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It’s 2021, so we all know that converting from Metal Halide (HID) lighting to LED lighting will save you money. The real question is how much money will it save you and why?
The biggest difference between metal halide and LED is: LEDs are much more energy-efficient. But, this isn’t the only reason that LED lighting is superior to HIDs. In fact, it’s just one of many.
Here, we’ll break down everything that you need to know about the differences between Metal Halide Lights and LED lights. Spoiler alert: LEDs are better. But how much better are they? Read on to find out.
Battle of the Bulbs – 9 Reasons LEDs are Better
1. Lumens Efficiency
First, we’ll take a look at the average stats of a typical 400 watt metal halide bulb.
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Color Temperature |
4000K |
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Initial Lumens |
32,000 – 36,000 |
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Life Hours |
20,000 |
However, a white paper by the Dark Sky Society rated the mean lumens for a 400 Watt Metal Halide to be 20,500 lumens and the life expectancy to be around 15,000 hours. This paints a much better picture of how HIDs behave in real life because it takes into account the very real problem of lumen degradation.
As you can see, metal halide bulbs start out with extremely high lumens output (known as initial lumens). But, the keywords there are “starts out with.”
It is not uncommon to lose 20% of those lumens within the first 6 months of use. 36,000 initial lumens is bright. Unfortunately, you won’t get to enjoy that powerful shine for long. Chances are that within 6 months your new HID light will be below 30,000 lumens.
Metal halides are known to lose their lumens quickly. At half-life, around 4,000 to 10,000 hours, lumen depreciation is already at 50%. But this doesn’t take into account lumen loss due to reflected light. Let us explain.
Metal Halide bulbs emit light omni-directionally. Omnidirectional means light from the bulb is distributed in every direction. It equally produces light in every direction.
In order to make this distributed shine useful, you need to collect and focus the Metal Halide lumens. You need to add a reflector to do this. But there is an inherent problem with the physics of reflected light.
A lumen that bounces off the reflector and doesn’t immediately leave and is pointed back at the reflector or bulb itself is a lost light lumen. Any light particle that bounces more than once can be considered lost, or not usable. You can lose as much as 30% of the light in this reflective bounce. We’ve given you the facts, so now it’s onto the figures.
An industrial metal halide high bay, one that is rated at 400 Watts, produces around 36,000 lumens. After 6 months we would expect the fixture effective lumen efficiency to be:
36,000 lumens – 20% (initial lumen loss) = 28,800 lumens.
Lumens loss from reflected (more than one) bounce: 8,640
Total lumens after 6 months: 20,160
This also does not take into account any lenses or shields that the fixture might already have in place, which would decrease lumens even further. We refer to this number as bulb lumens. Figures that take into account lenses or shields on the fixture are called fixture lumens.
Now, let’s compare this to an LED light. Whether its a brand new LED fixture or a Metal Halide Retrofit Kit, almost always the light LED produces is directional.
It does not need a reflector to gather and focus light. Comparatively, lumen depreciation in LED is minimal and takes much longer to occur. L70 times in LED can exceed 100,000 hours.
2. LEDs Superior Operating Life
As mentioned, the expected life of a typical Metal Halide bulb is, at most, 20,000 hours. Some 100 Watt metal halide bulbs advertise their expected life to be around 15,000 hours.
And in commercial and industrial settings where you’re likely using much more powerful lights, this drop in lifespan is significant.
There are several different ways suppliers describe the life of a product. One of these ways is to measure lifespan via the L70 method. L70 is not a measurement of the end of a light’s life.
Instead, it is a measurement of lumen degradation up to 70% of initial lumens. This measurement does not include external circumstances, like if the driver or ballast or some other component were to fail.
The life of a Metal Halide bulb is around 15,000 to 20,000 hours. But, at the light’s half-life, it has already lost 50% of its initial lumens.
So while it’s not necessarily dead, it’s definitely ineffective. And, just so you have the full picture, even though the light isn’t producing at its initial lumen output, it still consumes 400+ watts.
3. Efficacy (lumens/watt) – LED vs Metal Halide
Efficacy is how efficient a light source converts watts to visible light. For the purpose of this blog we will only compare LED and Metal Halide. But all bulb sources efficiencies can be calculated. Understanding efficacy is important to understand why LEDs save you so much on energy costs.
Here’s how to calculate lumen efficiency.
Take the total lumens produced and divide it by the total watts consumed. In the case of Metal Halide lights, you’ll also need to include the ballast draw.
On average, the total watts consumed by a 400 Watt Metal Halide bulb is around 455 watts. (this includes the additional ballast draw)
Calculating lumen efficiency for metal halide: 36,000 lumens / 455 watts = 79.12 lumens / watt.
Compare that with our 150 Watt LED High Bay: 27,000 lumens / 150 watts = 180 lumens/watt. That’s over 2X the efficiency of Metal Halide.
Remember the golden energy saving rule: Efficacy (efficiency) Saves You Money!
4. LED vs Metal Halide Energy Savings
Now that you understand efficacy you have a little more insight on how and why LEDs are more energy efficient. They are able to produce more lumens with less energy. Converting from metal halide to LED, you’ll end up with brighter light and a lower lighting bill. We call that a win-win.
In the above example, we compared a 400 Watt metal halide bulb with a 150 Watt LED retrofit kit. This showed just how much more efficient LEDs are, but now how much more powerful they are.
Here are two practical real life examples. As LEDs become more efficient, the actual LED watts you need becomes less and less. For warehouse applications a 100 Watt LED High Bay producing 18000 lumens is a great option. For parking lot applications, a 100 Watt Shoebox Parking Lot Light will do the job, and if you’re looking for a bit more, try the 150 Watt version
Here is a recent example by a customer who wanted to compare our retrofit kit to his existing Metal Halide fixture. You can plainly see that the LED retrofit kit installed inside the shoebox fixture is brighter than the metal halide bulb beside it (even though it produces fewer lumens).
In fact, it’s so bright that it casts a shadow where the metal halide light is shining.
5. LED Wins with Savings on Maintenance
Far and wide, LEDs are touted for being energy-efficient lights that save you tons of money on your electrical bill. However, this is not the only place where LEDs will save you money over metal halide bulbs. An often forgotten aspect of LED lighting is its low maintenance requirements.
When we discussed the lifespan and efficiency, we mentioned that over the life of one LED product, a customer would have to do 5-6 bulb replacements on a metal halide light.
Replacement bulbs add up fast, especially when you’re replacing bulbs for an entire warehouse or factory. And, the higher the installation height, the higher the cost of replacement. If you have a facility loaded with lights, this cost of replacing bulbs every year adds up quickly.
The money you save on replacement bulbs admittedly won’t be as much as you save on your energy bills. However, these low maintenance lights save you more than just money. They save you and your employees time. Employees can delegate their hard work to much more important tasks, instead of switching out light bulbs, which will improve overall efficiency and productivity.
6. Quality of Light – LED has high CRI
When using a light meter to measure a light’s output, it detects lumens. Metal Halide creates visible and invisible (to the human eye) light. This includes UV (Ultraviolet) and IR (Infrared) spectrums visible to light meters but not visible to humans. LEDs, on the other hand, don’t produce UV and IR light. It only produces light in the ranges we can see.
Like lumens, foot candles are also a measurement of light intensity. One foot-candle is defined as enough light to saturate a one-foot square with one lumen of light. So instead of measuring the amount of light that leaves a light source, foot candles measure the amount of light that reaches a surface area.
If you compare brand new Metal Halide lights and LED lights, you’ll likely find that initially metal halide lights produce slightly higher foot candle readings. Yet, the light produced under LED seems brighter. Why? Some of the light detected by the light meter is including undetectable light that we can’t see (UV and IR). LEDs produce only usable light.
Another factor that plays into the way we perceive light is accounted for by the Color Rendering Index, or CRI. CRI is a measurement of Quality of Light. On a scale between 0 and 100, 100 is excellent. And LEDs tend to have a high CRI value.
This allows us to perceive color more accurately and helps prevent eye strain and headaches. With LED lighting, you’re choosing quality over quantity and reaping the benefits.
7. Photopic vs Scotopic Lumens
Photopic and scotopic lumens is a technical discussion of how people see visible light (scotopic) and how light detection devices, like light meters, detect and measure light (photopic). The human eye uses rods and cones to detect light and color. Rods are responsible for night vision, but can’t detect color.
The key takeaway – human eyes read light in a very different way than light meters. In order to account for these difference, light scientists have developed a new way to measure and compare light, S/P Ratios.
S/P ratios compare light from different sources and measures how light appears: scotopic versus photopic. And using a scale between 0 and 3, it creates a level playing field between different light sources. The S/P factor for LEDs is always higher than ones for Metal Halide lights.
So in layman terms, what does this mean? Lets discuss this in terms of extremes, LED versus High Pressure Sodium. For purpose of this example, we will use an average SP ratio associated with LED, 2.0
8. Works great with Photocells, Motion Sensors and other controls
LED has two features that metal halide just cant compete with.
1. Instant On / Instant Off
2. Dimming
While alone these features are great, when matched with lighting controls, they turn lighting into a smart appliance that’s bright when needed and energy savings when its not.
Motion sensors detect movement. With LED, the fixture can increase brightness when movement is detected. It happens instantly. After a specified period of time, if no additional movement is detected, the light turns off or dims. Because LED is dimmable, this isn’t a problem. Fixtures can be set to dim to certain percentage levels. The dimmer its set to, the more energy you save.
With Metal Halide, it suffers from extremely long strike times. Strike times are the time it takes for the bulb to get to full brightness once its turned on. Metal Halide can take up to 30 minutes to get to full brightness.
Even worst, if you turn it off, it needs time to cool down. Then you go through the long warm up time again. Dimming is not an option. Motion sensors were not a good match using Metal Halide. Now, it is extremely common to see lighting controls matched with LED.
Here’s a basic rule – nothing saves energy better than a dimmed light or one that’s turned off. So when you’re doing the calculation of energy savings when converting from Metal Halide to LED, consider adding one of the available light controls. The energy savings from 400 Watts Metal Halide to 10 Watts LED (100 Watts LED dimmed to 10%) is incredible.
9. Available Rebates from your Utility Company
Demand for electricity grows every day, but this is a finite resource. There’s only so much energy that a power company can produce each day. In order to combat this ever-growing need for electricity, power companies are offering rebates to customers that make energy-efficient upgrades.
An easy way to earn a rebate is to convert from Metal Halide to LED. Every utility company runs their own rebate program. But in general, there are some consistent processes and guidelines. For the most part utility companies offer both prescriptive and custom rebate options.
A prescriptive rebate specifies which LED fixtures can replace a metal halide fixture. A custom rebate is for those exceptions not covered by prescriptive conditions.
And, generally speaking, the LED products need to be DesignLights Consortium Qualified. This is a universal symbol of efficiency and performance. It can be thought of as the equivalence of Energy Star for consumer products. It tells the customer the lights passed a specific lighting standard.
These rebates help reduce the initial cost of installing LED lights and will speed up the pay back period. Rebates aren’t the only incentive to switch to LED lighting, but they sure are a good one.
With Metal Halide there are no rebates. Sorry.
First step to start a conversion to LED?
Without a doubt, the best first step is to ask us to do a free lighting planning for you. Converting your facility (indoors or outdoors) to LED starts by deciding how many foot candles you need. Supply us with your project information, and we’ll take it from there.
And we do lighting plans for free for our commercial and industrial customers. Why? We know that a lighting plan will be the roadmap to a successful conversion to LED. And we want your project to be a success too!
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About the Author
Dwayne Kula is President of LED Lighting Supply. On any given day, Dwayne is writing content for the site and helps manage the marketing initiatives that are on-going. He has a Software Engineering degree and still dabbles in writing software for the company as needed. When not working, he enjoys spending time with his family, working out, playing the occasional game of golf and exploring New England.