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Business: Industrial


High-Bay Lighting

How Much Will I Save?

Table 1 below compares annual electricity consumption of a T5 HO fluorescent high-bay system with that of a metal halide HID system in a typical warehouse.

In this example, with the fluorescent system there is a reduction of between 20 and 40 percent in annual electricity use, for an annual energy saving of $1,850 ($1,530 for the rack area, and $320 for the non-rack area). The cost difference can be even greater with savings from the rapid switching capabilities of electronic ballasts and the associated longer lamp life.

The incremental cost of the fluorescent lighting was about $3,100 - a 30 percent premium, with a payback of less than 1.7 years ($3,100 difference in initial cost divided by the $1,850 in annual energy savings). Table 1 does not include savings from the usual operation with two lamps off, as noted in Figure 2, and does not include the extra cost of relamping the 250W HID lamps more frequently due to their shorter life.

Table 1
Comparison of Annual Electricity Use and Initial Cost of a T5 HO Fluorescent High-Bay Lighting System to a Metal Halide (HID) System

  Application and System Type


Rack Area

Non-Rack Area


One 400W Metal Halide HID Lamp T5 HO: Six Lamps per Luminaire One 250W Metal Halide HID Lamp T5 HO: Four Lamps per Luminaire
Luminaire count 30 24 19 19
Lamp life 20 000 hours 20 000 hours 15 000 hours 20 000 hours
Initial system lumens 745 000 596 000 308 000 320 000
Total system watts 13 800 8 400 5 600 4 500
Annual hours of operation 2 500 2 500 2 500 2 500
Annual kWh 34 500 21 000 14 000 11 200

Annual cost of electricity*

$3,920 $2,390 $1,600 $1,280
Annual savings


Percent savings 40% 20%
Cost and Payback for Overall Lighting System**
  Metal Halide Fluorescent
Initial cost $9,800 $12,900
Payback 1.7 years

*Assumes an electricity cost of $0.08 per kWh and a demand charge of $7 per kWh.

**Luminaire prices may vary widely depending on, among other things, the volume of the purchase, supplier relationships and contracts.

Figure 2 shows the use of six-lamp T5 HO fluorescent luminaries in the rack area and four-lamp luminaries in an open area. The fluorescent system is particularly effective in illuminating the rack aisles.

Six-lamp T5 HO fluorescent high-bay luminaires in a rack area

Figure 2(a). Six-lamp T5 HO fluorescent high-bay luminaires in a rack area.

Four-lamp luminaires in an open area

Figure 2(b). Four-lamp luminaires in an open area.

In both cases, the luminaries in this installation are normally operated with two lamps off.

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