oh ok then you know how to go probably, put furnitures on differents layers (from 2015 layers can be nested if I understood well) otherwise just put all furnitures in layers like furniture house1 / furnitures house 2 / etc... and switch them off when unneeded according to the location you are rendering... there's no point in calculating the light below a table 150 meters from your view, well may be corona is good enough to not taking care too much about hidden corners but if you have your main rays reflections set to 25 bounces, who knows where it get for not much at the end. By the way I would say that you can reduce that too (render settings, main settings), better for interior where light bounces means realism, outside are more straightforward in my opinion 10 bounces and that's it... but let's hear some experts advices...
Hidding un-needed objects would for sure save some ram. (all the fans etc, cannot see them after 40meters anymore)
You should try to do the same with vegetations, don't need to render grass or stones behind a wall, or far away, just use a simple texture with proper color to tint things around properly.
I know you can constraint instances to the camera angle with forest, but I don't think you can dismiss instance in the camera's angle hidden behind something else, so try to make good use of it, use the distance parameters (scale a bit instance far away and use less)
http://www.itoosoft.com/forestpack/reference/refcamera.phpIf because of your animation you need everything to be visible along one sequence, just break it down in shorter pieces.
Note : about visual, I would try to harmonize color of that tall dry grass a bit too white, adding relief to the curved roof to, it looks a bit too much mapped right now (though i'm not sure it is). Have you tried to use round corner advanced material option for distant buildings ? the bump map of water is a bit to strict on some view too...
