An Illuminating Comparison
of Three Commonly Used
Lighting Technologies
High Intensity Discharge, Induction and LED
Today’s lighting technology provides business owners with a variety of options for applications
such as parking lots and garages, stairwells, warehouses and cold storage areas, etc. Three of
the most commonly used lighting solutions for these types of settings include:
1. HID (high intensity discharge) lighting
2.Induction lighting
3.LED (light emitting diode) lighting.
Selecting the right one for your particular need depends on several critical variables. Energy
efficiency is, of course a key factor, but other considerations should not be overlooked. Let’s take
a look at these three lighting technologies individually.
HID LIGHTING
High Intensity Discharge (HID) lamps are a type of electrical lamp which produces light by means of an electric
arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube.
This tube is filled with both gas and metal salts. The gas
facilitates the arc’s initial strike. Once the arc is started, it
heats and evaporates the metal salts forming plasma, which
greatly increases the intensity of light produced by the arc
and reduces its power consumption. Some high intensity
discharge (HID) lamps make more visible light per unit of
electric power consumed than fluorescent and incandescent lamps since a greater proportion of their radiation is
visible light as opposed to heat. With HIDs, the point source
is easily controlled and can be aimed accurately. HIDs are
not temperature sensitive (cold or warm). Three of the most
common types are:
High Pressure Sodium (Amber light)
• Product life - At 16,000 to 24,000 hours, HPS lamps have a
shorter life than either Induction or most LEDs, but longer
than Metal Halide, below.
• Energy efficiency - HPS lamps have an efficacy of 50 to
140 lumens per watt.
• Light quality - 2200 Kelvin. 22 CRI for standard HPS, and
up to 65 CRI for color-corrected premium bulbs.
• Applications – High Pressure Sodium (HPS) lamps provide effective light while using electricity efficiently. They
are commonly used to provide outdoor lighting for buildings, parking lots, commercial garages, streets, and walkways where color is not critical.
Metal Halide (White light)
• Product life - Metal Halide lamps have a rated life of up to
20,000 hours.
• Energy efficiency - Efficacy of 50 to 75 lumens per watt.
• Light quality - 3200 to 5200 Kelvin. CRI of 65 to 70.
• Applications – Metal Halide lamps are energy efficient
and allow for good optical control. Low operating costs
and good light quality make them an attractive alternative for general lighting purposes like parking lots, athletic
facilities, and garages. They may provide better peripheral visibility at low illumination levels than High-Pressure
Sodium.
Key Terms
Color Rendering Index (CRI) measures on a scale
of 1 to 100 the accuracy of a light source to render
colors of an object when compared to natural light.
Lumen is a measure of the amount of light emitted
by a light source in all directions.
Efficacy measures the efficiency of a lamp in lumens per watt (LPW). The higher the LPW, the more
efficacious the lamp.
Kelvin is a unit of measure for temperature.
Correlated Color Temperature (CCT) is the appearance of visible light that correlates to the appearance of an object heated to a specific temperature
in degrees on the Kelvin scale.
Ceramic Metal Halide (white light)
This is a relatively new technology and a variation of mercury vapor technology.
• Product life - Rated life of 15,000 to 24,000 hours.
• Energy efficiency - Typically, CMH lamps use about 20
percent of the electricity used by comparable incandescent light bulbs for similar light output (80 to 117 lumens
per watt). They can also be more economical to use as
street lights than the old mercury vapor and sodium vapor
lamps, and give a clearer, more natural looking light.
• Light quality - 2700 to 5000 Kelvin. 80 to 96 CRI. Consistent lamp-to-lamp color and solid color stability.
• Applications - Retail space, television and film making,
shop lighting, and digital photography.
Induction LIGHTING
Induction lighting is fluorescent lighting without cathode
tubes (electrodes). Instead of an electrode, induction lighting uses magnetic induction to excite the phosphors inside
a sealed lamp. Electrodes are the components that burn out
in other types of lamps and create the necessity for frequent
replacement.
• Product life - With no cathodes to burn out, some induction lamps are rated at 70,000 hours. That is roughly
equivalent to 100 incandescent bulbs, five HID lamps or
five standard fluorescent lamps.
• Energy efficiency - Induction fixtures are equipped with
electronic ballasts which operate at a high frequency rate.
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Light output from a 200 watt Induction lamp compares to
the light output of a 400 watt HID lamp at 40 percent of its
rated life. Induction fixtures also generate less heat, a key
energy saver in indoor applications. They can produce up
to 120 lumens per watt.
• Light quality - Induction fixtures are equipped with fluorescent lamps with a CCT of 3000 to 6500 Kelvin and up
to 85 Color Rendering Index (CRI).
• Applications - Parking garages, hard to reach areas like
street lighting or tunnels, wall packs, canopies like those
in gas stations, banks, etc.
LED LIGHTING
Light-emitting diodes (LEDs) are electronic components that
let current pass in only one direction and that emit visible
light when electricity is applied. LEDs are an efficient option
for task-oriented lighting applications, or applications such
as exit signs, traffic lights, signage, etc. LED light is inherently directional, so applications that require a more direct
light are ideal. If general lighting is desired, (office space,
warehouses, etc.), LED products need additional optical
control or the light can produce unwanted glare. However,
recent advancements offer better options for illuminating
areas, rather than objects. LED tolerates cold exceptionally
well, so cold storage applications also work well. Dimming
and programmable controls for LED can provide additional
flexibility and savings, but need professional specification of
system for best results.
• Product life - LEDs are rated at 50,000 to 100,000 hours.
• Energy efficiency - Initial purchase costs can be high, but
they may be cost effective in the long run. Longer product
life and lower maintenance costs offer substantial savings
compared to HID and other traditional lighting systems.
Furthermore, LEDs may use as little as 10 percent of the
electricity required by an incandescent light, and less than
half of that used by a standard fluorescent. The most efficient white LEDs produce about 80 to 100 lumens per watt.
• Light quality - LEDs may offer more vibrant color than traditional forms of lighting. They are available in all colors
and wavelengths from infrared to ultra violet and white.
They have a CRI ranging from 50 to 99.
• Applications - Exit signs, traffic lights, signage, cold
storage, task lights, step lights, small illumination areas,
areas that require low light levels or have space constraints, down lights or track lights. LED fixtures are also
often used for exterior parking lots and garages, pedestrian walkways and landscape lighting.
The initial lumen output of an LED fixture may not be equivalent to the initial lumen output of a 400 watt HID. However,
LEDs experience minimal lumen depreciation if the LED
product is designed to manage heat effectively. Not all LED
products are created equal. Documentation of performance
metrics is needed to evaluate how well a product will perform in a given application.
Technology Comparison
Induction
Light Color
MH
HPS
LED
Cool White
Cool White
Yellow
White to Cool White
Color Rendering Index (CRI)
>80
65-95
21
>70
5000
4300
2200
2700-7500
100,000
10,000-24,000
15,000-24,000
50,000-100,000
Lamp Longevity (years)
22.83
2.28
4.57
11.42-22.83
Remaining Life @ 25000H
75,000
Exceeded Life
Exceeded Life
25,000-75,000
Color Correction Temperature (CCT)
Economic Lamp Life
Emission Reduction
Restart
Environmental Concerns
Yes
No
No
Yes
Instant
10-15 minutes
10-15 minutes
Instant
Uses mercury amalgam
Contains mercury
Contains mercury
No mercury
Which technology is right for you?
There is no simple answer. While efficiency and energy savings are important considerations, aesthetics, productivity and
worker satisfaction should never be discounted. Depending on the specific circumstances of your lighting application, each
technology may have advantages over others. Consider consulting a lighting design professional to ensure all of your requirements are taken into account, including determination of appropriate light levels and uniformity based on the tasks being performed in the space. This will help to ensure the lighting system is designed appropriately, regardless of which technology is selected. And, whether retrofitting an existing facility or building a new one, Duke Energy’s Smart $aver® Incentive
program can help reduce the upfront costs of your next lighting project. For more information, visit www.duke-energy.com.
©2013 Duke Energy Corporation 110371LU 4/13
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