6. A room with the internal dimensions of 25 (m) length x 25 (m) width * 3 (m) height is to be artificially lit by lumin

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6 A Room With The Internal Dimensions Of 25 M Length X 25 M Width 3 M Height Is To Be Artificially Lit By Lumin 1 (86.74 KiB) Viewed 13 times

6 A Room With The Internal Dimensions Of 25 M Length X 25 M Width 3 M Height Is To Be Artificially Lit By Lumin 2 (27.55 KiB) Viewed 13 times

6. A room with the internal dimensions of 25 (m) length x 25 (m) width * 3 (m) height is to be artificially lit by luminaires mounted at ceiling level. This room required the illuminance of 400 (lx) on the working planes 0.5 (m) above the floor. The 100 (W) tubular florescent lamps with initial luminous efficacy of 79 (Im/W) and basic downward Light Output Ratio (LOR) of 50% are selected to provide the required artificial light. Florescent lamps are placed in recessed louver through luminaires with optically design reflecting surfaces. The reflectance of ceiling is 0.5 (-) and the reflectance of walls is equal to 0.3 (-); the light loss factor is 0.8 (-). Reflectances Description of fitting/ typical outline LOR Basic down ward LOR ( 0.7 0.5 0.5 0.5 0.3 0.1 0.3 0.3 0.5 0.1 03 0.1 Coling Walls Room index 70 Aluminium industrial reflector aluminium or enamel high- bay reflector 03 0.6 08 1.0 1.25 1.5 20 25 30 4.0 50 0.6 0.8 10 125 1.5 20 50 Noar spherical diffuser, open beneath 0334 026 Ontho 0.39 0.48 0.52 056 0.60 0.65 0.67 0.69 10.71 0.72 0.28 0.39 0.43 0.48 0252 0.58 0.62 0.65 0.68 0.71 0.28 034 0.37 0.40 0.43 046 0248 0.49 0.50 0.51 0336 0.33 0.39 0.36 0.43 0.40 0.46 0.43 0.49 045 0.52 0.48 0:55 0250 0156 0.53 0.57 0.54 0.59 0.57 0.62 0.50 0.63 0.60 0.64 0.62 0.65 0.62 0.68 0.64 0.67 0.64 058 0.67 0.69 0.67 0.70 0.69 0.71 0.89 0.22 0.18 0.25 020 0230 0.26 0.33 028 0 36 0532 0.38 041 0.37 04 038 046 0.41 0.46 04 0.52 0.47 0.50 0.48 0.50 0.52 0.54 050 0.60 0.56 0.57 05 0.64 0.61 0.60 0 56 0.60 06 0.62 0.59 0.25 023 0.28 025 0:31 02 0:33 0.30 0.36 032 0.37 0:34 0239 0235 040 0.61 0.38 0.42 0.40 0.44 0.42 0.45 04 0.46 0.44 0.47 0.45 047 046 0.48 0.46 0.48 049 0.41 0.50 0:49 05 0.49 0.33 0.39 0.35 0.33 0.40 0.46 0.43 0.40 0.45 0.52 0.48 0.45 0.49 0.56 0.42 0.53 0.59 0.57 0.53 0 58 063 059 0.57 0.81 0.65 0.02 0.00 0.63 0.67 0.64 0.62 0.65 0.69 0.66 0.64 0.67 0.71 0.67 0.66 0.17 0.22 0.18 0.16 0.23 027 0 25 0.22 029 0 31 029 0.33 0.34 032 0.29 0.37 0.37 0.35 0.32 0.43 0.42 0239 0.36 0.67 0.45 0.42 0.40 0.50 0.48 0.45 0.48 054 0.51 0.48 0.45 0.57 0.53 0.50 0.48 023 028 0.25 0.23 028 0.33 0.30 0.28 0.32 0:37 0:34 0.33 0.35 0.40 037 0.35 0.38 0.42 0.39 038 0.41 0244 042 0.41 0.43 0.46 0.44 0.43 0/45 0.47 045 044 047 0.48 0.47 0.46 0.48 049 0.48 0.47 25 50 Recessed louvre trough with optically designed reflecting surfaces 30 40 50 08 0.8 10 125 15 20 25 30 40 50 031 0.49 Table 2-Utilisation Factors
Determine the: (a) Room Index (5 marks) (b) Utilisation factor (UF) of the luminaires (using Table 2) (5 marks) (c) Number of luminaires (considering one florescent lamp fitted in each luminaire) (5 marks) (d) Maximum horizontal space between luminaries (5 marks) (e) Layout of the luminaires considering the maximum horizontal space between light fittings (5 marks)