Retrofitting Old Fixtures with LED

As you know, converting to LED from a Metal Halide or a High-Intensity Discharge will save a great deal of money. However, how much do you actually save? Is there any difference or reason you should be aware of Metal Halide vs LED lights? Here, we will discuss some of the important factors that a buyer needs to consider before making a choice to convert Metal Halide lights to LEDs. Find here nine reasons why you should go for LEDs over a Metal Halide lamp.

1. Fixture (System) Efficiency Vs Lamp (Source) Efficiency


Now, let’s see the details on a common 400W metal halide lamp. While the specifications might vary, looking at a popular site that vends Metal Halide lamps indicate that anew lamp comprises the specifications as follows:

4000K: Color Temperature
32,000-36,000: Initial Lumens
20,000: Life Hours

A recent study done by Dark Sky Society claimed that the average lumens for a Metal Halide bulb of 400Wis around 20,500 lumens with average life expectancy of about 15,000 hours. However, for the purpose of our discussion, we are going to stick to the figures we are well-acquainted with. We have lots of interesting facts to consider here.

Initial lumens comprise very high numbers. However, in reality, metal halide bulbs start off really bright. Then, drop their lumens rather rapidly. They settle in at a low lumen output rapidly. It is quite common to see a drop of about 20% in just the first six months. Though 36,000 lumens are incredible, it can drop down to 30,000 lumens or less within a period of six months.
This lumen depreciation in metal halide bulbs is relatively fast. It should be noted that at the bulb’s half-life, about 8000-10,000 hours, the lumen depreciation can be at 50%.

Likewise, let’s consider the bulb’s operating nature. Metal halide bulbs are omnidirectional. This means that light is circulated in all directions. So, they produce as much the light parallel horizontally to the floor as they do while facing downwards.

For making this light helpful, you have to collect and distribute it to anywhere you actually need it. In the fixture design, people need a reflector for carrying out this job, where it bounces off the light to the ground. The main issue with directed light is the efficiency of the reflector. Lumens that bounce off this reflector and then, bounce back into this fixture is referred to as loss lumens.
Anything that occurs more than a bounce is just a throw-away. In this reflective bounce, more than 30% of light gets lost. So, on doing some mathematics of metal halide lamps in industrial bay fixtures with initial lumens at 36,000, you would find that the effective fixture lumen efficiency after 6 months to be:

So, 36,000 lumens – initial lumen loss (20%) = 28,000 lumens
Thus, lumens loss from the reflector bounce: 8,640

Complete lumens in the indoor bay fixtures after 6 months: 20,160
It does not include any shields or lenses that the indoor fixture may already have. Always remember that this is lumens of the bulb and not that of the fixture. So, everything else that you add gets in the path of getting the light to the floor will be out from the effective lumens.
As compared to this, LEDs are efficient. This is because, in LED fixtures that replace HIP and MH technology, you have directional light.

Meaning that light is focused on the place where it’s required. So, there is no requirement of reflectors because nothing is to be reflected. When we talk about lumen depreciation, this happens in LEDs but takes a bit longer to occur. For instance, our retrofits feature an L70 (or lumen depreciation of about 70% of the initial lumens) of more than 100,000 hours. Whereas Metal Halide bulbs, in the first six months, lose lots of lumens, LEDs tend to maintain their lumens for a bit longer. However, there is more that you need to know. Read more about it below!

2. Operating Life

As stated above, the operating life of a common Metal Halide lamp seems to be about 20,000 hours. Bigger bulbs, such as 1000W Metal Halide are about 15,000 hours. When it comes to LED solutions, there are various ways suppliers indicate the product’s life. One method is to write L70, where it is not a measurement of the life’s end but of lumen degradation that goes down 70% of the original lumens. However, this does not mean that components like the ballast or driver may fail prematurely.

However, we know that the average life of MH lamps is about 15,000-20,000 hours. Also, we know that at half-life, they have already lost over 50% of their initial lumens. While not completely dead, they become highly infective. For a record, they still consume over 400W even though they are half as bright.

When you compare these bulbs to our retrofit products rated at L70 (100,000 hours). By the time, the LED heads reach 100,000 hours, people have done five metal halide bulb replacements and possibly more. Now, you know what you have to do.

3. Efficiency (lumens/watt)

This is a precursor to our next topic, which is energy savings. However, the basic rule is the more efficient your bulb is, the more money you save. Now, let’s calculate the efficiency (watt/lumens) of metal halide vs LED.

For calculating lumen efficiency, people have to take the whole lumens produced and then, divide it by the whole watts consumed. When taking a metal halide bulb, you also need to add ballast draw. So, if you record the total watts consumed of a common 400W bulb, it takes around 455 watts, where the ballast consumes around 15% more energy over the bulb’s consumption.

When calculating the lumen efficiency for a metal halide, it makes 36,000 lumens/455 watts or 79.12 lumens/watts.
On comparing this with our retrofit unit of 150 watts, it makes 23,250 lumens/150 watts or 155 lumens/watt, which is double of a Metal Halide. Now, choose efficiency if you want to save money!

4. LED vs Metal Halide Energy Savings

As mentioned above, the mean lumens is somewhere about 20,500 lumens for a 400W metal halide, while our 150W retrofit kit gives 23,250 lumens. Also, instead of consuming 455 watts, our retrofit kit consumes just 150 watts. This represents a 66% savings in energy as consumed for producing more light. However, we believe that 23,250 lumens for replacing 400W MH are overkill.

We have been offering our 105W retrofit for years and it is an efficient replacement to replace 400W MH with 100W retrofit at 15,500 lumens. Our customers report that the lumen output of our 105W kit would be great then the MH options they normally use. Also, the LED produces so much bright light that it can cast a shadow from the pole in the light produced by the metal halide bulb.


5. Savings on Maintenance

Many consumers opt for LEDs because of their maintenance savings, just like their energy savings. As discussed earlier, over the lifespan of the LED item, consumers would have to go for 5-6 lamp replacements. Also, if the installation height is higher, the replacement cost will also be higher.

Also, if you have a unit filled with lights, this can turn out to be a significant amount of budget every year, which you have to consider. However, we recognized that lower maintenance time on lights does not result in fewer dollars spent because it is not possible that people are going to lose their jobs just because they do not have much work to perform. However, they will get time now to work on other things that actually matter, such as fixing the tools or machines that run the company instead of replacing bulbs that cost the unit money. LEDs are the best option if you want to cut down maintenance costs.

6. Quality of Light

When you measure light using a light meter, you get lumens. This measurement of every light that contributes to the entire light at the unit produces a measurement known as foot candles. However, let’s consider the light that you are measuring.

Metal Halide bulbs create all kinds of light in all spectrums, whether it is visible or not. This even includes IR and UV spectrums, which are visible to a measuring device but human eyes cannot see them.

On contrary, LEDs do not produce IR and UV. Thus, their readings only pick up visible spectrums when measured with the same light meter.
So, there is a fun activity that you can perform. Take two light sources, Metal Halide and LED. Firstly, you should ask which light is bright. If you select the correct LED source, then the answer will be LED. Using a light meter, measure the light. You will find that the light meter will say that the Metal halide area produces more foot candles. Now, you actually know why this happens. However, there are two things that you should know here. First, there is something called CRI or Color Rendering Index.
This measurement refers to the Quality of Light, which is measured on a scale between 0 to 100. The score of 100 is great, where LEDs tend to show a higher CRI value. Thus, the golden rule is “You need less quantity when you have more quality”. Metal Halide lamps can be nice and are much better than High-Pressure Sodium lights. However, LEDs tend to be better and thus, the light produced by them seems brighter to us.

7. Photopic vs Scotopic Lumens

Many years ago, no one believed that there will be a discussion on scotopic vs photopic lumens. There were people who believed in this difference, while there are many others who did not. This discussion is about how people perceive light i.e. scotopic vs how a light meter or camera perceives light i.e. photopic.

There is no denying that we can see and light plays a big role in our ability to see. Just walk into a dark cave and you will know how significant light is. The eyes consist of cones and rods and how they function enables us to perceive objects at night and see colors. You will find that it is quite difficult to see colors in complete darkness. That’s how our eyes function. Light meters and cameras function differently. They detect light in a very different manner. However, they read what they register and then, interpret what they read.

Then, physicists and scientists came along and tried to make sense of everything. This is how they came up with the concept of scotopic lumens. However, for taking it a step further, they decided to put up various factors considering the light source. Here, they studied how lights appear to beings scotopically and how light is measured photopically. Then, they came out with a range of factors between 0 to 3. Several effective lumens of light sources were reduced by such factors, such as High-Pressure Sodium, whereas lumens were increased in several light sources by the same factors, such as LED. However, the study discovered that the factor linked to LED was higher as compared to Metal Halide. So, when we talk about the perceived light, it really helps us to understand why we find LEDs brighter in comparison to other light sources, even when the light meter shows us something different.

8. Rebates at time of purchase

Utility companies try to get their consumers to convert to LED. This is because, for them, it is a matter of economics. As the demand for electricity is growing, when they reach capacity, they need to have a choice, reduce demand, or build more capacity.

Dropping down demand is more cost-effective as compared to increasing capacity. So, these utility companies provide rebates for purchasing LEDs. Thus, they need you to convert from Metal Halide. All utility companies run their own rebate program. However, there are various consistent guidelines and processes, in general.

Mainly, the main things are:

Utilities provide both custom and prescriptive rebate options. Prescriptive rebates are where they would say a 4000W MH bulb needs to be replaced with LEDs with such specifications. On contrary, custom rebates are those exceptions that are not covered by the prescriptive conditions.

Many LED products require to be the DesignLights Consortium Qualified, which symbolizes performance and efficiency. It is kind of the equivalence of Energy Star for customer products. This tells customers that the lights have passed and are tested to the standard.

These rebates assist in reducing the buying cost and affect the swiftness in the investment’s payback. With reduced cost at the time of purchase, the time it takes for repaying the investment drops down along with the addition of rebate cost. However, there are no rebates with Metal Halides.

9. New versus Retrofit

So, these are some of the nine legitimate and highly backed up reasons why the fight of MH vs LED is not a fight anymore. LEDs win the competition in all aspects when it comes to light. LEDs help you save money, improve productivity, increase proficiency, and could even earn you extra money. These produce a higher quality, brighter light with no to little lumen waste. We consider LEDs as the perfect replacement of an HID bulb. This is from where you can start your LED journey.

So, you should switch to LEDs as they are better. LED lights are expensive initially but between massive energy savings, low maintenance costs, and rebates, you will see a rapid return on investment. Also, there is always an option to retrofit for further cutting back on the cost. There are other things that you need to consider but converting to LEDs from metal halides is unquestionably a great decision.


There you have it, 9 highly backed up and legitimate reasons the fight of LED vs MH is no longer a fight. LED is a clear winner in every aspect of a light. We think of it as the perfect HID Replacement.

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