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GPG OUTBRIEF 31
LED Lighting and Controls Guidance
If you missed our latest webinar on LED Lighting and Controls Guidance for Federal Buildings, a recording of the webinar and presentation slides are now available.
Many thanks to the presenters and to the participants for their thoughtful questions, some of which are answered below:
Q: Is this guide applicable to commercial and industrial facilities?
A: The guide is applicable to commercial facilities; most GSA properties are commercial. It is less applicable to industrial applications and does not cover topics like high-intensity discharge lamps.
Q: Is delamping a reasonable solution, and is there guidance about how to accomplish it?
A: Although delamping reduces energy use, it is not a straight savings reduction because the ballast is optimized to operate a set number of lamps. We recommend solutions other than delamping to achieve long-term savings, especially because many states are starting to ban fluorescent lamp sales. Further, delamping can affect the fixture’s light distribution and the lighting quality of the space.
Q: Does the 50% fluorescent to LED savings cited exclude any savings that might be realized by reduced load on the HVAC system?
A: Most older lighting technologies generate heat and therefore impact the heating, ventilation, and air conditioning (HVAC) system. Consider cooling savings, particularly in hot climates, when converting to LED lighting. In a deep retrofit, if lighting is part of the process, consider downsizing the HVAC system. In a cold climate, converting to LED may increase HVAC energy use.
Q: How does Power over Ethernet (PoE) lighting improve efficiency?
A: Most buildings use alternating current (AC) wiring, while LED fixtures operate on direct current (DC). LED drivers in each fixture convert AC to DC, and savings come from minimizing both the number and size of these conversions. For example, in a space with 10 LED fixtures, each fixture converts AC to DC individually. Alternatively, if there are 10 Power over Ethernet (PoE) fixtures, a PoE switch efficiently powers them through a CAT cable, minimizing the total number of AC to DC conversions.
Q: Do we have to worry about power quality when using LEDs? And what is the impact of harmonics from the LED power supplies on noise-sensitive systems like communications training facilities or instrument landing systems?
A: We have not experienced any issues with total harmonics, power factor, and power quality with LEDs. LEDs use electronic drivers, and most have high power factors
(> 0.9) and low total harmonic distortion (< 20%). LEDs have been used near sensitive systems. In 2022, the Federal Aviation Administration released a report about LEDs in airfield lighting applications.
Q: Class P fluorescent ballasts had internal thermal protection, and it was a best practice to provide external thermal protection with in-line fuses at the light fixture. Should in-line fuses (external thermal protection) be installed for LED lights?
A: Class P ballasts contain a thermal protection device that disconnects the ballast from the power source if the ballast begins to overheat. Class P is a UL designation, and Class P LED drivers exist. Consult your project needs and determine if a Class P LED driver or in-line fuses are necessary for your installation.
Q: I have found that the lumen output is greater with LEDs than fluorescent, should I do a study before retrofitting?
A: Yes. We recommend installing a mock-up in place. Lumen is the basic amount of light generated, but it does not indicate where the light is going, the intensity, degradation, brightness/glare, and other factors that affect how the light is perceived.
Most fluorescent tubes produce 2,800 lumens. Once installed in a fixture, the fixture will absorb 25–40% of the light. The equation to quickly estimate your fluorescent light output is 2,800 lumens x number of lamps per fixture x 70%. The result is roughly the lumen output of the fluorescent fixture.
Reference to any specific commercial product, process, or service does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
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