When Tubular Daylighting Devices Aren't the Right Choice
By Jeff Brain | August 14, 2015
Tubular daylighting devices carve out a unique niche in the world of skylights. Their design, innovated by Solatube Inc., utilizes flexible and reflective light tubes to direct light downward into a building. Because of this, they require cutting a significantly smaller hole in the ceiling than other skylights. Their compact, innovative design provides a set of unique benefits, but also makes tubular devices best suited to only specific applications.
The Advantages of Tubular Devices
There are several key benefits to tubular daylighting devices’ compact design. First, their flexible light tubes can be integrated even in cramped ceiling spaces, circumventing obstacles that would render other skylights useless. This also allows these systems to carry light into difficult to reach places—including the lower floors of a building. Secondly, they are more energy efficient than traditional skylights. Their small opening allows light to enter while letting less heat transfer take place than traditional skylights. This can reduce your building’s HVAC dependence by up to 60%. Finally, because of their small size, not only are these devices priced lower than their competition, they also offer a lower installation cost per-unit than other daylighting devices.
Why Not To Integrate Them
Despite the benefits they can provide, there are several reasons tubular daylighting devices might not be the best fit for your facility. While tubular devices are well suited for confined spaces, such as offices or residential homes, their efficiency suffers in large industrial or commercial complexes, especially those with high ceilings. In large complexes, their small size actually hampers their ability to illuminate the facility. According to statistics released by the National Fenestration Rating Council, tubular skylights must consume 5-10% of your roof space just to provide adequate light. In large industrial buildings this not only leads to a high cost for installing a large number of units, but it also reduces the amount of roof space which could otherwise be used for integrating other rooftop sustainability measures.
The other major reason not to integrate tubular daylighting devices actually ties into one of the system’s benefits. While these systems’ light tubes can be curved, angled and stretched across greater distances than other skylights, doing this with the tubes often results in problems with diminishing light intensity. This is because even light entering a tube made out of the most advanced reflective materials, at an optimal angle, will experience a 3% loss of intensity for every 10 feet the light travels. Even more if the tube is curved, because the light must reflect more times before reaching its destination. This can actually mean that taking advantage of tubular skylights’ capabilities will hamper your system’s efficiency.
Ciralight manufactures the SunTracker, a solar tracking skylight system. These skylights combine solar-power and GPS technology to precisely track the sun with a set of mirrors and reflect high quality natural light into a building for 10.5 hours a day. Their active design and larger size makes them an excellent fit in facilities where tubular devices are not a suitable lighting option.