Newsletter spotlight—how metal halide lamps stack up

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Metal halide lamps are used both for general industrial purposes, such as in warehousing, and for very specific applications which require specific UV or blue-frequency light, such as hydroponics plant growing and for coral in aquariums. They are most often used in athletic facilities, and in higher end professional lighting fixtures, especially automated stage lighting. Like all other gas discharge lamps, metal halide lamps require control equipment or electronic ballasts to provide

proper starting and operating voltages  and to regulate the 

A light fixture using a metal halide lamp.

current flow in the lamp. A few electronic ballasts are now available for metal halide lamps. The benefit of these ballasts is more precise management of the lamp's wattage, which provides more consistent colour and longer lamp life.

An example of their efficiency capabilities was performed in 2005, on a trial project that took place on a busy commercial street in Sydney. In this trial involving Sydney council’s and an energy provider, new metal halide lamp technology was retrofit into existing mercury vapour luminaries without the need to change any other components in the luminaries. The purpose in staging the trial was to demonstrate that new metal halide lamps could achieve high reliability levels while delivering improved energy efficiency and quality of light. The results showed the metal halide lighting used (250W) delivers approximately 50% more light and a higher quality of light for the same energy used in the mercury vapour lamps. Not only is this a more efficient use of energy but, where upgrades are needed, it potentially avoids the installation of additional lighting. The list cost of the lamps were cheaper too.1

About 24% of the energy used by metal halide lamps produces light, making them generally more efficient than older style fluorescent lamps, and substantially more efficient than incandescent bulbs. In addition to their natural efficiency advantage, if they are used in conjunction with voltage reduction power saving units, such as the GEL Energy Saving System, they are proven to deliver substantial savings of 30% or more. The table above demonstrates this enhanced efficiency. For example, a pilot installation was undertaken in a warehousing environment with 400 watt metal halide lamps.

The pilot was run over a period of 2 weeks with three phases of operation, non-saving, maximum saving and minimum saving mode (a timetable mode with differing power saving levels at different times of the day). A third party data monitoring tool was also installed to provide some independent data for comparison with the GEL proprietary data tools. The environment also uses a “daylight harvesting” technology that turns off half the lamps when the ambient light reaches a certain level. The results as shown below demonstrate that after taking into account the “daylight harvesting” energy reductions the GEL Energy Saving System delivers an additional power saving of between 28% and 38%.

References

1: Metal Halide Retrofit Lamp Trial South Sydney Regional Organisation of Councils (SSROC) - Energy efficiency lighting case study

2: Global Enviro Light Case Study: Trial installation of energy saving device used in conjunction with 400w metal halide lamps