Benefits

Sunlight—solar energy—can be used to generate light in buildings. In commercial buildings, electric lighting is the greatest consumer of electricity. Unfortunately, the generation is the most significant cause of air pollution in the building sector. Hybrid solar lighting technology could benefit buildings, particularly in the Sunbelt, where cooling is a significant source of energy use.

Full-spectrum solar energy systems provide a new and realistic opportunity for wide-ranging energy, environmental, and economic benefits. Because it has no infrared component, HSL can be considered a high-efficiency light source. Other advantages of HSL include

Roof penetrations are small and minimal, reducing the potential for leaks.
Infrared and ultraviolet energy in sunlight is separated from the visible light, rather than being transmitted into buildings. Heating, ventilation, and air-conditioning loads (HVAC) loads are thus reduced by 5% to 10%, compared to electric lighting systems.
HSL systems are readily adaptable to commercial buildings with multiple floors, relatively low ceiling heights, and interior walls. A single system can distribute enough sunlight to co-illuminate several rooms in a typical office building.
Large portions of precious plenum space—the area between the roof and drop ceiling—are not needed, so there is little competition with other building services, such as HVAC ducts, sprinkler systems, and electrical conduits.
HSL can be used in direct, ambient lighting (as in sky lights), but also, for indirect, task, and accent lighting applications.
In retrofit markets, HSL is easily incorporated into existing building designs, and the optical fibers can be rerouted to different locations as lighting needs change. By intentionally misaligning thesolar collector from the sun, occupants can even dim or curtail distributed sunlight.

Lighting consumes almost a third of the
electricity use in commercial buildings

Finally, full-spectrum natural light may have health benefits. Studies have shown that natural light is important for setting our body’s internal rhythms. Some doctors also attribute Seasonal Affective Disorder (SAD) to a lack of full-spectrum natural light. Melatonin, a sleep-related hormone, has been linked to SAD. This hormone, which may cause symptoms of depression, is produced at increased levels in the dark. Phototherapy or bright light therapy has been shown to suppress the brain’s secretion of melatonin. Although, there have been no research findings to definitely link this therapy with an antidepressant effect, many people respond to this treatment.

Projected HSL Savings

By the year 2010, HSL aims to be saving the nation over 50 Million kWh/yr while also improving lighting quality in commercial buildings. Through commercialization efforts with industry partners, over 5000 HSL systems will be installed by 2011 in regions of the U.S. where solar availability and electricity rates make this technology cost effective to consumers. Developing an initial system tailored to commercial buildings with mixed fluorescent and incandescent lighting (commonly found in retail applications) has been identified as the most likely first market for this technology. Given that market, a system cost goal of $4000 (installed) has been identified as necessary to meet the previously stated energy savings by 2011.

ORNL has patented the technology and anticipates that the bundled package will be commercially available by 2007.

The first HSL market will likely be on the uppermost two floors of commercial buildings having the following characteristics: (1) located in the Sun Belt and in areas where day-time electricity prices are highest, (2) occupied every day, including weekends, and (3) in lighting applications where lighting quality (or color rendering) is important and less-efficient electric lamps are currently used.

For incandescent applications, one HSL unit will typically save 8,000 kWhr in energy savings (associated with lighting) and 27 million Btu of air cooling per year. The cooling savings alone are equivalent to roughly 8000 kWhr per year of electricity (assuming electric cooling). Affordability of solar energy could be doubled or tripled when compared to other forms of solar lighting. Additional benefits would include improved lighting quality and positive environmental impacts associated with reducing the need to generate electricity.

HSL has the potential to significantly reduce energy consumption for building owners while also maintaining or exceeding the lighting quality requirements of the building. Implementation of the HSL technology across the U.S. represents a significant energy savings to the country and provides building managers with a near-term, energy-efficient, higher-quality, economically viable alternative to incandescent lamps.

Benefits in the Buildings Sector