METHODS OF ILLUMINANCE CALCULATION Estimate proposal of lighting

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

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 Walls and ceiling of Illumination factor *) illuminated area light medium dark p direct indirect dark (W. m-2) *) 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. 2 25 28 30 2 to 4 19 20 22 4 15 16 18 2 42 60 80 2 to 4 28 36 48 A illuminated area (m 2) Em maintained illuminance (lx) 4 20 26 32 . W-1) z specific power of sources (lm Electric power of lighting system Pp = p. A. ( Em / 100 ). ( 10 / z ) EN 15193 Energy performance of buildings - Energy requirements for lighting (W)

ESTIMATION OF ELECTRIC POWER OF ROAD LIGHTING Example values of specific power p (k. W. km-1) of road lighting to achieve average road illuminance Etab = 1 lx with selected light sources 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 (k. W. 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 0, 4 - 0, 7 12 1, 0 - 1, 4 0, 5 - 0, 8 0, 4 - 0, 7 14 1, 1 - 1, 6 0, 6 - 1, 0 0, 6 - 0, 9 0, 5 - 0, 8 16 1, 2 - 1, 7 - 0, 7 - 1, 0 0, 5 - 0, 8 18 1, 3 - 1, 8 - 0, 7 - 1, 1 0, 6 - 0, 9 20 1, 5 - 1, 9 - 0, 8 - 1, 2 0, 7 - 1, 0 Electric power Pp = p. ( Em ). (road lenght) 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, 2. luminaire suspension height h = 8 to 14 m, 3. maintenance factor MF = 0, 5. Area of road section A = w ·l Em – maintened illuminance lx (k. W; k. W. km-1, lx, km) 3

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, m 2) where - is maintained illuminance (lx) at task area (usually horizontal plane at height 0, 85 m over the floor), A - illuminated area (m 2), MF - maintenance factor, ηE - utilisation factor. Lumen method is mostla used for estimate lighting proposal 4

MAINTENANCE FACTOR MF = LLMF · LMF. RSMF. LSF MF < 1 LLMF – lamp lumen maintenance factor LMF – luminaire maintenance factor RSMF – room surface maintenance factor LSF – lamp survival factor Average at time maximal (initial) illuminance: z = 0, 5 Ein = Em / MF Ein = 2. Em Guide on the maintenance of indoor electric lighting systems CIE 97: 2005 5

Changes of average illuminance during lighting system operation Ein = Em / z Maintenance factor Ein MF(t) z(t) Emin= mainained illuminance t 1 t 2 First luminaires cleaning Second luminaires cleaning tk . . . Luminaire cleaning + light sources replacing + surface cleaning 6

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

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

CAVITY METHOD Premise : illuminated area is ashlar-shaped + one type of luminaires Ceiling cavity Ceiling Plane of luminaires Inner cavity Square luminaire placement at the ceiling 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 9

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 10

Average surface reflectance Average reflectance ρs of surface A , which contains of n surface parts A 1 , A 2 , A 3. . . An with particular reflectances ρ1 , ρ2 , ρ3 … ρn Example: Average reflectance where ρ11 c, d h 1 ρ21 ρ1 s of ceiling cavity surface at bottom - average ceiling reflectance, - room width and lenght (m), - distance between ceiling and luminaires (m), - average reflectance of walls in ceiling cavity. 11

Thank You for Your attention! 12