High-intensity discharge (HID) lighting is commonly used in outdoor and industrial applications due to its potent output per bulb.
Unfortunately, HID lighting comes with a high cost of ownership:
- Installation costs are high because these fixtures are normally located high above the ground, hanging from industrial rooftops or mounted on poles.
- The service life of HID fixtures is decent, ranging from 10,000 to 24,000 hours depending on the specific type of bulb, but frequent replacements are required because these lamps work for long hours and are susceptible to switching and thermal stress.
- The power consumption of HID lighting is high: they are more efficient than incandescent lamps, but less efficient than fluorescent tubes, and significantly less efficient than LED fixtures.
The three most common subtypes of HID lamps are metal halide (MH), high-pressure sodium (HPS) and mercury vapor. There is also a type called low-pressure sodium (LPS), which offers a very high luminous efficacy but a very poor lighting quality, which limits its applications.
LED lighting offers significant advantages over HID lighting, in great part due to its energy efficiency and long service life. When the upgrade is carried out, energy savings can range from 40 to 80 percent, which lamp replacements becoming 5 to 10 times less frequent.
Service Life Comparison Between HID and LED Lighting Products
To get an idea of how LED lighting provides maintenance savings when replacing HID fixtures, consider the typical service life of the three main types of HID lamps:
- Metal halide: 9,000 to 12,000 hours
- Mercury vapor: 18,000 to 24,000 hours
- High-pressure sodium: 18,000 to 24,000 hours
Metal halide lamps are commonly used for indoor industrial lighting, since they provide the best lighting quality of all three types despite their reduced service life. The other two types are more common in outdoor applications, where the colour performance of lighting is less critical.
However, LED bulbs typically last for 50,000 hours, while integrated LED fixtures can reach up to 100,000 hours. If you were to upgrade the lighting from MH to LED fixtures in an industrial warehouse, for example, lamp replacements would become 10 times less frequent. When you consider that these lamps are high above the ground, and qualified personnel must climb on a ladder or hoist to replace them, the labour savings associated with avoiding ten replacements are significant.
LED Lighting is Much Better Suited for Lighting Automation
Each time an HID lamp is activated, it establishes an electric arc to ignite a gas and produce lighting, and this process can wear down the lamp very quickly if it is frequently switched on and off. Hence, HID lighting is better suited for applications where the lights will operate for long periods of time. If lighting controls are deployed to activate and deactivate lamps as needed, their service life is cut short and replacement costs offset any energy savings achieved.
LED lighting does not suffer from this limitation, as the lamps are much more tolerant to frequent switching: they are solid-state devices that don’t rely on gas ignition. Automation can enhance the savings achieved when upgrading from HID to LED lighting. For instance, if you reduce the lighting power by 50% and the time of use by 20%, your lighting costs are being reduced to only 40% of their previous value.
LED lighting also makes facilities safer, since it can be reignited instantly after a service interruption. This is not possible with HID lamps, which typically have a restrike time of several minutes, leaving facilities and outdoor locations in the dark during their cool down period.