Reading, wRiting, and aRithmatic are the three R’s we were all taught in elementary school. In some schools today, learning these basics has been made easier (and less expensive) where technological advances in fluorescent lighting systems have been employed. A better learning environment can be created and substantial energy dollars saved where schools re-lamp existing fixtures with higher quality bulbs, retrofit fixtures with outdated T-12 lamps and replace inefficient fixtures that can not be retrofitted.

The vast majority of educational institutions use fluorescent light fixtures for their classrooms, lecture halls, and general lighting. Most schools today replace burned out tubes with the least expensive fluorescent tube available. Unfortunately, the least expensive tube often produces a lower quality and quantity of light at a higher cost. Most lamp companies manufacture a lower quality (700 series) and higher quality (800 series) fluorescent lamp. Some companies offer a third variety which has a longer rated life. The lower quality lamp is typically 20%-25% cheaper. This bargain lamp also: produces less light (10%-20%) using the same energy burns out faster (10%-30%) and produces light with a lower color rendering index (approximately 12%) These deficiencies make the bargain lamp more expensive to purchase in the long run than the premium lamp. In addition, the lower quality lamp can create a learning environment that is less than ideal. For many years it has been known that students that see better learn better. Research has shown that students see better with less eye strain under scotopically enriched light than under light sources that are scotopically deficient. The scotopic value of light is a function of its color rendering index and color temperature. Fluorescent tubes (lamps) are readily available in a variety of color temperatures and color rendering indexes. (For an in depth discussion on the scotopic value of different light sources see, “The Coming Revolution in Lighting Practice”, by Sam Berman). The most common color temperature lamp used in schools is 4000-4100 Kelvin (cool white). According to Dr. Berman’s studies, students studying under fluorescents with a color temperature of 5000 Kelvin see up to 30% better than those using a light source at 4100 Kelvin (this difference seems primarily to be the result of smaller pupil sizes under the higher color temperature which increases visual acuity and reduces eye strain).

Fluorescent tubes come in a variety of diameters but most commonly are 1 ½” (T-12), 1” (T-8) and 5/8” (T-5). T-5 and T-8 lamps produce a similar number of lumens (light) per watt. T-12 lamps are less efficient and therefore require more energy to produce the same amount of light. Most fluorescent fixtures installed within the last 5 years are either T-8 or T-5.

In addition to being less efficient, T-12 lamps produce significantly less light as they age and usually have a color rendering index that is 15%-25% lower than T-8 or T-5 lamps. Recently T-12 lamps have become available in color temperatures of 5000 Kelvin or higher but are seldom found in use in schools.

 Most T-12 fixtures can be retrofitted to use T-8 or T-5 lamps at a fraction of the cost of purchasing new fixtures. By using specular reflectors and energy saving electronic ballasts, it is not unusual to cut energy usage in half with a T-12 to T-8 retrofit (see Paragon’s Guide to Common Fluorescent Retrofits).

In areas that are only occasionally used during the school day (such as locker rooms, bath rooms, etc.) motion sensors should be considered. Depending upon the frequency of occupancy and whether lights are turned off when the room is unoccupied, motion (occupancy) sensors can significantly reduce energy usage in these areas. (Caution should be used to make sure rapid start ballasts when using motion sensors. Using instant start ballasts with motion sensors can significantly reduce lamp life.)

Some older T-12 fixtures can not be retrofitted due to outdated design or poor condition. These fixtures should be replaced with T-8 or T-5 fixtures.

Other less efficient fixture types (such as high intensity discharge or incandescent) frequently found in schools can not be retrofitted with linear fluorescent tubes. Gymnasiums are often lit with metal halide fixtures (or occasionally high pressure sodium). These fixtures exhibit rapid lumen depreciation (light loss over time) without reducing their energy draw. A typical gymnasium 400 watt metal halide fixture uses 460 watts and can be replaced with a 6 lamp T-8 fluorescent fixture using 222 watts. This replacement can result in a dramatic increase in light levels as well, depending on the age and condition of the metal halide fixtures. 

Another energy saver for gymnasiums is to equip the fluorescent fixtures with bi-level switching ballasts. Bi-level ballasts allow the fixtures to be operated with less than all of the lamps when lower light levels are adequate. For example, the Wisconsin Interscholastic Athletic Association recommends 70-75 foot-candles in gymnasiums for athletic competitions. For practices or other physical education activities 40 foot-candles is adequate. 

By installing fluorescent fixtures with bi-level switching the school is able to get the recommended light levels for athletic events (high schools average 50 events per year at 5 hours each for a total of 250 hours per year) while operating at lower levels (say 60%) the rest of the year (on average 3,650 hours). In this example the school would save over 1/3 of the cost of operating the fluorescent gym lights in addition to savings 50% as a result of the HID to fluorescent retrofit. (For a more complete discussion of HID to Fluorescent retrofits see Paragon’s Guide to HID Retrofits). Some schools have had good results installing motion sensors in gymnasiums to extinguish lights when the gym is not being used. Where lights are typically left on when the gym is not in use, this is an excellent energy saver. (Caution should be used to make sure rapid start ballasts are used when using motion sensors. Using instant start ballasts with motion sensors can significantly reduce lamp life.) 

A forth R in school lighting would be Rebates. Rebates and low interest loans are available in many states from utility companies for energy saving lighting retrofits and replacements.

The quantity and quality of light provided in a learning environment can have a substantial impact on a student’s educational experience. Research has shown that students see better with less eye strain under scotopically rich light sources. Schools can give students a better chance to succeed by re-lamping using fluorescent tubes with a higher color rendering index and higher color temperature, by retrofitting outdated fluorescent fixtures with technologically superior lamps, ballasts, and reflectors, and by replacing older less efficient fixtures with new. In addition to the educational benefits, these improvements will save the school money. In many cases, payback from energy savings will be less than three years.