Article: Selecting an LED Driver for Title 24 Compliance

May 3, 2024 Deborah Perkins

It’s no surprise that California’s population and economy influences the US market when it comes to regulations. This is certainly the case for California Title 24—the complex and far-reaching set of rules that govern the energy efficiency and performance of new buildings and their electrical equipment.

Compliance with Title 24 is advisable for most LED fixtures produced for residential use and marketed anywhere in the US. This avoids the need for the manufacturer to offer one part number for sale in California and a different part number for sale in other states.

In addition to a luminaire, the LED driver substantially affects whether or not a fixture is compliant. Begging the question—what are the important factors to consider when selecting a driver for an LED fixture that must comply with Title 24?

Introduction Of California Title 24 Legislation

The California Energy Commission introduced Title 24 legislation due to the two twin crises in the state:

  1. Power Distribution: The state’s residents and businesses have long endured regular power outages and blackouts

  2. Climate Change: Drought, wildfires and dangerously high temperatures have made California a stark example of the way greenhouse gases caused the earth’s atmosphere to overheat

The commission’s role as the state’s primary energy policy and planning agency is to create the energy system of the future—one that’s clean, modern and ensures the fifth largest economy in the world continues to thrive. Combating climate change is fundamental to maintaining California’s future. The Energy Commission plays a key role in implementing and crafting policies and programs to create a low-carbon economy.

Title 24 Rules Impacting LED Driver Selection

In line with this mission, the regulations applying to new lighting equipment set minimum benchmarks for efficiency and compatibility with the grid infrastructure. These minimum benchmarks ensure the user experience is not compromised by the drive for high efficiency.

This means that a compliant lighting fixture must meet a set of minimum specifications described in the long and detailed California Title 24 regulations. For some of these specifications, a fixture’s LED driver partially or entirely affects its compliance.

Five California Title 24 Specifications For Compliant Lighting Fixtures

  1. Efficiency: The LED or light engine and the driver combination determines a fixture’s system-level efficiency

  2. Total Harmonic Distortion (THD): Distortion is a by-product of the high frequency switching operation of a driver’s power conversion circuit

  3. Power Factor: The ratio of actual power to ‘apparent’ power. A power factor correction (PFC) circuit in high-quality LED drivers maintains a high-power factor—reducing energy wastage and limiting disturbance on the mains power circuit

  4. Flicker: Visible and some non-visible flicker in LED lighting is associated with uncomfortable or harmful effects on the user. This includes headaches, eye strain and fatigue. At high frequencies or at low brightness, flicker is safe

  5. Start-Up Time: By mandating a maximum interval between switching a fixture and light appearing, buildings can maintain a uniform level of user responsiveness across a fleet of different fixtures

Choosing An LED Driver To Support Title 24 Compliance

Compliance with Title 24 is assessed at the fixture level according to tests mandated by the California Energy Commission and performed by accredited test houses. The evaluation of a single component (i.e. LED driver) doesn’t determine compliance—it’s the complete assembly of components and the interactions between them that makes that determination.

This means that fixture manufacturers can gain some helpful flexibility in system design if they select a driver that gives them room to maneuver within the parameters of Title 24 compliance. On the efficiency benchmark, the use of a highly efficient LED driver gives scope to consider a wider range of LEDs or light engines. This flexibility can allow the manufacturer to trade off, for instance, higher color rendering performance for lower efficacy in the LED or light engine.

eldoLED Compliant Title 24 LED Drivers

eldoLED LED drivers provide headroom above the minimum requirement set by Title 24 when it comes to efficiency, THD, power factor and flicker parameters.

Our eldoLED 0-10V LED drivers offer fixture manufacturers the flexibility to configure their system design in the way that best suits their customer and application for CA24 start-up requirements.

The 10W, 20W, 30W and 50W ECOdrive and SOLOdrive LED drivers listed offer a special ordering option ("CA24") to be programmed with a fast start-up sequence.

/B Form Factors:

  • 10W: ECOdrive (EC0161B) and SOLOdrive (SL0161B)

  • 20W: ECOdrive (EC0261B) and SOLOdrive (SL0261B)

  • 30W: ECOdrive (EC0361B) and SOLOdrive (SL0361B)

  • 50W: ECOdrive (EC0561B) and SOLOdrive (SL0564B)

/S Form Factors:

  • 10W: ECOdrive (EC0161S) and SOLOdrive (SL0161S)

  • 20W: ECOdrive (EC0261S) and SOLOdrive (SL0261S)

  • 30W: ECOdrive (EC0361S) and SOLOdrive (SL0361S)

  • 50W: ECOdrive (EC0561S) and SOLOdrive (SL0564S)

Telling Time: How To Retain Aesthetic Fade-In With Title 24

The final parameter where the driver impacts compliance is start-up time. The regulatory picture is more complicated since Title 24 isn’t the only standard that applies in the US. ENERGY STAR®—the US government-backed symbol for energy efficiency—is another factor at play that also sets a requirement for start-up time.

Simply put, the ENERGY STAR requirement is for the fixture to reach its maximum (nominal) light output within 750ms after the user turns on the light. The Title 24 requirement is different—the light source should have a start time no greater than 0.5 seconds’ (500ms).

Time To First Light

These rules have particular relevance to eldoLED LED drivers since they have an aesthetic fade-in feature. After the user turns on the light, the light brightens starting from its minimum dimming level—normally 0.1%—and rises in a smooth ramp to full brightness. This effect is extremely popular because it is a humanistic and comfortable way of making the transition from total darkness to bright illumination continuous without dazzling the user.

The Title 24 specification of a <500ms ‘start time’ denotes–for drivers which have an aesthetic fade-in–the time by which the fixture produces visible light and starts its fade-in ramp. This is known as ‘time to first light’.

Compliance with both Title 24 and ENERGY STAR requirements calls for both a time to first light of less than 500ms, and time to full brightness of 750ms.

The flexibility of programmable eldoLED drivers enables manufacturers and specifiers to choose features, such as dimming curves, which best suit their application. In the case of Title 24-compliant fixtures, drivers with a DALI or DMX control interface can be programmed to reach full brightness from start-up in less than 750ms for ENERGY STAR compliance. By design, all eldoLED DALI- and DMX-interface drivers comply with the Title 24 requirement, typically producing first light in around 470ms.

For single-channel eldoLED drivers with a 0-10V interface only, the standard aesthetic fade-in curve reaches full brightness in around 1,000ms. For Title 24 and ENERGY STAR compliance, a ‘CA24’ variant can be ordered which has an accelerated fade-in ramp, with time to first light below 500ms and time to full brightness of less than 750ms (see Figure 1). For fixtures which are not required to be Title 24 or ENERGY STAR compliant, customers can choose whether they prefer the slower or faster fade-in ramp.

Fig. 1: Typical start-up performance of an eldoLED LED driver programmed to a nominal output current of 350mA. The green line corresponds to the measured output current over time. The blue line corresponds to the incoming mains voltage. The start-up sequence consists of three distinct phases that are labelled in the graph: initialization (A), fade-in (B), and ramp-up (C). This LED driver was calibrated in the factory to yield first light within 500ms. The (b) represents the point where the light output is perceived to be on and continuously increasing until it reaches full output (C).

DALI And DMX LED Driver Considerations with California Title 24

There’s one thing for specifiers to note when it comes to DALI and DMX LED drivers. The operation of both the DALI and DMX protocols requires a connected node—such as a driver—to search on start-up for a controller for a defined period of time longer than 500ms before defaulting to a fully-on status.

During this search, the driver does not supply current to the light source. These protocols inherently conflict with the start-up requirements of Title 24 for a lighting network in the fully off state. Note: A driver in a sleep state but connected to the network will respond instantaneously to a turn-on signal. This feature of DALI and DMX equipment can lead to false failures in Title 24 compliance testing if the accredited test house is not familiar with this aspect of these protocols.

To solve this problem, we have a solution for an approved test rig for use by test houses—overriding the protocol’s requirement to search for a controller. This rig enables the test to correct the start-up response of the fixture.

We advise fixture manufacturers that use an eldoLED driver with a DMX or DALI interface to confirm with their chosen test house whether its test set-up is configured to take account of the protocol’s start-up behavior.

Drivers For Compliance And Value

The regulations detailing the requirements for compliance with Title 24—and with the related ENERGY STAR benchmark—are long and exhaustive. On the contrary, the process is simple and straightforward when it comes to LED driver selection.

The same factors which represent quality and value for fixture manufacturers are the factors which also give confidence that the driver will support compliance. A driver which offers superior quality and performance will also provide a superior foundation for building a Title 24-compliant fixture.

Quality and performance are the hallmarks of eldoLED drivers. The addition of dedicated CA24 variants of its 0-10V drivers and a solution for compliance testing of DALI and DMX drivers provides us with a proven platform for fixture manufacturers to achieve compliance with the Title 24 regulations.

Human-Centric And Flicker-Safe LED Drivers

Our LED drivers also enable human-centric and health-conscious approaches to lighting. We provide LED drivers for 0-10V, DALI-2 and DMX lighting control systems and support Tunable White and Dim to Warm circadian lighting applications.

Using an eldoLED LED driver also provides industry-best flicker performance. Our signature Hybrid HydraDrive technology results in our drivers maintaining a flicker-safe operation at all dimming levels and all drive current levels. The results in eldoLED-powered LED lighting yield no harmful visible or invisible flicker.

eldoLED drivers are also compatible with broadcast lighting requirements. Meaning that video or camera images aren’t affected by banding or other visible artifacts when lit by fixtures powered with our LED drivers.

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