A windowless office is to be illuminated for 12 hours per day, for 5 days per week, for 50 weeks per year. The floor is

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A Windowless Office Is To Be Illuminated For 12 Hours Per Day For 5 Days Per Week For 50 Weeks Per Year The Floor Is 1 (146.6 KiB) Viewed 39 times

A windowless office is to be illuminated for 12 hours per day, for 5 days per week, for 50 weeks per year. The floor is 30 m long and 10 m wide. An overall illumination of 450 Lux is to be maintained over the whole floor. The total light loss factor for the installation is 70 %. The designers have the choice of using 100 W tungsten filament lamps, which have an efficacy of 12 lm/W and need replacing every 3000 hours, or 65 W tubular fluorescent warm white lamps, which have an initial output of 5400 lm and are expected to provide 12000 hours of service. The room layout requires an even number of lamps. Electricity costs RM 0.22/kWh. The tungsten lamps cost RM1.00 each while the fluorescent tubes cost RM10.00 each. (i) Determine the total costs per year for lighting system which is designed with tungsten lamps. (ii) Determine the total costs per year for lighting system which is designed with fluorescent lamps.