[Archived phorum post from squ1.com v2 by Olivier]

Dan,

For RT calculation, I think the important factores are the volume of the zone and the material used in the zone to figure out the Sabine index.
So as long as you have a good calculation on your zone volume, which you can adjust in the zone management, I do not see an issue with using "none" for the overshadowing calculations.
I am not sure whether overshadowing calculations are responsible to detect the surface normal of an element, or if that is done in the IZA. I am thinking about the material of the element and whether Ecotect can determined what surface material is internal or external, although I do not know if it matters for RT calc, or if the absorbtion of the entire composite of the element is used (rather than say the one material facing the interior of the zone), which I think is the case.

Anyone eles has any comments on this?

[Archived phorum post from squ1.com v2 by craines]

The overshadowing option in the IZA calc is definately just for thermal, and solar etc... so we would definately suggest switching this option to none for an acoustic calc.

To clarify a bit for you Olivier, the Overshadowing is only calculating the shading masks for objects -- ie. to determine when they are overshadowed. These are just like the percentage shading calculations that you can do for an object via the sun-path diagrams calc, but they are done for all objects in the model, hence the reason they can take a while especially if the accuracy setting is high.

Hope this helps...
Regards,
Caroline

Caroline Raines
Square One research Pty Ltd

[Archived phorum post from squ1.com v2 by dan mcintosh]

Caroline and Olivier,

Thanks for the replies. That clears up my question perfectly, and am appreciating the faster RT calculations as I type

Cheers,
Dan