Facilities Planning/Management
December 1998
Nine Steps to a Successful Lighting Retrofit
Refurbishing your schools' lighting may be a bright idea, but if you're still in the dark about how to start, here are tips that should shed some light on the topic.

By Jack Ries
Many schools are removing older fluorescent lighting systems installed in classrooms and offices and replacing them with more technologically advanced systems. Often the motivation for a retrofit is reduced operating and energy costs.

However, schools are also reaping the benefits of higher-quality illumination.

At Northwood Middle School in Fort Wayne, IN, for example, retrofitting an existing fluorescent system boosted light levels to 50 foot-candles in classrooms. Replacing an aging fluorescent system in the library of Holy Spirit Catholic School in Tuscaloosa, AL, increased horizontal foot-candle levels by 34 percent; vertical foot-candles were increased by more than 25 percent.

To gain the best results from a lighting retrofit, here are nine suggestions to help you through the design process:

1. Set Project Goals
Some of the first questions to ask during the planning stage of a retrofit project are: What is the objective? What is the existing lighting system, and why do you want to replace it? What do you hope to gain with a new system? In many instances, schools will benefit from technological advances or energy savings that create "opportunity costs." Schools that installed systems with T-12 fluorescent lamps and magnetic ballasts during the 1950s and 60s have found the systems are not only inefficient but costly to operate. The trend is to replace these systems with more efficient T-8 lamps and electronic ballasts.

In the library at Holy Spirit Catholic School, 15 four-foot fluorescent fixtures with three T-8 lamps and electronic ballasts replaced 12 eight-foot units with two T-12 lamps and magnetic ballasts. According to Phil Onstott, owner of ProElectric in Tuscaloosa, who led the lighting project, the new system increased light levels and reduced energy and maintenance costs.

"The previous system generated a lot of heat on the ceiling, which increased air conditioning costs. Much less cooling is needed now, which saves the school money," Onstott explains.

2. Know What Function the Area Serves
The next questions are: How is the facility used? Are students involved in the learning process within this space?

Today, many students use computers within the classroom. Screens can be difficult to see if lighting fixtures produce a high level of glare. An ideal system for lighting a classroom with computer terminals includes an indirect system as the main light source, with a "wall wash" luminaire for perimeter chalkboards.

Using an indirect luminaire that provides too much uplight < 100 percent > will result in the cloudy day effect. When high levels of indirect illumination are used, foot-candle levels may be higher, but students and teachers will perceive the environment as gray < like a cloudy day>.

Providing some downlight with perforated holes or a lens in the bottom of the lighting fixture will make people think the atmosphere is brighter. They will feel more comfortable knowing the source of the light.

3. Choose a Light Source
Although fluorescent systems are probably the most popular for classrooms, other light sources may be appropriate for various areas. Most lamps on the market today can be categorized into three groups: incandescent, fluorescent, and high-intensity discharge (HID).

Incandescent lamps are the primary source of illumination in most homes. Short lamp life (750 hours) and low efficacy (lumens provided per watt) often limit their use as a light source for classrooms, libraries, and offices.

Fluorescent lamps produce light by activating selected phosphors on the inner surface of the bulb with ultraviolet energy generated by a mercury arc. The advantages of fluorescent systems are improved efficacy and longer lamp life (20,000 hours).

HID sources include mercury vapor, metal halide, high-pressure sodium, and low-pressure sodium. The benefits of HID are its high efficacy in lumens per watt and long lamp life (20,000 hours). HID is also a point source, which provides the opportunity for better light control.

4. Investigate the Latest Technology
Specular reflectors may be used for classroom applications. Specularity is the measure of a surface1s ability to reflect all the light at the inverse of the angle at which it is received. Specular reflectors are high in specularity (92 percent) and allow for a high degree of light control.

Many schools are being retrofitted with an industrial channel with a painted baffle under the lamps. This is sometimes referred to as an "ice cube tray" or "egg crate" fixture. Several problems are associated with this type of fixture: It produces non-uniform light, provides poor vertical illumination, and is inefficient. Essentially, there is no light control. All of the light is dumped under the fixture.

High vertical light levels are almost impossible to achieve with a baffled fixture because of its mechanical cut-off. The wide photometry produced by the specular reflector, on the other hand, facilitates high vertical light levels. Using specular reflectors with T-8 lamps and electronic ballasts will often reduce by half the number of lamps required. The result is better uniformity and higher light levels with fixtures that require half the energy.

To facilitate learning within a classroom or lab, consider color rendering. The higher the color rendering index (CRI), the more vibrant or closer to natural the color of objects will appear. A light source with a CRI of near 100 has the same rendering capabilities as daylight.

Lamps used in the new lighting system installed at Northwood Middle School are TA 33-watt with an 85 CRI. Jerry White, president, Engineering Consultants, Inc. (ECI), Fort Wayne, who designed the lighting, said administrators typically are not concerned about CRI.

"When we design a system for a school, we encourage the customer to consider color rendering to achieve the best possible illumination. Studies have shown that a school's educational benefits are directly proportional to the quality of the lighting. When students have difficulty reading because of poor visibility, it's hard for them to gather and retain information," White says.

5. Assess the Existing System
The layout and dimensions of classrooms and offices will help determine what lighting system is best. If you are retrofitting an existing system, you may have recessed fixtures installed in a finished ceiling. When these fixtures are removed, you will need a lighting fixture that will fit into the opening. If the school is older, the ceilings may be high enough to leave the recessed system in place and suspend the new fluorescent or HID fixtures below the existing units.

Often the artificial lighting in classrooms and offices is supplemented by daylight from skylights or windows. If this is the case, you may benefit from "daylight harvesting"? Turning off a select group of fixtures during the day so that only some units are energized. To achieve this, the fixtures must be circuited differently and controlled by a photo cell or relay switch.

6. Keep Costs Within Budget
To keep a lighting retrofit within budget, analyze such factors as energy consumption, lamps and ballast life, installation, and maintenance costs. Sometimes a system may cost more initially, but the savings realized over a number of years will justify the expense.

At Northwood Middle School, for example, the new lighting system cut energy consumption by 60 percent and reduced the number of lamps used in classrooms by 50 percent. "Although the new system was more costly to purchase, the school will save money in the long term because fewer fixtures are installed and they consume less energy," White notes.

7. Consider Financing Alternatives
When examining budget issues, consider financing alternatives. Check with your local utility company and determine if any rebates (particularly for energy savings) are offered. You should also explore leasing the system. Consider the payback. Sometimes a retrofit can be funded by the energy savings that accrue over time.

8. Keep Tomorrow in Mind
Keep flexibility in mind when designing the lighting system. Rooms within a school must be versatile. A space that is used as an office today may be used as a library, computer room, or lab in the future. The lighting system must be able to accommodate those changes.

9. Select a Reputable Contractor
Finally, select a reputable company to conduct the retrofit. Check with other schools or businesses that have implemented similar projects and obtain contractor names and recommendations. Determine how long any company you are considering has been in business and ask to visit past installations.

Doing your homework before a lighting retrofit will take time. But the results you achieve in terms of quality illumination and cost savings will likely be worth the hours invested.