[Bldg-sim] TYM2 weather data

Joe Huang yjhuang at whiteboxtechnologies.com
Thu Oct 18 14:40:19 PDT 2012


The only TMY2 files I'm aware are 239 files for US locations.  What is the source for the 
Poznan file that you mentioned?  Are you referring to the IWEC or IMGW file available in 
EPW format on the EnergyPlus web site?

It seems you're referring to TMY2 as a format, not a weather file type.  The TMY2 format 
was developed by NREL, and as in your quote below, it has both measured as well as 
calculated data.  To explain what the excerpt says,
the TMY2 data format contains dry-bulb, dew-point, and relative humidity. However,  
weather stations typically measure only two, mostly dry-bulb and dew-point, in which case 
the RH is calculated.  On the other hand, if the weather station measurements are dry-bulb 
and RH, then the dew-point temperature is calculated.

If you're trying to get your measurements into the TMY2 format, please note that you will 
have to calculate quite a bit of information, such as extraterrestrial radiation, three 
types of illuminances, precipitable moisture, RH, etc.
If the simulation program you're using (TRNSYS ?) doesn't read those, you could leave them 
as empty data fields.

It sounds like you're trying to strip out information from the Poznan TMY2(?) weather file 
and then combine that with your measured data.  I wouldn't recommend that because the time 
sequence is wrong,  so I don't know what you'll get in the end.

I've had a lot of experience working with various weather file formats, including TMY2.   
Let me know if you have more questions about this.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
www.whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"


On 10/18/2012 3:22 AM, Karol Bandurski wrote:
>
> Dear All,
>
> 1)
>
> I have already converted TYM2 data for Poznan (PL-Poznan-Lawica-123300) from text file 
> to excel using: http://sel.me.wisc.edu/trnsys/weather/tmy2data.htm.
>
> Some of meteorological data, which are there, have additional columns named /Flag of 
> Data Source/. Dry bulb temperature is one of these data. In my file is written that 
> *_data source for dry bub temperature is_* E, and in TYM2 manual 
> (http://rredc.nrel.gov/solar/pubs/tmy2/PDFs/tmy2man.pdf) I have read that it means:
>
> Modeled or estimated, except: precipitable water, calculated from
>
> radiosonde data; dew point temperature calculated from dry bulb
>
> temperature and relative humidity; and relative humidity
>
> calculated from dry bulb temperature and dew point temperature
>
> *Could you explain me what it is mean? I expected that temperature is measured...*
>
> 2)
>
> *_The second issue_* is that I would like to create my own TYM2 file to run TRNSYS 
> simulation with my own meteorological data. How should I model e.g. illuminance... of 
> maybe I don't need this value if I use in simulation only:
>
> ·Dry bulb temperature,
>
> ·Effective sky temperature,
>
> ·Humidity,
>
> ·Wind velocity and direction,
>
> ·Atmospheric pressure,
>
> ·Solar zenith and azimuth angle,
>
> ·Total surface radiation,
>
> ·Beam surface radiation,
>
> ·Angle of incidence for surface,
>
> ·Ground reflectance.
>
> *Which data (columns) do I need in TYM2 file to get above values?*
>
> I will be grateful for any tips!!!
>
> Regards
>
> ------------------------------------------------
>
> Karol Bandurski MSc.
>
> Institute of Environmental Engineering <http://www.ee.put.poznan.pl/>
>
> Poznan University of Technology
>
> www.ee.put.poznan.pl <http://www.ee.put.poznan.pl/>
>
> www.put.poznan.pl <http://www.put.poznan.pl/>
>
>
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