2 Linear Tube Spacing Criteria Reflectance Ceiling Cavity (pc) Recessed Lay-in 2 ft x 4ft Open Parabolic Troffer Luminaire (Two Fluorescent Lamp) Coefficient of Utilization (CU) 80 70 50 Wall Surfaces (pw) 70 50 30 70 50 30 50 30 Fluorescent Lamps (CS) Cavity Ratio (CR) 10 .41 .32 .26 .40 .30 .25 .29 .25 9 .44 .34 .28 .42 .34 .28 .33 .28 8 .47 .36 .30 .46 .36 .30 .35 .29 7 .51 .40 .34 .50 .40 .34 .39 .34 1.41 6 .55 .46 .39 .54 .45 .39 .42 .38 1.2|| 5 .59 .51 .44 .58 .50 .44 .47 .42 4 .65 .56 .50 .64 .56 .50 .54 .48 3 .70 .64 .57 .69 .63 .56 .60 .56 2 .78 .71 .66 .76 .70 .67 .68 .65 1 .84 .81 .79 .82 .80 .78 .77 .75 Reflectance Recessed Lay-in 2 ft x 4ft Open Parabolic Troffer Luminaire (Three Fluorescent Lamp) Coefficient of Utilization (CU) Spacing Ceiling Cavity (poc) 80 70 50 3 Linear Tube Fluorescent Lamps Criteria Wall Surfaces (p) 70 50 30 70 50 30 50 30 (CS) Cavity Ratio (CR) 10 .39 .29 .25 .38 .28 .23 .28 .23 9 .40 .32 .27 .40 .32 .27 .30 .26 8 .44 .34 .29 .42 .34 .28 .34 .28 7 .47 .39 .33 .46 .38 .33 .36 .32 1.41 6 .51 .42 .36 .50 .41 .36 .40 .35 1.2|| 5 .56 .46 .41 .54 .46 .40 .45 .40 4 .59 .53 .46 .58 .52 .46 .50 .46 3. .65 .58 .54 .64 .57 .53 .56 .52 2 .70 .66 .61 .68 .65 .60 .63 .59 1 .77 .75 .71 .75 .72 .70 .69 .68 Reflectance Recessed Lay-in 2 ft x 4 ft Open Parabolic Troffer Luminaire (Four Fluorescent Lamp) Coefficient of Utilization (CU) Spacing Ceiling Cavity (poc) 80 70 50 4 Linear Tube Fluorescent Lamps Criteria Wall Surfaces (p) 70 50 30 70 50 30 50 30 (CS) Cavity Ratio (CR) 10 .35 28 .23 .34 .28 .23 .27 .23 9 .38 .29 .26 .36 .29 .25 .28 .25 8 .40 .33 .28 .40 .32 .28 .32 .27 7 .44 .35 .30 .42 .34 .30 .34 .29 1.41 6 .46 .39 .34 .46 .39 .34 .38 .34 1.2|| 5 .51 .42 .39 .48 .42 .38 .41 .38 4 .55 .47 .42 .53 .46 .42 .46 .41 3 .58 .54 .48 .57 .53 .48 .51 .47 2 .64 .59 .56 .61 .58 .56 .56 .54 1 .68 .67 .65 .67 .65 .64 .63 .60 4 Linear Tube Fluorescent Spacing Criteria Reflectance Ceiling Cavity (ps) Recessed Lay-in 2 ft x 4 ft Lensed Troffer Luminaire (Four Fluorescent Lamp) Coefficient of Utilization (CU) 80 70 50 Wall Surfaces (p) 70 30 70 50 30 50 30 Lamps (CS) Cavity Ratio (CR) 10 .46 .35 .29 .44 .35 .29 .34 .28 9 .49 .38 .31 .47 .37 .31 .36 .31 8 .52 .41 .34 .51 .41 .34 .40 .34 7 .56 .45 .38 .54 .44 .38 .43 .37 1.41 6 .60 .49 .42 .58 .49 .42 .47 .41 1.2|| 5 .65 .55 .48 .63 .54 .47 .52 .46 4 .70 .61 .54 .68 .60 .53 .57 .52 3 .76 .68 .61 .74 .66 .61 .64 .59 2 .83 .76 .71 .81 .75 .70 .72 .68 1 .90 .86 .83 .88 .85 .82 .81 .79