
560 Principles of Sustainable Energy Systems
© 2008 Taylor & Francis Group, LLC
Step 5: Work-plane illuminances
As discussed earlier, Figure 9.17 illustrates the location of the work-plane illuminances
determined with this lumen method of sidelighting. The three illuminances (max, mid,
min) are determined using two coefcients of utilization, the C factor and the K factor. The
C factor depends on room length, width, and wall reectance. The K factor depends on
ceiling-oor height, room width, and wall reectance. Table 9.8 presents C and K values for
the three cases of incoming uxes: sun plus clear sky, overcast sky, and ground-reected.
Assu ...