What Does it Take to Replace a 1000 Watt Metal Halide?



A common lighting technology in the commercial space is metal halide, at least in the past it was. At an ever-increasing rate, businesses are actively searching for a more efficient lighting system that will allow them to cut energy consumption and in turn; reduce overhead expenses.





When companies or facility managers start their search, they often search for the wrong answer. Here are some common questions that we are asked:
"How many LED watts does it take to replace a 1000 watt metal halide bulb?" "How can I replace my metal halide light?" "Is it even possible to replace my metal halide fixture with another technology?"

This post specifically will be covering the first question, as for the other two: be sure to subscribe to our email list to know when new posts go live, we are always writing informational content to answer your questions just like these!  

How many LED watts does it take to replace a 1000 watt metal halide?

 
It's simply a simple question that requires a complex answer. The reason for this is simple: you can't base your decision entirely off of watts. Instead, you need to base your decision based on the amount of lumens you need. Once you get the lumens dialed in, the fixture that produces those lumens determines the watts required.

What is a lumen?

In simple terms, it's a unit or measurement of light that basically defines how much light a certain fixture gives off.

Why does this matter? A lot more than you may think, because it's all that matters when it comes to replacing old lighting systems with new and improved lighting technology.

When replacing an existing fixture (or entire system), you need to know your lumen output per fixture. Let's say your metal halide fixtures, at least when they were freshly installed, output at 100,000 (initial) lumens per 1000 watt bulb. So, instead of thinking "I need 1000 Watt LED to replace 1000 Watt Metal Halide," you need to be thinking "I need a LED that can replace 100,000 lumens." This way, you can forget about how many watts a fixture has and focus solely on the amount of lumens the replacement can output and ensure it matches your lumen output needs.

With this example of 100,000 lumens for a 1000 Watt metal halide, that means it is outputting 100 lumens per watt (initially). In the world of lighting in today's technology world, this isn't too bad. However, you need to be aware of some other factors going on here.

Understanding Initial lumens and L70

100,000 lumens may seem bright. It is. However, the bulbs were designed for high initial output because metal halide's suffer from pretty fast lumen depreciation. It is not uncommon for a metal halide bulb to have lost 50% of it's lumens at half-life.

L70 is a term for the number of hours before a bulb is performing at 70% of initial lumen output.

Which means it will be at 70% of its lumen output at approximately 5000 hours. So, while the specs proclaim 100,000 lumens, it won't be 100,000 lumens for long. LED, on the other hand, maintains its lumens extremely well.

You will notice L70 times for LED in terms of 50,000 and 100,000 hours, not 5,000 hours like it is for metal halide bulbs.

Loss of Light due to Reflection

LED light is directional, conventional light sources are omni-directional and require reflectors to gather the light and focus it to where it is needed. Any reflection that is over one bounce effectively loses the effect of the lumen. It has been proven that you can lose up to 30% of the effective lumens in the reflective process.

So, if a metal halide bulb has 100,000 initial lumens, the loss accounted to reflected lumens drops the lumen output to around 70,000 lumens.

Quality of Lumens

This is related to Color Rendering Index, or CRI, and the best explanation is seeing how much better you can see when comparing LED to other light sources. It's a measure on the quality of light. It is not uncommon to have customers tell us that 20,000 lumens of LED appear brighter than 60,000 lumens of other light sources, like HPS.

The basic truth is you need less quantity when you have higher quality.

Photopic vs Scotopic Lumens

This has to do with how a camera perceives lumens versus how humans perceive lumens.

Photopic lumens are lumens that are detected by a device that is similar to a camera. Scotopic lumens are lumens detected by the human eye.

LED produces light within these spectrums, which means the light perceived by LED is light that we use. It is rare to see a LED light produce IR or UV spectrums. These wavelengths are invisible to people, so they have no value to us from a vision perspective.

The science of scotopic lumens is associated with a factor that allows us to adjust the photopic value to give a true representation of how useful the lumens are. The factor, developed by scientists, is an attempt to level the playing field between different light sources. The factor is used to adjust the effective value of the lumen, either up or down from the advertised photopic lumen listed on the package.

Some lights, like HPS, have a factor that reduces the lumen amount. LED, on the other hand, typically has a factor of 1.7 or greater, which means the lumens it is producing are far more effective to us.

Therefore, light sources with higher scotopic factors need lumens for us to perceive and detect the light.


Putting This All Together

The basic takeaway from all of this is you need far fewer LED lumens than metal halide or HPS lumens.

  • Metal Halide bulbs are very bright out of the box, but not so much even after only six months of use.
  • LED light is directional. The light goes where it is needed. It is very efficient.
  • LED light is high quality light. You need less quantity.


So how much LED Lumens do you need?


Only a photometric can tell you exactly how much you need. But in our 10+ years of selling LED lighting, our general rule of thumb is:

  • Indoors: 45,000 to 55,000 lumens (depends on application and mounting height)
  • Outdoors: 40,000 to 60,000 lumens (depends on application and mounting height)

By searching for a LED equivalent to a 1000 Watt Metal Halide you can easily find fixtures that output at over 100+ lumens/watt. Especially when you go with quality products from reputable companies, you can reach higher than a 150 lumens/watt output. This will allow you to cut your wattage usage per fixture by 2-3 and sometimes 4 times which will prove to save substantial amounts of energy when you start talking about replacing multiple fixtures.
 

But What Does "replacing" Consist of?

Replacing can consist of two things: retrofitting or full replacement. The difference is simple, a retrofit kit is just like replacing the light source in the fixture. While on the contrary, fully replacing includes replacing not only the existing light source but the entire fixture. To be able to decide which one is best for you will depend on your facilities' situation. If your existing fixture shell is good to use and not outdated or falling apart, a retrofit kit will work perfectly. While if they are old, outdated, and need replacing: a full replacement is probably the best option.

Are the LEDs in a retrofit kit as good as a LED fixture

Yes. Despite of what you have heard or been told, there is no reason to think or believe that a retrofit/hid replacement kit won't perform or last as long as a new fixture. Retrofits don't always make sense, but they do if you have a significant investment in your fixture or the look of your fixture. Our retrofit kits are warrantied for 10 years, and they have been extensively installed inside a closed sealed fixture in hot locations, like Arizona, Nevada, California and some even in the Middle East.

Keep this in mind: retrofitting is always cheaper because it's easier to do and it's not as material-intensive as a full replacement is. So if you can retrofit, go with that over a full replacement!

MyLEDLightingGuide 1000 Watt HID Replacement Fixtures and Retrofit Kits




In Summary


It is possible to replace a metal halide fixture, that of any wattage (30 on up to 1000+), with LED technology. It can be as simple as retrofitting your existing fixtures or a little more work intensive to fully replace, but both will work.
So, although it may seem hard, confusing, or expensive: the benefits far surpass these common scares that people have when making the consideration of upgrading to a new luminary technology. An investment in LED products will payback in many ways, from less energy usage to higher quality of light that they produce.

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