Grantee Research Project Results

2011 Progress Report: Horizontal Hybrid Solar Light Pipe: an Integrated System of Daylight and Electric Light

EPA Grant Number: SU834748
Title: Horizontal Hybrid Solar Light Pipe: an Integrated System of Daylight and Electric Light
Investigators: Beltrán, Liliana O. , Fernández-Solis, José
Institution: Texas A & M University
EPA Project Officer: Page, Angela
Phase: II
Project Period: August 15, 2010 through August 14, 2012
Project Period Covered by this Report: August 15, 2010 through August 14,2011
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2010) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Sustainable and Healthy Communities , P3 Challenge Area - Air Quality , P3 Awards , Sustainable and Healthy Communities

Objective:

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 objectives of our lighting system 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, lighting controls, and automated shading devices; and, (4) reduce the energy consumption in buildings and slow fossil fuel depletion.

Progress Summary:

We have developed and installed our horizontal solar light pipe in our new 360˚ rotating daylight testing facility that simulates an open floor plan office space (20 ft by 30 ft) with electric lights, lighting controls and automated exterior blinds. The illuminance levels measured at the back of the space over the workplane showed a uniform illuminance distribution, and 300 lux and above was maintained over workplane for more than 9 hours during clear and partly cloudy days from the vernal equinox to autumnal equinox. Illuminance levels over the workplane reached more than 2,000 lux around noon hours. Under overcast sky conditions, workplane illuminance levels consistently remained above 200 lux. Results from energy simulations have shown that the light pipe can reduce more than 40% of the building's lighting loads and 10% of the cooling loads. Our solar light pipe system is an energy-efficient passive technology that brings free fullspectrum lighting to multi-story building cores in new and existing buildings.

Future Activities:

The proposed horizontal light pipe system is an effective energy-efficient passive technology that can provide healthy full-spectrum lighting in deep floor plan spaces for 9 hours under clear and partly cloudy sky conditions, which is the annual predominant sky condition in the central southern part of US. The light pipe introduces consistently throughout the year illuminance levels between 300-2,500 lux at 7.3 m from the window wall. Exposing building occupants to bright light (>1,000 lux) will help them regulate the timing of their circadian rhythms which also has a direct effect on alertness and performance. 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.

The lighting levels provided by the light pipe at the back of the space are similar to the ones provided by the sidelight window at the front of the space, even though the light pipe’s glass area is only 10% of the sidelight window area. Therefore, cooling loads generated by the light pipe will be insignificant compared to the ones generated by the sidelight window, and to the cooling loads generated by the electric lighting it offsets. Light levels are distributed uniformly throughout the space creating a visually comfortable space for occupants in deep floor plan buildings.

The light pipe is a sustainable technology that can change the way buildings will be designed in the future. It will not be necessary to have large expanses of glass to introduce more daylight to the core of buildings and deal with the effects of increased cooling loads. Several building types (i.e. offices, schools, nursing homes, hospitals, housing for the elderly and visual impaired people) can benefit from this technology which utilizes direct solar energy with no operational costs, and provides high illuminance levels and full-spectrum light.

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 deepfloor 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. The new rotating experimental room will be used as a lighting laboratory to continue testing our solar light pipe in different orientations. We are organizing educational tours to both students and professional architects to visit our solar light pipe and the rotating experimental room.

Journal Articles:

No journal articles submitted with this report: View all 6 publications for this project

Supplemental Keywords:

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

Progress and Final Reports:

Original Abstract

Final Report

P3 Phase I:

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