Import EPW_error with meteonorm epw data

Asisnath · September 29, 2020, 4:33pm

Hello all. I generated a future predicted Epw file for the year 2020 using Meteonorm for a location. I tried importing the file using LBT Import Epw component but it threw an error. The same file I tried opening with Ladybug Legacy it is working without issue.A bit confusing.

I am attaching the Epw file below.File.rar (613.3 KB)!

mostapha · September 29, 2020, 8:03pm

It looks like that the weather data is generated for a leap year and had 24 extra hours. That’s what the error message says.

Asisnath · September 29, 2020, 11:34pm

Hello Mostapha. Yes it says leap year. is there any walk around as leagcy version is able to read that

chris · September 30, 2020, 5:24am

Legacy might be able to import the EPW but I don’t think any of the Legacy climate graphics can handle the extra 24 values (or, if they do, the probably do so incorrectly).

You can import an EPW that’s for a leap year with the new Ladybug plugin as long as it’s internally consistent. For example, here I am loading up an EPW for Boston in 2016:

Perhaps Meteonorm hasn’t formatted their EPWs correctly. Maybe the “year” field of the EPW doesn’t have values that are all for 2020.

chris · September 30, 2020, 5:32am

Actually, you can see here’s that it’s one of the variables in the header of the EPW that tells EnergyPlus and Ladybug that the calculation is for a leap year:

github.com

ladybug-tools/ladybug/blob/master/ladybug/epw.py#L615-L617


# parse leap year, daylight savings and comments.
leap_dl_sav = self._header[4].strip().split(',')
self._is_leap_year = True if leap_dl_sav[1] == 'Yes' else False

So, if you just edit the incorrect header of your Meteonorm file, you should be able to import it with Ladybug and simulate it In EnergyPlus without issues.

Asisnath · September 30, 2020, 6:29am

Ok @Chris, now I understood the concept of leap year. Thank You

Asisnath · September 30, 2020, 7:31am

Hi again @Chris can you please share your 2016 boston file. Still i am not able to make it run on LBT. For now i just deleted the feb 29 data to make it work.

chris · September 30, 2020, 4:22pm

Hey @Asisnath ,
Here is the file for Boston in 2016 for reference:
https://drive.google.com/file/d/1HrWqfGR0MfzlrbG6j1QS2Rc6-OblYbio/view?usp=sharing

It has missing radiation values but this at least shows you how the header should be formatted for a leap year.

Asisnath · September 30, 2020, 4:38pm

Thanks @chris for the reference file