Lighting Calculations

COEFFICIENT OF UTILIZATION (LUMEN METHOD)

Luminous Element Type		Plastic Louvers White		Aluminum Louvers White Note No.1		Prismatic Lens Clear		Formed & Flat Plastic White		Parabolics 1/2" - 3" Specular Silver Note No. 2		Parabolics 1/2" - 1" Specular Silver Note No. 2		Skylites		Quad Cube & Quad Leaf White Note No. 3
Walls		50	30	50	30	50	30	50	30	50	30	50	30	50	30	50	30
J	0.8	.27	.23	.25	.19	.23	.17	.20	.14	.23	.19	.26	.23	.21	.17	.20	.16
I	0.9	.32	.27	.27	.23	.30	.24	.27	.21	.27	.23	.33	.30	.26	.22	.21	.19
H	1.0	.36	.31	.30	.27	.37	.30	.35	.27	.31	.27	.37	.33	.31	.27	.24	.21
G	1.25	.39	.35	.35	.29	.42	.33	.40	.33	.35	.31	.40	.36	.36	.32	.28	.25
F	1.5	.42	.38	.40	.33	.46	.37	.44	.42	.39	.35	.43	.40	.40	.36	.32	.29
E	2.0	.46	.41	.44	.39	.50	.42	.48	.45	.43	.39	.46	.43	.43	.39	.35	.31
D	2.5	.48	.44	.47	.43	.53	.47	.52	.48	.47	.43	.49	.45	.46	.42	.37	.33
C	3.0	.50	.46	.49	.45	.57	.52	.55	.51	.51	.47	.50	.47	.49	.45	.38	.35
B	4.0	.52	.49	.50	.47	.60	.57	.58	.54	.54	.50	.51	.49	.52	.48	.39	.37
A	5.0	.53	.50	.51	.49	.63	.61	.61	.57	.57	.53	.53	.51	.54	.51	.40	.38

Notes:
Many factors influence the efficiency of a lighting system. The C.U. chart above is a general guide. We are glad to provide data for your particular application.

1. Light Colors - deduct 30%.
Dark Colors - deduct 50%.

2. Specular Gold - deduct 5%.

3. Light Colors - deduct 30%.
Dark Colors - deduct 50%.

General Note: If overlay or diffuser is used: deduct 30%. For Coffer designs: deduct 20% - 40%. Contact us for correct deductions. Apply all percentage deductions to basic coefficient of utilization.

ROOM INDEX

For Direct, General Diffusing & Semi-Direct		MOUNTING HEIGHT ABOVE FLOOR - FEET
For Direct, General Diffusing & Semi-Direct		7 & 7-1/2	8 & 8-1/2	9 & 9-1/2	10 - 11-1/2	12 - 13-1/2	14 - 16-1/2	17 - 20-1/2
Room Width (Feet)	Room Length (Feet)	Room Index
9 8-1/2 - 9	8 - 10	H	I	J	J
	10 - 14	H	I	I	J
	14 - 20	G	H	I	J	J
	20 - 30	G	G	H	I	J	J
	30 - 42	F	G	H	I	J	J	J
	42 & up	E	F	G	H	I	J	J
10 9-1/2 - 10-1/2	10 - 14	G	H	I	J	J	J	J
	14 - 20	G	H	I	J	J	J	J
	20 - 30	F	G	H	I	J	J	J
	30 - 42	F	G	G	H	I	J	J
	42 -60	E	F	G	H	I	J	J
	60 & up	E	F	F	H	H	I	J
12 11 -1/2 - 12-1/2	10 - 14	G	H	I	I	J	J	J
	14 - 20	F	G	H	I	J	J	J
	20 - 30	F	G	G	H	I	J	J
	30 - 42	E	F	G	H	I	J	J
	42 -60	E	F	F	G	H	I	J
	60 & up	E	E	F	G	H	I	J
14 13-1/2 - 15-1/2	14 - 20	F	G	H	H	I	J	J
	20 - 30	E	F	G	H	I	J	J
	30 - 42	E	F	F	G	H	I	J
	42 -60	E	E	F	F	H	I	J
	60 - 90	D	E	D	F	G	H	J
	9 0 & up	D	E	E	F	F	G	I
17 16 - 18-1/2	14 - 20	E	F	G	H	I	J	J
	20 - 30	E	F	F	G	H	I	J
	30 - 42	D	E	F	G	H	H	J
	42 -60	D	E	E	F	G	G	I
	60 - 110	D	E	E	F	G	G	I
	110 & up	C	D	E	E	F	G	H
20 19 - 21-1/2	20 - 30	D	E	F	G	H	I	J
	30 - 42	D	E	E	F	G	H	I
	42 -60	D	D	E	E	F	G	I
	60 - 90	C	D	E	E	F	G	H
	90 - 140	C	D	D	E	F	F	H
	140 & up	C	D	D	E	F	F	H
24 22 - 26	20 - 30	D	E	E	F	G	H	I
	30 - 42	C	D	E	F	G	G	I
	42 -60	C	D	D	E	F	G	H
	60 - 90	C	D	D	E	F	F	H
	90 - 140	C	C	D	E	E	F	G
	140 & up	C	C	D	E	E	F	G
30 27 - 33	30 - 42	C	D	D	E	F	G	H
	42 -60	C	C	D	D	F	F	H
	60 - 90	B	C	C	D	E	F	G
	90 - 140	B	C	C	D	E	E	F
	140 - 180	B	C	C	D	E	E	F
	180 & up	B	C	C	D	E	E	F
36 34 - 39	30 - 42	B	C	D	E	F	F	H
	42 -60	B	C	C	D	E	F	G
	60 - 90	A	C	C	C	E	E	F
	90 - 140	A	B	C	C	D	E	F
	140 - 200	A	B	C	C	D	E	F
	20 0 & up	A	B	C	C	D	E	F
42 40 - 45	42 -60	A	B	C	C	E	F	G
	60 - 90	A	B	B	C	D	E	F
	90 - 140	A	B	B	C	D	D	E
	140 - 200	A	A	B	C	D	D	E
	20 0 & up	A	A	B	C	D	D	E
50 46 - 55	42 -60	A	A	B	C	D	E	F
	60 - 90	A	A	B	C	C	D	F
	90 - 140	A	A	A	C	C	D	E
	140 - 200	A	A	A	C	C	D	E
	20 0 & up	A	A	A	C	C	D	E
60 56 - 67	60 - 90	A	A	A	B	C	D	E
	90 - 140	A	A	A	B	C	C	D
	140 - 200	A	A	A	B	C	C	D
	20 0 & up	A	A	A	B	C	C	D
75 68 - 90	60 - 90	A	A	A	A	B	C	D
	90 - 140	A	A	A	A	B	C	D
	140 - 200	A	A	A	A	B	B	C
	20 0 & up	A	A	A	A	B	B	C

Formulas

Lamp Lumens Required = Foot Candles Desired x Room Area / C.U. x M.F.

Lamps Required = Lamp Lumens Required / Lumens per Lamp

Maintenance Factors

Good = .75; Fair = .70;
Poor = .65

Notes: Luminous ceilings are calculated like other florescent lighting. However, it is important to remember that the lighting efficiency depends heavily on an unobstructed, white plenum. Plenum reflectances, obstructions, room reflectances, etc., will affect the coefficient of utilization. These C.U. charts are based on 85 - 90% of the room area luminous, a ceiling reflectance of 80%, a wall reflectance of 50% and a floor reflectance of 20%. The C.U. chart is for approximate calculations only and applies only to Norton Industries, Inc. luminous elements.