Page 85 - GRIHA Manual Volume II - Introduction to National Rating System
P. 85
Sustainable site planning 77
Figure 3 Sample documents showing how to check lamp speciications from manufacturers’ cut sheets
Luminous eficacy calculation
given
Lamp type: Metal halide
Lamp wattage: 150 W
Ballast loss: 5 W
Lumen output: 12 100 lm
Solution
Total power input =150 + 5 = 155 W
Luminous efficacy = {lamp lumen output}/{lamp wattage + ballast power loss} = 12 100/155
= 78 lm/W > 75 lm/W
Figure 3 Sample documents showing how to check lamp speciications from manufacturers’ cut sheets
Luminous eficacy calculation
given
Lamp type: Metal halide
Lamp wattage: 150 W
Ballast loss: 5 W
Lumen output: 12 100 lm
Solution
Total power input =150 + 5 = 155 W
Luminous efficacy = {lamp lumen output}/{lamp wattage + ballast power loss} = 12 100/155
= 78 lm/W > 75 lm/W
