Fluorescent High-Bay Lighting Savings Calculator

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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 lumens

Correction 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.