Consider All Options: Guidance for TLED retrofits

By Craig DiLouie | Apr 15, 2024
Consider All Options
When upgrading an existing linear fluorescent lighting system, there are three main options.




When upgrading an existing linear fluorescent lighting system, there are three main options.

The lamps can be replaced with tubular LED (TLED) lamps, which may require other alterations to the luminaire. The luminaire can be upgraded with a retrofit kit, which retains the existing luminaire but provides a new light source, optics and power supply, resulting in predictable lighting quality and with typical energy savings ranging from 40%–60%. Or the luminaires themselves can be replaced with purpose-built LED luminaires as part of a redesign. For each, there may be an additional option to incorporate lighting controls.

The TLED replacement lamp persists as a popular retrofit for fluorescent luminaires, generating 25%–40% energy savings and an average payback of 1.8–2.5 years. However, with multiple types and various application and installation considerations, it is not exactly a simple retrofit.

In concert with the Department of Energy and Pacific Northwest National Laboratory, the General Services Administration (GSA) published “LED Lighting and Controls Guidance for Federal Buildings” in December 2023. This 58-page guide offers concisely worded instructions applicable to upgrading lighting systems to LED in offices and other building types using all three options.

This article attempts to summarize major GSA guidance regarding TLED lamps and information about retrofit kits as an alternative.

TLED lamps

TLED lamps offer a relatively low-cost option and typically take a little less time to install than retrofit kits, according to the GSA. As a result, by the first quarter of 2022 (the last period data was available), they had captured a third of the linear lamp market, according to the National Electrical Manufacturers Association and based on member shipments.

If the luminaires are in good condition, TLED lamps can be economical compared to retrofit kits or new luminaires. The challenge with all TLED lamps is the potential for glare, as the luminous surface area of these lamps is smaller than fluorescent and with direct light output, which the existing luminaire’s design may not be able to mitigate. With low-cost, low-quality TLED lamps, the diodes may be directly visible, producing a pixelated appearance. It is also important to ensure good lighting uniformity, as the TLED lamp will not have the same light distribution as a fluorescent lamp.

There are three main types of TLED lamps: UL Type A, which uses an internal driver and operates on the existing fluorescent lamp ballast; UL Type B, which uses an internal driver and bypasses the ballast to connect directly to line voltage for power; and UL Type C, which uses an external driver that replaces the existing ballast. According to the GSA, the most popular is UL Type B, accounting for about two-thirds of installed lamps.

General considerations

The GSA stated commercial lighting rebates of $1–4 are available for TLED lamps. Note, however, that most programs do not recognize Type A TLED lamps, as they are not considered a permanent upgrade, and a significant number do not recognize Type B.

When retrofitting with Type A and Type B lamps, the GSA recommends that all fluorescent lamps be removed from the site to avoid accidental installation, which would negate energy savings and pose a safety hazard in the case of Type B lamps. It is recommended that all discarded lamps be recycled, with this cost (about a dollar per lamp) accounted for.

The GSA does not recommend using hybrid Type AB lamps due to certain risks.

When retrofitting a T5 fluorescent installation or using T5 TLED lamps, ensure a good fit, as T5 lamp lengths are generally measured in metric units and not feet or inches.

Ensure the TLED lamp is compatible with the existing sockets. Note that if the lamp relies on the existing luminaire’s optics, the luminaire’s light output efficacy will be lower than the lamp’s.

Due to the potential risks to lighting quality, a trial installation or mock-up can be desirable. At this time, installation can be timed to get an idea of per-lamp and total installation time.

An interesting option for certain TLED retrofits is dimmability for user satisfaction (including glare mitigation) and other cost-effective controls that can maximize energy cost savings.


The GSA estimates the material cost of these lamps to be $10–20 with installation labor of about 5 minutes per lamp. In its decision flowchart for retrofitting linear LED lighting, the GSA states that if the lighting system will be held for less than three years, consider Type A lamps.

The immediate challenge is matching the TLED lamp to the existing ballast. First, these lamps are designed to operate with electronic and not magnetic ballasts, and they are not recommended for use with dimming ballasts. Otherwise, the TLED and ballast must be compatible. As gaining this information may require a look at the ballast label, a site survey can be beneficial. Note that the ballast will reduce rated efficiency.

While Type A TLED retrofits typically offer the shortest payback, the ballast introduces a future cost for replacement, which the GSA estimated at a material cost of $10–30 per ballast. As fluorescent is a declining technology, future availability of fluorescent ballasts may diminish.


The GSA estimated the material cost of these lamps to be $10–20 with installation labor of about 10–15 minutes per lamp. In its retrofit decision flowchart, the GSA states Type B lamps should be considered if the lighting system will be held for less than five years, has two or fewer lamps and does not require dimming. Due to potential lighting quality and dimming issues, the GSA also recommends these lamps be installed in transition and “back of house” spaces where aesthetics and lighting control are less important.

With this solution, the ballast is disconnected (and ideally removed and disposed of) and the lamps directly wired to the supply line voltage. For safety reasons, this requires a label to be affixed to each luminaire that warns against installing fluorescent lamps. For the same reason, Type A lamps should not be used in the same installation. Dimming would require that a control wire be connected to the luminaire or carefully rewired if present.

Note that the driver is very small so it can fit inside the lamp, which may produce flicker with some products. The GSA recommends diligence in removing any magnets used to hold the lamps in place during installation, as this can produce lamp strobing.


The GSA estimated the material cost of these lamps to be $10–20 with an additional $25 for the driver and about 10–20 minutes of installation time. The ballast is removed.

The advantages here are a lower likelihood of flicker, greater compatibility with dimming and other lighting controls—including availability of wireless connectivity if control wiring is not already installed—and greater likelihood of being eligible for rebates, as it is a permanent upgrade. GSA estimated satisfactory paybacks for Type C TLED lamps paired with zone-based lighting controls in the area of 2.2 years, based on a typical sample space.

In its retrofit decision flowchart, the GSA states that if the lighting system will be held for less than five years, the luminaire contains more than two lamps and dimming is required, consider Type C lamps. The GSA further recommends Type C TLED for applications where a retrofit kit doesn’t fit and a custom option is required. In particular, these lamps are suited to bay lighting, as one driver can operate multiple lamps. For all single-lamp luminaires, however, Type A or Type B may be more desirable.

One issue of concern is that the Type C driver market is small, and as LED technology changes and remains relatively unstandardized, future availability of compatible drivers is uncertain.

Troffer retrofit kits

LED retrofit kits consist of prepackaged lamps and electrical and optical components, offering a repeatable solution. The kit either replaces the ballast with an LED power supply or entails ballast removal with the LED module or lamp wired directly to the branch-circuit wiring. The LED light source may use original lampholders or be installed with new ones.

The advantage of retrofit kits is optics, and other elements such as heat sinking are engineered specifically for the LED light source, which can preserve or enhance lighting quality and optimize product life. In its retrofit decision flowchart, the GSA suggests if the lighting system will be held for five or more years and the ceiling won’t be altered anytime soon, consider a troffer retrofit kit. The space can be refreshed with new lighting, typically with a shorter installation time than would be required with new luminaires.

However, as these are not new luminaires, aesthetics are not guaranteed and a mock-up is recommended, particularly for applications where a high standard of lighting quality is critical. During the mock-up, installation can be timed to get an idea of actual installation time.

Another advantage is that the kits can be packaged with dimming drivers and integral occupancy and daylight sensors for more cost-effective adoption of lighting controls, maximizing flexibility and energy savings.

The GSA estimated the material cost of troffer retrofit kits to be $75–200 compared to $100–275 for a new troffer, with an installation time of roughly 15 minutes. Commercial lighting rebates for a troffer (1 x 4, 2 x 2, 2 x 4) retrofit kit are in the $20–40 range, according to the GSA.

Note that it is important to verify the existing luminaire can accommodate the particular retrofit kit. A survey of the existing luminaires at the site can be beneficial to ensure an appropriate match is found.

A guide for retrofits

This report offers concise, useful guidance for evaluating and implementing lighting and control retrofits in commercial buildings. It is available for free at

istock / peshkov / General services administration

About The Author

DiLouie, L.C. is a journalist and educator specializing in the lighting industry. Learn more at and





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