[TRNSYS-users] solar absorptance of walls

[David BRADLEY]

Wirich,
   If you are using Trnsys17 then there is almost certainly an automatic 
connection of solar radiation between the weather data reader and the 
building because in TRNBuild the default selection is that those 
connections will be made for you.

   I would guess that the difference lies in how you have treated the 
floor of your zone. If you created a BOUNDARY wall for your floor then 
Type56 is expecting you will provide a temperature on the back side of 
the floor (i.e. the interface between the floor and the soil). If you 
did not make a connection to the boundary temperature Type56 input then 
it is probably set to a constant value of 0 C, which would keep your 
zone temperature quite low throughout the year.
Regards,
  David


On 8/28/2014 03:30, FREPPEL Wirich wrote:
> Hello everyone,
>
> I'm running some tests in order to compare TRNSYS to another software, 
> which is Energy+.
>
> My model is simple, a 3 meters long cube, with the same composition 
> for all the faces, without windows.
> What I did in first place, was to create a new multizone project using 
> an idf file created from sketch up. Then I runned the simulation in 
> order to observe the evolution of the air temperature inside the box.
> Comparing it to Energy+ results, I noticed that in summer, the 
> temperature is far below those of Energy+. So I looked at the 
> connections in simulation studio to see if there was a problem on the 
> solar radiation on the walls, and I noticed that initially, there are 
> not any connection which give the solar radiation on the walls.
>
> My conclusion is that to take account of the solar radiation on walls, 
> we have to link it by ourself at the beginning, is it right or did I 
> miss something?.
>
> Furthermore, in the "wall type manager", there's a tab called "Solar 
> Absorptance of wall". When I change the value, nothing change 
> regarding the temperature inside the box. So when is this value used 
> exactly?
>
> Thank you in advance.
>
> King regards
>

-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com