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

Kapil Upadhyaya KapilU at kirksey.com
Tue Feb 10 15:58:13 PST 2015

After you pointed this out, we started exploring this issue and did find significant differences in current weather files and 30 year average/EPW files.
As IBPSA members, we should take this issue up on a national level to come up with a resolution.


Kapil Upadhyaya, ASHRAE BEMP, LEED AP
Senior Associate
Kirksey | Architecture
6909 Portwest Drive  |  Houston Texas 77024  |  www.kirksey.com<http://www.kirksey.com>
o  713 426 7508  |  f  713 850 7308  |  kapilu at kirksey.com<mailto:kapilu at kirksey.com>

From: Nathan Kegel [mailto:nathan.kegel at iesve.com]
Sent: Monday, February 09, 2015 10:37 PM
To: West, Scott P; 'RobertWichert'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Revised TMY3 Weather Files now available on the Web

To add to the list of tools that already does this for you:

IES VE does this for you in the Vista application.  Whether you’ve run an annual simulation or not, you can plot multiple variables overlaid on one another:

[cid:image001.jpg at 01D04557.6EF89300]

[cid:image002.jpg at 01D04557.6EF89300]

3D graphs:

[cid:image003.jpg at 01D04557.6EF89300]

“Heat Maps”:

[cid:image006.jpg at 01D04557.6EF89300]

You can also create your own custom variables in the VE (so you could create an enthalpy variable from the other variables and plot it on a graph or export to a spreadsheet, etc.):

[cid:image007.png at 01D04557.6EF89300]

This is a .EPW file format from: http://apps1.eere.energy.gov/buildings/energyplus/cfm/weather_data3.cfm/region=4_north_and_central_america_wmo_region_4/country=1_usa/cname=USA
For those of you still tuned in – a bit of a digression:

Note the values that are errors in June and August (the DB is well below freezing 10 F) – that’s never happened in the recorded history of the area – let alone in the timeframe that TMY3 files are comprised of).  The coldest value EVER for the entire state in the month of August is 21 F.  That occurred in Kelliher which is more than 200 miles north of this location.

I’d suggest opening any of the climate files you get and ensuring they aren’t full of invalid data points.  I’ve found far too many of them to be too error-filled to be useful for simulation.  Eden Prairie, MN (still spelled incorrectly on the DOE website – “Edin”) is also rife with sub-zero temperatures in May (also never happened in recorded history).  The Portland, OR TMY3 has 114 F days in late October (ditto).  I think you get the idea.

[cid:image008.png at 01D04557.6EF89300]<http://www.iesve.com/>

Nathan Kegel
Business Development Manager






Integrated Environmental Solutions Limited. Registered in Scotland No. SC151456
Registered Office - Helix Building, West Of Scotland Science Park, Glasgow G20 0SP

Email Disclaimer<http://www.iesve.com/disclaimer.html>

From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of West, Scott P
Sent: Monday, February 9, 2015 6:47 PM
To: 'RobertWichert'; bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] Revised TMY3 Weather Files now available on the Web

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:image009.png at 01D04557.6EF89300]

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<mailto: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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