When LED lights first started gaining popularity 20 years ago you had to pay an eye-watering $50 for a single light bulb. It took a few years but after prices dropped the technology has since become the go-to lighting source seen in just about any kind of building in many different applications.
HID lamps cover a range of lights, from the intensely bright xenon vehicle headlight with a blue tinge to lighting for sports stadiums, warehouses and large public spaces. The most common types of HID lights use mercury vapor, sodium (either high or low pressure) and metal halide as their light source.
Mercury vapor has largely been phased out and replaced by high-pressure sodium and metal halide lamps in streetlights in the United States.
So, Which One is Better?
The answer depends on several factors, so let’s examine the advantages of each.
HID lights are great at providing light over a large area where high-intensity lighting is required. A typical example is the lighting on sports fields or large indoor arenas. Street lamps in many areas have an orange glow caused by sodium gas in the bulb.
HID bulbs provide an intense white light superior to traditional halogen globes for cars and trucks.
LED lights use even less energy than their HID counterparts and have a much longer lifespan. In many instances, the cost advantage of HID lights is mitigated by the longevity of LED lights. In addition, LED lighting is getting cheaper, reducing the price difference between the two systems.
One of the most obvious distinctions between LED and HID lights is that LED lights produce almost no heat. In comparison, HID lights produce a significant amount of heat, so much so that HID lighting has to be positioned away from plants to avoid burning them.
Environmentally, LED lights are clear winners because they contain no harmful vapors like the mercury found in HID lights. In addition, their long life reduces their environmental impact.
HID lights emit light in 360 degrees, whereas LED lights emit light in a specific direction. This means you won’t have to purchase reflectors to direct light to a specific area when using LED lights.
LED lights are instantly at their brightest. They don’t need a warming-up time like HIDs and can tolerate repeatedly switching on and off. They are also ideal for use when access lighting is controlled automatically.
LED lights are ideal for displays that require the light source to change color. They don’t require transparent screens, which is essential when using HID lighting.
LED lights have a superior CRI (color rendering index) compared to HID lights and don’t suffer from the disadvantage of producing light in the UV spectrum.
Despite the rated lumen output of HID lamps being higher than LEDs, the latter delivers a higher lumen rating to the work area.
So LED lights seem to offer several advantages over HID lights, but let’s examine their different applications because they each excel in different functions.
LED Lighting Applications
The combination of solar PV panels and LED lighting has made solar lights immensely popular, with individually powered solar lights for gardens and security, all powered with light-emitting diodes (LEDs).
Solar powered fence post lights and roadway lights can provide nighttime lighting powered by the unit’s small solar panels and batteries.
Because LED lights are so energy efficient and consume so little electricity, they are ideal for a lighting system with a mini-PV panel charging a small battery.
Roadside solar-powered LED lamps are becoming more popular. They often incorporate a dimming feature: When there is no passing traffic, the lighting dims and only gets bright with approaching traffic. This would not be possible using HID lights, as they cannot accept intermittent power and have a time lag to achieve full brightness.
Packs of small LED lighting units are common in most garden and home décor stores. They offer the convenience of creating a nighttime garden without the hassle and danger of running power cables to the individual lights. The tops of the light units normally have a small PV panel that charges the battery during the day and governed by a light sensor switch, the LED lights up at night.
Pick up any electronic instrument today, and it will invariably have an LED light somewhere in the circuitry. LEDs typically supply a backlight to items such as TVs, cell phones and every flashing light in children’s toys. It is the miserly power consumption of LEDs that extends the battery life of your cell phone.
Advertising boards are frequently hooked up to LED lights to offer a multi-colored visual display with flashing features and the ability to light up messages for general information and traffic alerts.
LEDs are also excellent in situations where lighting needs to be dimmed. In the automotive industry, the lights in your car’s interior that fade away once you have closed the door are all the result of the dexterity of LEDs supplying varying amounts of light.
LED lighting has dominated the market in the world of camping and outdoor activities. Portable torches, lamps and spotlights are all powered by rechargeable batteries that offer long operating hours using LED panels.
HID Lighting Applications
HID lighting is typically used in sports stadiums, where several HID lights flood the field with lumens in excess of the normal daylight.
Traditionally, public spaces like parking garages and gas stations were flooded with HID lighting; however, as LED lights gain more popularity, the trend is to replace HID lights with more economical LED ones.
Streetlights still use metal halide and high-pressure sodium HID lamps, while some retail stores strive to entice customers into their stores with bright and vibrant lighting using HID lamps.
Low-pressure sodium HID lamps are excellent for areas that require only low-intensity light and are a gentle alternative for lighting in areas where wildlife may be affected.
Feature image: Pierre Châtel-Innocenti; Image 1: Hongwei FAN
