Cultivating research: resource-based design as an activating agent for energy and water conservation

Abstract

Green and living walls are an old idea made anew through the use of conventional construction materials used in new and creative ways. There is now a broad market for mass-produced prefabricated living wall systems that are made from PVC, metal, and or geotextiles. There exist hydroponic living walls made from geotextiles and fabric materials, rigid modular living walls made from PVC, and green façade structures made from cable and steel mesh to support ground-based vines. Most conventional materials for green walls in the market are derived from raw material or recycled PVC. This study investigates alternative materials already in the solid waste stream that were ready for creative reuse. The purpose of this project was to explore if existing sheet metal by-products could be repurposed as green wall systems and provide beneficial ecosystem services. A secondary purpose was to educate the campus community about sustainability through improving the value of industrial by-products thereby reducing waste streams in the production of new materials, energy conservation and reduced water use for green walls through the use of drought tolerant vegetation. Initial readings for the living wall system surface was 2.68 to 3.92 and up to 4.6 degrees Celsius cooler than the adjacent concrete wall. Students and faculty at Texas A&M university worked through a dozen different green wall modular designs. One design was refined and was trialed for cutting using a water-jet machine and assembled with manual folding. Three hundred prism-shaped modules were attached to a vertical steel frame. Drip irrigation lines deliver water to each module. Drought tolerant plants were used to minimize irrigation water. It is estimated that compared to conventional living walls, the proposed system uses about half of the volume of water needed for irrigation. More detailed analysis is currently under investigation.

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526 Cultivating research: resource-based design as an activating agent for energy and water conservation
Cultivating research: resource-based
design as an activating agent for energy
and water conservation
Ahmed K. Ali, PhD1, Bruce D. Dvorak1
1Texas A&M University, College Station, TX
ABSTRACT: Green and living walls are an old idea made anew through the use of
conventional construction materials used in new and creative ways. There is now a broad
market for mass-produced prefabricated living wall systems that are made from PVC, metal,
and or geotextiles. There exist hydroponic living walls made from geotextiles and fabric
materials, rigid modular living walls made from PVC, and green façade structures made from
cable and steel mesh to support ground-based vines. Most conventional materials for green
walls in the market are derived from raw material or recycled PVC. This study investigates
alternative materials already in the solid waste stream that were ready for creative reuse. The
purpose of this project was to explore if existing sheet metal by-products could be repurposed
as green wall systems and provide beneficial ecosystem services. A secondary purpose was
to educate the campus community about sustainability through improving the value of industrial
by-products thereby reducing waste streams in the production of new materials, energy
conservation and reduced water use for green walls through the use of drought tolerant
vegetation. Initial readings for the living wall system surface was 2.68 to 3.92 and up to 4.6
degrees Celsius cooler than the adjacent concrete wall. Students and faculty at Texas A&M
university worked through a dozen different green wall modular designs. One design was
refined and was trialed for cutting using a water-jet machine and assembled with manual
folding. Three hundred prism shaped modules were attached to a vertical steel frame. Drip
irrigation lines deliver water to each module. Drought tolerant plants were used to minimize
irrigation water. It is estimated that compared to conventional living walls, the proposed system
uses about half of the volume of water needed for irrigation. More detailed analysis is currently
under investigation.
KEYWORDS: Resource reuse, Living Walls, Energy saving, Automobile metal By-products,
Fabrication.
INTRODUCTION
Green walls began many decades go as simple installations with hanging plants on buildings
and vines selected and planted to grow vertically on stone walls and then later brick walls.
Wood trellises and pergolas became popular beginning in the mid-sixteenth century formal
gardens (Baran and Gültekin 2018, Köehler 2006). The Chrystal Palace built for the 1851
World’s fair in London was conceptualized by John Paxton and was perhaps the first inspiration
for indoor and vertical greening with modern materials. The massive glass, steel and wood
structure housed indoor trees, ferns, flowering and hanging plants. But these early versions of
greening buildings only set the stage for the development of more contemporary hydroponic
vertical gardens popularized by the French botanist Patrick Blanc since 2000 (Blanc 2008).
Blanc’s vertical gardens were each a custom fabrication and installation derived from fabrics,
however many vendors began exploring materials and methods to mass produce similar living
wall systems. Over the years there has been a limited number of investigations documenting
the ecosystem services that green walls can provide, thus the technology is in an early
adoption phase (Köehler 2006).
There is now a broad market for mass-produced prefabricated green wall systems that are
made from PVC, steel meshes and or geotextiles (Perini et al. 2013, Manso and Castro-Gomes

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ARCC 2019 | THE FUTURE OF PRAXIS 527
2015). Green walls consist of a variety of techniques to establish live plants on vertical surfaces
(Figure 1). Green facades are a type of green wall to establish twining vines on cable or on
wire mesh panels. Hydroponic living wall systems make use of shallow rooted plants, fabric
and nutrified irrigation water to feed plants. Each of these types of systems have limitations.
Most vines have vertical growth limits and hydroponic systems may not be adaptable to
climates with extreme heat or cold. Modular living wall systems attempt to grow plants vertically
in small PVC containers. Many modular systems have fundamental problems such as; limited
space to provide for growing medium and root growth, and some modular systems position
plants in unnatural orientations such as perpendicular to sunlight. Initial installations of some
of these modular living wall systems have demonstrated that some of these market-based
modular systems have limited application outdoors in extreme climates and some may not be
economically sustainable (Perini and Rosasco 2013, Dvorak et al. 2014).
Figure 1. Green wall systems include vines with adhesive root systems grown directly on walls (left image)
modular PVC-based systems (middle) and hydroponic systems constructed from fabrics (right). Source:
Authors
This study investigated alternative materials already in the industrial solid waste stream that
were ready for immediate use (Ali 2017). The purpose of this project was to investigate if sheet
metal by-products could be repurposed as a green wall system and provide beneficial
ecosystem services. A secondary purpose was to educate the campus community about
sustainability through adding value-by-design to the industrial by-products thereby reducing
solid waste streams in the production of new materials, energy conservation and reduced
water use for green walls through the use of drought tolerant vegetation.
1.0. METHODS
A mixed methodology including empirical, qualitative, and quantitative methods was used to
investigates the potential for alternative use of fabrication materials and methods for living
walls. The investigators engaged conversations with potential industry partners and secured
agreements with an automotive manufacturer sheet metal by-product. The authors invited a
group of interdisciplinary students to participate in a resource-based design-build process to
develop and fabricate new modules for a custom living wall, secured resources for fabrication,
installed the living wall system and pre-tested the wall for micro-climate characteristics.
1.1. Design and Fabrication
To investigate the potential use of alternative materials and methods, the investigators secured
agreements with a waste stream source in the automotive industry for available sheet metal.
The automotive industry fabrication process typically disposes large quantities of sizable
galvanized sheet metal as a byproduct of the automobile manufacturing process. Students at
Texas A&M university were invited to take a special topics courses to conceptualize modular

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528 Cultivating research: resource-based design as an activating agent for energy and water conservation
living wall design alternatives and to assist in the fabrication process. Students and faculty
prepared and presented materials to the university campus design sub-council to receive
permissions to install the wall. After approvals, the modules and frame were fabricated,
painted, planted and installed in place (Figure 2). Due to delays in the fabrication process, only
the first third of the wall was assembled and planted in the month of May (Figure 2). Plant
species included: Dichondra argentea, Yucca 'Color Guard', Phyla incisa, Agave lophantha
'Quadricolor', Hesperaloe parviflora, Hechtia texensis were placed in the modules and
watered. The wall frame as shown in Figure 1 and comprises a support for the entire living
wall. The living wall is approximately 5.48 meters wide and 4.26 meters high consisting of
23.41 m2 of surface area. The remainder of the wall was fabricated and installed in place during
the month of August.
Figure 2. Students working on the green wall system during the module installation process. The concrete
wall used to compare microclimate is visible to the right and left of the living wall. Source: Authors
1.2. Microclimate investigations
Students investigated several potential methods to measure surface temperatures and heat
gain. The first method was through thermal camera imaging. A FlIR©® camera was used to
capture a moment in time and reveal surface temperatures of the wall materials. A second
method was used to determine the measure of the wall surface temperatures observed with a
hand-held Extech IR©® infrared thermometer. The wall has a south/southwest aspect and data
was collected during the late afternoon generally one to two hours after direct solar exposure.
Surface temperatures were captured with an infrared hand-held device and recorded on a
table. By measuring after direct solar exposure, the effect of the wall was recorded at the end
of the solar exposure period. Twelve surface locations were identified to be measured daily
near the same time for twenty-one days between the months of June and August on days
without precipitation. Each located was measured three times and recorded. The average of
the three measurements was used in this study. Surfaces measured included the planted light

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grey-blue colored modules and white modules, exposed brick, exposed concrete, two metal
exterior doors and the immediate ground level pavement adjacent to the living wall. For each
temperature reading, three temperature readings were taken and averaged. Additionally, A
FIIR thermal camera was used to crosscheck thermal variance on wall surfaces.
1.3. Watering
Drip tube irrigation lines were installed to deliver municipal water to each module. A zone
control valve was set to deliver water once daily at 6:00 am. Each drip tube is capable of
delivering approximately 3.7 liters per hour. Irrigation was set to run daily for two minutes
duration or 0.126 liters per day.
2.0. RESULTS
The living wall system designed and fabricated by students and faculty was successfully
developed and installed during late 2018. The first phase included planted modules and was
installed in May. The remaining modules and frame (without plants) were installed during the
month of August. Twelve students meet once weekly to fabricate the modules in a fabrication
lab at the university. Later, students installed the irrigation system, retention fabric in the
modules, light-weight soils and plants.
By the month of August, all of the modules had been fabricated and the entire frame was
installed. All of the modules had been hung on the wall. However, the remainder of plants will
be installed during the spring of 2019, as faculty and students, and additional materials were
needed to grow and purchase. Some faculty and students were not available until spring 2019.
Figure 3: Southwest facing wall with 300 modules installed. Photo taken during the early morning. Source:
Authors
2.1. Waste stream reduction
Compared to market-based modular living wall systems, this system designed by students and
faculty used materials already in the metal solid waste stream. By retrieving refuse sheet metal
from the automotive industry, there was no need to extract raw materials. Figure 4 shows the

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530 Cultivating research: resource-based design as an activating agent for energy and water conservation
sheet metal used prior to fabrication of the wall. Each sheet was fitted for the module design
and cut. Waste from the cutout of the module could be sent back into a metal recycling center.
The module layout was adjusted to minimize cuts and reduce waste.
Figure 4. Sheet metal scraps in bundles prior to fabrication at the university (left) and after fabricating
(right). Source: Authors
2.2. Microclimate
Surface temperature observations were taken over the summer from June to August. The
thermal camera image demonstrates that the living wall modules (blue pixels) on average were
2.68 to 3.92 and up to 4.6 degrees Celsius cooler than the adjacent concrete walls (orange to
red pixels). There was some variation between modules as the white modules were generally
1-2 degrees Celsius cooler than the light grey modules. Figure 5 shows the temperature
variation in a thermal camera image of the wall taken in July. The image legend is located on
the right side of the image and correlates pixel color to thermal temperature with a range of
28.3 to 32.9 degrees Celsius.
Figure 5. Thermal image of the wall (left) was taken with a FLIR©® camera at 15:44 hrs on August 29,
2018. The heat energy visible in the image is latent heat, as the wall has a southwest exposure and was
in shade approximately two hours prior to the photo. The white circle on the left center of the thermal image
locates the 29.0 °C. The planted modules include darker blue pixels on the right side of the image. Source:
Authors
Although cloud cover was present during some of the observations, during the warmest time
of the summer temperature readings were taken during cloudless days to measure potential
effect of modules. Table 1 shows mean temperatures for several locations of different
surfaces. As the modules are diamond shaped and protrude away from the wall, the sun and
shade sides of modules were taken. The building wall also has two metal exterior doors and
some exposed light brown brick. The grey-blue module in the shade side of the module had
the lowest surface temperature at 39.78 °C for the living wall. The white modules had

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temperatures similar to the grey-blue modules but were slightly warmer. Most of the living
wall is in the blue temperature range, where the edge near the concrete wall can be seen in
the green and yellow temperature range. This means that the concrete thermal mass is
radiating heat to the living wall system (Figure 5).
Table 1. The handheld Extech infrared thermometer was used to observe floor surface mean temperatures
taken at 15:00 hrs on August 1, 2018 approximately two hours after direct sunlight. Maximum air
temperature for the daytime at the university was 36 °C.
Surface
number
Surface material
Surface
Temperature °C
1
Grey-blue Module
41.12
2
Grey-blue Module (shade)
39.78
3
Grey-blue Module (sun)
40.66
4
White Module
40.8
5
White Module (shade)
40.72
6
White Module (sun)
41.22
7
Exposed Brick Wall
42.78
8
Right Concrete wall
41.42
9
Left Concrete wall
42.48
10
Metal door
42.59
11
Right Concrete pavement
44.77
12
Left Concrete pavement
49.77
13
Exposed Brick pavement
48.27
2.3. Watering
Irrigation water was delivered daily during the summer. During late July, the watering was
changed from two minutes to one-minute duration. Some weeds were establishing in the
modules and it was thought that it may be due to excessive watering. On October 18, 2018 it
was discovered that the irrigation control valve was leaking. The irrigation was shut down for
the winter, as natural rainfall was assumed to be ample for the remainder of the year.
Compared to earlier studies on living walls on campus, this living wall system was set to half
the water, due to the use of drought tolerant plants. The same type of water delivery system
was used on three other living walls built from conventional systems available on the market.
Irrigation run times of five to ten minutes was required to irrigate the entire wall thoroughly. In
this study we found that the living wall planted with drought tolerant vegetation did not require
more than one to two minutes of irrigation daily to maintain live growth.
3.0. DISCUSSION
Compared to other conventional living wall systems available on the market, the uniquely-
designed galvanized sheet metal modules minimized the use of new materials, steel recycling,
and therefore energy consumed. The custom modules required paint, similar to typical car
finish to extend their life time and to protect the galvanized metal from oxidation and corrosion.
The thermal data demonstrates that the living wall compared to a concrete wall has a capacity
to reduce the heat gain on exterior wall surfaces. The effect of plants is not clear, as only one-
third of the wall was planted. The cooling effect was largely due to the effect of unplanted
modules. The additional systems layers of plants, soil, insulation, and moisture are anticipated
to further reduce the heat gain on exterior surfaces. The thermal images show that the plants
were the coolest features of the wall. Once the wall is complete, further investigation will be
conducted. The warmest measured locations were the ground pavement near the wall. It is
presumed that the pavement near the wall received direct solar exposure from sunlight and

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532 Cultivating research: resource-based design as an activating agent for energy and water conservation
radiated heat energy from the wall surfaces. Future studies will investigate the potential effect
of plants shading and cooling on the wall and pavement adjacent to the wall.
CONCLUSION
This study demonstrated that sheet metal by-products can be harvested and repurposed to
reduce solid waste streams and embodied energy through resource-based design approach,
typically present in the manufacturing of living wall modules constructed of PVC materials. A
more in-depth investigation is necessary to further investigate energy conservation of all
phases of fabrication and to better understand the dynamics of the potential heat energy
conservation of this living wall system. The use of drought tolerant vegetation allowed minimal
watering to gain effect of shading the modules. Future studies will investigate the fully planted
wall to extrapolate the results.
ACKNOWLEDGEMENTS
The authors would like to thank Texas A&M University and General Motors for funding this
study. Students of the interdisciplinary Tier One Program project during the year 2018, Patricia
Kio and Dr. Robert Brown for their data collection, including the thermal image used in Figure
4.
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