Is an LED right for your next retrofit project?
Building owners are asking lighting designers and electrical engineers to help them save on energy costs, and replacing fluorescent, HID, or other lights with LEDs is in high demand.
- Compare the codes and guidelines that define LED use, including ASHRAE Standard 90.1 and International Energy Conservation Code.
- Explore LED retrofit replacements, including replacing components, ballasts, and other items.
- Identify the pros and cons of specifying LED lights in certain building applications.
As LED illumination technology improves in efficiency, reliability, and quality, building owners become interested in cost-effective ways to apply LED lighting in their facilities. In many cases, retrofitting existing fluorescent or incandescent luminaires will be an attractive alternative to wholesale fixture replacement. This article explores the effects of some of the applicable codes on LED retrofit projects.
In this case, an "LED retrofit" is the replacement of a luminaire’s light source with an LED source while leaving some part of the fixture in service. A retrofit project also may include replacing other components, such as ballasts, reflectors, lamp holders, or lenses.
LED retrofit options
Many of the code issues that arise in LED retrofit projects are the same code issues involved in lighting-replacement projects, in which luminaires are removed and replaced in their entirety, while others have unique aspects related to retrofit projects, or to LEDs. Some of those code provisions are:
- Projects that alter or replace 10% or more of the lighting in that space will trigger lighting power density and control requirements of ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings, 2013 edition, and the International Energy Conservation Code (IECC), 2015 edition.
- Maintaining luminaire listings, required by the NEC, through a retrofit project requires a measure of care. Authorities having jurisdiction (AHJs) may view the listing status of altered luminaires in a variety of ways.
- Levels for emergency lighting must comply with the NFPA 101: Life Safety Code after the project is complete. Differences in photometrics between original and altered fixtures, lighting power density reductions driven by energy codes, and LED illumination characteristics may impact compliance.
LED retrofit kits can come in a variety of configurations. For fixtures using tubular lamps, these are the most popular options; government entities may have different requirements:
- Replacement of lamps with tubular LED assemblies together with replacement of ballasts with LED drivers.
- Replacement of lamps with self-ballasted LED assemblies, removal of ballasts, and direct connection of the ac source to the lamp holders.
- Replacement of lamps with tubular LED assemblies specifically manufactured for compatibility with a particular ballast type without other modifications to the fixture.
For downlights, retrofit kits normally provide for replacement of lamp holders with a self-contained unit containing an LED emitter and heatsink and a separate LED driver that replaces the ballast. A number of kits are available to retrofit screw-base lamps with one-piece units consisting of a trim ring, lens, emitter, and internal driver.
For exterior luminaires, particularly parking lot installations, the typical practice is to replace luminaires entirely while retaining the poles.
Retrofit of more than 10% of the lighting in a space must meet the lighting power density and lighting-control requirements of the energy codes. IECC requirements are invoked when more than 10% of the fixtures are modified, while ASHRAE 90.1 provisions become effective when more than 10% of the lighting load in the space is affected. Both codes require that the total lighting power does not increase for a project to enjoy the exception.
Lighting power density
Retrofits involving simple lamp replacement, without other modifications, are likely to be viewed by AHJs as maintenance activities rather than alterations, thus they will not trigger requirements of the energy codes. IECC specifically describes projects that replace only lamps, ballasts, or both as repairs. ASHRAE 90.1 specifically establishes that projects replacing both lamps and ballasts must meet its provisions, but does not address lamp replacement alone.
For projects involving only lamp replacements, this exemption will avoid any necessity for compliance with the energy codes while still providing the owner with energy and maintenance reductions associated with LED lighting. However, for projects involving other types of retrofits in addition to lamp replacement, other provisions of the codes will exclude power reductions due to straightforward lamp replacements from the calculated lighting power density of the overall project.
For nearly all lighting retrofit projects, the lighting power densities allowed by the current editions of the energy codes are much lower than any that were in effect at the time the original lighting was installed. To comply, the retrofit fixtures must generally use considerably less power than the original fixtures. Engineers designing retrofit projects under these codes must verify that the specified retrofit kits can provide adequate illumination. The power density allowances of the energy codes will, to some extent, drive the selection of retrofit kits toward more efficient yet costlier options.
ASHRAE 90.1 9.1.4 requires that lighting power densities be calculated using the highest wattage of each fixture, as stated on its manufacturer’s label or as determined from the ballast manufacturer’s product literature. This provision may make compliance difficult, if not entirely out of reach. Because fixtures remain unmodified, their original labeling remains in force. For older, less efficient fixtures, actual power reductions as a result of lamp replacement won’t impact the calculated value of the lighting power density.
More invasive retrofits involving removal or replacement of existing ballasts and other fixture components do not enjoy any repair exemption in the energy codes; when the threshold is reached, the requirements of the codes become enforceable.
ASHRAE 90.1 and the IECC require quite a lot of lighting control including automatic shutoff and either selectable lighting levels or dimming. These requirements can add considerably to the cost and complexity of a retrofit project. For further information, a number of recent articles covering energy code requirements for LED lighting are available.
For most spaces, both codes require multiple lighting levels, selectable by occupants, with the lowest stage limited to no more than 50% of the connected lighting power. These controls can be implanted by dimming all the luminaires, by selectively controlling some of the lamps in each luminaire, or by extinguishing some of the luminaires, so long as illumination levels are reasonably uniform when those controls are active.
Where daylight is available from windows or skylights, the codes require automatic daylight-responsive controls. IECC requires continuous dimming down to 15% of the total lighting power, and full shutoff.
ASHRAE 90.1 calls for a minimum of four illumination levels, but does not strictly require continuous dimming. For parking garages, ASHRAE 90.1 requires automatic shutoff and motion sensor control that reduces lighting power by at least 30% during periods of inactivity, while the IECC doesn’t describe daylighting-control requirements for parking garages.
Both codes include detailed requirements for occupancy sensing, vacancy sensing, and automatic shutoff.
Controls adequate to comply with the energy codes are unlikely to be installed in existing systems that do not warrant a lighting retrofit. Adding these controls can be costly. It’s worth noting that these requirements can largely be avoided by restricting retrofits of tubular lamps to the simpler options, in which tubes alone or tubes and ballasts only are replaced, depending on the applicable code.
National Electrical Code
NFPA 70: National Electrical Code (NEC) 410.6 requires that light fixtures and retrofit kits be "listed." A listed device appears on a list of acceptable products published by a testing organization. That testing entity must periodically evaluate the luminaire for acceptability, and it must be acceptable to the AHJ. Typically, any of the Nationally Recognized Testing Laboratories recognized by OSHA will be acceptable to the AHJ. Listings typically specify the intended purpose of the device and the conditions under which it may be safely installed. Light fixtures are generally listed for installation in wet, damp, or dry locations. In the United States, for light fixtures, the listing agency is often UL.
For installed lighting fixtures, listings matter. In applying the listing mark, manufacturers attest that fixtures meet the relevant UL standard for safety and operation leaving the factory. Depending on the details of the facility’s insurance policy, fixture listings may have an impact on the owner’s coverage. And, because the NEC requires them on light fixtures and retrofit kits, they’re typically required and verified by AHJs. In practice, AHJs will check luminaire listings in field inspections and also may require listing information as part of the permit application.
For lighting fixtures, listings are typically developed for particular housings, ballasts, lamp holders, lamps, and other components assembled in a prescribed fashion. Alterations to a fixture—as opposed to repairs—have an impact on the fixture listing. Replacing ballasts and lamps with similar devices are typically seen as maintenance activities by the AHJ, with no effect on the original listing when performed properly. On the other hand, replacing lamps and ballasts with LED drivers and LED lamps are seen as alterations, requiring some means of establishing that the resulting fixtures are listed.
The acceptability of the listing status of any particular installation is specifically left to the judgment of the AHJ. An AHJ may take one of several positions regarding whether a retrofit is acceptable:
- A retrofit is acceptable only if the kit is listed, the luminaire is listed, and the kit is certified by the manufacturer of the original luminaire. This is a restrictive position.
- A listed retrofit kit installed in a listed luminaire is acceptable.
- A retrofit made with listed components, without a listed kit. With no listing of any kind for the assembled retrofit components and the lack of installation instructions for the assembly, few AHJs would accept this installation.
UL has offered a number of guidance documents over the past few years describing its view of how a retrofit affects a lighting fixture’s listing. Early guidance was vague regarding paths to compliance and suggested that almost any alteration would void the listing and necessitate a costly field evaluation from the listing agency. As the retrofit market has matured, the clarity of UL guidance has improved. A "frequently asked questions" document from 2016 states that retrofits performed on listed fixtures using UL-classified retrofit kits will generally be compliant with UL standards for fixtures, and field evaluation or further assessment will typically not be required.
It’s worth noting that UL has issued a number of safety alerts for specific retrofit kits, normally involving unusual assembly instructions that may be overlooked by installing personnel. It also has issued warnings of counterfeit listing markings for various lighting components. While these issues are normally not the province of specifying engineers, contractors and installers would be well-advised to verify the UL listings of retrofit kits to avoid any unpleasant surprise at final inspection.
UL requirements also state that an altered luminaire that won’t accept fluorescent lamps after conversion must be clearly labeled to warn personnel not to attempt to install fluorescent lamps. These labels are normally provided by the manufacturer of the listed retrofit kit to both meet this requirement and relabel the luminaire for its new wattage as required by the energy codes.
Life Safety Code
NFPA 101: Life Safety Code, 2015 edition, specifies illumination requirements for egress lighting and for emergency lighting. The term "egress lighting" is generally held to describe lighting levels required when utility power is available, while the term "emergency lighting" refers to periods when utility power is unavailable. These requirements are applicable to passages that lead to an exit and, outside the building, that lead to a public way.
Egress lighting requirements are 1 fc for horizontal walking surfaces and 10 fc for new stairways. Emergency lighting requirements are 1 fc average over any walking surface with a minimum of 0.1 fc and a maximum-to-minimum ratio of no more than 40:1. AHJs typically take these requirements very seriously, and where there is doubt about compliance, will generally be eager to visit the facility after dark to ensure that measurements aren’t affected by outdoor light from windows and skylights. These requirements may be verified by the electrical inspector or by the fire marshal.
Power for emergency lighting is typically provided by individual battery packs installed with fixtures or from an alternate power source for the facility, such as a diesel generator. In architecturally significant spaces, battery-powered emergency lighting is usually implemented by adding an emergency ballast with battery backup to selected general-purpose light fixtures to avoid appearance issues with self-contained emergency lighting units, fondly called "bug eyes" or "frog eyes."
For these installations, LED retrofits present a special challenge. The LED market is still young and, in general, lacks standards for the power requirements for directly driving emitters. LED emitters can be configured in a variety of ways, with a variety of power requirements. Consequently, listing agencies are reluctant to certify any particular battery source to operate with any particular driver and emitter array in the absence of direct tests of the entire assembly. Manufacturers generally are reluctant to pursue these listings, as testing is expensive and the lifecycle of LED products is unpredictable and often short. There is a limited number of selections available for retrofitting battery-powered emergency fixtures. Where aesthetics are important, as a practical matter, either the appearance of emergency fixtures must be coordinated with the remaining fixtures or the same retrofit kits must be used throughout the project area.
In facilities with emergency generators, the normal practice is to serve standard fixtures from the generating system at regular intervals along the egress path. A typical design might call for every third fixture in the egress path to be served from emergency power. For any kind of lighting modifications, whether by retrofits with LEDs or another technology or by wholesale replacement of luminaires, it’s necessary to verify that the new lighting arrangement will provide adequate illumination in the egress path to satisfy the requirements of NFPA 101 by photometric studies.
For LED retrofits, emergency-egress lighting issues may be exacerbated. LEDs, at the component level, are generally directional emitters, throwing light in a narrow cone directly in front of the devices. Dispersion is effected using lenses, diffusers, or other optics in front of the emitters, or by the artful arrangement of the emitters. Due to the effort and cost of achieving adequate dispersion with LEDs, lower-end retrofit kits may present a more directional illumination pattern than the original fixtures, resulting in dark spots between fixtures—darker than the minimum 0.1 fc required by NFPA 101—and in bright spots below fixtures, resulting in maximum-to-minimum ratios higher than the code allows.
For any lighting replacement or retrofit broad enough to trigger the energy codes, allowable lighting levels typically will be lower than original illumination levels. Wherever the existing installation provides marginal compliance with the code—say, an average level of 1.2 fc in the egress path where 1.0 fc is required-levels may be too low after modifications are complete.
LEDs typically fail slowly, with light levels drifting downward over time due to aging and heating effects. In contrast, fluorescent lamps and ballasts typically fail more abruptly, providing nearly full output for their lifetime until they flicker or darken. LEDs can gently drift out of compliance.
Solutions generally involve supplemental lighting in the egress path. Additional fixtures may be sconces or downlights installed at dim spots, or bug eyes, where architectural considerations aren’t an issue. Fixtures may be rearranged and reinstalled in a denser pattern. Supplemental lighting conflicts with the requirements of the energy codes and with project goals for energy efficiency projects. Consequently, additional luminaires should be used sparingly.
By better understanding the code and listing requirements of LED lighting, engineers can better specify products to meet clients’ needs. Energy-efficient lighting also is in high demand, so knowing which products serve specific needs is beneficial.
Tom Divine is a senior electrical engineer at Smith Seckman Reid Inc. He has spent nearly 20 years in the consulting engineering field, with the past several years designing and engineering health care facilities. He is responsible for power, lighting, and fire alarm design for hospital and health care projects. Divine is a member of the Consulting-Specifying Engineer editorial advisory board.