Lighting

[ABH]

Hey, 

My ceiling is white but comes out in the rendering as dark gray, how can I fix that?

[Roy Hirshkowitz]

I don't have a lot of time to work on yours, but here are some general observations.

1. Omnidirectional sources cast light in all directions.  Don't use these for flush mounted figures.  At best you'll be wasting a lot of time calculating light that just end up in the ceiling space-- at worst you'll create a bunch of artifacts for yourself.  Select all of the circular downlights, right click, hit Properties, and change the distribution to Spot lights.
2. Use surfaces, not solids, for lights which are flush-mounted.  The light labeled "Mikveh Side" in the current view is an example of a solid which should probably be a region or 3dface.  This light also exhibits problem 3.
3. Be careful of coincident surfaces when rendering.  Two objects which occupy exactly the same space cannot be  resolved consistently by most renderers.  Make sure flush-mounted lights are displaced a fraction of an inch below the ceiling plane.  As noted before, this is not just a problem with the lighting in your model-- but some objects like the glass around the show occupy exactly the same space as some other objects.
4. It's probably better to break long cove lights into several smaller ones (perhaps a 4' limit in length).  This will also help you set your intensity.  100 watts of incandescent illumination (1700 lumens) is likely not nearly enough intensity for an entire wall of cove lighting.  Always use realistic lighting values.  These lights can have Omni distributions if they're modeled as tubes.
5. Be careful to only model those lights you're interested in.  More lights will result in longer rendering times.  More complex lighting will take longer to resolve.
6. Let the program inform you about the design.  It's good at simulating lighting-- that's its job.  For example, surrounding the Mikveh in dark materials is a really interesting idea.  Using a good simulation though, you can tell that it may be highlighting things like the shower-- which may not be your intent.