[Bldg-sim] Beijing weather data

[Sami, Vikram]

Thanks Joe - this is good input. I didn't realize that you worked on this.



You're right - it does mean 100% humidity - which I think looks wrong.



Heres a view of the entire year from the CSWD file plotted over the entire year. That looks completely wrong to me. I think I'll stick with the CTYW or the SWERA.



[cid:image001.png at 01CB11FA.6037B1B0]



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

Perkins+Will.  Ideas + buildings that honor the broader goals of society





-----Original Message-----
From: Joe Huang [mailto:YJHuang at whiteboxtechnologies.com]
Sent: Tuesday, June 22, 2010 10:55 AM
To: Sami, Vikram
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Beijing weather data



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/>

>

> *Perkins+Will.*  Ideas + buildings that honor the broader goals of society

>

> *75logo_only.gif*Years of Design Innovation* *

>

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