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How can I generate a windrose chart through the .epw?

asked 2017-02-28 04:00:55 -0600

poppo92's avatar

updated 2017-05-04 06:50:36 -0600

I would like to create a windrose chart using the epw in order to see the direction and the intensity of the prevailing winds. How can I generate it in excel?

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answered 2017-02-28 11:49:03 -0600

updated 2017-02-28 18:39:25 -0600

If you would like a quick way to generate windroses from .epw files, check out epwvis, a web-based visualizing/analyzing tool for weather files. You can drag-drop an .epw file onto the page to generate a windrose. It is open source (MIT License). The specific javascript code for generating the windrose is on github with a d3.js dependency.

Example epwvis windrose: image description

You can also generate windroses with ladybug, which is also open source. Python code here.

There are other free but closed source tools for generating windroses listed here.

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thank you, a very quickly way. Can I save the windrose as a jpeg or copy it in Word in someway?

poppo92's avatar poppo92  ( 2017-02-28 17:25:47 -0600 )edit

Screenshot it (snipping tool on windows). There is a way to export the svg image to .png. I know how to do it, just need to spend ~2-4hrs coding to enable that. Sorry it's not available yet :(

mdahlhausen's avatar mdahlhausen  ( 2017-02-28 18:38:39 -0600 )edit

answered 2017-02-28 05:27:08 -0600

banicu's avatar

Also, Climate Consultant is a great tool to analyze weather data: link text

You have to import the “.epw” file for your location and it does the rest.

All weather data can be exported as "CSV".

image description

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I thought about Climate Consultant too. I has the ability to cycle through each month which is really nice, but I find this wind wheel to be overloaded with information and a bit hard to read as a result. Having 36 bins seems maybe a bit extreme too. I love climate consultant, but wish there was a way to customize this chart further.

Julien Marrec's avatar Julien Marrec  ( 2017-02-28 06:36:19 -0600 )edit

thank you a lot

poppo92's avatar poppo92  ( 2017-02-28 17:26:13 -0600 )edit

answered 2017-02-28 05:00:26 -0600

updated 2017-03-08 08:05:31 -0600

Download your EPW. Convert it to CSV using the WeatherConverter from EnergyPlus.

Open that in Excel, you'll get many variables including hourly Wind Speed (m/s) and Wind Direction (degrees).

Define what kind of wind rose you want to achieve: do you want to plot the only wind direction, or do you want to also take wind speed into account? I have a preference for the second one of course...

Assuming you just want to take the wind direction into account, you need to "bin" the number of occurrences of a given direction, excluding cases where wind speed is zero. You'll basically want to convert the angles to cardinal directions (see here for tips on how to do it), then do a COUNTIF (eg COUNTIF(ColumnOfCardinalDirection, "NE") to get the number of hours where the wind blows from the North East), either using a formula or a pivot table.

If you want to take wind speed into account, you'll need to bin, for each cardinal direction, the wind speed in increments as well, so that you end up with a table made with COUNTIFS (eg COUNTIFS(ColumnOfCardinalDirection, "NE", ColumnOfWindSpeed, ">1", ColumnOfWindSpeed, "<2") to get number of hours where the wind blows from the North East, and the wind speed is between 1 and 2 m/s).

There is plenty of examples online, including some Excel workbooks you can reuse, for example here or here.

Side note: there's a python module called windrose that works really well. Here's an example notebook.

There's also @Jamie Bull's Excel tool:

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thank you a lot

poppo92's avatar poppo92  ( 2017-02-28 17:26:23 -0600 )edit

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Asked: 2017-02-28 04:00:55 -0600

Seen: 3,055 times

Last updated: Mar 08 '17