The B2B Dilemma: Retrofit vs. Replace
For facility managers and property owners, outdoor lighting is rarely just about "visibility." It is a calculated capital expenditure (CapEx) decision involving security, liability, and long-term operational costs (OpEx). When an existing high-pressure sodium (HPS) or metal halide (MH) wall pack begins to fail, or when energy mandates require the addition of occupancy sensors, the immediate question is: Do we retrofit the existing fixture with a sensor and LED kit, or do we replace the entire unit with a modern, integrated LED wall pack?
While the material cost of a standalone sensor might seem lower, the "Payback Math" often reveals a different reality. Labor rates, utility rebate structures, and long-term lumen maintenance frequently tilt the scales toward full fixture replacement. This article provides a pragmatic framework to navigate this decision, backed by industry standards and real-world field data.
The Hidden Labor Trap in Retrofit Projects
A common mistake in B2B lighting audits is underestimating the "fully burdened" cost of labor. Conventional wisdom assumes that adding a sensor to an existing fixture is a "simple add-on." However, in my experience auditing industrial sites, I’ve found that retrofitting a sensor onto an older wall pack often takes 60 to 90 minutes, compared to 30 to 45 minutes for a complete fixture swap.
The "Bucket Truck" Factor
Most outdoor wall packs are mounted between 12 and 20 feet. Accessing the wiring compartment of an existing fixture on a wall mount or pole often requires a bucket truck and, for safety compliance, two electricians. According to national data from Angi, professional electricians charge between $50 and $150 per hour. When you factor in the rental of specialized equipment, the labor cost for a "cheap" retrofit can easily exceed the cost of a new fixture.
Wiring Complexity: Class 1 vs. Class 2
Modern LED wall packs often utilize 0-10V dimming. Retrofitting a sensor into an old housing often requires pulling new low-voltage control wires through existing conduits that may already be at capacity. This introduces "friction points" like cable tension limits and potential interference. In contrast, a new integrated fixture comes factory-prewired, ensuring that the sensor-to-driver connection is optimized and weather-sealed.
| Metric | Retrofit (Sensor Add-on) | New Integrated LED Fixture |
|---|---|---|
| Estimated Labor Time | 60–90 Minutes | 30–45 Minutes |
| Special Equipment | Bucket Truck / Scissor Lift | Bucket Truck / Scissor Lift |
| Wiring Risk | High (Field Splicing) | Low (Plug-and-Play) |
| Warranty Coverage | Component Only | Full System (5+ Years) |
The Rebate Gap: DLC Premium vs. Standard Retrofits
The DesignLights Consortium (DLC) Qualified Products List (QPL) is the primary gatekeeper for utility rebates in North America. To maximize ROI, B2B buyers must understand the distinction between DLC Standard and DLC Premium.
According to the DesignLights Consortium (DLC), products must meet rigorous efficacy (lm/W) and lumen maintenance standards to qualify for the "Premium" tier. Many utility programs offer tiered incentives where a DLC Premium fixture receives a $25 to $75 higher rebate per unit than a standard retrofit kit.
Why Integrated Wins the Rebate War
Utility companies favor integrated fixtures because they provide a "known" performance profile. A retrofit kit's efficiency is often compromised by the old fixture's yellowed lens or inefficient internal reflectors. By replacing the entire unit with a high-efficiency wall pack—often delivering 130 lm/W or higher—you satisfy the strict requirements of ASHRAE Standard 90.1-2022, which mandates specific lighting power densities (LPD) and automatic shut-off controls for commercial exteriors.
Title 24 Controls for Warehouse High Bay Lighting provides a deeper look at how these mandates apply to large-scale facility upgrades.
Technical Performance: LM-79, LM-80, and the L70 Calculation
When comparing a retrofitted existing LED versus a new integrated wall pack, the performance differential is often underestimated. While both may save 80% energy compared to old HID systems, the new fixture typically yields an additional 10-15% efficiency gain due to advanced optics and superior thermal management.
Interpreting the Performance Reports
- LM-79-19: This is the "performance report card." According to the IES LM-79-19 Standard, this test measures the total luminous flux and efficacy of the entire fixture. Retrofit kits often cite the "chip" lumens, which do not account for the light lost through the old fixture's housing.
- LM-80 and TM-21: These standards define how long the light will last. The IES LM-80-21 Standard tests the lumen maintenance of the LED chips over 6,000+ hours. We then use the mathematical models in IES TM-21-21 to project the L70 life—the point where the light output drops to 70% of its original brightness.
Integrated wall packs are designed as a single thermal unit. The aluminum housing acts as a heat sink, keeping the LEDs cooler than a retrofit kit stuffed into a confined, unventilated old box. This translates to a significantly longer L70 life, often exceeding 60,000 to 100,000 hours.
The Environmental and Disposal Factor
One "hidden cost" of full replacement is the disposal of the old fixture. If you are replacing older fluorescent or HID systems, you must account for hazardous waste handling. According to the U.S. Environmental Protection Agency (EPA), older ballasts may contain PCBs (polychlorinated biphenyls), which require specialized disposal procedures costing between $15 and $45 per fixture.
However, leaving these old ballasts in place (as is common in some retrofit scenarios) leaves an environmental liability on your balance sheet. A clean break—replacing the fixture and properly disposing of the old unit—removes future risk and ensures compliance with modern environmental standards.
The 5-Year Heuristic: A Decision Matrix
Experienced facility managers use a simple heuristic to decide between retrofitting and replacing:
- If the existing fixture is < 5 years old and LED-ready: Explore a sensor retrofit. The housing and lens are likely still in good condition, and the "sunk cost" of the fixture hasn't been fully depreciated.
- If the existing fixture is > 5 years old or HID-based: Replacement is almost always the better long-term TCO (Total Cost of Ownership) move. The gains in efficacy, the higher utility rebates for DLC Premium units, and the reset of the 5-year warranty period provide a much stronger ROI.
Scenario Analysis: The Security Perimeter
Consider a warehouse with 20 wall packs.
- Retrofit: Adding photocell sensors to old units. Cost: $40 per sensor + $100 labor = $140/unit. Total: $2,800. No new warranty on the fixture. Efficacy remains at ~90 lm/W.
- Replacement: New 130 lm/W full cut-off wall packs with integrated photocells. Cost: $110 per fixture + $75 labor = $185/unit. After a $50 DLC Premium rebate, the net cost is $135/unit. Total: $2,700. You get a brand-new 5-year warranty and higher energy savings.
In this scenario, the "more expensive" hardware actually results in a lower net cost and a vastly superior technical outcome.
Compliance and Safety Verification
In B2B procurement, safety certification is the first point of verification for insurance and building codes. You should always verify that a fixture is UL Listed or ETL Listed. These marks prove the product has been tested to meet North American safety standards (like UL 1598 for luminaires).
Furthermore, ensure the fixture is IP65 rated according to IEC 60529. This ensures the housing is dust-tight and protected against water jets—a requirement for any fixture exposed to the elements. For high-traffic areas or loading bays, look for an IK08 or IK10 rating, which measures impact resistance.
A Specifier’s Guide to Low-UGR High Bay Lighting discusses similar durability and comfort standards for industrial interiors.
Summary Checklist for Facility Managers
Before signing off on a lighting upgrade, run through this technical audit:
- Verify Rebate Eligibility: Check the DLC QPL for the specific model number.
- Audit Labor Quotes: Ensure the contractor has accounted for lift rentals and potential wiring complexities.
- Check Voltage Compatibility: Verify the sensor’s datasheet matches the existing driver’s voltage (e.g., 120-277V).
- Assess Lens Condition: If the old fixture lens is yellowed or cracked, a retrofit kit will lose 20-30% of its lumen output.
- Request IES Files: For large projects, use IES files in software like AGi32 to ensure the new layout meets ANSI/IES RP-7 industrial lighting standards.
Frequently Asked Questions (FAQ)
Can I use a 0-10V sensor with an older LED driver? Only if the driver has dedicated dimming leads (usually purple and gray/pink wires). If the driver is not dimmable, a standard occupancy sensor can only provide ON/OFF functionality, missing out on the "bi-level" dimming savings required by codes like IECC 2024.
What is the difference between a photocell and a motion sensor for wall packs? A photocell (dusk-to-dawn) reacts to ambient light, turning the fixture on at night. A motion sensor (occupancy/vacancy) reacts to movement. For maximum ROI, many B2B projects use a "bi-level" approach: the photocell turns the light on at 20% power at dusk, and the motion sensor ramps it up to 100% only when someone is present.
Does a retrofit kit void the original UL listing of the fixture? Technically, yes, unless the retrofit kit is "UL Classified" for that specific fixture housing. This is a significant liability risk for property owners. Installing a new UL Listed fixture avoids this legal gray area entirely.
Is 5000K or 4000K better for outdoor security? While ANSI C78.377 defines both, 5000K (Daylight White) is often preferred for security because it provides higher contrast for surveillance cameras. However, 4000K is often chosen for "neighbor-friendly" applications to reduce blue-light pollution.
YMYL Disclaimer: This article is for informational purposes only and does not constitute professional electrical engineering or financial advice. All electrical installations must be performed by a licensed professional in accordance with the National Electrical Code (NEC) and local building regulations. Consult with a tax professional regarding specific energy tax credits or utility rebate eligibility.
Sources
- DesignLights Consortium (DLC) Qualified Products List
- IES LM-79-19 Standard for Optical/Electrical Measurement
- U.S. EPA - Disposal of Fluorescent Light Ballasts
- UL Solutions Product iQ Database
- ASHRAE Standard 90.1-2022 Energy Standard for Buildings
- Angi - How Much Does it Cost to Hire an Electrician?