RE: Overhang and wingwall shading

[Michaël Kummert <kummert@xxxxxxxxxxxxx>]

Dear Dorota,

> I would like to know if it is the only way? 
> It would be complicated for me because i have 
> got 25 zones ( two windows >with overhang and 
> wing wall in each). Could you explain me when 
> I should use external shad. factor as option 
> in Windows' description in PREBID.

It is possible to use ESHADE to approximate the shading effects due to
overhangs and wingwalls. However, you have to use equations between Type 34
and Type 56. One equation should be defined for each Type 34. The equation
computes a shading factor:
ShadFact=[1-(Tot. shaded rad.)/(Tot. unshaded rad.)]

The Total shaded radiation is output 1 from Type 34 and the Total unshaded
radiation is available from Type 16 (attention, input 5 of Type 34 is the
incident BEAM radiation while you need the TOTAL radiation in your
equation).

In Prebid, you have to define the shading factor as an input. You can then
connect the corresponding "ShadFact" equation to the Type 56 inputs in
IISiBat.

If I am right, there will be a slight difference between the solution here
above and the solution described by David Bradley, because the diffuse
radiation will not be treated in the same way. I don't think the difference
is too important unless you would want to study a particular shading device
or window in detail.

The next Trnsys release will include a modified Type 34 which will output
ESHADE directly, so you will not need the equations anymore.

Michaël Kummert

_________________________________________________________

Michaël Kummert

Solar Energy Laboratory - University of Wisconsin-Madison
1303 Engr Res Bldg, 1500 Engineering Drive
Madison, WI 53706

Tel: +1 (608) 263-1589
Fax: +1 (608) 262-8464
E-mail: kummert@engr.wisc.edu (*****NEW*****)

SEL Web Site: http://sel.me.wisc.edu 
TRNSYS Web Site: http://sel.me.wisc.edu/trnsys