DLC V3.0 vs. V4.0: Is Your Lighting Supplier Behind the Curve

February 2026 may look ordinary on the calendar, but in horticultural lighting, the future arrived earlier than expected. The DLC V4.0 Horticultural Technical Requirements opened for applications on April 18, 2025. Then, on January 5, 2026, the industry reached a clear turning point when DLC V3.0 products were officially delisted.

For years, the DesignLights Consortium (DLC) has acted as the benchmark for efficiency standards. This change, however, is more than a routine update. It represents a meaningful shift in expectations around Photosynthetic Photon Efficacy (PPE), spectral transparency, and overall performance.

The horticultural lighting industry is moving forward. The question is simple. Is your lighting supplier moving with it?

What Is DLC and Why Does It Matter

The DesignLights Consortium (DLC) is an independent nonprofit organization that maintains the industry’s most widely recognized Qualified Products List (QPL) for energy-efficient commercial lighting. To earn a place on the QPL, a fixture must undergo third-party testing to verify efficacy, spectral quality, and long-term performance.

DLC qualification plays a critical role in both rebate eligibility and performance validation.

Rebate Eligibility

Approximately 75 percent of utility companies across North America require a DLC listing for lighting products to qualify for energy rebates. Without a DLC listing, rebates are typically unavailable. That makes DLC-listed products essential for meeting customer expectations and helping growers reduce upfront and operating costs.

Performance Validation

A DLC certification also provides confidence that performance claims are real. Products listed on the QPL have been independently tested by accredited laboratories, confirming that they deliver the stated photon output and efficiency. Meeting these standards means fixtures are not only more efficient on paper, but also in practice, resulting in lower energy consumption and reduced utility bills over the life of the system.

Differences Between DLC V3.0 and V4.0

DLC Version 4.0 places a stronger emphasis on energy savings and transparency, particularly when it comes to how spectral performance is measured and reported.

Higher Efficiency Requirements

One of the most notable updates is the increase in minimum PPE (photosynthetic photon efficacy), the metric that measures how efficiently a fixture converts electrical power into usable light for plant growth. Under DLC 3.0, the minimum requirement was 2.3 μmol/J. DLC 4.0 raises that threshold to 2.5 μmol/J, an increase of roughly 8.7%.

While that difference may sound small, the cumulative effect is substantial. Across hundreds of fixtures operating 12 to 18 hours per day, higher efficacy can translate into thousands of dollars in annual energy savings, especially in large-scale commercial grow environments.

No More Individual Lamps 

DLC 4.0 removes individual replacement lamps, such as screw-in or plug-in LED bulbs, from the Qualified Products List altogether.

The reason is simple. The market has largely moved on. Commercial growers now favor fully integrated fixtures that provide better thermal management, more consistent light distribution, and longer service life. By eliminating replacement lamps, the DLC keeps the QPL focused on durable, professional-grade lighting systems rather than short-term retrofit solutions.

Stricter Testing Rules

Version 4.0 also introduces stricter testing requirements, particularly for fixtures with tunable or adjustable spectra.

Fixtures that allow spectrum changes across different growth stages must now clearly disclose which spectrum setting was used during testing to achieve the reported efficiency rating. Under DLC 3.0, manufacturers could test fixtures at their most efficient spectrum setting while knowing that most growers would operate them at less efficient, real-world settings. DLC 4.0 closes that gap.

In addition, the DLC clarified which LED components require separate reliability testing. For example, it requires clearer data on chip reliability. This makes it more difficult for manufacturers to bypass rigorous testing by claiming components are sufficiently similar to previously tested parts, further strengthening product accountability and long-term performance validation.

What DLC 4.0 Signals: Higher Efficiency and Quality Standards

DLC 4.0 reflects a broader shift in how controlled environment agriculture must operate to remain both economically viable and environmentally sustainable. These updates go beyond incremental technical changes. They redefine what is considered acceptable performance in commercial horticultural lighting.

Efficiency as a Survival Strategy

In the early days of DLC Version 1.0, the minimum efficacy requirement was just 1.9 μmol/J. With Version 4.0 raising that benchmark to 2.5 μmol/J, it is clear that energy efficiency is no longer a premium feature. It is the baseline requirement for commercial viability.

As energy costs continue to be one of the largest operational challenges for growers, the DLC is sending a clear message. Low-efficiency lighting is no longer a competitive disadvantage.

Quality Standards Are Tightening

By strengthening testing requirements for spectrally tunable fixtures and demanding greater transparency around LED chip reliability through LM-80 data, the DLC has made it increasingly difficult for underperforming products to hide behind marketing claims.

The industry is moving away from retrofitting legacy technologies and toward purpose-built LED systems designed to manage heat, light distribution, and spectral quality as a single, integrated platform. These changes close the door on inflated spec sheets and ensure that what growers see on the Qualified Products List is what their crops actually receive in the greenhouse or grow room.

Why a Trusted Supplier Matters More Than Ever

As DLC requirements continue to change and efficiency standards keep rising, choosing the right lighting supplier matters more than ever.

Meeting DLC 4.0 requirements is not as simple as adjusting a few numbers on a spec sheet. It takes real work behind the scenes, including:

• Investing in research and development to design more efficient fixtures
• Completing thorough third-party testing through accredited labs, such as LM-79 and LM-80
• Maintaining strict quality control so production units perform the same as the tested samples
• Managing the supply chain to ensure components meet higher performance standards
• Planning ahead to transition product lines before compliance deadlines arrive

This is where a trusted supplier makes a real difference.

At Atop, we do more than manufacture lights. We help our partners navigate these changes with confidence.

• OEM Services: We build fixtures to your exact specifications, helping you bring your own designs to market using our proven manufacturing process, quality systems, and DLC qualification support.
• ODM Services: You can also leverage our in-house engineering team and ready-to-deploy, high-performance designs. We handle the technical details, testing, and compliance so you can stay focused on your brand and your customers.

If you’d like to learn more about our R&D team, manufacturing facilities, and capabilities, feel free to contact us.