Final Report: Horizontal Hybrid Solar Light Pipe: an Integrated System of Daylight and Electric Light

EPA Grant Number: SU834349
Title: Horizontal Hybrid Solar Light Pipe: an Integrated System of Daylight and Electric Light
Investigators: Beltrán, Liliana O. , Camacho, Gema , Diaz, Oscar , Farias, Francisco , Fernández-Solis, José , Gignac, Nicholas , Jiang, Yin , Lee, Johnny , Mansour, Nesrine , Miller, Paul , Negandhi, Vanita , Pathak, Rutuparna , Porwal, Vishal , Shirodkar, Rohan , Wang, Julian
Institution: Texas A & M University
EPA Project Officer: Nolt-Helms, Cynthia
Phase: I
Project Period: August 15, 2009 through August 14, 2010
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2009) RFA Text |  Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Built Environment , P3 Challenge Area - Energy , P3 Awards , Sustainability


The goal of this research was to develop and construct an advanced energy efficient perimeter lighting system that integrates daylighting, electric lighting, and lighting controls to reduce electricity consumption. This lighting system was designed to provide adequate illuminance levels in deep-floor plan spaces during building operating hours year-round. Our horizontal light pipe is a unique system that passively redirects daylight through a relatively small window opening to minimize energy consumption by reducing lighting and cooling loads.

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.

Summary/Accomplishments (Outputs/Outcomes):

We have built a test room at the Texas A&M University, Riverside Campus where the horizontal light pipe was installed and monitored for several days. The test room represents a typical 30ft deep-floor plan office with a south-facing sidelight window and external horizontal shading devices. Measured illuminance levels at the back of the space over the workplane in the test room showed a uniform illuminance distribution throughout a deep-floor plan space, and 300 lux and above were maintained over workplane for more than 9 hours during clear and partly cloudy days around the vernal equinox. Workplane light levels dropped below 300 lux when the exterior horizontal global (EXHG) illuminance values were below 22,000 lux. During overcast sky conditions when the EXHG remained above 22,000 lux, workplane illuminance levels consistently remained above 300 lux.

Results from energy simulations using a preliminary light pipe pilot study have shown that the light pipe can reduce more than 40% of the building’s lighting loads and 10% of the cooling loads. The total annual energy reduction of the office building is over 10% or 23,808 kWh; this is equivalent to $4,837.00 and a reduction of 8.1 Metric Tons of CO2 emissions per year.


The proposed horizontal light pipe system is an energy-efficient passive technology that can provide a well-daylit healthy interior environment. Such environments can have a positive effect on building occupants who spend long hours indoors. Measured illuminance levels at the back of the test room showed adequate ambient lighting to perform most visual tasks throughout daytime hours (9am-6pm). No need of supplementary electric lighting was required during sunny days. The high illuminance levels achieved with the light pipe can help building occupant’s to adjust their circadian rhythms by providing alertness throughout the day, in a glare free environment. Recent studies of LEED office buildings have shown that building occupants enjoy working in spaces with high ambient daylight levels, and complain only when they cannot control direct glare over their workspaces (Beltran 2009.)

Results from energy simulations have shown that the light pipe is a promising technology that has the potential to largely reduce energy consumption and CO2 emissions of multi-story deep-floor plan buildings as well as existing ones.

Architecture students had a unique opportunity to work in a multidisciplinary environment where they had a chance to interact outside the classroom with other students and faculty from other fields providing wider viewpoints to their education.

Supplemental Keywords:

natural light, energy efficiency, electric lighting, lighting controls, human comfort

P3 Phase II:

Horizontal Hybrid Solar Light Pipe: an Integrated System of Daylight and Electric Light