TMY3 to TMY2 Conversion Problem

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It is my understanding that beginning Jan. 2014, California Climate Zone 8 will change from El Toro MCAS to Fullerton Municipal Airport.

I downloaded and installed the TMY3 to TMY2 conversion utility from NREL and also downloaded the Fullerton Airport data in a .csv file. The converted file is 326 kb in size versus the normal 146 kb for .bin weather files. After renaming the converted file to include the .bin extension, I tried running a sample simulation, but it crashed.

First, I get an invalid argument message box, which has been covered here quite a bit. The simulation output only has one page with the error shown below.

[cid:image001.png at 01CE8163.BAC2D840]
Has anyone experienced a similar problem and if so, do you know the procedure/work-around to keep eQUEST from choking on the weather file?

Thank you.

Mike Busman

Michael R. Busman, CEM

Busman, Michael R's picture
Joined: 2012-07-12
Reputation: 0


Your first statement is not quite correct. The California Energy
Commission had commissioned in 2009 the creation of a new set of
standard weather files to replace the pre-existing 16 CZXXRV2 weather
files, for which I was the contractor. This work, which was finished in
December 2011, resulted in a set of 86 CZ2010 weather files and are
available for public download on my company Web site at, click on CZ2010 (all files
contain the same weather file in three formats - archival *.TM2,
*.EPW, and *.BINM).

The California Energy Commission has yet to decide whether to allow the
use of all 86 weather files in Title-24 calculations, or to limit it to
a subset of 16, i.e., one standard file per Climate Zone as before.
From a technical point of view, I strongly support the former position,
although there are administrative issues that need to be addressed to
avoid creating confusion or "gaming the system" that I hope the
Commission will address in the coming year.

As an interim place-holder, I worked with the Commission staff and
consultants in late 2011 to assign representative locations out of the
86 for each of the 16 Title-24 Climate Zones. This list was shown at a
Nov. 2011 workshop in Sacramento (see attached, full PPT available on
the Commission Web site - search for "Huang Weather Data Presentation")
and is probably the basis for what you've heard about the CZ08 file
changing from El Toro to Fullerton.

Although I am not violently opposed to such an interpretation, I do wish
to mention the following caveats:
1) the pre-existing CZXXRV2 weather files were adjusted in the early
1990's (that's the reason for the RV2 designation) to be more
representative of the climates within each Climate Zone; therefore, it's
incorrect to refer to any of them as being from a specific location,
i.e., CZ08RV2 != El Toro.
2) the new CZ2010 weather files have not undergone any such adjustment
process (nor would I recommend so doing), and should be regarded as
"representative" rather than "average" weather files for each Climate
Zone, selected based primarily on population and only secondarily on
climate considerations.

The last point I want to make is that the CZ2010 files are different
from the TMY3 weather files for the same stations in many ways:
1) uniform period of record (1996-2009)
2) uniform typical months for all 86 stations
3) solar radiation from remotely-sensed data, i.e., satellite-derived
4) different software used to fill missing data

So, to make a long story short, if you're concerned about the
Commission's change in standard weather data, please download the new
CZ2010 weather files at


Joe Huang

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Joined: 2011-09-30
Reputation: 406


Thank you for your detailed response and for making the weather files available on your website.

A number of months ago I attended a workshop given by Martyn Dodd (who you most likely know), of EnergySoft, LLC, regarding the Title 24 changes that take effect in 2014. It was there that the "reference" city for zone 8 would change from El Toro MCAS to Fullerton was discussed. Within about a month we anticipate beginning the investment grade audit phase of a project with a school district in a city adjacent to Fullerton, which is why I was interested in the Fullerton data. By the time we finish the development work, get under contract, and begin final design, we'll probably be looking at late 2013 or early 2014. Forgetting about Title 24 for the moment, just having more representative weather data available is a big plus.

Again, thank you for the response.

My best,

Mike Busman

Michael R. Busman, CEM

Busman, Michael R's picture
Joined: 2012-07-12
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