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Room Cavity Ratio

The room geometry is accounted for in cavity ratios or CR.

The equation for Cavity Ratio is:

__CR = 5 x H x (L + W)__

(L x W)
CR equals 5 times Height x the sum of length plus width divided by the result
of length times width.

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Cavity ratios can be calculated for the ceiling, room and floor by using the
appropriate cavity dimensions.
Let's calculate the CR for a room with the dimensions of Height=6, Length=12,
and Width=10.

*12x10 equals120. So CR = 5x6x120 or 660 divided by 120. The result is a
Cavity Ratio of 5.5.
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*For a given space, calculate the CR and then use the fixture manufacturer's CU
table to select the appropriate CU.