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As costs come down, advantages over fluorescents make them popular

There's an unexpected trend gathering momentum across North America.

Almost out of nowhere, sales of dimmable tubular LEDs (TLEDS) have increased by around 30% in some markets. Why? They may be a bit more expensive than the fluorescent tubes they replace, but their efficiency edge and potential compatibility with lighting controls is making them increasingly popular.

"More and more, there's an appetite among customers for dimming," says Cristian Suvagau, a specialist lighting and energy efficiency engineer with BC Hydro. "So as the cost of dimmable TLEDs continues to fall, they became a great option for customers."

From a utility's standpoint, conversion to much more efficient LED luminaires is the ultimate goal. But Suvagau says there's growing evidence that dimmable TLEDs are an effective transition, as they can work as a linear fluorescent replacement en route to a switch to luminaires down the road. And so far, the market has been driving a trend recently recognized by the Design Lighting Consortium (DLC), which acts as a gatekeeper in the LED market.

While only about a third of TLEDs in its 2019 market survey were dimmable, the DLC is moving to require that all TLEDs on the Solid State Lighting (SSL) qualified product list be dimmable by 2022. Benefits of dimmable TLEDs cited by the DLC include:

• Reduced energy use through manual or automatic dimming, allowing users to fine tune light levels and mitigate issues with glare.
• Additional savings through networked lighting controls, which can ensure the right amount of light, and only when needed.
• Avoiding stranded savings, as non-dimmable products lock out energy savings over the life of the product, which could easily surpass a decade.
• While dimmable TLEDs are modestly more expensive than non-dimmable TLEDs, pairing dimmable lamps with networked lighting controls is much less expensive than pairing controls with an LED luminaire.
• Dimmable TLEDs comply with new quality metrics for colour performance and light distribution.

"It's a bit of a game changer," says Suvagau. "Some customers may have a short time lens to their economic development. They might not be looking at 20 years, but will look for a solution for maybe the next three to five years. They say 'Wait a minute, I don't have the money to put in full LEDs now, so let's maintain the system and use TLEDs for now. If I'm happy with that and my equipment starts to expire, LED luminaires will be cheaper by then.'"

What about incentives for TLED lamps?

TLED lamps don't currently qualify for incentive funding through our Business Energy Saving Incentives (BESI) program. But if they're considered for BESI, having products listed on the DLC Qualified Products List will be a requirement.

At this time, TLED applications can only be considered for the custom incentive program, for eligible Key Account customers, and for the industrial self-serve incentive program (SIP) for qualifying large industrial customers.

Doing the math: costs, controls, and savings

Suvagau says pairing dimmable TLEDs with lighting controls could require installing and commissioning wireless systems.

In a cost comparison study in Rhode Island for the fourth quarter of 2019, the DLC found the sales-weighted average price of qualified dimmable TLEDs was $7.08 US, compared to $6.87 US for DLC-qualified non-dimmable models.

In terms of savings over T8 fluorescents, the DLC offers the following four scenarios, based on replacement of a two-lamp F32T8 fixture, at 3,128 annual hours, and (for the dimmable products), assuming 6.2% manual dimming savings and 47% networked lighting control savings:

• V4.4 non-dimmable TLED (2020): 76.4 kWh savings
• V5.0 non-dimmable TLED (2021): 85.1 kWh savings
• V5.1 dimmable TLED (2022), using manual dimming: 91.0 kWh savings
• V5.1 dimmable TLED (2022), using networked controls: 130.2 kWh savings

In its move to require that all TLEDs on the qualified list are dimmable, the DLC notes that all three types of dimmable TLEDs can be dimmed through a wired or a wireless option, from a wall switch, sensor, or networked lighting control. Type A TLEDs can use a dimmable fluorescent ballast or can use a wireless signal. Type B TLEDs may be dimmed using phase-cut dimming or via a wireless signal. Type C TLEDs are paired with an LED driver as part of the system, so if the driver is dimmable, TLEDs are dimmed through a signal sent to the driver, which can also be done wirelessly.