[TRNSYS-users] Type 34, again ...

[Enertech]

Dear TRNSYS Users,

When I want to simulate a building, the biggest difficulty is to take into 
account the good insolation. For a big building with a lot of balconies, 
it's impossible to be accurate in calculation of shading masks, without 
using hundreds of type 34. So we have to simplify the phenomena.

I find a new problem (for me) with Type 34 : I simulate a building without 
any overhang and wingwall and I find a certain quantity of Qheat = Qheat1 
(for example). I want to test wingwall, so I add a type34. At first, I test 
a type 34 with all overhang and wingwall lengths equal to 0. The problem is 
that I don't find the same quantity of Qheat (Qheat2) for my building. 
Qheat1 is bigger than Qheat2.

To refind the same Qheat in the 2 cases, I have to change the Sky Model for 
diffuse radiation in the type 109 Wheather data, from the Perez Model to 
the Isotropic sky model.

So, what should I think about that ? What is the impact of the Isotropic 
sky model on the accuracy of a building simulation ? Is there a way to keep 
the Perez Model and to refind the same Qheat in the 2 cases (with and 
without type34).

Thanks for your help.
Christophe.


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