This tool was updated to v1.02 on 2/11/2012 *

Ever had the problem of looking at all the weather files available from the EnergyPlus weather files site and wondering which is closest to the location you’re modelling in? The oCo Carbon Weather file finder will save you the trouble of looking them up, downloading them, opening up the statistics file to check their suitability, and once you’ve found the right site it also has links to download the file or files you need.

Each white dot on the map is the location of a weather file. You can see how hard it can be to pick the nearest one if you don’t happen to know the name of your local weather stations.

For use in building energy simulations .epw files can be read by EnergyPlus, as well as DesignBuilder and other tools which use EnergyPlus as the simulation engine, IES:VE. They can also be converted by TAS using their Weather Utility macro. They can also be used for other purposes such as understanding the influence of local climate on building design using Climate Consultant [Windows] [Mac].

The weather file finder tool looks up the latitude and longitude of an entered location. You can enter anything from a postcode/zipcode to a country name, or even a latitude/longitude pair if you know them. It then calculates the great circle distance to each weather file location (taken from the first line of each weather file on the US Department of Energy website) and creates links to download zip archive containing the .epw weather files for the closest three locations.

The tool also tells you the difference in latitude, longitude and elevation between the two sites which can help you to see whether the two locations are likely to be similar. Locations which have a large difference in elevation or latitude are likely to have quite different weather.

Finally, it lists a number of key statistics about the location including heating and cooling degree days, extreme temperature conditions and climate classification zone.

This tool can save you a lot of time, especially if you’re somewhere with a lot of nearby weather file locations (Poland, I’m looking at you here).

Download oCo Carbon Weather File Finder v 1.02 here.

* With particular thanks to Luke McGuire, Max Tillberg and Patrick Bivona for their useful comments and feedback.

Jamie Bull |

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6 Comments on “Weather file finder”

  • Max Tillberg says:

    Great tool but it does not work if you have “,” as decimal separator in your computer.

    • Jamie Bull says:

      I’ve just updated the tool so that it works with commas as decimal separator. I’ve also added a readout which shows the difference in latitude, longitude and elevation between the entered location and the nearest .epw location.

      Thanks for the spot and I hope it comes in handy for you.

  • Tris says:

    Great tool, but doesnt appear to work with newer versions of excel? Visual basics opens and complains about an error?


  • Sandeep Ahuja says:

    Jamie, thanks for putting this together. it is helpfu. It seems that the doe website that hosted the EPW files has changed and now all the links are
    on the energy plus website “”, is it possible to change that?

    • Jamie Bull says:

      Hi Sandeep, there’s an update coming in the next day or so to fix that, as well as to add the IWEC2 files which are available from WBT.

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