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Metal Halide vs LED Comparison

Supplier: Orb Engineering Services Pty Ltd By: James Palmer
22 November, 2018

Have you ever considered the differences between a Metal Halide light and LED lighting?

Topic

LED Notes

Metal Halide Notes

Winner

Cycling (Turning On/Off)

LEDs are an ideal light for purposely turning on and off because they respond rather instantaneously (there is no warm up or cool down period). They produce steady light without flicker.

Metal Halide lights require a notoriously long warm up period. Many stadiums have traditionally relied on metal halide lights but the bulbs can take 15-30 minutes to get to full operating power.

LED

Directionality

LEDs emit light for 180 degrees. This is typically an advantage because light is usually desired over a target area

Metal Halide lights are omnidirectional meaning they emit light for 360 degrees. Much of these emissions must be reflected and/or redirected which means losses and lower overall system efficiency.

LED

Efficiency

LEDs are very efficient relative to every lighting type on the market and extremely efficient relative to incandescent bulbs. Typical source efficiency ranges 90 and 150 lumens/watt. Where LEDs really shine, however, is in their system efficiency (the amount of light that actually reaches the target area after all losses are accounted for). Most values for LED system efficiency fall above 100 lumens/watt.

Metal Halide lights have average efficiency (75-100 lumens/watt source efficiency). They lose out to LEDs principally because their system efficiency is much lower (<30 lumens/watt) due to all of the losses associated with omnidirectional light output and the need to redirect it to a desired area.

LED

Emissions (In the Visible Spectrum)

LEDs produce a very narrow spectrum of visible light without the losses to irrelevant radiation types (IR, UV) or heat associated with conventional lighting, meaning that most of the energy consumed by the light source is converted directly to visible light.

Metal Halide lights produce relevant amounts of both IR and UV radiation.

LED

Infrared

None

Metal Halide lights emit IR radiation which is a waste of energy for the purposes of regular illumination.

LED

Ultraviolet

None

Metal Halide lights emit UV radiation and require a filter built into the bulb to keep these emissions from being radiated into the atmosphere. These filters are required to prevent fading of dyed surfaces exposed to metal halide light otherwise serious damage can occur to light fixtures or even human beings and animals (e.g. serious sunburn or arc eye).

LED

Heat Emissions

LEDs emit very little forward heat. The only real potential downside to this is when LEDs are used for outdoor lighting in wintery conditions. Snow falling on traditional lights like HID will melt when it comes into contact with the light. This is usually overcome with LEDs by covering the light with a visor or facing the light downward towards the ground.  

Metal halide bulbs emit a significant amount of heat (roughly 10-15% of the total energy consumed is emitted as heat). In some circumstances this could be beneficial, however, it is a generally a bad thing as heat losses represent energy inefficiencies. The ultimate purpose of the device is to emit light, not heat.

LED

Failure Characteristics

LEDs fail by dimming gradually over time. Because LED lights typically operate with multiple light emitters in a single luminaire the loss of one or two diodes does not mean failure of the entire luminaire.

Metal Halide lights exhibit an end-of-life phenomenon known as cycling where the lamp goes on and off without human input prior to eventually failing entirely. For this reason in many applications (such as a sporting stadium) metal halide lamps must be changed out prior to the end of their useful life.

LED

Foot Candles

Foot candle is a measure that describes the amount of light reaching a specified surface area as opposed to the total amount of light coming from a source (luminous flux). LEDs are very efficient relative to every lighting type on the market. Typical source efficiency ranges 90 and 150 lumens/watt. Where LEDs really shine, however, is in their system efficiency (the amount of light that actually reaches the target area after all losses are accounted for). Most values for LED system efficiency fall above 100 lumens/watt.

Foot candle is a measure that describes the amount of light reaching a specified surface area as opposed to the total amount of light coming from a source (luminous flux). Metal halide lights are very efficient compared to incandescent lights (75-100 lumens/watt source efficiency). They lose out to LEDs principally because their system efficiency is much lower (<30 lumens/watt) due to all of the losses associated with omnidirectional light output and the need to redirect it to a desired area.

LED

 

Lifespan

LEDs last longer than any light source commercially available on the market. Lifespans are variable but typical values range from 25,000 hours to 100,000 hours or more before a lamp or fixture requires replacement.

Metal Halide lights have a better lifespan relative to old technology like incandescent lights but they have a short lifespan compared to LED. Typical lifespan values range from 6,000 hours to 15,000 hours before a bulb requires replacement.

Note: sometimes metal halide lights need to be changed out before the end of their useful life to pre-empt serious degradation effects like colour changes or cycling.

LED

Lifetime Costs

LED lighting has relatively high initial costs and low lifetime costs. The technology pays the investor back over time (the payback period). The major payback comes primarily from reduced maintenance costs over time (dependent on labour costs) & secondarily from energy efficiency improvements (dependent on electricity costs).

Metal halide lights are relatively cheap to purchase but they are relatively expensive to maintain. Metal halide bulbs will likely need to be purchased several times and the associated labour costs will need to be paid in order to attain the equivalent lifespan of a single LED light.

LED

Maintenance Costs

As a result of the operational lifetimes of LEDs and the frequency with which bulbs have to be changed out, LEDs are by far the best on the market in regards to lifetime costs.

Metal halide bulbs require regular re-lamping and ballast replacement in addition to the labour cost to monitor and replace aging or expired lights several times within the typical lifespan of a single LED.

LED

Shock Resistance

LEDs are solid state lights (SSLs) that are difficult to damage with physical shocks.

Metal halide bulbs are relatively fragile. Perhaps more importantly, broken metal halide bulbs require special handling and disposal due to hazardous materials like mercury inside of many lights.

LED

Size

LEDs can be extremely small (less than 2mm in some cases) and they can be scaled to a much larger size. All in all this makes the applications in which LEDs can be used extremely diverse.

Metal halide bulbs can be small but typically aren’t produced below roughly a centimetre in width.  The size of the lamps is limited by the wattage and light output required for a given application.

LED

Cold Tolerance

Minus 40 Degrees Celsius (and they will turn on instantaneously).

Minus 40 Degrees Celsius.

LED

Warm-Up Time

LEDs have virtually no warm-up time. They reach maximum brightness near instantaneously.

Metal halide lamps require a noticeable warm-up time that varies depending on the light. Metal halide lights for sporting stadiums might take 15-20 min to arrive at maximum brightness.

LED