LED vs Metal Halide
What are LEDs?
Before we breakdown the contenders, let’s talk about the current reigning champion.
For those who have yet to discover the beauty of the LED, LED bulbs are “Light Emitting Diodes,” where electricity flows through two electrodes - an anode and a cathode). Diodes are constructed of semi-conductive materials and do not use any type of filament.
Benefits of LEDs
The benefits of using LEDs are extensive.
The most significant benefits are: extremely long lifespans (50,000 to 100,000 hours or more), very high energy efficiency, extremely high light quality and little to no maintenance costs. LEDs have a wide range of color temperatures, and though the CRI is dependent on the particular light fixture, LEDs have a general CRI range from 65-95. LEDs have instant on/off, meaning they require no warm up or cool down time. This significantly extends their lifespan and produces smooth, steady light with no flicker.
LEDs emit light with a 180-degree spread, which is ideal for directional lighting – the usual desire for illumination – and doesn’t require reflection and redirection, adding to its efficiency. LEDs produce no infrared or UV emissions and very little heat, converting the majority of energy directly to visible light.
The initial cost of LEDs is higher than Metal Halide and other traditional fixtures, however the payback over time is very high. LEDs last exponentially longer, requiring little to no maintenance and have great energy efficiency.
What are Metal Halides?
Metal Halide lamps produce light by passing an electrical current through a mixture of mercury and Metal Halide gas. Unlike LEDs they do contain fragile filaments.
Benefits of Metal Halides
Metal Halides are much more efficient and higher quality than incandescent bulbs. They are useful for high intensity applications because of their high color temperatures, and this is by far their most positive characteristic. Metal Halides also have a very high source of white CRI light, making them ideal for applications that need the most correct representation of color possible such as paint spray booths.
Disadvantages of Metal Halides
While Metal Halides are great for high output applications such as vehicle headlights, sports stadiums and construction, they have the longest warm-up time period of any light, sometimes up to 20 minutes to reach full operating temperature. Because of this extreme warm-up period, Metal Halides must be operated for longer periods of time since on/off is not instant, unlike LEDs. This drastically shortens their lifespan with the average length being 6,000 to 15,000 hours at most for each bulb.
Another disadvantage of Metal Halides, is that they are omnidirectional meaning they product 360 degrees of light. This requires the light to be reflected and redirected where needed which causes light spillage and lessens the light’s efficiency overall. Also, Metal Halides do produce UV and infrared radiation. Infrared radiation is a waste of energy, and UV emissions cause harm to the atmosphere, animals and human beings. The heat emissions from Metal Halides are also much greater than LEDs, which means less energy is directed towards the actual illumination.
Furthermore, Metal Halides are relatively fragile and when broken require special handling, because they contain hazardous materials such as mercury. Overall, Metal Halides are cheap in the short-term, but expensive in the long-run due to constant maintenance and replacement costs.
LED vs High Pressure Sodium
What are High Pressure Sodium Lights?
High pressure sodium lights work by creating an electric arc through vaporized sodium metal, while additional materials and gases work to start the lamp and control the its color.
Benefits of High Pressure Sodium
The main benefit of using HPS is that they are the only light source with a similar efficiency to LEDs and maintain luminescence fairy well. They also do have great lifespans – around 24,000 hours – though this is significantly less than LEDs. They also are fairly cheap to purchase and cheap to maintain, and do not emit infrared or UV radiation.
Disadvantages of High Pressure Sodium
Firstly, HPS lights have a very narrow color spectrum, limited to warm deep yellow light. Although they are very popular for street lights, they don’t serve many other applications. They also have the worst CRI of any light source, falling around a 25 and like Metal Halides, require a warm-up period and may flicker or cycle on and off at the end of life.
Like Metal Halides, High Pressure Sodium lights are omnidirectional, which wastes light and makes them less efficient. They lose roughly 15% of their heat emissions which adds to their inefficiency.
HPS light costs differ based on the particular fixtures, but are cheap compared to LEDs. However, they are very fragile and operate with a glass bulb, making them unsafe for hazardous or explosive environments. This makes maintenance and replacement costs much higher than LEDs and more comparable to Metal Halides.
Hopefully, from this information you were able to gather that the LED is generally the worthier opponent when matched up against HID lights. Though it’s important to note both Metal Halide and High Pressure Sodium lights do offer some benefits over LEDs for specific applications and smaller budgets.