[Radiance-general] Radiance and Ecotect

[Nick Doylend]

Thanks very much for your suggestions.

I looked briefly at outputting glazing data from Optics.  It's probably the
way to go if I want to model a 'real' glazing type.  I don't really
understand how the BRTDfunc is used; it sets the surface reflectance as well
as transmittance doesn't it?  At the moment I'm only considering a
'notional' glazing so I'm just calculating the transmissivity and editing
the Radiance file output from Ecotect by hand.  For typical glass types, how
much difference would using the BRTDfunc definitions make to my internal
daylight calculations?

As far as reliability of results is concerned, It seems Radiance (in the
hands of an expert user) is more capable of realistic results than Ecotect.
I've noticed that Ecotect's speed of calculation is influenced quite
significantly by the number of windows.  It doesn't appear to make much
difference to Radiance's calculation time.  I guess it's down to the
differences in calculation method but it does make me wonder how well
Ecotect handles models with many windows.

On the other hand, I find Radiance doesn't seem to behave quite as expected.
For example, for an equal glazed area I would expect fewer, larger
rooflights to give the same average %DF across the whole floor as more,
smaller rooflights.  In this case, Ecotect seems to behave as I expect, but
Radiance suggests fewer, larger rooflights give the better average %DF.  I
wonder why this should be.  Maybe my assumption is incorrect.

Nick