Coefficient of Utilization (CU) is the percentage of light generated by the lamps in a luminaire that reaches the work plane in the room. The CU accounts for both the room surface reflectances and the room geometry. The numbers listed in a CU table may be percentages (for example, 39, meaning 39%) or may be decimal values (for example, 0.39, meaning 39%). The CU table shows the luminaire's performance under different combinations of wall and ceiling cavity reflectance conditions and room shapes.

Original Chapter Source: Luminaires
Provided By: North/Naomi Miller