How to calculate the number of luminaires

Basic data

Room:

length – а;
width – b;
height – h;
reflection coefficients of the ceiling, walls and floors.

Luminaires:

coefficient use of luminaires;
estimated height (distance between the luminaire and the working surface).

Lamps:

lamp type;
power.

Norms:

required illumination.

The calculation of luminous flux:

Supporting materials:

Table of coefficients of use
Table of reflection of coefficients
Table of recommended levels of illumination
Table of initial luminous flux of fluorescent lamps

Calculation formulas:

Definition square room: S = a × b .
Definition of index room: φ = S / ( h - К_s ) * ( a + b ).
Definition coefficients use the lighting system for tables the various series fixtures from the values of reflection coefficients and the index premises.
Definition the required number of fixtures: N = ( E * S) / ( U * n * F_l * К_s )

Е – required horizontal illuminance, lx.

S – coefficient square room, sq.m.

К_s– safety factor (К_s = 0,8)

U – coefficient of use the lighting system.

F_l – luminous flux of a lamp, lux.

n - number of lamps in one fixture.

Example calculation:

Office, light ceilings, light walls, gray carpet. Baseline data: room a = 9 m, b = 6 m, h = 3,2 m. Lamp LPO 12-2 × 40-904, fluorescent lamp 36 W, in a single lamp 2 lamps, F = 2850 lm (production PHILIPS) . The norm of the E = 500 lux at 0.8 m above the floor. The safety factor Ks = 0,8. The reflection coefficient of the ceiling - 0,5, walls - 0,5, sex - 0,3.

Calculation:

define square room: S = a × b = 6 × 9 = 54 m2
define the index room: φ = S / (h - Ks) * (a + b) = 54 / (3,2 - 0,8) * ( 9 +6) = 1,5
determine coefficient of use the lighting system, based on the reflection coefficient and the index space U = 0,51
determine the required number of Lamp: N = (E * S) / (U * n * Fl * Ks) = (500 * 54) / (0.51 * 2 * 2850 * 0.8) = 11.6
accepted 12 fixtures.

Table for calculating of illumination

ceiling	0,8	0,7	0,7	0,5	0,5	0,5
Wall	0,5	0,5	0,3	0,5	0,3	0,3
floor	0,3	0,3	0,3	0,3	0,3	0,1
0,60	0,33	0,32	0,25	0,3	0,24	0,24
0,80	0,41	0,39	0,32	0,36	0,3	0,29
1,00	0,47	0,45	0,38	0,42	0,35	0,34
1,25	0,53	0,51	0,44	0,47	0,41	0,39
1,50	0,58	0,55	0,48	0,51	0,45	0,43
2,00	0,65	0,62	0,56	0,57	0,52	0,49
2,50	0,7	0,67	0,61	0,61	0,56	0,53
3,00	0,64	0,71	0,65	0,64	0,6	0,56
4,00	0,79	0,75	0,7	0,68	0,64	0,6
5,00	0,83	0,78	0,74	0,71	0,68	0,62

Table of reflection of coefficients

The plane made of materials with high reflectivity	0,8
The plane with a white surface	0,7
The plane with a bright surface	0,5
The plane with the gray surface	0,3
The plane with a dark surface	0,1

Table illumination levels for certain types of premises

№	Name of premises	The estimated plane	Illumination in lux
1	Offices and other operating room	Horizontal 0.8 m from the floor	500
2	Design, engineering and drawing office	H 0,8	500
3	Reading Rooms	H 0,8	300
4	Room with a PC	H 0,8	400
5	Meeting rooms and boardrooms	H 0,8	200
6	Laboratories	H 0,8	400
7	Classrooms, auditoriums, classrooms	H 0,8	400
8	Blackboard education institutions	Vertical 1.5 m from the floor	500
9	Classrooms and teachers rooms	H 0,8	300
10	Gyms	on floor	200
11	Bedrooms kindergartens	on floor	150
12	Foster, locker rooms, gaming, dining kindergartens	on floor	200
13	Showrooms	H 0,8	200
14	Trading rooms of grocery stores	H 0,8	400
15	Salesrooms other stores	H 0,8	300
16	Offices of physicians	H 0,8	300
17	Hairdressers	H 0,8	400
18	Lobbies and public buildings wardrobe	on floor	150
19	Lobbies and wardrobes of industrial buildings	on floor	75
20	Staircases industrial buildings	on floor	100
21	Staircases of residential buildings	on floor	10
22	Operating rooms, box office premises	H 0,8	400
23	Hotel rooms	H 0,8	100
24	Washing, cleaning, smoking	on floor	75
25	Showers	on floor	50
26	Corridors and passages in public buildings	on floor	75
27	Corridors and aisles of residential buildings	on floor	20

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