For facility managers and industrial property owners, the decision between maintaining a legacy T5HO fluorescent system and upgrading to modern LED linear high bays is no longer a matter of "if," but "when." While T5HO was once the gold standard for high-ceiling illumination, the rapid evolution of Solid-State Lighting (SSL) has created a performance gap that traditional tubes can no longer bridge.
The conclusion for any data-driven decision-maker is clear: Modern LED linear high bays offer a 60–70% reduction in energy consumption, near-zero maintenance costs for the first decade, and an ROI that typically pays back the initial investment in under 12 months for 24/7 operations.
This guide provides a technical head-to-head comparison, analyzing efficacy, maintenance debt, and compliance standards to help you build a bulletproof business case for your next lighting retrofit.
1. Efficacy and Optical Performance: The Lumen Gap
The most immediate differentiator between these technologies is system efficacy—the ratio of light output (lumens) to power consumed (watts).
The Efficiency Baseline
According to the U.S. Department of Energy (DOE) Federal Energy Management Program (FEMP), high-performance commercial and industrial LED luminaires are now expected to exceed 140–150 lumens per watt (lm/W). In contrast, typical T5HO systems operate in a range of 70 to 100 lm/W.
While a T5HO lamp itself might have a high initial efficacy, the "system efficacy" is significantly lower due to ballast losses and fixture inefficiency. Fluorescent tubes emit light in 360 degrees, requiring reflectors to bounce light downward. This process inevitably leads to "luminaire dirt depreciation" and optical losses. LED linear fixtures, however, are inherently directional. They utilize precision optics to deliver light exactly where it is needed, minimizing wasted "trapped" light within the fixture housing.
Color Consistency and Visual Clarity
Visual performance is governed by the ANSI C78.377 standard, which defines the chromaticity specifications for SSL products. LED technology allows for much tighter control over Correlated Color Temperature (CCT) and Color Rendering Index (CRI).
In high-ceiling workshops or retail aisles, a CRI of 80+ is standard for LEDs, ensuring that colors are vibrant and safety signage is clearly legible. Fluorescent lamps often suffer from "color shift" as they age, leading to a mismatched, patchy appearance across a warehouse floor that can compromise safety and employee morale.
2. The Hidden Cost: Maintenance Debt and Ballast Failure
A common misconception in facility management is that the primary cost of maintaining a T5HO system is the lamps. In reality, the ballast is the most significant financial and operational burden.
The Ballast Lifecycle
Electronic ballasts in T5HO fixtures typically fail every 3 to 5 years in 24/7 environments. Replacing a ballast in a high-bay application isn't just a part cost; it requires:
- Rental of a scissor lift or articulated boom.
- Specialized electrical labor ($120+/hour in many regions).
- Potential downtime or disruption of the production floor.
In high-utilization scenarios, the labor cost to replace a single ballast often exceeds the cost of the part itself. LED linear high bays eliminate this cycle entirely. Modern LED drivers, certified under UL 8750, are designed for thermal stability and long-term reliability, often lasting as long as the LED chips themselves.
Lumen Maintenance (LM-80 and TM-21)
Fluorescent lamps degrade rapidly. A T5HO lamp may lose 10–20% of its light output within the first 8,000 hours of operation. To determine the true lifespan of an LED fixture, professionals look at the IES LM-80 report, which measures the lumen maintenance of the LED source over time.
Using the IES TM-21 mathematical method, engineers can project when a fixture will reach $L_{70}$ (70% of its original light output). Most project-ready LED linear high bays achieve $L_{70}$ at 50,000 to 60,000 hours, providing over a decade of consistent light in a standard 12/5 operation.
3. ROI Deep Dive: 24/7 Warehouse Simulation
To demonstrate the "Value-Pro" logic, we simulated a retrofit for a 25,000 sq. ft. distribution center operating 24/7 (8,760 hours/year) with 50 legacy T5HO fixtures.
| Metric | Legacy T5HO (6-Lamp) | LED Linear High Bay (210W) |
|---|---|---|
| System Wattage | 354W (including ballast) | 210W |
| Annual Energy Use | 155,052 kWh | 92,000 kWh |
| Annual Energy Cost ($0.12/kWh) | $18,606 | $11,040 |
| Annual Maintenance Cost | $11,771 | ~$0 |
| Total Annual OpEx | $30,377 | $11,040 |
The Results:
- Annual Operational Savings: Over $19,000.
- Payback Period: Approximately 3 to 4 months when factoring in typical utility rebates.
- HVAC Impact: LEDs generate significantly less heat. In climate-controlled facilities, this results in a "cooling credit," further reducing energy bills by an estimated 3–5%.
For a deeper dive into how these metrics vary by fixture type, see our analysis on HID vs. LED Floodlights: A 5-Year Maintenance Cost Comparison.
4. Compliance, Rebates, and the DLC Premium Advantage
In the North American market, the DesignLights Consortium (DLC) Qualified Products List (QPL) is the gatekeeper for utility rebates.
DLC Standard vs. Premium
While "DLC Standard" fixtures meet basic efficiency requirements, "DLC Premium" fixtures (governed by V5.1 and V6.0 drafts) require higher efficacy and documented glare control. For many utility programs, choosing a DLC Premium fixture is non-negotiable; projects using non-Premium fixtures often see their rebate amounts slashed by 50% or disqualified entirely.
Safety and Interference
Every industrial fixture must carry a UL 1598 listing for safety. Furthermore, high-quality LED drivers must comply with FCC Part 15 to ensure they do not produce electromagnetic interference (EMI). Cheap, uncertified LED drivers can interfere with Wi-Fi networks, handheld scanners, and sensitive manufacturing equipment—a "gotcha" that can derail a project's success.
5. Lighting Design and Controls: Meeting Modern Codes
A common retrofit mistake is a "one-for-one" swap without a photometric redesign. Because LED linear fixtures have superior optical control, you can often achieve better light levels with 20–30% fewer fixtures than your original fluorescent layout.
The Power of .IES Files
Professional lighting designers use software like AGi32 to simulate light distribution. This requires IES LM-63 photometric files, which act as a digital "thumbprint" of the fixture's light output. Before purchasing, always ensure your supplier provides these files to verify that your new layout meets IES RP-7 industrial lighting standards for foot-candle levels and uniformity.
Mandatory Controls (ASHRAE 90.1 & Title 24)
Modern building codes, such as ASHRAE 90.1-2022 and California Title 24, now mandate lighting controls in most commercial spaces. This includes:
- Occupancy Sensing: Automatically dimming or turning off lights in unoccupied aisles.
- Daylight Harvesting: Reducing light output when natural sunlight is available through skylights.
LED linear high bays are uniquely suited for these controls. Unlike T5HO lamps, which suffer reduced lifespan from frequent switching, LEDs can be dimmed or switched instantly via 0-10V protocols without any degradation in performance. For more on the strategic direction of industrial lighting, consult the 2026 Commercial & Industrial LED Lighting Outlook: The Guide to Project-Ready High Bays & Shop Lights.
6. Installation Strategy: Avoiding "Friction Points"
The physical installation of linear high bays presents specific challenges that contractors must address to ensure long-term reliability.
Mounting and Weight
LED linear high bays are often lighter than their 6-lamp fluorescent predecessors, but they require robust mounting points. Whether using aircraft cable (steel wire rope) or pendant mounts, ensure the mounting hardware is rated for the fixture's weight. A common error is "cable tension at max height," where installers do not leave enough slack for future adjustments, leading to unnecessary strain on the ceiling grid or trusses.
Wiring and Dimming
Standard industrial LED fixtures use 0-10V dimming. It is critical to distinguish between Class 1 and Class 2 wiring per the National Electrical Code (NEC). Running low-voltage dimming wires in the same conduit as high-voltage power lines without proper insulation can lead to signal interference and flickering.
The Pragmatic Choice for Facility Growth
Upgrading from T5HO to LED linear high bays is not just about energy savings; it is about reclaiming the "maintenance hours" lost to lift rentals and ballast swaps. By choosing DLC Premium-certified fixtures with documented LM-79 performance, you ensure that your facility meets current energy codes while providing a safer, more productive environment for your team.
When evaluating your options, prioritize fixtures that offer adjustable wattage and CCT. This "Value-Pro" feature allows you to fine-tune the lighting levels on-site, providing flexibility if your warehouse layout changes from open storage to high-density racking in the future.
Disclaimer: This article is for informational purposes only and does not constitute professional electrical or engineering advice. Always consult with a licensed electrical contractor and local building authorities to ensure compliance with the National Electrical Code (NEC) and regional energy standards.
Sources
- DesignLights Consortium (DLC) Qualified Products List
- IES LM-79-19: Optical and Electrical Measurements of Solid-State Lighting Products
- DOE FEMP: Purchasing Energy-Efficient Commercial and Industrial LED Luminaires
- ASHRAE Standard 90.1-2022: Energy Standard for Sites and Buildings
- UL 1598: Standard for Luminaires