a value. The new cell will then contain {0.8}.
RE: setting Window to Wall Ratio (WWR) - Rose - 01-12-2015
Hi Dear oddovalspin,ohhhh,Thanks for your answer in detail and for your time too.It seems to me a little hard to do and Unfortunately i was not familiar about everything you wrote for me,But i am going to try and learn it.Thanks again for your time and respond.
Best wishes
Rose