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

Jason Glazer jglazer at gard.com
Wed Feb 11 05:26:36 PST 2015


Nathan,

Looks like you have been thinking about a way to improve 
Appendix G. Anyone can submit proposals to improve Appendix 
G using the procedure described on:

https://ashrae.org/standards-research--technology/standards--guidelines/continuous-maintenance

If you do decide to submit a proposal, please think about 
the proposed language carefully and the direct and indirect 
implication of the proposed requirements.

Thanks

Jason

On 2/11/2015 12:51 AM, Nathan Kegel wrote:
>
> Hi Kapil,
>
> Several people have emailed me off the list to express a 
> similar sentiment.  I’ll let them remain anonymous unless 
> they choose to chime in.
>
> Two parts to this email: further exploration of the 
> problems in part 1 and some ideas for solutions in part 2.
>
> Part 1.
>
> I’ve presented on this topic at ASHRAE conferences as well 
> as whenever I do a training on doing LEED or code 
> compliance energy simulation.  I’ve done my own 
> sensitivity analysis of many of the free Minneapolis area 
> climate files and found I can vary the EUI of an office 
> building with a VAV system by 14% just by selecting a 
> different climate file that’s 12 miles away.  Even more 
> interesting (at least to me) was that I could change which 
> design decision was best by changing the climate file.  
> For example, the MSP climate file resulted in glazing X 
> being the lowest EUI while selecting the Eden Prairie file 
> (12 miles away) resulted in glazing Y being the best.  
> There’s no micro climates involved and both of these files 
> “bin out” to CZ6.  However, neither of them are 
> particularly “representative”.  Eden Prairie has -12 F 
> hours in May while the MSP file has 92 F degree hours in 
> April.  A quick check of the historical records show that 
> -12F has never happened in recorded history in May in the 
> Minneapolis area.  Anyone who lives in Minneapolis can 
> tell you that 90+ in April isn’t common.  Even 70+ in 
> April isn’t that common.  A quick check of the historical 
> record shows one time in nearly 200 years of records where 
> above 90 was recorded before April 15.  The third file, 
> Crystal, was documented as having sub-freezing temps in 
> the summer months in my previous reply to this thread.  So 
> that’s not representative, either.  If there were no other 
> options (which there are), I’d go with MSP as the best of 
> a bad hand of climate files.
>
> Appendix G only requires in G2.3 (90.1-2010): “The 
> simulation program shall perform the simulation using 
> hourly values of climatic data, such as temperature and 
> humidity from representative climatic data, for the site 
> in which the proposed design is to be located.  For cities 
> or urban regions with several climatic data entries, and 
> for locations where weather data are not available, the 
> designer shall select available weather data that best 
> represent the climate at the construction site.  The 
> selected weather data shall be approved by the rating 
> authority.”
>
> The way this is written, I can literally pick any weather 
> file – even if it is known to be filled with errors – and 
> use it for LEED compliance and/or code as long as its 
> nearby my proposed building.  It’s up to the rating 
> authority to question it.
>
> I’ve gotten many LEED review and code review comments in 
> doing simulation.  I’ve never once been asked about the 
> quality of the climate data that was used in the 
> simulation.  Yet it impacts everything in the simulation: 
> envelope, equipment performance (as many equipment 
> performance curves are dependent on ambient conditions), 
> and glazing selection just to name a few.
>
> The mentality of “plug and chug”, or worse, not even 
> bothering to know which climate file your simulation 
> program is actually using when it spits out results, is a 
> very dangerous game if you’re at all concerned about a 
> reliable result – and by extension – providing your 
> customers with sound recommendations on how to spend their 
> money.
>
> While nothing is perfect, I’ve had good experiences with 
> using www.weatheranalytics.com 
> <http://www.weatheranalytics.com>as a source for both TMY 
> and AMY files.  If there’s a problem with a file they 
> create, they’ve been really good about making it right 
> quickly.
>
> Another big problem with the free TMY3 files is they 
> aren’t very up to date (2005 was ten years ago).  Which is 
> another reason why I like weatheranalytics.com – I can get 
> more up-to-date weather data to help make a more informed 
> decision.
>
> Part 2.
>
> In my opinion, Appendix G needs a new section for 
> compliance: Pre-simulation Climate Analysis (call it Table 
> G3.09).
>
> 1.Perform analysis on at least 1 TMY and 3 AMY (within the 
> last 10 years) climate files near your site.  If three 
> aren’t available, document where you looked and what 
> process was done to select the climate file used in 
> simulation. (Although with services like Weather Analytics 
> now available, this shouldn’t really be a problem for 
> pretty much any project anywhere).  Submit plots of 
> dry-bulb temperatures and provide a narrative describing 
> the process used in selecting the climate file used in the 
> simulation. Include metrics like climate zone, bin 
> analysis, and numerical justifications as well as local 
> knowledge from trusted data sets in either the public or 
> private domain.
>
> 2.Document both the ASHRAE defined climate zone from 
> 90.1/169 and perform your own BIN analysis in accordance 
> with ASHRAE methodology for non-defined locations.  Submit 
> both the defined climate zone and the derived climate 
> zone.  If they are different, advise as to which climate 
> zone is being used in the simulation for baseline building 
> generation.
>
> ·Fun facts (using TMY3 data sets): Dallas is defined at CZ 
> 3A, it bins out to 2A.  Nashville is defined as CZ 4A, it 
> bins out to 3A.  Toronto is defined as 6A, it bins out to 
> 4A.  All these are listed in 90.1-2010 which is the 
> referenced standard in LEED v4 as well as an approved 
> compliance path in IECC 2012.  This is another potential 
> design quandary: to get code approval and/or LEED points, 
> I use a defined list in a table.  However, the building is 
> being built and will never actually see the weather that 
> was used to define the climate zone.
>
> Better yet – get rid of defined climate zones altogether 
> when taking a performance path.  Require professionals who 
> do simulation to understand how to open and analyze a 
> climate file and derive the climate zone.  Require review 
> of that process by the AHJ and agreement that the analysis 
> is valid and the CZ selected makes sense for the project.
>
> <http://www.iesve.com/>
>
> 	
>
> *Nathan Kegel*
> *Business Development Manager*
>
> 	
>
> O:
>
> 	
>
> 763.276.9981
>
> M:
>
> 	
>
> 415.420.9314
>
> http://www.iesve.com <http://www.iesve.com/>
>
> 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:*Kapil Upadhyaya [mailto:KapilU at kirksey.com]
> *Sent:* Tuesday, February 10, 2015 5:59 PM
> *To:* Nathan Kegel; West, Scott P; 'RobertWichert'; 
> bldg-sim at lists.onebuilding.org
> *Subject:* RE: [Bldg-sim] Revised TMY3 Weather Files now 
> available on the Web
>
> Nathan,
>
> 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.
>
> Regards,
>
> *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 
> <mailto: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:
>
> 3D graphs:
>
> “Heat Maps”:
>
> 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.):
>
> 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.
>
> <http://www.iesve.com/>
>
> 	
>
> *Nathan Kegel*
> *Business Development Manager*
>
> 	
>
> O:
>
> 	
>
> 763.276.9981
>
> M:
>
> 	
>
> 415.420.9314
>
> http://www.iesve.com <http://www.iesve.com/>
>
> 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
>
> Robert,
>
> 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:
>
> http://www.energy-design-tools.aud.ucla.edu/climate-consultant/request-climate-consultant.php
>
> 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.
>
> 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
> CEPE  CEA  HERS I/II BPI BA
> +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
>     -- 
>     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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