# cavity ratio, CR

[9.4.5] A number indicating cavity proportions.

The cavity ratio is computed from:

$CR = frac{5 left ( Height_{cavity} right ) left ( Length_{cavity} + Width_{cavity} right )}{left ( Length_{cavity} right ) left ( Width_{cavity} right )}$

For cavities of irregular shape:

$CR = frac{2.5 left( Height_{cavity} right ) left ( Perimeter_{cavity} right )}{(Area of Cavity Base)}$

Note: The relationship between cavity ratio and room coefficient (Kr) should be noted. If the entire room is considered as a cavity, the room height becomes Heightcavity, and CR = 10 Kr.

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