A 160 ft by 200 ft practice space for a hockey team will have luminaires for ambient lighting hung 24 ft above ice level. It is anticipated that the ceiling reflectance is 0.80 and the average wall reflectance is about 0.50. The space will be illuminated with intermediate distribution, ventilated reflector luminaires, as shown in Figure 20.16 with 1000 W clear metal halide lamps with an initial output of 110 000 lm. The target illuminance is 50 fc at the floor plane. The light loss factor will be assumed to be 0.60.
a. Neglecting the spacing criteria (initially), determine the number of luminaires required to provide uniform illumination in the space.
b. Determine the maximum center-to-center spacing of the luminaires.

Figure 20.16
 

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4 Linear Fluorescent Lamps 10 0 O Spacing Criteria (CS) 1.51 1.2|| Surface Prismatic Wraparound Fluorescent Luminaire (Four Lamps) Reflectance Ceiling cavity (Pec) Wall Surfaces (Pw) Cavity Ratio (CR) 10 9 8 7 6 5 4 3 2 1 0 50 80 30 .26 .29 .31 27 .35 .29 .39 .44 .48 10 .21 .17 .23 .19 .23 .26 50 Coefficient of Utilization (CU) 30 30 50 30 10 .24 .19 .26 .29 32 .36 .31 .29 .33 .29 .38 .34 .39 .35 .44 .39 .44 .40 .54 .49 .46 .48 .61 .56 .53 54 .51 .67 .66 .63 .61 .76 .76 .76 50 10 .16 .22 .18 .25 21 22 .25 .21 .28 .24 28 25 .30 .27 .33 .32 .37 .33 .29 .29 .31 .41 .38 .36 .37 .46 .43 .46 .43 .40 .43 .40 .48 50 58 .47 .47 .46 .57 .56 .55 .53 .52 51 .59 .67 .67 .67 .63 .63 .63 .57 .57 .18 .15 .18 50 10 30 10 .21 .17 .23 .20 .21 .26 23 .24 .29 .26 .25 .31 .30 35 .35 .39 .17 .17 .20 23 .26 .29 .33 .38 .44 .50 .57