For the glases of the windows, you use only one plane with thin(no refraction) and portal lights or the brute force method, you know, with a box.
When a slight possibility of visible refraction (like glass edges) exists, I always use box. For this project, Box glass and no portals (not needed, look at how open these spaces are).
For projects with very little windows, thin and yes, portals.
I wonder how long they took to render.
Not the type of answer people would perhaps like: A lot of hours :- ) In the end it's not much issue since I have few computers to do that job, but it's not fast.
I render quite hi-res (for big commercial project I start in December, we agreed with client on 8400px because of print, so that has some cost too) but they're not super fast even in lower res :- )
Exteriors are fast, but GI+Glossies have their cost, regardless of rendering engine ( that I use/used ).
Can I ask what your opinions are about Corona compared to Vray?
Don't like to go into this territory :- ) I have a love/hate relationship with Vray. Don't get me wrong, I am not evangelist, Vray 3 is excellent rendering engine. For all my animations jobs, it's till what I use primarily.
I
could give you some tangible answer what is faster and when, but people would rip me apart because it's such a emotional topic. If I said Vray is faster here, someone would tell me I don't know how to use Corona,
if I said Corona is faster here, Vray fanboys would tell me I don't know how to use Vray correctly and so... I am tired of that and not interested in software wars. I don't even care, I am utilitarian, I am always trying something else and having fun, checking if it works for me.
I invested
thousands of hours into Vray, not just using it, but getting super deep into every parameter. Yet, I use Corona for 80perc. of my commercial work, and 100perc. of my "hobby" work. That should give you quite an answer
what I think is the better engine
for me and my type of work.