T8 and T5 fluorescent lamps powered by electronic ballasts, the high-efficiency standards of the ’80s and ’90s, may now be easily replaced by light-emitting diode (LED) systems that cut wattage and carbon emissions by half or more while providing the same amount of light. In Con Ed territory, LEDs may pay for themselves in 2-4 years. That’s an ROI of 25%-50%, better than most cost-cutting options available to buildings. Toss in the near elimination of re-lamping (due to 15-20-year LED lifetimes), and no more lamp recycling (LEDs contain no mercury), and even Yosemite Sam will feel like he’s struck gold.
Many Choices and Options
Fluorescent lamps can be replaced either one-for-one in the same fixtures with the same ballasts using tubular LED (TLED) lamps or with retrofit kits that make old fixtures look new. For facilities with a few extra bucks to spend, new LED fixtures may provide built-in motion sensing and dimming, in a wide range of 21st-century shapes that could have come from Marvin the Martian’s office.
For specialized facilities such as hospitals and schools, off-the-shelf LED units are available with circadian color adjustment. They can gradually, or manually, adjust color temperature in a room from morning daylight (i.e., over 5000 K) to evening twilight (around 2000 K) to relax mood and calm occupants.
Because LEDs are effectively immune to the lamp life-reducing cycling of occupancy sensors, they may allow shorter cycling of existing fixtures merely by adjusting the sensors, saving more energy and carbon. In stairwells, dimming based on occupancy becomes easy with fixtures that have built-in sensors that bring lighting to full the instant motion is sensed. The lights never go completely off, thus maintaining safety and security, while cutting stairwell kWh by 50%-75%, depending on existing foot-candle intensities.
But First Do Your Homework
As with any new technology, care is needed when choosing LEDs. When first introduced earlier this decade, some were made cheaply and overheated, emitting smoke. Thousands were then withdrawn from the market. However, there are now dozens of suppliers with clean records, including the major lamp manufacturers.
Some TLED savings come from a narrowing of light distribution: many types emit light out of only part of their circumference, unlike fluorescents that send light in all directions. That may yield the same light levels at a task but exaggerate the “cave effect” wherein light on the upper half of walls is minimal, making a room feel darker. However, in some enclosed fixtures, TLEDs which are immune from fixture temperature may raise light levels too high because – unlike temperature sensitive fluorescents – they do not dim in hot fixtures.
Bottom line: before signing any big purchase orders, test samples of your chosen TLEDs or retrofit kits in a typical room containing fixtures common to a building. Take before-and-after foot-candle readings at the task level and on upper walls. Note any significant changes in the appearance of walls and furnishings (e.g., wood surfaces) by photographing them prior to and after retrofitting. Leave the LEDs installed for at least 2 weeks, and then assess their acceptability with occupants and department heads.
Facility managers new to TLEDs may need to bone up on the 3 basic TLED types, as well as issues such as light distribution, subtle changes to the color of furnishings, and non-visible flicker. Two useful (and free) comparisons of LED options from a recent local upgrade project may be downloaded at
- CONVERTING A CENTURY-OLD TOWN HALL’S LIGHTING TO USE LED TECHNOLOGY
- A Living LED Lighting Lab – In Croton’s Village Hall
Other handy and free publications on those issues may be found at:
- CALiPER Report 21.2 – Linear (T8) LED Lamp Performance in Five Types of Recessed Troffers
- UC Davis California Lighting Technology Center – Linear LED Lamps: Application and Interoperability Evaluation
Time to Get Movin’ Pardner!
The National Electric Manufacturers Association (NEMA) found that TLEDs have already captured over 30% of the market share of fluorescent lamps. So make like Speedy Gonzales and switch out those old fluorescents today!