Dr. David Tilley’s “Ecosystem Engineering Design Lab ”Receives Funding for Promising Green Wall Experiment

When studying Green Wall efficiency, look no further than Environmental Science & Technology’s “Ecosystem Engineering Design Lab,” headed by Associate Professor Dr. David Tilley. Tilley’s research has catapulted the lab into one of the top centers in America to study vegetation-draped buildings’ effects on environmental sustainability. Now, ENST has received a joint $50,000 award with British Columbia Institute of Technology’s Centre for Architectural Ecology to perform cutting-edge Green Wall research in North America.

Green Wall Research to Focus on Energy Savings and Water Management

The grant, which comes from Green Roofs for Healthy Cities, is the product of four years of ongoing research on green facades and green roofs by the Lab. The funding will allow the Lab to measure the amount of cooling energy that can be saved by equipping buildings with green walls, says Tilley. UM’s research team will focus their efforts at better understanding the thermodynamic properties of two distinct green wall systems, while the Canadian team will study the ability of green wall systems to reduce storm water runoff.

What are Green Walls?

Draping a building with vegetation cools the exterior surface by reflecting solar radiation and by transforming absorbed solar radiation into water vapor via transpiration. As part of their research, the ecological engineers will measure the reflectance and transmittance of vine species used on green walls.

There are two distinct types of green walls – Green Facades and Living Walls. Green Facades are a type of green wall system in which climbing plants or cascading groundcovers are trained to cover specially designed supporting structures, such as modular trellis panel systems or cable and wire-rope systems. The plants, which take several years to mature, are rooted at the base of these structures or in planters at different levels.

In contrast, Living Walls are composed of pre-vegetated panels, vertical modules, or planted blankets that are affixed to a structural wall or frame. These panels can be made of plastic, expanded polystyrene, synthetic fabrics, clay, metal or even concrete. Living walls typically require more intensive maintenance than green facades.

The research teams will be studying both types of green wall systems over a three-year period. “Green walls have enormous potential to improve the health and well being of people by providing aesthetic benefits, green jobs, filtering air pollution, reducing energy use, cutting greenhouse gases and managing stormwater” said Steven Peck, Founder and President of Green Roofs for Healthy Cities. “We are very pleased to have these research institutions involved in this unique program to help us quantify these benefits,” he added.

Student’s Thesis Opens a New Opportunity for Ecological Engineering

This experiment follows the successful completion of Laura Schumann’s Masters thesis, “Ecologically Inspired Design of Green Roof Retrofit,” completed in August of 2007. Laura’s work opened a new avenue for ecological engineering. “Her thesis showed that vine vegetation suspended above a building roof could have a significant effect on reducing building temperatures and on delaying storm water runoff,” explains Tilley. The experiment found that a building covered with a full canopy had its maximum daily summertime inside temperature reduced by 5.9 °C (11 °F). Scaling the findings to a one-story, 2000 square feet Mid-Atlantic region building with a properly sized air conditioning unit would yield a decline in energy consumption during the summer of 18%. This energy savings could translate into a $100 or $200 savings per season, depending on other factors.

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Last updated: 06/2/2009

Riparia Gloire

Riparia Gloire (Vitis riparia) grows in late Spring 2009 in the greenhouse among 120 other grapevine cuttings waiting to be planted on the experimental building facades. It is long-lived and capable of reaching into the upper canopy of the tallest trees.

Jeff Price

ENST graduate student, Jeff Price, shows one of the experimental buildings during its construction phase. This is one of the four buildings to be outfitted with over twenty temperature sensors to measure summer heat transfer reduction using green walls.