Hello,

Does anyone know if the errors described in TMY3 files in this post from Joe Huang on Jan 14 2015 still exist in files on the http://climate.onebuilding.org/ website? And were these errors also fixed in TMYx files?

Specifically I'm interested in this issue:

1) Illuminance. The TMY3s contain values for Global Horizontal, Direct Normal, Diffuse
Horizontal, and Zenith Illuminance that are calculated based on the sun position and solar
radiation. Although the documentation states that the units are 100 lux for the first
three illuminances, and 10 candela/m2 for the Zenith Illuminance, all the TMY3 files used
these units only for the period Jan. 2-31, and for the rest of the year used units of lux
and candela/m2, respectively. NREL put out a notice in August 2008 (see the link listed
earlier) informing users of this discrepancy and promising a corrected version that didn't
make it out until now! In this revision, we've decided to keep the units in the original
TMY3 documentation, i.e., 100 lux or 10 candela/m2, which is the same as what was in the
TMY2, and avoids the superfluous five-digit precision.

If I use a TMY3 or TMYx file from the climate.onebuilding.org website, am I getting a TMY3 or TMYx version in which these issues are corrected?

Thank you,

--
Anna Brannon, PE, LEED AP BD+C, ASHRAE BEMP
Senior Environmental Designer

Atelier Ten
Environmental Design Consultants + Lighting Designers

443 Tehama Street, 1st Floor
San Francisco CA 94103
M +1 (720) 662-6389
anna.brannon at atelierten.com

www.atelierten.com

Please note that Atelier Ten is closed for the holidays December 24th through January 1st. We will also be drawing down operations starting December 21st to allow our staff additional time to relax during the holidays. We will reopen on Monday January 4th

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