Epw file - Tokyo 476620 - wind only from one direction



Hello everyone!
I’m relatively a Ladybug newbie, so sorry if might seem a fool question, but i really need to solve this problem…
I’m working on an architectural project for Tokyo, specifically investigating wind direction and speed on site. I managed to work with LB wind rose and wind profile components, but i don’t understand why the Tokyo epw file downloaded from Onebuilding (meteo station 476620) displays the wind like it comes from 180° degrees (south) for every hour in every day of the year! Looks like it is actually an inherent problem of this specific epw data, because using Tokyo- Hyakuri, epw data, produces a realistic wind rose instead.

I know i just could use the tokyo hyakuri file, but the actual distance of Hyakuri aeroportual meteo station from Tokyo area seems really too much for a realistic analysis! (100 km north from Tokyo, more or less).

Any hint on the origin of this probably “corrupted” wind direction values?
Found the same .epw file at 40 $ downloadable on this site http://weather.whiteboxtechnologies.com/IWEC2
Think would be worth buying the file elsewhere? Maybe data is corrupted only for onebuilding portal?

Thanks so much in advance


@badio93 ,

Sorry for the late response and I see the issue that you are talking about in the Tokyo 476620 file:

I am actually not sure what this means since the EnergyPlus reference on EPWs (go to Chapter 2.9) says that the value for missing wind data is supposed to be 999 and not 180.

I know that the file is hosted by onebuilding.org and they have some mailing lists where this question could be asked. I am not sure which one of their lists is the best for this type of question but I sent an email to a friend a onebuilding asking if there is a particularly good one. If I hear back, I will post here.

If all else fails, the IWEC file is probably not too far off but you might want to adjust the overall intensity of the wind using the wind profile component. Alternatively, now that the US government shutdown is finally over, the complete database of all publicly available weather data is back online. You can probably get some data there that can help you.


@badio93 ,

My friend at onebuilding.org got back to me and she plans to ask the person who provided the data.
Apparently, those Japanese EPW files were developed them for the EnerWin program – and using monthly data and algorithms to come up with hourly profiles/data.

I I find out any more info, I will let you know.


I will also add that, if onebuilding.org updates the EPW files, this might a better place to check instead of EPW map:

We only update EPWmap every few months but I know that onebuilding.org might make changes faster than we can.


Hey @chris, no problem for the wait.
Thank you so much for taking care of this issue and for the direct contact you made with your friend at onebuilding.

Glad to have helped to reveal those problems with japanese files!
At this point, i think i’ll try to use the adjusted IWEC file, keeping updated with this tread and onebuilding page, at the same time. A “fixed” Tokyo file would be great, and not just for my case, but for others eventual in the future, of course.

Last question: When you talk about “adjusting” the IWEC file using wind boundary profile component, are you referring to the possibility to change the terrainType_ input?
My approach would be to keep EpwTerrain_ input at standard value (2), been Hyakuri meteo station placed on an airport flat area, than changing the terrainType_ to (0) to simulate the condition in Tokyo urban area.
Is that correct?

Thanks again.


@badio93 ,

I agree that’s the right approach for now since there’s no specific time frame for when the EPW files will be updated (though they surely will be updated eventually).

For the edits to the wind profile, yes, that is what I was recommending. It looks like the biggest difference between the two sites is the fact that the IWEC file is located closer to the shore and in a rural area, which probably means higher wind speeds than one would find in the middle of Tokyo. So, if central Tokyo is what you are trying to estimate, it makes sense to adjust the wind speeds accordingly.