Definitions for "Room cavity ratio"
(Abbr. RCR) A ratio of room geometry used to quantify how light will interact with room surfaces. The room cavity is the portion of the space from bottom of the luminaire to the workplane.
In lighting calculations, a measure of room proportion as determined by dimensions of length, width, and height.
A shape factor (for a room, etc.) used in lighting calculations. RCR = 5H (L+W) / L x W, or, alternately, RCR = (2.5) Total Wall Area / Floor Area. Where H = height, L = length and W = width of the room. A cubical room will have an RCR of 10; the flatter the room the lower the RCR.