Simple cleaning can save on lighting costs

Real Estate Weekly, Oct 21, 1998

Known as the Luminaire Dirt Depreciation (LDD) study, the half million dollar federally funded project has involved taking scientific measurements of available light over the past three years throughout the test group sampling to determine the benefits in terms of both improved lighting and reduced costs - of simple periodic cleaning of the lighting fixtures themselves, with a goal of installing fewer fixtures in the first place.

The study targets office buildings, schools, health facilities and retail stores.

"For the past half century, the negative effect of light loss due to dirt accumulation on lamps and luminaire surfaces has resulted in reduced light levels," said Norma Frank, past president of NALMCO and chairman of the Illuminating Engineering Society of North America's (IESNA) Lighting Maintenance Committee, which has been looking into the problem.

Designers Over-Lighting to Compensate for Dirt Build-Up

"In addition, architects and lighting designers have been specifying and installing overlighted initial design levels to compensate for accumulation of dirt, resulting in unnecessary up front costs and more electrical power wasted daily," she added.

"We expect this study to establish new standards for lighting in the work place that will have long-term benefits to both building owners and the environment, all from recommendations we expect to suggest that building owners install fewer lighting fixtures than before and schedule regular professional cleaning of lighting fixtures, generally when maintenance crews are replacing lamps and ballasts anyway," Frank said.

She pointed out that while existing standards acknowledge that lighting systems must be maintained to assure the lighting quantity and quality intended, designers have been installing more fixtures than necessary for years. The results of this study, she added, will enable designers to quantify based on scientific data the precise numbers of fixtures needed and the savings possible for specific applications and task requirements, all with varying operating hours, mounting heights, environments and maintenance policies.

"The need to periodically clean luminaires has been recognized, but has not been a high priority with many users as maintenance budgets are reduced," she said, resulting in yet additional system overdesign.

Results to Provide Factual Basis for Proper Lighting Design

Results of the study ultimately will provide factual maintenance data that can be used in the design of both new facilities and lighting retrofit projects as systems are updated.

The $500,000 nationwide study, funded primarily by the U.S. Environmental Protection Agency in a grant to NALMCO, is the most comprehensive and scientific study of its kind since the introduction of the fluorescent light fixture 50 years ago.

Dr. Robert Levin, Corporate Scientist for Osram Sylvania and a 40-year industry veteran, called the LDD project "the first study ever on the subject to be completed in both a comprehensive and scientific manner."

Data was informally collected in the 1950's on maintenance, but not as a controlled study," he said.

Dr. Levin, who has served as the principal technical advisor to the project through his work with the IESNA Lighting Maintenance Committee, pointed out that the original 50-year-old study was conducted in the era before widespread air-conditioning, during which many office and industrial tasks were different and produced different types of dirt in the work place than is commonplace today.

For example, office windows typically were opened from time to time, and electronic machines were not in use, but early duplicators and lead pencils were commonplace. Also, different types of paints and building materials were in use 50 years ago. And lighting fixtures themselves have changed over the past five decades.

"We know the dirt environment changed and that is quantitatively what we're trying to find out now," he said. "If we have a loss of light over two or three years, either design to allow for that decrease or maintain the system."

However, he added, it was the potential energy savings and cost savings to users of lighting that inspired the study. Dr. Levin sees potential for 10 percent energy savings.

There is a potential for reduction of energy use for lighting of at least 10 percent," Dr. Levin said.

Data produced by the three-year study will be incorporated in a paper to be written by the IESNA committee and, ultimately, approved by the IESNA Board of Directors as part of the peer review process for inclusion in the IESNA Lighting Handbook, the industry's book of references and application standards.

IESNA, for more than 80 years the recognized technical authority for the illumination field, comprised of engineers, architects, designers, contractors, utility representatives, scientists and more, is charged with communicating information on all aspects of good lighting practice to its members, the lighting community and consumers.

"All lighting systems lose light as they operate, fixtures get dirty, and lighting standards are provided to account for this," Dr. Levin said. "So initially, you provide for more light, which means more expensive installation, more energy consumed, which also is more operating costs."