The change by commercial users to the energy-efficient fluorescent bulbs with electronic ballasts has saved consumers more than $1 billion in avoided energy costs. Further efficiency gains have come from switching to smaller fluorescent bulbs (T12 to T8). This market success has led to the development of compact fluorescent light bulbs (CFLs) as an energy-efficient alternative to the common incandescent bulbs in residential, commercial, and industrial use. Not only do CFLs use less energy, but they have a dramatically increased life per bulb.

Yet lighting energy can still be squandered if it is not well managed. Lighting controls that use both occupancy sensors and scheduling to reduce the lighting of unoccupied spaces, as well as photo-sensors to integrate daylight, can reduce lighting energy consumption by at least 30%-35% compared to an already efficient electronic ballast system. This reduction can lower building operating costs by 10% or more.

The Lighting Technologies Resource

Buildings currently consume more than one-third of all sources of energy used in the United States, and electricity accounts for almost 80% of the energy costs in buildings. Lighting is the largest end use of commercial energy, and lighting within buildings is estimated to account for 23% of national electrical consumption. Of the total national lighting energy used, commercial lighting accounts for 60%, residential 20%, industrial 16%, and outdoor (street) and other uses make up the last 4%. Improvements in lighting efficiency represent a huge resource to state and local policymakers.

In addition to the energy saved by using fewer or more efficient lights, there are also important secondary effects from lighting — chiefly that the electricity used for lighting primarily turns to heat. Due to the heat generated by internal sources such as lights, people, and equipment, most commercial buildings in the United States require some cooling — even in the winter. The additional air-conditioning load created by offsetting the heat from electric lighting can add another 20% to the electricity use attributable to lighting. The Rocky Mountain Institute estimates that, in some cases, as much as 40% of the air conditioning load for some buildings in summer months is simply used to cool the heat produced by inefficient lighting.

Additionally, the majority of commercial lights used and the associated added cooling loads often occur during periods of peak electrical demand, therefore increasing the need for additional generation and distribution systems.

If every U.S. household changed the lighting in one room of their home to ENERGY STAR we would save 800 billion kilowatt-hours of energy and keep one trillion pounds of greenhouse gases out of the air. National annual energy savings would be equivalent to the annual output of more than 20 large power plants. Our annual energy savings could power more than 4 million U.S. homes for one year.

Business and Market Opportunities

Every building needs lighting. While the cost-saving benefits of energy-efficient lighting are clear, the initial costs and longer payback times (2 - 4 years) may discourage some people. When life-cycle accounting is used and the potential gains in productivity are considered, however, market opportunities will continue to expand significantly.

Using effective daylighting has benefits beyond saving energy. At Wal-Mart, improved sales in areas lit by skylights were noted — no matter what merchandise was placed in the day-lit area. Wal-Mart never published any statistics on this phenomenon, but within the past year Wal-Mart management decided to build all its new stores with more natural light. Studies also indicate that well-designed daylighting is associated with enhanced student performance, as evidenced by 13 to 26% higher scores on standardized tests.

In commercial settings, a typical office worker requires about 100 square feet (ft2) of dedicated space. Standard lighting systems consume energy at an average rate of 1.2 watts / ft2 and the annualized cost of owning ($30/yr) and operating ($35/yr) a lighting system is approximately $65 per employee per year. Top of the line lighting systems with dimming controls and energy-efficient equipment cost $250-$500 per worker, or roughly the equivalent of a good office chair. Any improvement to an ordinary lighting system that improves productivity is very quickly repaid. For example, if the direct cost of the employee is $50,000/yr, (wages, taxes, benefits, and overhead) and the employee has an assumed productivity ratio of 1:1, (i.e., the employee produces $1 of revenue per $1 of cost), a 1% increase in productivity throughout the year would realize a benefit of $500—a 100% return on investment. In reality, employee benefit ratios significantly exceed 1:1, so the actual return on increased productivity should be even greater than in this example.

What Does it Cost?

As noted above, the cost of lighting is relatively small when compared to potential productivity gains.

The price of a compact fluorescent light bulb may seem daunting compared to an incandescent bulb $14 versus 50 cents for an equivalent lighting level. However, when you add the cost of the electricity and the costs of replacing the incandescent bulb 10 times more often, the CFL will cost $63 less over the lifetime of the bulb.

Source: US Department of Energy