The Pennsylvania Green Buildings Operations and Maintenance Manual says that operation and maintenance practices for lighting systems, therefore, must also be considered as an important part of the building energy efficiency equation.

In addition, many newly-available lighting technologies require building lighting maintenance personnel to stay in formed to get the most out of existing systems as well as identify new technologies that can help improve O&M practices.

All of these factors point to the difficult tasks that the building maintenance engineer and the maintenance staff must carry out in order to keep maintenance costs low while balancing occupant lighting needs with equipment efficiency.

It is a challenging task because a building’s lighting quality has a direct impact on employee productivity, and a reduction in employee output may outweigh the cost of lighting their workspace.

Lighting Maintenance Considerations

Overall lighting maintenance considerations should do the following:

• Provide good, high-quality lighting suitable to the work being performed;

• Consider external factors that affect lighting levels and comforts, such as direct sunlight or the layout of partitions, but may not be in the control loop;

• Look for low-cost or no-cost system modifications such as occupancy sensors in low-use areas or de-lamping over-lit areas;

• Keep up with “regular” system maintenance such as fixture cleaning and bulb replacement.

Lighting maintenance practices vary widely, depending on the type of equipment, building type, and the tasks performed by its occupants, as well as building location, size, use pattern, and purpose. Thus, it is almost impossible to come up with a set of specific maintenance practices that fits all of the possible combinations.

Rather, the set of maintenance practices below should be used as guidelines to help you develop a combination of building maintenance and operation practices as well as schedules that will best serve the occupants’ lighting needs while maintaining the proper lighting levels and light quality.

One of the possible first steps in improving system efficiency is a preliminary energy audit to assess the savings potential of various efficiency measures. A preliminary audit can be obtained from energy service companies, architecture and engineering firms, or utilities.

Audits can also be done by qualified internal staff or maintenance engineers. These audits are essential for lighting energy efficiency because there are a number of easy efficiency measures available that offer very short payback periods, depending on the age and type of lighting equipment you have in service.

Sensors:

Use occupancy sensors to switch lights off when not needed. A basic sensor usage guide should include:

• Set sensors to avoid “false-offs;”

• Watch for non-human sources of motion that can trigger sensors;

• Be aware of equipment that uses radio frequencies or emits infrared signals, which may affect sensor settings;

• Set sensors to fail on the “on” position in dark areas;

• Inspect regularly for user overrides to the sensor settings; and

• Keep clear and accurate diagrams with marked areas of sensed zones, distinguishing high and low-sensitivity areas.

As with almost any energy-consuming equipment, the easiest way to save energy is to switch it off when not needed. Lights that can be shut off during unoccupied hours should be shut off promptly at the end of the workday, and over weekends and holidays. Additional savings can be achieved in commercial and institutional buildings through close coordination with janitorial hours.

Where zone control is available, lighting in unoccupied zones can be shut off with no loss to occupant comfort. “Zoned” systems can provide better control of building lighting during both occupied and unoccupied hours.

Using sensors located throughout a building can help in maximizing the potential of a “zoned” system at minimal cost. Some sensors allow for both temperature and occupancy detection, and can be the basis of an automated setback system for both lights and HVAC.

In general, simple occupancy sensors are the most common lighting control used in buildings today. For outdoor lighting, the simple photocell helps to turn lights on at dusk and off at dawn, which can help to reduce energy use further.

Two technologies currently dominate the market for occupancy sensors: infrared and ultrasonic. Infrared sensors detect temperature changes in a room, and work well where the entire room is within the sensor’s field of view. Ultrasonic sensors use high frequency sound to detect motion (even around corners).

There are also dual-technology sensors that use both methods, increasing accuracy and flexibility, but they are more expensive. Even though lamp life may be somewhat shortened by increased on-off switching, the overall life of lamps is usually extended by the reduced daily burn hours.

Sensors work best in areas with low occupant densities, such as single or double  offices, meeting rooms, lunchrooms, locker rooms, hallways, bathrooms, or warehouses and storage spaces. Note that care must be used in setting sensors for adjoining offices, as ultrasonic sensors may interfere with each other.

In higher-density areas such as “cube farms” with many partitions or other open area offices, an automated, scheduled on off system may make more sense, unless occupants tend to keep an irregular schedule, then a wide-area infrared sensor could be used. In these areas, it is important to remember that partitions can easily mask occupants, especially if the work being done there is mostly desk-related.

As with any type of automated controls, maintenance practices must ensure that any existing automatic controls are operating properly. Additionally, outdoor lights are often controlled by photocells, and these may need to be cleaned occasionally or replaced.

• For computer intensive office environment, sensors need to be set to avoid “false-offs” such as when a computer user remains motionless for long periods;

• Beware of other false sources of sensor triggers, such as air diffusers or curtained windows;

• Radio frequencies such as remote controls or other emitters may affect sensor settings;

• Set sensors to fail to the “on” position in dark areas to avoid creating dangerous conditions;

• Routine inspection of sensors may be needed to account for user overrides;

• Keep clear and accurate diagrams with marked areas of sensed zones, distinguishing high and low sensitivity areas.

Main lighting level maintenance goals should include:

• Set lighting at levels that are appropriate to the tasks, rather than uniform everywhere;

• Check lighting levels for compliance with IESNA lighting recommendations for adequate light;

• De-lamp over-lit areas;

• Clean and maintain fixtures so they distribute  light as designed and provide the intended light quality;

• Reduce operating time;

• Use daylight wherever possible;

• Use the most efficient luminaries when installing replacements;

• Invest in a light meter and use on a regular basis.

As discussed above, it is more important to provide illumination suitable for the task or tasks being performed, rather than to provide an area with a uniform, pre-determined light level. The human eye is more sensitive to contrast and difference in lighting levels rather than the highest level of light available to it. Because different tasks require differing light levels, it is also better to provide high-quality light where needed, rather than high levels of light.

It is also important to keep in mind that many fluorescent lighting systems put in place a decade or more ago tend to provide too much lighting, or may provide the inappropriate type of lighting for current office use. These ten or fifteen years-old systems also tend to use more energy and produce excess heat, resulting in high energy consumption and user discomfort.

Strategies to bring these spaces into conformation with the IESNA recommendations include:

• Bringing over-lit areas to more comfortable lighting levels through de-lamping;

• Improving existing fixtures (through add-ons) to distribute and improve light quality;

• Installing control technologies such as sensors or automatic switching systems to reduce operating time;

• Retrofitting or replacing existing systems with the most efficient luminaries.

In addition to these strategies, following IESNA recommendations allows the ambient light levels in public areas to be reduced or turned off if sufficient day-lighting levels are available. Where possible, lighting levels in areas such as interior hallways (where no natural light is available,) can also be reduced, yielding additional savings.

Areas that are typically over-lit include public spaces, corridors with outside windows, as well as hallways, storage areas, and meeting spaces — where the lighting levels in these areas can be reduced by “de-lamping.” ❑