[Bldg-sim] Beijing weather data

[Joe Huang]

Vikram,

I like your plots, but I have one suggestion - you should plot the total 
and diffuse radiation as solid shades and the direct normal as the solid 
line, since diffuse is always a subset of the total horizontal, while 
the direct normal can be higher than either of the other two because of 
the sun angles.

I helped in the creation of the CTYWs back about 14 years ago, and am
aware of the CSWD and SWERA efforts, but have not compared the three 
sets in detail. I agree with you that the solar and humidity on the CSWD 
look suspicious. Do the 3-4 months showing only a single temperature 
line indicate that the wetbulb is identical with the drybulb, i.e., that 
RH is at 100% for the whole month? That's hard to believe. Likewise, the 
spikes in direct normal solar are no doubt a problem with the algorithm 
used to distribute the measured daily to the hourly solar values.

The SWERA and CTYW both use similar raw data originally from the US 
Climate Data Center. In both files, the solar is estimated using various 
radiation models based on cloud cover and other climate parameters. When 
"tuned" to measured data, these models have been found to be pretty 
accurate on the aggregate, i.e., monthly or annual means, level, but can 
be considerably off for any particular hour or day.

Joe


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


Sami, Vikram wrote:
> 
> 
> Apologies for the size of the attachment.
> 
>  
> 
> I'm looking for weather data for Beijing, and I see three weather files 
> on the Energy plus site.
> 
>  
> 
> The first one is the CSWD (Chinese Standard Weather Data) source.
> 
> The second is the CTYW (Chinese Typical Year Weather) source
> 
> And the last is the SWERA (Solar & Wind Resource Assessment).
> 
>  
> 
> It seems like the first one has very strange solar radiation data - 
> strange spikes that really look wrong. It also seems like the humidity 
> numbers are too high - pretty much 100% most of the year.
> 
>  
> 
> The last two look more reasonable and are pretty similar (which would 
> indicate that they are more reliable). However - they both show really 
> low direct solar in the summer months (less than diffuse).
> 
>  
> 
> Has anyone had any experience with this? Which one should I use?
> 
>  
> 
>  
> 
>  
> 
> *Vikram Sami*, LEED AP
> 
> Sustainable Design Analyst
> 
> 1382 Peachtree St. NE, Atlanta, GA 30309
> 
> t: 404-443-7462    f: 404.892.5823       e: 
> vikram.sami at perkinswill.com   www.perkinswill.com 
> <http://www.perkinswill.com/>
> 
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