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Re: [EnergyPlus_Support] Negative Zone Transmitted Solar

This sounds like a weather file problem. My suspicion is that your 
direct normal solar converted to a horizontal value is larger than the 
global horizontal radiation, since direct horizontal + diffuse 
horizontal = total global horizontal. To convert the direct normal to 
direct horizontal, divide it by the cosine of the solar angle.

Joe

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


On 4/14/2012 2:49 PM, custudent213 wrote:
>
> I created a weather file using the E+ utility and monitored weather 
> conditions from a weather station I installed. The weather station 
> provides wind speed, global horizontal radiation, dry bulb temp, and 
> relative humidity. It looks like the utility works great - I have 
> acceptable numbers for direct and diffuse solar - but when I use the 
> custom weather file with my building E+ model, I get brief moments of 
> negative transmitted solar energy right at sunset for about a week in 
> March, which never appears when I use the standard EPW file for a 
> near-by city.
>
> I am trying to figure out how to interpret the negative transmitted 
> solar energy. Is it just solar energy reflected out of the house? If 
> so, why doesn't it happen with the standard epw file? My diffuse and 
> direct solar energy is of course always positive. Ultimately it isn't 
> large enough to have a major impact on the building energy use, but I 
> have to defend the process for my research and it raises some red flags.
>
> Danny
>
> 


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