[Radiance-general] Re: Radiance and Ecotect

[Reinhart, Christoph]

>>John wrote : So, to answer your ultimate question, I generally trust
Radiance results over Ecotect results. But then again, this is just my
opinion. The difference between Ecotect and Radiance results are simply
because of the algorithm used. This does not necessarily mean that one
is wrong and the other is right.

I largely agree with what John wrote except that I would add that once
the material properties have been properly assigned in your Ecotect and
Radiance models, Radiance should be your benchmark. In case you are
close to a window, the simulation results of both programs should (and
do) largely coincide, but if you use an L-shaped room with a single
window in one of the 'end' walls and run an Ecotect DF simulation,
you'll see that as soon as a sensor does not 'see' the window any more,
the DF become zero which is of course physically incorrect. On the other
hand, Ecotect is somewhat faster than Radiance so for the 'easy' cases
it might be your preferred choice. 

In the end you should think twice before using the daylight factor as
its capability to improve your design is somewhat limited. You might
want to look at dynamic metrics instead such as daylight autonomy,
useful daylight index, or continuous daylight autonomy using either SPOT
or DAYSIM. The new Daysim calculates all three metrics for you and you
can load the results back into Ectoect.

One useful feature that might be of interest is that the export function
from Ecotect to Radiance can be set so that Ecotect checks whether a
file <layer name>.rad exists in the "Material Export Directory" (Menu
option: FILE >>> USER PREFERENCES). If so, it uses the content of the
*.rad file as the material description for the layer in the Radiance
model. 

Christoph