Coefficient of Utilization 1

[rrzzan]

Hi Guys,

I'm doing a lighting design for interior lighting.

To find the total # of luminaries I need to know the "coefficient of utilization" (C.U.)

I have effective reflectance of ceiling and walls as 50 and 10 respectively. And the room cavity ratio (RCR) is 0.54

When I look up the table for C.U., the RCR starts from 1

Can anyone suggest how the extrapolation is done for RCR?

(I've used the table on page 763)

Thanks in advance.

 

[EEJaime]

The CU function is a curve that is a first quadrant polynomial function. I don't know the function itself, but if you graph the points you will find that a curve fit, (didn't take the time to do this mathematically), will give you a value for the CU=.54 of somewhere near 0.73. It's just a rough approximation, but you can do it with greater care.

I think there's a lighting forum that would better fit this post, but I don't think it's very active.