Online Lighting Calculator

TBC = to be calculated

Factor
Metal halide
Fluorescent
Initial lamp output (lumens)
Design (40% of life) lamp output (lumens)
Lamp life (hours)
Fixture quantity
Fixture input power (watts)
Total kilowatts
Fixture efficiency (%)
Design lumens from fixture(s) (lumens)
Conversion factor, standard lumens to pupil (lumens)a
Net design pupil lumens from fixture(s) (lumens)
Annual operating hours
Annual electricity consumption (kilowatt-hours per year)
Annual savings (kilowatt-hours per year)
NA
Electricity cost per kilowatt-hour ($)
Annual kilowatt-hours cost ($)
Annual savings ($)
NA
Cost of retrofit ($)
NA
Simple payback period (years)
NA
NA = not applicable
 

Notes:
a. Use data from Table 2 for the appropriate conversion factor. Use values of 1.0 to do the calculation without considering pupil lumens

Table 2: Conversion factors for lumens to pupil lumensCorrection factors applied to conventional values of lumens per watt yield a value for pupil lumens per watt, which is a measure of how effectively the eye sees the light that is emitted. The pupil is more receptive to light at the blue end of the spectrum.
Light source
Conventional lumens per watt
Correction factor
Pupil lumens per watt
Low-pressure sodium
165
0.38
63
5,000-K T5 fluorescent
104
1.83
190
4,100-K T8 fluorescent
90
1.62
145
Clear metal halide
85
1.49
126
5,000-K pure triphosphor fluorescent
70
1.58
111
3,500-K triphosphor fluorescent
69
1.24
85
50-watt high-pressure sodium
65
0.76
49
2,900-K warm white fluorescent
65
0.98
64
Daylight fluorescent
55
1.72
95
35-watt high-pressure sodium
55
0.57
31
5,000-I 90 CRI fluorescent
46
1.7
78
Vitalite fluorescent
46
1.71
79
Deluxe mercury vapor
40
0.86
34
Standard incandescent
15
1.26
19
Tungsten halogen
22
1.32
29
Notes: K = Kelvin; CRI = color rendering index.