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Living Walls Provide Shade, Beauty . . . and Data
Author: Department of Architecture
Posted: August 16, 2012

The Shattuck Hall Ecological Learning Plaza, at SW Broadway and College Street, is the new home to a collection of “living walls,” which provide a beautiful backdrop for an afternoon walk in this lovely urban green space, but also generate useful data regarding water usage and storm-water management. These living walls, sponsored jointly by Metro and PSU, are one of the first research projects in this new outdoor lab. 

Made possible by a $40,000 grant by Metro, the living wall installations and interpretive displays on the site will enable designers, developers, and the community to see first-hand how three very different systems perform over the course of two full growing seasons.  Metro envisions this project as a valuable part of the agency’s ongoing efforts to promote low-impact development practices throughout the Portland region.

The Plaza's research data intended for use in the real world 

The PSU Department of Architecture’s research will focus on the amount of water each system uses and the rate the water flows through living walls.  This information will help to determine the long-range costs for the individual systems and their potential suitability for storm water management.  Additional research will look at temperature changes on wall surfaces behind each living wall.  This data will help individuals from the building industry to understand if there are any thermal benefits to the living wall strategies.  Researchers will also monitor the performance and mortality rates of the plant materials, the amount of fertilization used and the component maintenance levels in order to further clarify the operational costs for each system.

Three similar but different vertical planting systems

The Plaza is home to three different vertical planting systems, all of which are being tested.  The first system is a lightweight felt-based pocket system developed by the manufacturer Solterra.  This system is supported by an integral aluminum frame that sets off of the face of a new or existing wall. The system, with its pre-formed pockets, is hung in vertical locations; lightweight soil is added to the pockets; and plants are inserted into the soil.  It is the lightest overall system being tested. 

Prof. Jeff Schnabel and two graduate architecture students install the final unit to the Tournesal systemThe second system, developed by manufacturer Tournesol, is composed of plastic crates and felt bags.  Ten-inch-deep crates are assembled with a custom-fitting fabric bag that receives the soil.  After the soil is added, the crates are placed flat on the ground. Slits are cut into the bag and plants are inserted.  The plants are then allowed to grow in that same horizontal position for several weeks prior to being placed vertically on the wall.  Each crate receives four anchor bolts and is hung onto a steel frame provided by the manufacturer.  This system has the deepest soil profile of those being tested and is therefore the heaviest of the systems. 

The third system is a custom planter designed by Portland landscape architects Nevue Ngan.  The system consists of locally fabricated horizontal metal planters that are lined with a natural fiber pad.  The bottom of each planter, filled with pumice, serves as a water reservoir. Nylon rope is woven between the pumice and soil layers in order to wick water into the soil profile.  Like the other systems, these planters utilize a lightweight soil mixture.

The wall structures supporting the three systems are constructed from a wood frame and clad in Corten steel and were fabricated by architecture students in a manner that will allow the materials to be reconfigured or reused once the initial experiment is complete. 

Plants for all four directions

Each system has a north, south, east and west aspect.  The plant palate varies depending on the orientation of each wall, but some commonalities exist between the systems for purposes of meaningful comparison.  Locations for the walls were chosen to best create comparable conditions for each system being tested. Large trees and existing buildings surrounding the Plaza do have the potential to affect the performance of the growing systems.  However, because we are aiming to gauge the systems’ performance under real, urban conditions (which are likely to have buildings, trees and other factors that occur in an urban environment), the collaborators determined that the site would be an ideal location for the test. 

For each orientation, a blank wall clad with a concrete siding panel collects baseline data for the project.  Housed within the walls is monitoring equipment that was specified and installed by students from the PSU Green Building Research Laboratory.  All the equipment, including the irrigation, is powered through photovoltaic panels located in the Plaza. 

Data from the project is collected and sent wirelessly to a computer in the office of the Department of Architecture.  We intend to make the data available at www.pdx.edu/eco-learning-plaza in the near future, so that anyone will be able to see for themselves the benefits of creating a living wall.