[Bldg-sim] Revised TMY3 Weather Files now available on the Web

West, Scott P Scott.West at jacobs.com
Mon Feb 9 15:48:18 PST 2015

Once you get two psychrometric data points of moist air, you should be able to derive the other properties that you desire.  A lot of the hourly weather files just happen to provide humidity in DP.  Obviously if you have more than a few data points to evaluate (like a full TMY3 file), looking them up on a psych chart isn’t very practical.  Unless you’re particularly interested in evaluating partial pressure equations, I would recommend using readily available software as a data filtering tool.  I recommend ClimateConsultant which is a free software produced by UCLA:

The software can be used for visualizing weather data and evaluating heating and cooling strategies.  It’s great for that, but I often simply use it to filter raw weather files and then export to Excel.  The whole process takes 5 minutes once you have the software installed.  You simply find the appropriate EPW weather file (EnergyPlus format) from the web (link provided in the software) and import it into ClimateConsultant.  You can then export to csv.  I like how the software will automatically convert from SI to IP units.  You can choose other ways of representing humidity like RH and WB.  You can also use it to quickly construct daily or monthly averages if desired.

[cid:image001.png at 01D04490.51334BC0]

Anyway, that’s my plug for ClimateConsultant for those of us that can’t program good data filters (or are too lazy).  I hope it’s helpful.

Scott P. West, P.E., LEED AP BD+C, BEAP, BEMP | JACOBS | Mechanical Engineer | Energy & Power Solutions | 817.222.8512 office | 817.897.1882 cell | scott.west at jacobs.com <mailto:scott.west at jacobs.com> | www.jacobs.com<http://www.jacobs.com/> | www.jacobs.com/energyportfolio<http://www.jacobs.com/energyportfolio>

From: RobertWichert [mailto:robert at wichert.org]
Sent: Monday, February 09, 2015 2:34 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Revised TMY3 Weather Files now available on the Web

These weather files are great, thanks for the info, but I am trying to get wet bulb temperature too, and they do not seem to give wet bulb temperatures.

Any ideas on that, perhaps?


Robert P. Wichert P.Eng.  LEED AP


+1 916 966 9060

FAX +1 916 966 9068

On 1/30/2015 9:10 PM, Joe Huang wrote:
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<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 Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com<mailto: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"


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