1. METHODS OF ILLUMINANCE CALCULATION
Estimate proposal of lighting system methods working with average E , L
Point calculations
Detailed calculation of direct and indirect components of parameters at selected control points
Estimation of electric power of lighting system based on table of specific powers (W.m-2 )
Lumen method
● general illumination ● one type of luminaires ● reflected component included ● obstacles not respected

2. ESTIMATE PROPOSAL OF LIGHTING SYSTEM
Example of the table of specific power p (W.m-2) for interior lighting to achieve average level of illumination Etab = 100 lx using light sources with luminous efficacy zt = 10 lm .W –1
*) factor  is proportional to width w of the room divided by computing height hv [  = w / hv ] .
For direct and indirect illumination hv is height of the plane of luminaires over task area.
For indirect illumination hv is height of ceiling over task area.
Illumination
factor  *)
Walls and ceiling of illuminated area
light
medium dark
dark
p (W.m-2)
direct 2 25 28 30
2 to 4 19 20 22 4 15 16 18
indirect 42 60 80 36 48 26 32
A illuminated area (m2) Em maintained illuminance (lx) z specific power of sources (lm .W-1)
Electric power of lighting system Pp = p . A . ( Em / 100 ) . ( 10 / z ) (W)
EN Energy performance of buildings - Energy requirements for lighting

3. ESTIMATION OF ELECTRIC POWER OF ROAD LIGHTING
Example values of specific power p (kW.km-1) of road lighting to achieve average road illuminance Etab = 1 lx with selected light sources
x) Values valid for :   1. straight road illuminated with luminaires with wide luminous intensity
curve with spacing l equal
to treble of luminaire
suspension height h,
luminaire suspension height h = 8 to 14 m,
3. maintenance factor MF = 0,5.
road width w (m)
luminaires with high pressure discharge lamps
metal halide 400 W
sodium 70 W
sodium 150 W
sodium 250 W
Specific power p (kW.km-1) for Etab = 1 lx x) 8
0,8 - 1,2
0,4 - 0,7
0,3 - 0,6 10
0,9 - 1,3
0,5 - 0,8 12
1,0 - 1,4 14
1,1 - 1,6
0,6 - 1,0
0,6 - 0,9 16
1,2 - 1,7 -
0,7 - 1,0 18
1,3 - 1,8
0,7 - 1,1 20
1,5 - 1,9
Area of road section A = w ·l
Em – maintened illuminance lx
Electric power Pp = p . ( Em ) . (road lenght)
(kW; kW.km-1, lx, km)

4. LUMEN METHOD
Total initial luminous flux z of light sources of lighting systém, which are needed to be installed to provide average maintened illuminance by general illumination is determined as
(lm; lx, m2)
where is maintained illuminance (lx) at task area (usually horizontal plane at height 0,85 m over the floor),
A illuminated area (m2),
MF - maintenance factor,
     ηE   - utilisation factor.
Lumen method is mostla used for estimate lighting proposal

5. z = 0,5  Ein = 2 . Em MAINTENANCE FACTOR MF = LLMF · LMF . RSMF . LSF
LLMF – lamp lumen maintenance factor LMF – luminaire maintenance factor RSMF – room surface maintenance factor LSF – lamp survival factor
Ein = Em / MF
Average at time maximal (initial) illuminance:
z = 0,  Ein = Em
Guide on the maintenance of indoor electric lighting systems CIE 97:2005

6. Changes of average illuminance during lighting system operation
Ein = Em / z
Maintenance factor
Ein
MF(t)
z(t)
Emin= mainained
illuminance t1 t2 tk 1
First luminaires cleaning
Second luminaires cleaning
Luminaire cleaning + light sources replacing + surface cleaning
. . .

7. LLMF – LAMP LUMEN MAINTENANCE FACTOR
Incadescent bulbs
Fluorescent tubes
HP sodium lamps
Metal halide lamps

8. LAMP SURVIVAL FACTOR LSF
Simplified calculation of LSF
LSF example
Lamps in operation (%)
50 % lamps damaged
Lifetime (%)

9. Square luminaire placement at the ceiling
CAVITY METHOD
Premise : illuminated area is ashlar-shaped + one type of luminaires
Ceiling cavity
Ceiling
Plane of luminaires
Square luminaire placement at the ceiling
Inner cavity
Task area
Floor cavity
Cavity definition: ceiling, inner and floor
Square luminaire placement at the ceiling
Parameters are calculated for inner cavity
Influence of ceiling cavity - equivalent ceiling cavity reflectance
Influence of floor cavity - equivalent floor cavity reflectance

10. Geometric parameters of the area
dimensions: c - width ; d - lenght ; h - inner height
Room index m
Space index k
Surface reflectance
integral reflectance - average (over surface) values
ρ1 - plane of luminaire reflectance
ρ2 - wall reflectance
ρ3 - task area reflectance

11. Average surface reflectance
Average reflectance ρs of surface A ,which contains of n surface parts A1 , A2 , A An with particular reflectances ρ1 , ρ2 , ρ3 … ρn
Example: Average reflectance ρ1s of ceiling cavity surface at bottom
where ρ average ceiling reflectance,
c, d room width and lenght (m),
h distance between ceiling and luminaires (m),
ρ average reflectance of walls in ceiling cavity.

12. Thank You for Your attention!