Metrolight eHID retrofit

January 13, 2012

Recently, EMC converted a large retail store in Massachusetts from lowbay, 350W, pulse start, Metal Halide fixtures to 200W eHID Metrolight fixtures. With Metrolight’s EcoPod product we were able to re-use the existing lamp enclosure and lens, saving the customer the expense of replacing a part of the fixture that was still viable.

The Metrolight system allows us to address each ballast individually, dim each fixture individually down to 50% power, set up schedules, and make changes to light levels based on input signals. We made full use of those capabilities and designed a control scheme that:

  • Rotates night light circuits to balance lamp aging
  • Receives a signal from a low voltage switch at the front of the store to put the store into stocking mode
  • Receives a signal from the Building management system to put the store into customer mode
  • Uses the ballast’s dimming capabilities to have appropriate light levels during all of those times, saving extra energy

I was on site for the installation and commissioning. The installers said it was very easy for them to retrofit with the EcoPod product and the managers really liked the “softness” of the new lights. The commissioning, which might seem daunting, went very smoothly. Even when the inevitable loose control wire issue popped up, it was easy to trace through the control system, and rather than spend hours trying to guess at which connection was loose, we were able to direct the installers to the precise location. It was a 5 minute fix.

We involved the local utility, NSTAR Electric, early in the process, and they were very receptive to a technology that didn’t fit into their prescriptive rebate program. We showed them the benefits of this new system and how the scheduling and dimming could drive savings. They were eager to participate, worked with the customer to understand their financial needs, and offered a strong incentive under their Custom Retrofit program that enabled the project to go forward.

My biggest surprise, and I think the biggest surprise of the client, was the improved look of the space. What was generally intended to be an energy savings retrofit has had the added feature of really giving the space a warmer feel, which I can’t attribute to any one thing.

The lamp (Venture 200W in this case), other than wattage is fairly similar to the old lamp, and the new eHID ballast is likely running the lamps “cleaner.” It is probably a combo of those two changes. What I do know is that the difference was quite noticeable and most importantly, the client liked the new look.

At the end of the day, for the sales floor portion of the project, we were able lower the lighting load by 53%, improve how the store staff and corporate personnel felt about the space, and achieve a total project payback that the customer was very happy with.



Tony Johnson is Energy Management Collaborative's Technology Manager. In this role he combines his background in lighting & controls design and solid state light fixture design with his expertise in energy savings to evaluate emerging technologies for EMC customers.