Cost-Effective Visibility-Based Design Procedures for General Office Lighting

The concept of cost benefit analysis leads directly to the use of visual performance (i.e., the speed or accuracy with which a visual task is performed) rather than derived metrics such as ESI or VL as the basic visibility related performance parameter. The 1977 IES Design Committee's recommended specification procedure does not have visual performance in its formulation and hence will not lead to cost~effective general lighting designs. We discuss the direct calculation of average relative visual performance (RVP) and then present a reasonably accurate approximation which has significant advantages in speed and flexibility. Finally, we attempt to assess the conditions under which this procedure will provide useful information