White Box Technologies (WBT), in collaboration with the National Renewable Energy
Laboratory (NREL), has revised the TMY3 weather files to correct inconsistencies in units
for illuminances, improve the reporting of Liquid Precipitation, replace all missing
records with interpolated or filled values (chiefly for visibility, ceiling height,
aerosol optical depth, and albedo), and add a new variable for Present Weather.
Since their release in 2005, the TMY3 weather files covering 1,020 locations in the US and
dependencies has become the standard set of weather files for use in computer simulations
of solar energy conversion systems and buildings. The intent of this revision is not to
redo the fundamental analysis, but correct some known errors and make modest improvements
in the reporting of subsidiary climate variables.
The only impact from these corrections and changes are for daylighting simulations that
use the illuminance values, and for building simulations that use the liquid precipitation
to model green roofs or moisture transport through the building envelope. The added
Present Weather variable is not directly used in any simulation program, but allows the
DOE-2 BINM files to have correct IRAIN and ISNOW flags, although these two variables are
not being used in DOE-2. Filling in missing data for Visibility, Ceiling Height, etc.,
should have no impact on the use of the TMY3s, but improves their overall record-keeping.
The revised TMY3 files in their native CSV format have been provided back to NREL and are
available here: http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3
The revised TMY3 files in EPW and BINM formats are available for free download on the
White Box Technologies web site at http://weather.whiteboxtechnologies.com/wd-TMY3 or by
selecting File Type as "TMY3" at http:/weather.whiteboxtechnologies.com/search to search
using GoogleEarth. The zip file names are unchanged, but the underlying EPW and DDY files
will have the *TYA designation to distinguish them from the previous TMY3 versions.
For a more detailed description and full documentation of the revision, please see the
attached memorandum.
Joe
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Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
