QUESTION:

Why do my lighting calcs take a really long time, i.e. about 5 hours to get to 2% ?

ANSWER:

Not to put too fine a point on it, this usually happens when you import a massive triangulated model from a 3D CAD program and then click Calculate. There are so many planes to check, half of which are probably redundant, that the lighting functions are likely spending most of their time checking if the curved bevels on the skirting boards in flat 15 obscure the lower floor window in Flat 3, for example. The number of planes required to define a filleted skirting board is massive compared to one or two required to define the wall on which it sits. ECOTECT has no way of telling which planes are more significant than any others so it will check every single one of them.

The solution to this is some common sense. It's much easier for you the user to determine which planes in the model are really going to affect the lighting and those that won't.

So to speed up the lighting calcs, you should delete the ones that won't have any significant effect, such as the skirting boards, the carefully constructed flowing folds of curtain (replaced with a single flat plane with a reduced transparency), etc...

It is important to note as well, that importing a 2D DXF to trace from in ECOTECT can also cause the same issue. In this instance it is best to save 2 versions of your model, one with the DXF (in case you need to refer to it again later) and one with the imported DXF geometry removed so it does not slow down any calcs.