Frequently Ask Questions
This page provides quick answers to some of the most common questions we receive regarding our products. For more in-depth data, please visit our Technical section or contact us online or in person!
Q. How much light can one
system deliver?
A. One HSL3010 system can deliver 50,0000 lumens of sunlight. This is equivalent to approximately 17 fluorescent lamps or 45 PAR38 60W halogen lamps.
Q. How does the color of the light compare to sunlight?
A. For all practical purposes, the delivered light is equivalent to direct sunlight in every way. The delivered light has a color correlated temperature of 5400K and a color rendering index of 100 (as does sunlight). In the mornings and evenings, the delivered light will have a reddish tint just as the rising and setting Sun. An option on the HSL3010 light switch panel allows this shift in color to be eliminated, if desired. The delivered sunlight does not contain IR or UV wavelengths.
Q. What if I want a warmer color temperature?
A. The HSL technology was developed to pipe full spectrum sunlight, at a CCT of 5400K, into a building. However, because it does contain full spectrum light, it can be filtered to match nearly any desired lamp temperature. Filters are available for use with the HSL3010 that
allow the collected sunlight to match 3000K and 3500K lamps (call for other color temperatures).
Q. Will this technology work for my building?
A. In general, the system is designed for buildings with a non-sloped roof and good visibility of the sun throughout the day. Because of limitations with the optical fibers, only single story buildings or spaces on the top floor of a multi-story building are currently accessible. See our Architectural Design Information page to further evaluate the suitability of your particular space.
Q. What happens when clouds obscure the sun?
A. The Hybrid Solar Lighting system collects primarily direct sunlight. Therefore, when cloud coverage is dense, very little light is delivered by the system. Under these circumstances, electric lamps are used to compensate for the reduced sunlight. A daylight harvesting sensor monitors the room illumination to maintain a constant intensity level.
Q. How much space will one system illuminate?
A. Although the exact value depends on lighting requirements for the space, a typical lighted area would consist of 750 - 1000 square feet.
Q. Why not just use a skylight?
A. Skylights have been around for many decades and function as a simple means of bringing natural light into a building. In certain applications, they are the most logical and cost effective daylighting solution. However, skylights have a number of drawbacks that can limit their application, limitations that Hybrid Solar Lighting does not. These can include:
- Significant source of heat loss or heat gain
- Can constrain design of building shape and orientation
- Difficult\Complicated to specify
- Point of condensation
- Uncontrolled, uneven illumination
- Susceptible to water leakage
- Susceptible to ventilation leakage
- Not appropriate for low ceilings
- Difficult to relocate or reconfigure
- Suitable for downlighting only (i.e. N/A to directional lighting or uplighting)
- Does not maximize the use of available sunlight
- A source of light pollution at night
- Cannot be easily turned off
- Security concerns
Hybrid Solar Lighting provides all of the benefits of natural lighting
with the flexibility and convenience typically associated with electric lighting. It can do all of this without any of the disadvantages listed above.
Q. Since this technology dims artificial lighting, will it reduce the lifetime of my lamps?
A. No. In fact, in some instances it will actually improve the lamp lifetime by 10-20 times. Research has shown that halogen lamps that are dimmed during the day and operated at full power in the evening will experience extended lifetimes that can be 10 to 20 times longer than non-dimmed lamps. Unfortunately, these advantages do not extend to fluorescent lamps. Fluorescent lamps can be dimmed without reducing the lamp lifetime but they must be "seasoned" (or operated at full power) for at least 10-hours prior to being dimmed. Under these conditions, fluorescent lamps will not experience any reduction in lifetime. For fluorescent applications, Sunlight Direct has designed the HSL technology to work with T8 lamps and recommends that all lamp replacements be performed at night to ensure proper lamp seasoning.
Q. Why wasn't this technology
invented earlier?
A. The concept for Hybrid Solar Lighting has been around since the early 1970s. However, only recently was a technique developed for using plastic optical fibers to provide a low cost and flexible method of distributing the light. Plastic optical fibers are extremely durable, low cost, and can be easily installed, polished, and repaired. At right a researcher investigates the optical heating in a bundle of plastic
optical fibers. (Photo courtesy of Oak Ridge National Laboratory)
Q. How can I participate in the beta testing?
A. We are currently seeking new applicants for our 2005 beta tests. Because of the high cost of the beta testing program, we are encouraging partnering with local utilities or state renewable energy offices to permit cost sharing. For more information, you can contact Sunlight Direct or visit Oak Ridge National Laboratory's website to learn more about the Sunlight Inside Initiative.
Q. When will a commercial product be available?
A. A commercially available product will be available in early 2007.
Q. Can I buy a system for my home?
A. No. Currently, Sunlight Direct only offers hybrid solar lighting systems for commercial buildings. However, we are developing a residential model that we plan to start beta testing in 2008.
Q. How much energy and money will I save with this technology?
A. Unfortunately, that answer depends on your location within the United States, your local utility costs, and your current lighting technology and use. The Northeast U.S., Southwest U.S., and Hawaii are the geographic areas most likely to benefit from this technology. As an extreme example of the energy and cost savings, an installation in Kauai, Hawaii that normally uses incandescent lighting would likely receive $1100 or 8,000 kWh a year in energy savings due to lighting displacement alone. If the cost savings associated with extending
the life of existing incandescent lamps and reducing building cooling
load is factored into the savings, a Kauai customer could save as
much as $2000 - $3000 per year per system.
Q. Can I turn the collected sunlight off?
A. Yes. A switch is provided that allows the collected sunlight to be easily turned off. This is accomplished by intentionally mis-tracking the sun by five degrees.
Q. Why not just use full-spectrum fluorescent lighting?
A. Full spectrum fluorescent lamps utilize a blend of phosphors to create an output that mimics natural sunlight. However, these lamps often display spectral properties that are actually a poor match to the continuous spectrum of natural sunlight (see figure). In addition, the lamps can cost as much as $20, are less energy efficient, and contain substances harmful to the environment. Hybrid Solar Lighting
provides natural, full spectrum light hat truly matches the spectrum of sunlight because IT IS sunlight. And just as the sunlight outside changes color throughout the day, so to will the collected light. Although the red shift in the sunlight of early morning and evening can be eliminated if desired, many past users have indicated that they prefer this feature. Being exposed to the Sun's changing color throughout the day is an important contributor to the regulation of many bodily processes important to good health and psychological
well being. It is possible that this dynamic property is also
responsible for the increased sales and productivity associated with natural lighting. Plus, unlike full-spectrum fluorescent lamps, this natural light source significantly reduces energy costs instead of raising them.
