Lights and Florescents

After World War II, many commercial and industrial facilities began switching to fluorescent lighting technology. Developed in the late 1930s, fluorescent lighting proved to be every bit as good a light source as incandescent, but at roughly a 25% reduction in lumen cost. By the 1960s, more than two-thirds of the light used in commercial and industrial facilities in the U.S. was generated by fluorescent sources. This was at a time when the cost of light fell and illumination levels increased, otherwise known as the “age of abundance.” Although early fluorescent bulbs experienced some crude behavior (flickering, buzzing and off-color shades), the technology has evolved dramatically. Originally rated at 1000 hours of life, the fluorescent lamp has achieved life levels of 20,000 hours and higher in some cases. Of course, improvement in ballast technology has helped the technology achieve these recent feats.
The Original T12
The linear T12 lamp (the name comes from its diameter size: 12/8” or 1.5”) was the workhorse of the industry since its development. However, with the focus on energy conservation and the rising cost of electric power, a new size (T8) was developed to meet the new requirements. It’s very rare that T12s are specified in new construction projects today. But there are areas of the country that keep the T12 lamp alive. That is due to the low cost of power produced by coal-fired electric generating plants, predominately in the Midwest. These geographic pockets enjoy 3 or 4 cents per kilowatt-hour utility rates, whereas the national average is 10 cents per kilowatt-hour. For facility managers in these regions, it is uneconomical for them to conduct a retrofit to a more energy-efficient lamp.
The writing on the wall for T12s came when utility companies started providing energy rebates and incentives for facility managers to replace T12s and magnetic ballasts with the new T8s and electronic ballasts. With these new incentives, the payback period was dramatically shortened which made the decision to retrofit an easy one.
The New T8
New technology advances in the 1980s produced a new smaller, more energy-efficient linear lamp, the T8 (the name comes from its new smaller diameter size: 8/8” or 1”). Improved rare-earth phosphors and electronic ballasts resulted in improved energy efficiency, longer life (20,000-30,000 hours), and better color rendering. In addition, switching from a T12 to a T8 lamp is relatively simple since the T8 lamps fit into the standard socket of the T12 lamp and the lamp length is the same (another dagger for the T12). By the late 1990s, the T8 rapidly became the most commonly used lamp in North America. Building owners also began to recognize that with increased lamp life, they no longer had maintenance crews spending the bulk of their day changing lamps. This labor cost was now being factored into lamp retrofit calculations.
Architects and lighting designers have recognized the lamp’s slim profile. Now smaller fixture designs using the T8 lamp are more aesthetically appealing and the old T12 fixtures are rapidly disappearing. In addition, the smaller lamp size reduces shipping and storage costs.
Improved color rendering is another benefit for the T8 lamp. The color rendering index (CRI) for most T8 lamps is between 70 and 95. For this index, the higher the number the better the color render, with the maximum being 100 (sunlight). The T8 also provides a wide range of color temperatures. Light gets progressively whiter and accents more of the blue end of the spectrum as color temperature increases. Low-temperature 3000 lamps shed a soft light that highlights reds, yellows, and browns. 3500 lamps are generally neutral and highlight no particular color. High-temperature lamps of 4100 and up highlight progressively more blues, greens and grays.
New high-performance linear T8s (also known as super T8s or HPTs) are now available. This new lamp features a high lumen, longer life and a lower watt electronic ballast. It generates the same total light output as the standard T8, but uses about 20% less energy, which is a dramatic difference. These lamps are typically rated to last about 4,000 hours longer than the standard T8 or T12 lamps.
The Metric T5
The T5 lamp is the newest member of the linear fluorescent lamp lineup. It’s 5/8” in diameter, but the lengths are only offered in metric sizes for metric fixtures. As you might expect, their metric lengths and socket design requires significant changes to existing fixtures. The higher lumens can cause glare problems in existing equipment. They are making their way into a wide variety of special applications such as troffers, wall washers, ceiling cove applications and decorative fixtures.
The new High Output T5 (T5 HO) nearly doubles the lumens of a standard T5. It has roughly the same lumens output as two T8s or two T12s. The advantage here is that once you go to a T5 HO, you can reduce your lamp count. Once again, due to the brightness, glare may be a problem.
CFL – Big Savings Over Incandescent
The compact fluorescent lamp, or CFL, was developed in the 1970s and was introduced to the U.S. market in the 1980s. The first designs featured a screw-in Edison base with an integrated ballast. This new design provided easy direct replacements for many facilities that have applications for long-burning-hour applications such as hotels, schools and apartment complexes.
As the popularity of this lamp grew, production costs dropped dramatically. Although this type of lamp is three to ten times more expensive than a comparable incandescent lamp, CFLs last six to fifteen times as long. In addition, CFLs are rated at 10,000 to 12,000 hours of life vs.1,000 to 2,000 hours for an incandescent lamp. According to the U.S Department of Energy’s Energy Efficiency and Renewable Energy (EERE) office, CFLs can save up to 75% in energy costs over standard incandescent lamps.
As with early models of the linear fluorescent lamps, early CFL models were noisy and provided poor color rendering and slow start-up. Although improvements have been made, certain limitations still exist. CFLs have a limited temperature operating range and may not operate at the extremes of this range. Some CFLs can be used outside but may take longer to reach full brightness when it’s very cold. Some may not operate at all in the cold. Since CFL specs vary by manufacturer, it’s important to read the manufacturer’s specifications carefully before purchasing.
Reducing Lighting Maintenance Costs
With fluorescent technology, it’s important to select the best lamp and ballast combination for your application. The proper combination helps to dramatically reduce the maintenance required. For example, installing long life lamps in areas that are hard to access or in areas that require lift equipment will help save time and labor costs.
Selecting the proper ballast is equally important in maximizing lamp life. If fluorescent lamps are burning out prematurely, the problem may be an incompatible ballast. Various types of ballasts including rapid start and instant-start are available, but they need to be matched with the correct lighting control application. Proper installation is important. If the lamp isn’t connected securely in the socket, it may light up for awhile, but it will tend to short arc which will reduce the lamp life.
In a large facility, the chore of replacing burned out lamps one at a time can become a tiresome and costly task for maintenance professionals. The ENERGY STAR program points out that this method of “spot relamping” wastes valuable labor. Since the expense of labor far exceeds the cost of fluorescent lamps, group relamping may be a more cost-effective strategy. This method requires that all of the lamps in an area are replaced at one time at a pre-determined interval, before they start burning out on a regular basis. The rule of thumb for economical group relamping is around 70% of the rated life of the lamp. Some key benefits of group relamping are:
* Staff can schedule a time that is least disruptive to the occupants
* Work efficiently with equipment and supplies
* Bulk purchase discounts of lamps may reduce unit cost
* Less storage space is needed for replacement lamps
The Mercury Factor
The light generated by a fluorescent lamp is produced by an electric current conducted through mercury and inert gases. Since mercury is a neurotoxin known to cause health issues, disposal of these lamps has cause for concern. When a lamp is broken, crushed or dispensed in a landfill or incinerator, mercury may be released to the air, surface water or ground water. Over the years, lamp manufacturers have reduced the amount of mercury in their fluorescent lamps by more than 90 percent. However, it is best to handle all fluorescent lamps as hazardous or universal waste. There are several options for proper disposal such as taking spent lamps in bulk to a designated drop-off point in your area, shipping them in special containers to a recycling company or having them picked up as recyclable material. Of course, state and local regulations will vary.
Since the EPA issued the universal waste rule to address many hazardous wastes that were previously discarded in the trash, lamp recycling has increased rapidly. In the fall of 2007, NEMA (National Electric Manufacturers Association) reported that lamp recycling had increased from 70 million lamps in 1997 to 156 million lamps in 2005. Lamp manufacturers realize that their products may have a negative impact on the environment. They have a long history of being environmentally responsible and have advocated recycling.
The Future
Although LEDs have made great strides in recent years, linear fluorescent lamps should be the workhorse for commercial and industrial lighting applications for years to come. LEDs simply do not have the output at this point in time, and may not for the next decade.