We won’t dwell on this one too much. Let’s face it though, LED lighting has been proved time after time to cut energy use – massively. In fact, you can make savings of 50% or sometimes even more.
Again, another area where LEDs have been shown to beat Metal Halides hands down.
Metal Halide lamps degrade much, much faster than LEDs. So they often need replacing, even before a lamp has failed totally. That’s not all. Because of the way they’re built, Metal Halide lamps can’t cope well over time with things like vibrations on cranes and high masts. This can lead to components breaking and the lamps dying. Not a problem at all with solid-state LED systems.
What does this all mean for you? You’ll have to pay several hundred Euros for each new lamp you need. You’ll also need to pay for someone to replace them. You might need to get in specialist equipment too like cherry pickers to reach them – yet another big cost. And we’ve not even mentioned yet the problems and costs caused by downtime, or an immediate failure, you could incur.
Efficiency and efficacy
At the start of its life, a Metal Halide lamp can deliver a high lumen output. Obviously, this lumen output is related to efficiency. However, give it six months or so and 20% of that lumen output will be lost as the bulb degrades. It’ll still be consuming the same amount of energy though, meaning it’s getting more and more inefficient. And by the time it’s reached its half lifetime it’ll need replacing because it won’t deliver the quantity and quality of light needed.
The way Metal Halides cast their light, compared to LEDs, can lead to further inefficiencies. Metal Halides throw light in all directions and to focus it on a target they need reflectors. These reflectors aren’t nearly as efficient as the optical systems, such as lenses, used in LEDs. So, straightaway with Metal Halides you’re looking at an effective light loss of 20 to 50% depending on the photometrics you want to achieve.
Just remember too… A well-built LED will achieve around 110 to 130 lumen per watt. Whereas with Metal Halides, after taking optical losses into consideration, you’re looking at only 70 lumen per watt. That’s costing you twice the installed power to achieve the same lighting levels! What’s there to think about?
Light quality and CRI
All the light emitted from LEDs is in the visible spectrum. But when it comes to Metal Halide lamps, as well as visible light, they emit both infrared (IR) and ultraviolet (UV) light. The IR emitted is one of the reasons Metal Halides are so inefficient compared to LEDs as you’re wasting energy on heat. The UV light emitted doesn’t waste much energy. Too much exposure to it in a confined space could cause skin damage and health issues, however.
Metal Halides don’t fare well compared to LEDs when it comes to their colour deviation and Colour Rendering Index (CRI) values. With a well built LED system both colour deviation and CRI changes don’t really come into play. As Metal Halide lamps age though, you’ll get colour deviation, and the CRI value won’t be stable. In fact, with Metal Halides you can only be sure of the CRI when it’s very first installed – it starts to change very soon after.
LEDs can be turned on and off thousands of times a second with no impact on lifetime or performance. Which makes them perfect for things like light shows in places like large sporting venues. It also means they can be used with controls such as motion sensors to dim or turn them on and off instantly when required – helping save money lighting areas when they’re not needed.
Because they’re electromechanical Metal Halide lamps need time to reach full power. And when they’re turned off, you’ll need to wait fifteen minutes or more for them to cool and restart before they can reach full power again. So in terms of controls, the best you can do is dim them with voltage regulators – which are very expensive. You’ll also have to invest in having a separate power line for them so they can be dimmed independently of any other systems.
So why are Metal Halide systems going cheap?
We’re not going to ‘pull any punches’ here. Basically, because of all the reasons above, the Metal Halide era is coming to or has already reached its end. And to clear their stocks, manufacturers are cutting their prices. An added issue that’s starting to emerge is that once those stocks are cleared, finding replacement parts is going to become impossible.
Paolo Corno, Technical Director & Co-Founder, Midstream Lighting
With over ten years of LED lighting industry experience, Paolo is an invaluable and highly regarded member of our core leadership team.
Coming on board as one of the company’s co-founders in 2013, Paolo’s responsible for overseeing our Lighting Design, Engineering, and R&D Teams. He personally leads the design and development of Midstream’s comprehensive product portfolio – including the Atlas, Titan and Modus Floodlight Series – which are installed in over 85 airports globally.
An experienced designer, who holds a degree from Bocconi University in Milan, Paolo has led the design of over 100 LED lighting solutions in the aviation, maritime, sports and horticultural markets. ensuring that all national, local, industry and customer requirements are met.
March 11, 2021