In the past, whenever a commercial space or a large indoor space needed to be illuminated, the first lighting option contractors and electrical professionals thought of was metal halides. But these lamps consumed a lot of electricity and did not have long lifespans, that’s why LED lighting was such a welcome change.
Many businesses and building managers are now converting to LED lighting in an effort to lower energy consumption and save money. One question we get asked all the time is, “Which LED light is a perfect replacement for a 1000-watt metal halide lamp?”
We are addressing this question today once and for all in this detailed post so you can always refer to it whenever the need arises.
LED Watts to Replace a 1000-Watt Metal Halide Lamp
The truth of the matter is, it’s never just about watts. LED bulbs usually have 3 important specifications: Watts, Lumens, and Kelvin. Lumens are the most important feature as they allow you to buy the specific amount of light you want. When it comes to LEDs, you should think lumens, not watts. Watts are used to measure the energy consumption of LEDs while Kelvin measures the color temperature.
What Exactly Are Lumens?
Lighting is all about lumens, but what exactly are lumens?
In layman’s terms, a lumen is a measurement of the total amount of visible light discharged by a light source. Lumens mean brightness, not watts. They are the only thing you should look at when replacing HID lighting with LED technology. Watts are important, but they measure energy consumption, not light output.
When replacing metal halide lights with LED lighting, what you should carefully look at are the lumens the LEDs produce. Remember, LEDs are more efficient than metal halide lamps, so you cannot buy 20 1000-watt LED bulbs to replace 20 1000-watt metal halide bulbs. Instead, look at the initial lumens produced by the traditional bulbs then get LEDs that produce the same amount of lumens. Only focus on the lumen output to ensure it matches your needs.
Lumen Depreciation and L70
One of the most unpleasant aspects of metal halide bulbs is lumen depreciation.
Let’s use a 400-watt metal halide bulb as an example. When this bulb is brand new, it may produce 20,000 lumens, which is pretty good. However, this number will quickly decrease because metal halides suffer from serious lumen depreciation. If the bulb has a lifespan of 11,000 hours, it may only produce 10,000 lumens by the time it gets to 5,000 hours. And the worst part is that its energy consumption will remain the same.
This brings us to L70…
L70 is a term used to define the time it takes for the lumen output of a LED module to reach 70% of the initial output.
LEDs must retain 70% of their lumens during their lifespan. For instance, if a LED has a lifespan of 50,000 hours, it must maintain 70% of its lumens during its entire lifespan. This rule doesn’t apply to metal halides. While the specifications on the box may say that a light produces 20,000 lumens, this won’t be the case for long because of rapid lumen depreciation.
Metal Halides Lose Light Because of Reflection
LED lights are directional. This means they discharge light in a specific direction. Metal halides are omnidirectional and discharge light in all directions. To avoid light wastage, reflectors are used to redirect the light and focus it to a specific area.
Since reflectors are never 100% efficient, some lumens bounce off them and back to the fixtures, leading to lumen loss. Research has shown that up to 30% of lumens can be lost because of this. So, in reality, a metal halide bulb that’s supposed to emit 20,000 lumens only emits 14,000 lumens.
There are three things that determine light quality: lumens, Kelvin, and CRI (Colour Rendering Index). Since we’ve already discussed lumens and Kelvin, let’s talk a little about CRI. CRI measures a light’s capacity to reveal the true color of objects. LEDs usually have high CRI ratings, which means a bulb that discharges 20,000 lumens may seem brighter than a HID light that emits 50,000 lumens.
Perceiving Light: Photopic vs Scotopic Lumens
Lights usually produce two different types of lumens: photopic lumens and scotopic lumens. Both lumens are visible to the human eye. However, photopic lumens are seen by the eye in well-lit conditions while scotopic lumens are seen in dimly lit environments.
Until recently, only photopic lumens were measured, no one really thought of the fact that human eyes perceive light differently than manmade devices, or that a bulb can appear different during the day and in the night. But thanks to technological advancements, there are now two ways to label lumens.
The light LEDs produce falls within the visible spectrum, the spectrum that can be seen by the human eye. LED lights meant for humans do not produce UV or IR spectrums as they are invisible to the eye and of no benefit to us visually.
A correction factor is usually applied to photopic lumen readings to determine the usable light (scotopic lumens) a light source produces. This factor was developed by scientists to create common ground between different light sources, because two different bulbs with similar photopic lumen readings can have very different usable light outputs. The correction factor adjusts the actual value of the lumen downwards or upwards from the advertised photopic lumen.
The factor usually reduces the lumen quantity of some HID lights and increases the lumen quantity of LED lights (by 1.7 or more). This means the scotopic lumens LED lights produce are more beneficial to humans.
A Little Recap
The most important message we are trying to put across in this post is that you need more metal halide lumens to get the same amount of light fewer LED lumens produce. Even if you forget everything you read in this post, don’t forget these three things.
- Metal halide bulbs are very bright when they are new, but after 6 months of use, they can lose their brightness by up to 50%
- LED lights produce directional light which is very efficient. There are no lumens wasted
- LED light is of high quality, you need less lumens for optimal brightness
So, How Many LED Lumens Are Enough?
Photometry is the most accurate way to determine the exact amount of lumens you need. But since we’ve been selling LEDs for more than 10 years, we know the general amount of lumens needed for both indoor and outdoor applications.
Indoor spaces usually need about 45,000-55,000 lumens and outdoor spaces need approximately 40,000-60,000 lumens, but this all depends on the application and the mounting height.
When you look for the LED equivalent of a 1000-watt metal halide lamp, you’ll find bulbs that discharge 100 lumens or more. High-quality lights made by reputable manufacturers can emit 150 lumens or more. These lights can decrease wattage consumption by up to 4 times. If you replace multiple bulbs, you can save a significant amount of electricity.
Replacement Options for Metal Halide Bulbs
When it comes to replacing metal halides, there are two options: Retrofitting or a full fixture replacement. Retrofitting simply means replacing metal halide bulbs with LED bulbs while a full fixture replacement means replacing the bulbs as well as the housing (the light fixture).
The condition of the existing light fixtures will determine which option is better for you. If the fixtures are new or in good working condition, there’s no need to replace them – simply get retrofit kits. If they are old or worn out, a full fixture replacement is the only option.
How Efficient Are the LEDs in A Retrofit Kit?
One common misconception is that the LEDs in retrofit kits are not as good as those in new fixtures. This is simply not the case. HID replacement kits last just as long as new fixtures. Don’t replace lighting fixtures that are functioning well just because of some untruth you may have heard.
Our retrofit kits come with a 10-year warranty and have been installed in sealed fixtures in both hot and cold regions. None has ever malfunctioned.
Retrofitting will always be cheaper because installation is easier and the process doesn’t require as many materials as a full replacement. If there’s no need to replace the existing light fixtures, always choose retrofitting.