AFMG Network Forum

franzv78 · Member

Hi and thanks in advance for the reply.
When dealing with complex models, sometimes to me it's necessary to create elements, composed of two-folded faces, contained into the main model in order to be able to keep a closed room. Think for example to a classical theater where a balcony it's created as a two-folded faces box simply contained into the main room. I'm pretty aware of the fact that this could not be 100% technically correct as each inner element should be created as "negatively" inscribed into the room, but as a matter of fact sometimes the complexity of the model requires a certain flexibility.

What I noticed is that both faces (orange and blue to simplify) of those "inner" elements (even for a closed volume) contribute to RT60 calculation, that in my opinion could affect the precision of the results depending on the ratio between surfaces of model and inner elements.

If we think of a simple "wall" inserted into a room, both sides should contribute, and this is ok.
If we think of a closed volume (the balcony of the above example), theoretically the blue faces should be excluded from the calculation as not impacting RT60 in reality. Is it correct? Is there a way to exclude those?

Thanks,
Francesco

AFMG Frank Siegmann · Member

Hi Francesco,

yes,. that's correct. For closed volumes only the outer side should contribute.

As workaround you shouldn't use two fold faces for closed volumes.

Frank Siegmann
AFMG

Bruce · Member

The box for the balcony should be done with single-fold faces with the yellow side towrds the room. This means that the faces are all inverted from their normal orientation when creating a room. This then means that only the back surface of the balcony, the one that is normally the back wall of the theatre is adding surface area that should not be in the room because you may be unable to coat the face to that back wall. Now it also subtracts the volume contained in the balcony as well from the total volume.

franzv78 · Member

Thanks Bruce, your explanation works. I created a room made of a cube with a smaller cube inside and tested different scenarios and to me results are coherent. Volume, surface and RT calculation are impacted according to inner element face orientation and possible coatings.
Going back to the balcony, I believe that as soon as you coat the face of the inner element on the one that overlaps of the main room, results should be coherent.
Many thanks,
Francesco