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Showing true Aggie ingenuity, Texas A&M students developed a device that transports natural light into the interior of buildings. The system, designed with faculty advisor Liliana Beltrán, associate professor of architecture, was constructed and installed to illuminate a simulated office space inside an old rail car at the College of Architecture’s Digital Fabrication Facility, located at Texas A&M’s Riverside Campus. Utilizing an outdoor light collector, the apparatus funnels sunlight from the collector through a duct, or pipe, of highly reflective material, then through light-diffusing film that directs the light into a simulated office space in the rail car. The device is called the "Horizontal Hybrid Solar Light Pipe: An Integrated System of Daylight and Electric Light." It provides an advanced energy-efficient perimeter lighting system that integrates daylighting, electric lighting, and lighting controls to reduce electricity consumption.
The pipe was Texas A&M's entry in the "P3: People, Prosperity, and the Planet Student Design Competition for Sustainability," an annual contest sponsored by the U.S. Environmental Protection Agency. The contest is part of the EPA's April 24 and 25 sixth annual National Sustainable Design Expo, a gathering of professional scientists, engineers and business leaders.
The expo showcases the work of "P3" student teams that develop innovative design solutions for addressing sustainability-related issues such as alternative energy technologies; collection, purification and distribution of water; agricultural practices to reduce pesticide runoff; and new technologies for green buildings.
The event also provides a forum for government, nonprofit and business communities to demonstrate their diverse approaches to sustainability.
The Aggie group was one of 41 that received a one-year, $10,000 grant from the EPA "to develop an idea focused on benefiting people, promoting prosperity, and protecting the planet through an innovative design to address challenges to sustainability in both the developed and developing world."
"Our goal is to use natural light and reduce the need for electric lighting in buildings," said Beltrán, the project's principal investigator.
"With an efficient design and intelligent use of materials, it will be possible to passively introduce adequate light levels to illuminate areas between 15 to 40 feet from the perimeter of a building."
The pipe also uses high-efficiency electric light sources such as light-emitting diodes and sulfur lamps.
Beltrán and Texas A&M team members exhibited a scale model of their device on the National Mall for the April 2010 competition and public exposition.
José Fernández-Solis, assistant professor of construction science and the project’s co-principal investigator, directed the construction of the simulated office space at the Riverside Campus.
The students also set up a live webcast from their booth on the National Mall, where they showcased a live feed from their Riverside Campus project site.
To develop the lighting system, the Aggie team:
• researched materials and selected the light pipe's components;
• designed the pipe;
• designed and optimized the interaction of daylight and electric light sources and lighting controls;
• built the pipe and its components,
• installed it in the faux office space, and
• performed data acquisition set-up and preliminary data collection.
A light guide, designed to move the maximum amount of collected sunlight into the simulated office space, is a key component of the student’s light system design.
Sunlight is captured by the guide, which includes a relatively small piece of glass resembling a small window, about 52 inches wide by 11 inches deep. The rest of the guide is a rectangular box the glass sits upon.
"The sunlight collection is maximized with very complex ray tracing computer programs, where we trace 10,000 rays or more and observe how each ray of the sun will be entering the tube," said Beltrán. "All the light guide's surfaces, especially on the front part, have a series of angles with reflectors, all directing sunlight through the shaft."
The Aggie design's passive features have advantages over active light guides that require more maintenance, such as mechanical systems that track the sun.
"With our system, you install it, seal it, and it's there. All you have to do is clean the glass on the top, but if you use self-cleaning glass, you wouldn't even need to do that," she said.
After the light travels through the tube's highly reflective surface, made of a polymeric film with 99.3% reflectivity, it is spread into the simulated office space through a new daylight diffusing film developed by 3M, which is embedded with special patterns to spread the light at a wide angle.
Beltrán and students measure the illuminance delivered by the pipe with miniature light meters set on tables in the faux office, a space that's 75 percent of the size of an actual office area.
The pipe, she said, stems from an idea she initially developed at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, that was further developed at Texas A&M by Betina Martins, one of Beltrán’s former students who now teaches at the Monterrey Institute in Mexico. Martins earned a Master of Science in Architecture degree from Texas A&M in 2005. Another MSARCH former student, Kapil Uppadhyaya, also helped with the light pipe. He earned his degree in 2008.
The Horizontal Hybrid Solar Light Pipe was a multidisciplinary project involving students from Texas A&M’s environmental design, construction science and electrical engineering; the electrical engineering students installed the project's electric lighting and dimming controls.
Following is the proposal as submitted to the EPA:
This project will test the feasibility of an advanced energy efficient perimeter lighting system that integrates daylighting, electric lighting, and lighting controls to reduce electricity consumption. The system is designed to provide adequate illuminance levels in deep-floor plan spaces during building operating hours year-round.
Our proposed hybrid light pipe is a unique system that integrates daylight with high-efficiency electric light sources (i.e. LED, sulfur lamps) and intelligent lighting controls to offset the use of standard light sources in the core of buildings mainly during peak demand hours. Our team believes that technology is currently available to produce a hybrid solar lighting system based on the efficient design of a horizontal light pipe and the intelligent use of materials. It will be possible to passively introduce adequate light levels to illuminate areas between 15 to 40 feet from the perimeter of the building. Preliminary evaluation of the light pipe has shown that it can provide high illuminance levels, 300-1,500lux at the back of the space (15-30ft) for more than 7 hours (between 8:45am to 4:15pm) under clear skies.
The goals of this project are to: (1) quantify the energy savings of an integrated hybrid solar light pipe system over extended periods throughout the year; and (2) give students invaluable hands-on learning experiences in high-efficiency lighting design. The proposed system will passively integrate daylight and electric lighting in a single unit. The objectives of the proposed lighting unit are to: (1) extend the daylighted area of the perimeter zone of the building from 15 feet to 40 feet; (2) provide adequate brightness at the back of typical spaces without the associated high daylight/ solar radiation levels near the windows; (3) integrate auxiliary electric lighting; and, (4) reduce the energy consumption in buildings and slow fossil fuel depletion.
To develop the lighting system, the team will execute the following tasks: (1) research of materials and selection of individual components; (2) design and computer modeling of proposed light pipe; (3) lighting design optimization (daylight and electric light); (4) design/ interaction of electric light sources (color change capability and dimmable), and lighting controls; (5) construction of light pipe and assembling of components; (6) installation of system in testing room; (7) data acquisition set-up and preliminary data collection.
The expected outcome of this research will be the construction and installation of the proposed lighting unit in an existing space (20 ft wide by 30 ft deep) at the TAMU-College Station campus. The system will be monitored continuously for a whole year to collect data of the lighting performance and energy consumption under different sky conditions and different sun position. The lighting performance of the light pipe will be assessed both quantitatively (illuminance and luminance levels) and qualitatively (visual inspection and High Dynamic Range photography).