SAVING LIGHTING ENERGY in COMMERCIAL BUILDINGS

Many scientists now say that global climate change is underway due primarily to the burning of fossil fuels and the resulting build-up of carbon dioxide and other "greenhouse gases" in the atmosphere. Climate change threatens human health and well-being because it causes more severe storms and droughts, rising sea levels, increased spread of infectious diseases, and other adverse effects.

As the debate unfolds over a stronger international treaty to curtail greenhouse gas emissions, there is much that individual Americans can do in homes and workplaces to reduce our contribution to global warming. The good news is that many of these actions can save money as well as protect our environment.

Lighting accounts for about 20% of all electricity use in the U.S. and more than 40% of electricity use in offices, stores, and other commercial buildings. In a typical commercial building with 50,000 square feet, about $45,000 is spent on lighting energy each year. Much of this energy is wasted, resulting in higher energy bills and needless air pollution.

Lighting technology has evolved rapidly in recent years. In office buildings, the typical fluorescent lighting fixture with four 4-foot fluorescent tubes (referred to as “lamps” in the lighting trade) and two magnetic ballasts uses 160 to 180 watts of power. However, new fixtures with special thin-diameter lamps and electronic ballasts use about 115 watts. In spaces that are overlit — and many are — further energy savings are possible by switching from 4-lamp fixtures to 3- or even 2-lamp fixtures. Special reflectors can be installed to optimize light distribution for the reduced number of lamps in each fixture. The energy use of a 2-lamp fixture can be as low as 58 watts, a savings of up to 70%.

In stores, most displays are lit by incandescent spotlights, typically using 150 watts apiece. Special “halogen IR” lamps reduce energy waste and burn more brightly, permitting a 60 watt halogen lamp to be substituted for a standard 150 watt spotlight — a savings of 60%. The halogen lamp costs more — about $8.50 versus $2.50 — but typically lasts 50% longer and saves $20 in energy costs over its lifetime.

Thousands of buildings have installed high-efficiency lighting systems and reduced lighting energy use substantially. For example, Mount Sinai Medical Center in New York recently replaced standard fluorescent tubes and incandescent lamps in one of its facilities with high-efficiency fluorescent lamps, electronic ballasts, and new reflectors. As a result, lighting energy use in the one million square foot facility was cut almost in half, saving $485,000 per year and yielding a 45% annual return on a $1,086,000 investment.

Efficient commercial lighting has other advantages as well. Many high-efficiency fixtures reduce glare, which helps to reduce eye strain and improve worker productivity. With electronic ballasts, fluorescent lamps no longer flicker and hum. High-efficiency thin diameter lamps produce a more natural-looking light that does not distort skin tones. And the focused white light produced by halogen lamps can increase the appeal of retail store displays and contribute to increased sales.

Nationwide, if all commercial buildings installed state-of-the-art energy-saving lighting systems, their lighting energy use could be reduced by at least 40%. Doing so would lower U.S. carbon dioxide emissions by about 175 billion pounds per year. This action alone could halt the growth in carbon dioxide emissions in the U.S., given recent growth rates. By using high-efficiency lighting equipment, a business can help the environment and its own bottom line. If many businesses do this, they will be taking an important step toward protecting the planet from global warming.