Custom Grocery LED Lighting Fixture Retrofit Solution

Grocery Aisle Light Application Photo

Custom Grocery LED Lighting Fixture Retrofit Solution

Part Number: Custom Grocery LED Lighting Fixture Retrofit Solution

Project Overview

End-User – Large Grocery Chain in Northeast US
Partner – CT based ESCO
Application – General Aisle Lighting

ILT AisleLight retrofit for Zumtobel T5 fixture

Summary - Custom-designed linear reflector with LED array for large, Northeast grocery chain. Objective is to retrofit existing, high-end fluorescent aisle fixtures with LEDs, resulting in reduced power and improved illumination of product on shelves.

Project Overview – Improve illumination of shelves/aisles while maintaining existing fixture (retrofit). Reduce energy and maintenance from an existing efficient and reliable T5 solution. Retain existing, high-end fixture rather than replace while upgrading to LED technology. End-customer has more than 80 locations, most of which use these fixtures with nearly 600+ per location.

Incumbent Technology – T5 fluorescent fixture from Zumtobel. This is a high-end fixture, not a standard troffer with reflector. The existing fixture is constructed of an aluminum extrusion with a reflector inserted, along with a snap-on grid to minimize glare.

Problem – Retrofitting an existing, high-end fixture with LED technology in a manner that provides energy savings and an improvement to light distribution while doing this cost-effectively.

Design Approach – Basic assumptions were made at the beginning of this project as follows:

  • Optical design - A custom, thin, formed aluminum reflector would need to be designed to achieve the light distribution required
  • Circuit design - Selection of the LED and power supply circuit is critical to achieve the efficacy needed to save energy over existing T5 fluorescent.
  • Thermal management is always a consideration with LEDs. In this case, with the output required and power density, this is of utmost importance. We assume we can make use of the significant aluminum construction of the existing fixture to act as the ultimate heat-sink.
  • Field retrofit – Total project cost includes the labor to install a retrofit kit in the field by electricians who tend to be higher paid than in-house assembly labor. Need to keep retrofit time down to 10-15 minutes or even less.
  • Cost is one of the most important factors to justify this project!

Challenges

First challenge (Our partner provided us with sample fixtures to evaluate.) - We noticed that it would be very difficult to position the LEDs and reflector against the existing extrusion for heat-sinking purposes. A thin, formed aluminum reflector would not have the heat sinking capacity to work for the power density. Therefore, we came up with a different concept – aluminum extrusion. We have used Brite Anodize aluminum for other applications and it proves to be a great reflector. We can design the extrusion with features and overall mass to work effectively as a heat sink. If designed effectively, parts can be made without any post-machining saving significant cost.

Second Challenge - LED selection is the next most significant challenge. Our experience with linear LED fixture design made us lean toward mid-power LEDs. We have found mid-power are higher lumens/watt and lower dollars/lumen in most cases. This approach also spreads out the light and minimizes hot-spots and glare. We reviewed the top manufacturers (Nichia, Cree, Lumileds, Osram-Opto, etc.) and found that Lumileds and Osram-Opto both have LEDs that could work. Availability of supply and cost will be a deciding factor.

Third Challenge - Power supply configuration also became a challenge as the space allocated for the existing fluorescent ballast is long and thin. The LED driver selected must meet this space requirement along with the voltage, current and efficiency requirements.

Solution

  • Optical design – Our in-house optical engineer designed a custom-shape to provide the desired light distribution. Working with our aluminum extruder, we have created a profile that can be easily snapped into the existing fixture, provide the heat sink properties necessary and doesn’t require post-machining, minimizing the cost per fixture.
  • LED strip design – Osram-Opto LEDs are assembled to a strip, powered by a constant current, 40W power supply to achieve the highest efficiency. The total output of greater than 4200 lumens and consuming less than 31WAC for a net of 135 lm/W.
  • Power supply – Philips, like others, has expanded their programmable power supply offering for the LED industry. We selected their new Xitanium, 40W supply for this application based on size, efficiency, and electrical characteristics.
  • Networked Lighting Control – A feature of the Philips supply is its input for integration to a networked lighting control scheme. Although the end-customer may not use this feature immediately, functions such as dimming, daylight harvesting, energy management, occupancy sensing and other, can be implemented at a future date with the installation of a network control platform. DLC has implemented a qualification for Networked Lighting Controls and some utilities are starting to require the “hooks” for products to be qualified for incentives.