University of Hawai`i at Manoa Green Roof Experiment
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The University of Hawai`i at Manoa Green Roof Experiment with Leyla Cabugos; Photo by Scott T. KuboProject Name: University of Hawai`i at Manoa Green Roof Experiment
Year: 2007
Owner: University of Hawai`i
Location: Honolulu, HI, USA
Building Type: Educational
Type: Semi-Extensive, Test/Research
System: Custom
Size: 576 sq.ft.
Slope: 2.4%
Access: Accessible, Open to Public
Submitted by: Leyla Cabugos, University of Hawai`i at Manoa

Designers/Manufacturers of Record:
MS Candidate, Primary Investigator: Leyla Cabugos, University of Hawai`i at Manoa
Assistant Professor: Travis Idol, UHM College of Natural Resources and Environmental Management
Assistant Professor and Director: Steve Meder, Center for Smart Building and Community Design and UHM School of Architecture
Staff Specialist: Olwen Huxley, SeaGrant Program Hawaii Branch
Landscaping Manager: Roxanne Adams, UHM Office of Buildings and Grounds
Associate Professor: Loren Gautz, UHM Department of Agricultural Engineering
Assistant Professor: Andrew Kaufman, UHM College of Tropical Plant and Soil Sciences
Professor: Will McClatchey, UHM Botany Department
Associate Professor: Tamara Ticktin, UHM Department of Botany
Valley of rainbows; Photo by Leyla CabugosGreenroof plants in a Hawaiian paradise; Photo by Scott T. KuboThe verdant greenroof plots; Photo by Leyla Cabugos
Hawaii`s first institutional green roof research has been underway at the University of Hawai`I at Manoa (UHM) since August, 2007 on the Capital Isle of O`ahu. The project was developed as a masters (MS) thesis research project by Leyla Cabugos in the Department of Botany, and involves the efforts of seven academic departments and numerous volunteers. The project is designed to provide baseline information for the development of living roofs in Hawai`I, and a prototype for future green roofs on the UHM campus.

The plants, horticulturally-established native species selected from coastal dryland environments, have been growing in the ground-level planters since August, 2007. Climatic variables are recorded on site on a continuous basis to characterize conditions affecting plant growth and evapotranspiration rates, and to allow comparison with studies from other areas. Information on water balance and spontaneous plant recruitment are reported to project the maintenance needs and environmental performance of plantings in this region. The experiment is built to accommodate future studies of building temperature dynamics with green roofs in the Hawaiian climate. The research is supported by a UHM Chancellor?s Sustainability Council Seed Grant, and by material donations from Swinerton Builders, Colbond USA, Hawaiian Irrigation and Sprinkler Company (Hisco), Hawaiian Sunshine Nursery, Hui Ku Maoli Ola native plant nursery, the UHM School of Architecture and Office of Buildings and Grounds.
Sesuvium; Photo by Leyla CabugosSida; Photo by Leyla Cabugos
The layering system includes a recycled plywood box frame, (improvised) waterproofing of 4mm plastic dropcloth, an Enkadrain 3811R drainage fabric, and a local soil mix consisting of 2 parts black cinder from the island of Hawai`I, one part locally produced compost and one part coconut coir (chips and dust imported from Sri Lanka, mixed with local material shredded in a hammermill. We were trying to see if locally produced coir could be a viable substitute for imported material). Volunteers mixed and moved eight cubic yards of soil media into the planters by hand, and installed 580 perennial plants. The elevated boxes were designed to accommodate thermal insulation for the purpose of comparing temperature dynamics below green roofs and bare roof control plots.

The plots were irrigated for the first month with ?? Netafim lines, and 2 gal/hour Rainbird emitters. After the summer installation period, the valley received enough rain to make irrigation unnecessary. The precipitation gradient from the back of Manoa Valley to the campus at the mouth, a distance of less than 3 miles, spans the range of 120-40? per year.

Additional thumbnail photos:

Coir preparation; Photo by Leyla CabugosStephen planting; Photo by Leyla CabugosThe University of Hawai`i at Manoa Green Roof Experiment Weather Station; Photo by Leyla CabugosPlanting plants - see irrigation; Photo by Stephen PearsonVitex; Photo by Leyla Cabugos
Additional information:

Leyla's academic website:

Plant Propagation Database:

SeaGrant Green Roof page where you can read more indepth about the various testing experiments:

Leyla Cabugos can be contacted at:
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