Until a few years ago, there was a huge misconception that LED lighting was not a good replacement for traditional metal halide lighting. While this was true back in the 1970s when LED technology was still in the early stages of development, it is no longer the case. Advancements in technology have finally gotten rid of this fallacy.
For very many years, the industrial sector heavily relied on metal halide technology for its lighting infrastructure. It had the ability to deliver enhanced levels of illumination and was much better at rendering colors than other traditional lighting sources. This is why it was widely regarded as sturdy and fit for purpose.
But the arrival of energy-efficient, reliable, and high-performance LED lighting meant that it was only a matter of time before metal halides were replaced. But as the saying goes, “old habits die hard”. It has taken longer than we all expected for widespread adoption of LED to occur.
But as LED technology has continued to spread its wings through residential and commercial spheres – and as the technology has become more efficient and easy to implement – the case for converting to LED has become more compelling. Over the last 3 years, the number of LED installations in industrial environments has gone up significantly. LED technology has finally “come of age” and is now the first choice for most contractors, facility managers, and commercial property owners.
But just how different is LED lighting from metal halide lighting? How much money will LEDs help you to save? How soon will you recoup your investment after you switch to LED lighting?
Since we know that all these questions are running through your mind, we have decided to tackle them all, and a few more, in this post.
Here are eight reasons why replacing metal halides with LEDs is the best option.
1. LED Lights Are More Efficient: They Have Better Lamp and Fixture Efficiency
First, let’s take a look at the lamp and fixture efficiency of a metal halide. A brand new 400-watt metal halide bulb has a color temperature of 4000K, a rated life of 20,000 hours, and its initial lumens are 32,000-36,000. While these figures are very impressive, a study carried out by The Dark Sky Society showed that the initial lumens of a 400-watt metal halide lamp are 20,500 and its rated life expectancy is around 15,000 hours.
But in order to prove our point, let us stick to the figures that are usually marketed. While a metal halide bulb has a very high light output initially, it loses its lumens very quickly. It is very common for a metal halide to lose 20% of its lumens in its first six months of use. This means that after 6 months, the lamp will be giving off 28,800 lumens. And since lumen depreciation for metal halide bulbs is very fast, when the bulb gets to half of its lifespan (around 10,000 hours) lumen depreciation may have gotten to 50%.
Another thing we need to consider is the operating nature of a metal halide bulb. Metal halides are high intensity discharge lamps and all HID lamps are omnidirectional. These lamps distribute light in every direction; they discharge light both vertically and horizontally. Since a lot of the light that is produced is wasted, reflectors are normally added to metal halide fixtures to gather the light and direct it where it is needed.
But the biggest problem with reflectors is that they are not very effective at capturing the light that bounces off them to the ground. Lumens that bounce off a reflector and back into the light fixture are lost. During the reflective process, up to 30% of lumens are lost.
So, if we were to calculate the number of lumens produced by a six-month-old metal halide bulb, we will get the following figure.
20% lumens lost after 6 months = 28,800 lumens.
Lumens lost during the reflective process = 8,640
The total number of lumens produced by the light fixture = 20,160
Our calculation does not take into account any shields or lenses that may have been used in the fixture. Anything added to a metal halide fixture that may get in the way of light being emitted to the ground can reduce the total lumen output.
LED lights are different
LED lights are built differently and produce light that is directional. All the light is focused where it is needed. There are no lumens to be reflected hence reflectors are not required. And while LEDs also experience lumen depreciation, their lumen depreciation rate is not as fast as that of HID lamps.
LEDs have the L70 rating, which means they retain 70% of their lumens for their whole lifetimes. Our new LED fixtures and retrofits retain 70% of their lumens for more than 100,000 hours. So, unlike metal halide lamps that do not produce bright light for very long, LEDs maintain most of their initial light output much longer.
2. They Have a Longer Lifespan
The average life expectancy of metal halide lamps is 20,000 hours. However, larger lamps, like 1000-watt metal halides, have a lower life expectancy – approximately 15,000 hours. When it comes to LED lighting, manufacturers use the L70 rating to define the life expectancy of their products.
The L70 rating indicates the period of time a LED will work for before it starts generating 70% of its initial lumens. This is because the human eye never notices a gradual reduction in light output. It only becomes aware that the light output has gone down when a bulb starts producing less than 70% of the lumens it produced originally.
For conventional lighting systems, the rated life refers to the time they operate for before burning out. But since LEDs do not burn out like traditional lights, the L70 rating is used to indicate how long it will take for them to drop 30% of their lumens. High-quality LED fixtures have an L70 rating of 100,000 hours.
Since metal halide lamps have a rated life of 20,000 hours, by the time high-quality LEDs get to the end of their lifespans, you may have replaced your metal halides 5 times or more.
3. Higher Luminous Efficacy
The luminous efficacy of a light source is what determines how much electricity it will save. In simple terms, luminous efficacy is the number of lumens a bulb generates for every watt of energy it pulls. To get the luminous efficacy, you can also divide the total lumens the lamp produces by the total watts it consumes. With this in mind, let us look at the luminous efficacy of a metal halide lamp versus that of a LED lamp.
A 400-watt metal halide bulb consumes about 455 watts of electricity. But metal halides cannot work without ballasts – and ballasts also draw a small amount of electricity (approximately 15%).
The luminous efficacy of a 400-watt metal halide bulb is: 36,000 lumens divided by 455 watts = 79.12 lumens per watt. This is assuming the metal halide produces 36,000 lumens, which is not the case.
A 150-watt retrofit unit sold by The Lighting Center generates 23,250 lumens. 23,250 lumens divided by 150 watts = 155 lumens per watt.
Just by looking at the figures, it’s clear that a LED lamp is more efficient than a metal halide. And when it comes to lighting, efficiency is the most important thing because efficient lights save you money.
4. More Energy Savings:
As we previously pointed out, a 400-watt metal halide lamp produces approximately 20,500 lumens. On the other hand, our 150-watt retrofit unit generates 23,250 lumens. But instead of consuming a massive 455 watts, it only uses 150 watts. If you replace the 400-watt metal halide lamps in your commercial application with these LED units, you will reduce energy consumption by 66% and also provide better illumination in the space.
But to be honest, we think our 150-watt LED lamps are too powerful to replace 400-watt metal halide lamps. The light they produce may be too much for your space. This is why we recommend replacing your 400W metal halides with our 100W retrofit units. Each 100-watt retrofit emits 15,500 lumens and makes a perfect replacement for a 400-watt metal halide.
If you’re still not convinced that lower-wattage LED lamps can replace higher-wattage conventional lamps, here’s some news that may help you to make up your mind about converting to LED. As metal halides get old and lose most of their lumens, their electricity consumption never goes down. As a matter of fact, they consume the same watts they consumed initially and do so up to the end of their lives.
5. Better Light Quality
When a light expert measures light using a light meter, they get the readings in lumens. And when they take a measurement of all the light sources that contribute to the light in the specific location, the reading is in foot candles. But first, let us consider the light being measured. Metal halide lamps generate light in all spectrums – both visible and invisible.
Visible light is the light that can be seen by the human eye while invisible light includes infrared (IR) and ultraviolet (UV) spectrums. LED lamps that are designed for humans do not produce light in IR and UV spectrums, because this light is not useful to humans.
This means that a light meter only picks up the visible spectrum of LED light. While a light meter may show that the area illuminated by a metal halide lamp has more foot candles, the reason is because it also measures the invisible light spectrum.
Additionally, LEDs have better-quality light because they have a higher color rendering index. When you install light sources with a higher color rendering index, you will need fewer fixtures because the quality of the light will be better. And while the color rendering index of metal halides is much better than that of other traditional light fixtures (such as high pressure sodium lamps), they do not render colors as well as LEDs.
6. They Lower Light Maintenance Costs
Another way LEDs help you to save money is by decreasing light maintenance costs. As we earlier said, metal halide lamps do not have a long lifespan and have a very quick rate of lumen depreciation. They have to be replaced every now and then. When used in large commercial applications, they have to be replaced in groups as changing out single bulbs can be very expensive.
The higher the bulbs are installed, the higher the cost of replacement will be. And if your commercial application is filled with lights, you may spend a lot of money every year replacing burnt out bulbs. Since LEDs have a very long lifespan, you won’t have to spend money on new bulbs every now and then or pay electricians to replace spoilt light fixtures. If you have in-house electricians, they won’t spend a lot of time fixing or changing out bulbs. They can spend this time carrying out tasks that boost the company’s bottom line – like fixing machines that bring the company money.
7. Scotopic vs. Photopic Lumens
Light sources usually produce two types of lumens: scotopic and photopic lumens. Scotopic lumens are the lumens that can be seen by the human eye while photopic lumens are not visible to the eye. A device that is very similar to a camera is normally used to measure photopic lumens.
For a long time, light experts only measured photopic lumens. The thing is, they never considered the fact that human eyes see light differently than man-made gadgets, or that the light emitted by an artificial light source can appear different during the day and during the night. But because of technological advancements, there are now two methods of labeling lumens.
In order to determine the visible light (scotopic lumens) a light source produces, a correction factor is normally applied to photopic lumen readings. This factor was created by scientists to provide common ground between different light sources. This is because different bulbs with the same photopic lumen readings can have varying visible light output.
The correction factor usually alters the value of the lumens upwards or downwards from the stated photopic lumens. The lumen quantity for most high intensity discharge lights (including metal halides) is usually reduced by the correction factor. But the case is different for LED lights; the factor increases the lumen quantity by 1.7 or more. This means that the scotopic lumens produced by LEDs are more than those produced by metal halides.
Why are utility companies always trying to convince their customers to switch to LED technology? It’s all about economics for them. The demand for electricity is constantly increasing, so once a utility reaches its capacity, it can choose one of two options: to build more capacity or to lower the demand for electricity. No doubt about it, lowering demand is way more cost-efficient than increasing capacity.
For this reason, utility companies normally give out rebates to businesses and companies that switch to LED. Your utility company knows that if you replace your current metal halide lamps with LEDs, your demand for electricity will go down. While each utility runs its own rebate program there are two similar processes and guidelines.
- Utility companies provide both custom and prescriptive rebate options. A prescriptive rebate states the exact LED bulbs that should replace traditional bulbs. For example, a utility company can say that a 150-LED bulb should replace a 400-watt metal halide bulb. Custom rebates are usually for exceptions that are not covered by prescriptive rebates.
- The LED products must have DLC certification. DLC, DesignLights Consortium, is a non-profit organization that is committed to increasing the universal use of high-functioning commercial lighting solutions. DLC qualification is a symbol of performance and efficiency and is the equivalent of Energy Star for commercial lighting products.
The rebates given by utility companies help reduce the initial cost of purchase and help you to recoup your investment in a short period of time. Not a single utility company gives rebates for metal halide lamps.
Should You Buy New LED Fixtures or Retrofit Units?
Now that we have explained why LEDs are much better than metal halides, we’re sure you’re thinking of switching to LED technology. However, you have one more decision to make: whether you’ll install new LED fixtures or retrofit your existing light fixtures. The choice you make will ultimately determine how much you spend.
New LED fixtures are more expensive than retrofit units and may take time to be installed in your property. If your existing light fixtures are in good condition, we recommend retrofitting as it won’t disrupt your business operations and the process only takes a short time. Well-built retrofits work just as well as new fixtures. Why not make the switch today?