ring. Example Classroom Summary Pages 83-84 600 sq. ft. Dimensions: 20' W, 30' L, 9' H,...

Transcribed Image Text:

ring. Example Classroom Summary Pages 83-84 600 sq. ft. Dimensions: 20' W, 30' L, 9' H, area = Fixture: #2, 24" x 48", 3 lamp fluorescent Lamps: F40 CW (34 watt), 2,900 lumens each Reflectance: pc = 80%, pw = 50%, pf = 20% Cavity ratios: CCR = 0, RCR = 2.7, FCR = 1.0 Coefficient of utilization: CU = 60% Light loss factor: LLF = 70% a No. of fixtures required = 8.2 for 50 footcandles No. of fixtures provided = 9 for 55 footcandles 1. Classroom lighting operates 2,500 hours each year, and electricity costs $0.08 per kWh. Find the annual cost of lighting the classroom. 2. Classroom lamps are cleaned once a year with labor cost of $1 per fixture. Fixture re-lamping is scheduled every six years (75% of lamp life) at a cost of $6 per fixture for labor and lamps. Find the annual cost of cleaning and re-lamping. 3. Estimate the annual cost per square foot for classroom lighting. 4. If classroom ceiling reflectance is changed to 50% (instead of 80%), less light will reach the work plane. Find the CU change and the footcandle change. 5. If clacoragg are changed to 10' x ring. Example Classroom Summary Pages 83-84 600 sq. ft. Dimensions: 20' W, 30' L, 9' H, area = Fixture: #2, 24" x 48", 3 lamp fluorescent Lamps: F40 CW (34 watt), 2,900 lumens each Reflectance: pc = 80%, pw = 50%, pf = 20% Cavity ratios: CCR = 0, RCR = 2.7, FCR = 1.0 Coefficient of utilization: CU = 60% Light loss factor: LLF = 70% a No. of fixtures required = 8.2 for 50 footcandles No. of fixtures provided = 9 for 55 footcandles 1. Classroom lighting operates 2,500 hours each year, and electricity costs $0.08 per kWh. Find the annual cost of lighting the classroom. 2. Classroom lamps are cleaned once a year with labor cost of $1 per fixture. Fixture re-lamping is scheduled every six years (75% of lamp life) at a cost of $6 per fixture for labor and lamps. Find the annual cost of cleaning and re-lamping. 3. Estimate the annual cost per square foot for classroom lighting. 4. If classroom ceiling reflectance is changed to 50% (instead of 80%), less light will reach the work plane. Find the CU change and the footcandle change. 5. If clacoragg are changed to 10' x