Tractor Supply Company (TSC), the largest rural lifestyle retail store chain in the United States, was seeing approximately 8% store growth per year, but because some of that growth was occurring in states with a higher cost for electricity compared to other stores, utility expenses were growing at a faster rate. TSC needed a way to reduce utility expenses, but before exploring alternative lighting options, several questions needed to be considered, such as:
What are the goals for expense reduction?
How are stores being illuminated?
Are fixtures standardized?
How bright (foot candles) are the stores?
How much is consumed for the ‘fixed’ lighting load?
How are lamps maintained?
How long are existing lights lasting?
Based on store load profiles, hours of operation and an opportunity to reduce expenses, TSC decided to evaluate different types of LED lamps with internal drivers, as well as LED lamps with external drivers. Foot candle measurements were taken, and readings confirmed the ability to reduce the number of lamps and maintain light quality.
The Tennessee Valley Authority was contacted to assist in Measurement and Verification (M&V) steps. These findings not only confirmed the calculations by TSC, but also showed instances where lamps were being over-driven.
TSC selected a standard GE lamp and driver, or equivalent, and executed a RFP for product and installation. One criterion was the ability to execute in a one- to two-year program. Scheduling, delivery, installation, appropriate disposal of removed parts, and warranty for installation and materials were integral parts of the bid process and contract.
The project, which will be completed in 2017, includes a survey, cataloguing of interior and exterior lighting, removal and replacement of existing lamps and ballasts with LED lamps and external drivers, de-energizing excess lighting fixtures, identifying fixtures needing repairs or replacement and repair based on pre-approved metrics. The surveys for interior and exterior lighting configurations resulted in a standardized lighting package for interior lighting and a known and identifiable asset base for exterior lighting.
Based on the test findings and verification of the project ROI, work was accelerated from three years to eighteen months.
Findings and results to date include:
Lighting configurations were quite varied ranging from 4’ T8, 32W, and two lamps per four foot section to 8’ T12 75w lamps. Other types including 2’ and 4’ U shaped lamps, 400W HID and 175W HIDs were found. This wide range of lamp configurations negatively impacted budgeting for utilities and caused maintenance to be higher than would have otherwise been expected.
Light levels (fc) and light quality in stores have consistently improved post retrofit.
Savings are currently ranging from 29% to 50% less energy comparing CY to PY.
Outages are covered under warranty thus eliminating interior maintenance expense.
The project is on track for completion and ahead of estimates for energy savings.
Expected payback is less than 2 years.
The project ROI is over 50%.
- The utility rebates received to date, over $2.3 million, have served to enhance the ROI and payback.