Lighting Equipment and Lamps
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3 |
Reduces lighting energy use while maintaining appropriate light levels and improving visual acuity |
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3 |
One to six months for lamp and ballast replacement and six to 18 months for fixture replacement (may be completed in a series of stages); best implemented during regular re-ballasting or re-lamping, or concurrently with controls improvements |
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2 |
Replacement lamps or ballasts and high-efficiency light fixtures |
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FAC, FIN, GEN, BPO |
The first step to an efficient lighting system is to ensure light levels are appropriate for the tasks performed in the space. According to the Illuminating Engineering Society (IES) recommendations, general lighting levels in an office should be 25 to 35 footcandles (fc) (269-377 lux), with task lighting delivering upward of 50-60 fc (538-646 lux). Hand-held light meters are useful for evaluating existing lighting levels.
The second step is to deliver the necessary light using efficient equipment. Daylight is the highest quality and most energy efficient light source. Electric lighting should be used as a supplement to natural daylight where necessary to achieve the recommended light levels (see Energy: Daylighting).
As of 2014, per EISA, incandescent light bulbs may no longer be sold in the U.S.. Replacing one 100 watt (W) incandescent lamp with a 23 W compact fluorescent lamp (CFL) has little effect on human vision, but saves nearly $27 of electricity per year in a typical office with an electric rate of $0.08 per kilowatt-hour (kWh).
Replacement of inefficient lamps and ballasts can have a significant effect on energy consumption. Incandescent and halogen lamps are easy to replace with CFLs and LEDs, both of which are available in standard bulb base sizes and often do not require any change to the light fixture. Wherever possible and cost-effective, give preference to LED lamps, as they save more energy, do not contain mercury, last longer, and can provide more pleasing color resolution.
Table 3: Benefits of using LED lighting
Data Source: U.S. Department of Energy
Beyond phasing out all incandescent bulbs, aging linear fluorescent lighting systems are also prime candidates for upgrades. Low-wattage 28W T-8 lamps fit into the same fixtures as standard 32W T-8 and 40W T-12 lamps, but reduce energy consumption by 12-30%. Electronic ballasts are interchangeable with inefficient magnetic ballasts, eliminate flicker and noise, and raise the efficiency of the fixture 12%–30%.10
For all lamp and ballast replacements, implement the following best practices:
- Select dimmable lamps for fixtures that are located near windows or that have multi-purpose tasks requiring different amounts of light.
- Do not install instant-start lamps in fixtures that are controlled by occupancy sensors, as rapid on-off cycling reduces lamp life.
- Energize linear fluorescent lamps for 100 hours at full intensity before dimming.
- Match color temperature and color rendering index of new lamps to existing lamps, to avoid noticeable mismatch between fixtures.
- Group re-lamp rather than spot re-lamp, for color consistency and ease of maintenance, whenever possible.
Consumers can choose from a variety of energy-efficient lamps
Image Source: Dennis Schroeder, NREL 19469
Lighting equipment changes are likely to affect lighting quality, so it is important to consider impacts on light levels, contrast ratio, color index, and glare. Consult a lighting engineer to evaluate light level and quality before embarking on any significant retrofit projects.