A Christian retreat facility located in Texas contacted Access Fixtures with a problem. They had 20 decorative street lights lining their private access road in their facility. The decorative street lights used 175w mercury-vapor lamps and ballasts, and were installed well before 1945, the year the Christian retreat purchased the property. The access road had to be effectively lit since it was used by both cars and pedestrians. It was a matter of aesthetics and safety.
The Problem with Mercury Vapor
Over the course of 70+ years, the mercury-vapor lamps burned down to the point where they emitted minimal light. In some instances, the lamp and/or ballast failed, leaving the luminaire completely out of service. As a band-aid solution, the property manager installed 500w incandescent lamps. While this solution used a lot more energy, the lamps were cheap and at a minimum, the access road was illuminated.
Mercury-vapor (MV) lamps are high-intensity discharge lamps that use an arc through vaporized mercury in a high-pressure tube to create light directly from its own arc. As an early, if not the earliest, HID light source, MV became a workhorse for society for lighting streets, factories and large areas for more than 100 years. The advantages were good efficiency relative to the time they were installed, better color rendering as compared to high-pressure sodium (HPS), and an average of 24,000 hours operating time. Today, the disadvantages include: the lamps contain mercury, lower lumens per watt (LPW) than HPS, and poor CRI except when compared to HPS. The biggest issue with MV is the lamps have rapid lumen depreciation. The lamp will stay on, sometimes for as long as 40 years, but very little light will be emitted. This wastes a lot of electricity.
Retrofitting the Antique Street Lamps
The Christian retreat had a number of requirements for their new lighting. They liked their antique street lighting and wanted to keep the luminaires. The new lighting had to be low maintenance, as they already have enough things to maintain and repair. The light had to be warm in color and couldn’t be blueish. Energy efficiency was preferred in order to lower operating costs and be as “green” as possible. Also, a low-cost solution was necessary as any money spent on lighting was money that could not be spent on their programs.
For an Access Fixtures lighting specialist, it was obvious that they should use a 30w post top LED retrofit. Installation would be as simple as changing the wiring to bypass the old ballast, and then screw in the post-top LED retrofit in place of the MV lamp or the 500w incandescent lamps. The whole process would take very little time, which would minimize the installation costs.
The LED post-top retrofits fit the needs of the Christian retreat. The retrofits are available in four different color temperatures, so they selected the warmest with 2700 Kelvin. Able to operate on 120-277v line voltage, the retrofit would work on their voltage. At 105 lpw, the LED retrofit was energy-efficient. Rated to maintain greater than 90% of initial light output after 60,000 hours, it would be virtually maintenance free for 20+ years. It all made sense.
The Bottom Line
So how will the LED post-top retrofit affect their bottom line? The decorative street lights operate on average 12 hours per day 365 days per year. Using the What’s a Watt Worth Chart, assuming the cost per kWh is $.15, each watt of energy is worth $.66. A 175w MV lamp uses 200 watts including the ballast, so it costs $132.00 to operate each 175w MV luminaire. The 500w incandescent lamps cost $330.00 per year to operate. The 30w LED post-top retrofit only costs $19.80 per year, or $112.20 less than the MV. Twenty LED post-top retrofits will save $2,240.00 per year as compared to MV and even more if you count the many that use 500w incandescent lamps/
If you want to discuss LED retrofits or how your organization can properly illuminate your facility, be sure to speak with an Access Fixtures lighting specialist.