exitance coefficient, EC

[] The ratio of the average (time zero) wall exitance or ceiling cavity exitance to the quotient of the total lamp flux divided by the floor area.


(i) Exitance is in lumens per unit area, where the units of area agree with those of the floor area.

(ii) Average wall luminance or ceiling cavity luminance can be determined by noting the underlying assumption of lambertian room surfaces, where L = M/π; L is in candelas per unit area; and the units of area agree with those of M.

(iii) Exitance coefficients and former luminance coefficients are numerically identical.

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