Daylight Harvesting

Linear Fluorescent Systems

There are over a thousand different linear fluorescent lamps available on the market today and it can be very difficult for the average person to determine which system would be a smart choice for them. The choices in lamp size, wattage, color, lamp life, etc. are mind boggling.

The most common retrofit of linear fluorescent systems today involves converting from T12 lamps (1.5 inch diameter lamps) driven by magnetic ballast to T8 lamps (1.0 inch diameter lamps) driven by electronic ballast. These retrofits can be tailored so that the customer can achieve up to 40% savings on their lighting with a simple lamp and ballast change out. The new linear fluorescent systems also offer extended lamp and ballast warranty, improve quality of light and often have simple paybacks of 3 years or better.

T5 linear fluorescents (0.625 inch diameter lamps) have also made a big impact in recent years in replacing high bay systems. The T5 system offers the same efficiencies as the T8 systems but offers the ability to deliver greater light output than T8 and has allowed them to be used in place of many HID fixtures in warehouse type lighting designs. These systems maintain a more consistent level of lighting than HID, allow greater flexibility in the use of lighting controls and can also provide good paybacks.

Three other techniques are often employed in a linear fluorescent lighting retrofit project that can provide additional savings. One, is the use of reflectors on existing strip fixtures inside recessed fixtures. This may allow the fixture to be operated with fewer lamps saving additional energy without compromising light levels. The second technique is the use of conversion kits which eliminates the use of 8 foot lamps by converting the fixture to 4 foot lamps. This allows the customer to use a lamp that lasts longer, performs better and on aggregate cost less to purchase. The third technique is the adding controls or sensors. See the section on sensors for more information.

Compact fluorescent systems have progressed dramatically over the last decade and like linear fluorescents, there is an ever increasing variety of lamps and manufacturers to chose from. Applications using compact fluorescents have been developed for table lamps, downlights, sconces, recessed cans, flood lights, track lighting and even general lighting. The vast array of choices available can often make it difficult to make a decision on what to use. Generally speaking, the more expensive the system, the better its performance characteristics and reliability (but the payback may not be as good as other alternatives). The are some very simple and inexpensive options now available as well that simply involve unscrewing the existing incandescent lamp and installing an appropriate compact fluorescent. On a one for one basis, the typical compact fluorescent lamp will produce the same amount of light as an incandescent while consuming 25% of the energy.

When deciding what path to take, be sure to involve a lighting professional if you do not have the expertise internally in your organization to make the decision.

Just like the fluorescents, there is an overwhelming number of different lamps and systems available in this family. These lamps and systems are typically used for exterior lighting, high ceiling applications, architectural situations, sports and entertainment complexes and industrial facilities. There are many techniques that can be employed with the existing systems to save energy ranging from a simple lamp change out using or lower watt lamp to a complete fixture change out to a newer more efficient technology/system. Each application and solution needs to be considered on its own merit by an experienced professional.

One of the most common uses of LED’s for lighting retrofits has been with exit signs and traffic signals. All new traffic signals and exit signs are almost exclusively manufactured with LED’s. While not yet as efficient as fluorescent systems, the extremely long life of these systems make them the best choice for exit signs and traffic signals applications.

LED’s are also increasingly used in signage and linear applications that used to be provided by neon lights. This is a very promising opportunity for both new and retrofit projects. Researchers and developers are also making progress in enhancing LED’s such that they may also begin to contribute in other applications for interior and exterior lighting and should be reviewed on an ongoing basis as the technology improves.

The type of controls chosen is dependent the specific needs of the areas being lit by the lighting system. Controls are a very effective means of enhancing the efficiency of the systems but a misapplication of the technology can be a disaster for the users of the new system. Consult with a lighting professional before implementing any system.

Daylight harvesting is more common in new construction due to mandatory regulations in some states and it is being increasingly used in retrofits. As daylight collector technology improves, retrofitting will become even more common for these systems.