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How can I change weather data ?

asked 2021-06-08 03:11:00 -0500

Frank Wang's avatar

updated 2021-06-09 07:27:07 -0500

Hello everyone.

Is it possible to change the hourly dry bulb temp. of an exsited weather file? I have tried to paste it in CSV format but when I applied it in DB, it showed a format error. After that I tried to change it in Elements, however I couldn't paste a column from CSV to an exsited weather file.

Is there another way to change some data in a weather file? I would appreciate it if I can get some guide. Thanks.

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@Frank Wang what weather file format are you trying to edit (TMY, EPW, BIN, ...) and what simulation tool are you planning on using with the custom weather file you will create?

Aaron Boranian's avatar Aaron Boranian  ( 2021-06-08 07:13:52 -0500 )edit

Hello Aaron, the original format is EPW, and I want to use it in Design Builder and EnergyPlus.

Frank Wang's avatar Frank Wang  ( 2021-06-08 20:07:22 -0500 )edit

@Frank Wang great, I have added more tags for this information. In the future, using multiple tags related to your question helps others know how to provide better answers.

Aaron Boranian's avatar Aaron Boranian  ( 2021-06-09 07:25:25 -0500 )edit

Got it, thank you, Aaron.

Frank Wang's avatar Frank Wang  ( 2021-06-14 20:19:59 -0500 )edit

2 Answers

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answered 2021-06-08 13:55:48 -0500

sashadf1's avatar

I first opened a weather file I had, USA_ME_Caribou.Muni.AP.727120_TMY3 - Copy1, in Elements.

This is what the data looked like to start: USA_ME_Caribou_Unedited

Then, I created my own timeseries data in excel: hourly dry bulb temp

For no particular reason, decided to set the variable to -10 deg C for the entire year. I then highlighted the entire column in elements by clicking on the header of the Dry Bulb Temperature [C] column.

Then, I went into excel, selected the -10 deg C (control+shift+down) column, and used control C + control V to paste into elements. Then, control S to save.

The new data looks like this: USA_ME_Caribou_Edited

Note that when changing the DBT I selected Relative Humidity, Atmospheric Pressure as my Variables to Hold Constant in the psychometric state. As a result, other variables like Dew Point Temp and Wet Bulb Temp changed in response to changing DBT. You will need to choose which variables you want to hold constant when changing the DBT based on your application.

Not sure if that will solve your formatting error, but editing data within Elements is typically a safer option because it will preserve the relationship between solar variables and psychometrics. If you decide to import to Excel as a csv and make edits manually there (see, be careful, because I don't think that Excel will automatically preserve the relationship between timeseries variables the way Elements does.

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you can see for instructions.

sashadf1's avatar sashadf1  ( 2021-06-08 17:31:51 -0500 )edit

Hello sashadf1, thanks for ur elaborate instructions. I had done exactly what u describe before I asked this question. Though it failed at the step " and used control C + control V to paste into elements.". The Elements didn't react when I used Crtl+V or "paste" in "Edit". It would be great if u have further advice about that.

Frank Wang's avatar Frank Wang  ( 2021-06-08 20:54:33 -0500 )edit

Make sure that the timeseries data is highlighted in excel before you paste into elements. When you press control C in excel, dashed lines moving clockwise should appear around the selected data. These dashed lines NEED to be around the data before you transfer to elements. Try 1. first selecting the entire column data in elements. 2. copying data in excel, then 3. pasting into elements.

Sometimes when switching between excel and elements I noticed that I would have to reselect data in excel, because I would lose the dashed lines.

sashadf1's avatar sashadf1  ( 2021-06-08 21:02:27 -0500 )edit

Ok, I got the dash line but it still doesn't work, I guess I have to try another way to deal with it. Thank you anyway.

Frank Wang's avatar Frank Wang  ( 2021-06-08 22:37:18 -0500 )edit

This is an excellent response. Thank you @sashadf1. @Frank Wang, does your Excel use a "." as the decimal separator? Unfortunately, Elements is unable to interpret a "," as the decimal separator but you can change the settings temporarily if this is your case. Otherwise, just click on one of the cells in the dry bulb column before pasting.

Michael OKeefe's avatar Michael OKeefe  ( 2021-06-09 08:16:48 -0500 )edit

answered 2021-06-10 08:55:19 -0500

lklawrie's avatar

The standard way to do this is to use the weather converter that comes with EnergyPlus to create a "EnergyPlus CSV" file. Then, make your changes -- FYI, you should change dewpoint to missing (99.9) and relative humidity to some number (100?).

Then, use the weather converter again to change the EnergyPlus csv format to an EPW.


FIBPSA, FASHRAE - free repository of climate data for building simulation Climate.onebuilding is a FREE service not supported by any outside organization or government agency.

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Thank you Linda, I have successfully changed my weather file using your way, the data catagories include Dry Bulb Temperature , Dew Point Temperature, Relative Humidity and Atmospheric Pressure.

Frank Wang's avatar Frank Wang  ( 2021-06-14 20:39:20 -0500 )edit

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Asked: 2021-06-08 03:11:00 -0500

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Last updated: Jun 10 '21