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:
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.
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 :(
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".
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.
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: http://oco-carbon.com/wind-energy/vis...
Asked: 2017-02-28 04:00:55 -0500
Seen: 3,121 times
Last updated: Mar 08 '17
