Sometimes a new technology comes along that appears futuristic and revolutionary but, at the same time, embraces sheer simplicity. Core sunlighting is a system that gathers natural sunlight, concentrates it and delivers it deep into a building’s interior, not just the area along the glazed perimeter. The revolutionary aspect comes from the savings that can be achieved by using core sunlighting to reduce the amount of artificial lighting required within a building. A larger global benefit may come from reducing greenhouse gas emissions and the overall carbon footprint the world is treading.
The idea of core sunlighting was conceived by Dr. Lorne Whitehead, a professor of physics at the University of British Columbia. SunCentral Inc. was incorporated in 2008, to commercialize the core sunlighting technology.
The core sunlighting system is made up of two components. The sunlight concentration panel is an assembly that houses optics that can be installed on the exterior of a building or integrated within a building’s curtain wall. The hybrid light guide is the series of reflective guides that carry the light into the building.
Optics track the sun’s movement throughout the day and then collect and concentrate the sunlight by a factor of 10. The intensified light is transmitted into the hybrid light guides via small glazed windows. The hybrid light guides are long, narrow corridors coated with a reflective film. Ultimately, the natural light cascades down into the work environment through numerous commercial lighting fixture designs. The full spectrum natural sunlight is noticeably warmer in colour than commonly used fluorescent lamps and provides a high colour rendering.
Bringing sunlight to the core
There is a distinct difference between core sunlighting and standard daylighting solutions.
Daylighting uses design elements such as atria, skylights or large windows. These elements typically only light areas up to a maximum of five metres (or 16.4 feet) from the perimeter and are not always applicable or effective in multi-storey buildings.
In contrast, the core sunlighting system brings the light horizontally right into the building’s core, up to twenty metres (or 65.6 feet) from the building perimeter.
Another advantage of the core sunlighting system is that it can reduce HVAC cooling loads by up to 25 per cent, partly because sunlight emits less heat than artificial light and the core sunlighting system does not create the solar heat gain associated with daylighting design.
SunCentral has also found that the core sunlighting system is seven times more effective than photovoltaic systems (solar panels) that convert sunlight into energy and then use the energy to power lighting units.
The demonstration systems that have been installed by SunCentral are hybrid lighting systems in which a series of artificial light fixtures are installed in the sunlighting system’s reflective guide above the ceiling or suspended from the ceiling. The artificial lights automatically turn on during cloudy periods and at night.
SunCentral is quick to point out that even in British Columbia, a place notorious for rainy weather, the core sunlighting system is five to seven per cent effective even on overcast days. Overall for B.C., the core sunlighting system allows artificial lights to be extinguished 40 per cent of the time, averaged over the year during daytime hours.
Kamal Athwal, vice-president of marketing and business development at SunCentral, says that in areas of the world that receive considerably more average sunlight per year, the system performance could allow lights to be shutoff up to 75 per cent of the time.
From demonstration sites to marketed product
To garner interest from the commercial property development industry, SunCentral has installed demonstration systems at several sites, including the British Columbia Institute of Technology (BCIT), the University of British Columbia and Okanagan College. SunCentral’s goal is to begin commercial manufacture of its system by the end of 2012. Upon commercial launch, the company’s sunlight concentration panel will be miniaturized to be integrated within a building’s six-inch-thick curtain wall for new building construction projects. Subsequent technical demonstrations will feature curtain wall integrated sunlight concentration panels. In building retrofits, the concentration panels can be installed on the exterior of the building.
In North America, the target markets for SunCentral are Class A commercial space, government buildings, health care facilities and educational institutions. These environments typically have lights on for long periods of time.
Athwal reports that for installation in the average commercial building, the estimated payback period would be between three and 10 years. He stresses, however, that those calculations are made before consideration of government subsidies that this type of clean technology would receive. These grants would greatly reduce the return on investment time.
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