The Green Roof as a Complex System

This event is co-hosted by the University of Notre Dame, Bradley University, Illinois Institute of Technology, Northwestern University, Purdue University, and University of Illinois Chicago


The Green Roof as a Complex System

Cliff Davidson, Syracuse University

4:00 p.m., March 31, 2023   |   Morris Inn, Ballroom C, University of Notre Dame

As cities grow and modify the natural environment, many municipal governments have recognized the benefits of installing green roofs and other types of green infrastructure. Green roofs can reduce combined sewer overflow, minimize flooding, decrease the intensity of the urban heat island, and provide habitat for urban wildlife.

In this talk, we consider how the performance of a green roof can be modeled and measured in an effort to understand its benefits in built-up urban areas, using the instrumented extensive green roof on the Onondaga County Convention Center in Syracuse, NY.

Cliff Davidson
Cliff Davidson

We examine two general categories of performance, energy flow and storage, and water flow and storage. In the first category, the soil and vegetation that make up the green roof can dissipate heat much more quickly than concrete and other building materials, reducing high temperatures that can impact people’s health and damage urban ecosystems. By installing temperature sensors in the various layers of a green roof during its construction, we can produce thermal profiles as a function of time that can aid in estimating the heat flow through the roof.

Regarding water flow and storage, the soil of the green roof can hold stormwater until evaporation as well as transpiration by the plants can remove it. The total rate of water loss influences the time it takes for the roof to recharge its water-storing capacity after a rainstorm. By conducting a water balance on the roof, we can understand the complexity of factors that influence how much incoming rainwater flows down the roof drains and how much is retained by the soil and vegetation to evapotranspire slowly over time.

Finally, we attempt to explain why some cities have moved forward with many green infrastructure projects, while other cities have preferred traditional gray infrastructure such as regional treatment facilities and storage tanks to reduce flooding and combined sewer overflow.

Cliff Davidson is the Thomas and Colleen Wilmot Professor of Engineering in the Department of Civil and Environmental Engineering at Syracuse University. He also serves as Director of Environmental Engineering Programs and Director of the Center for Sustainable Engineering.

He received his B.S. in Electrical Engineering from Carnegie Mellon University and his M.S. and Ph.D. degrees in Environmental Engineering Science from California Institute of Technology. Following his PhD, he joined the Carnegie Mellon faculty in the Department of Civil Engineering (currently Civil and Environmental Engineering) and the Department of Engineering and Public Policy, where he served for 33 years. He joined Syracuse University in 2010.

He has 140 publications in peer reviewed journals, and has given roughly 200 presentations at conferences, seminars, and workshops. He is a Fellow in four organizations: American Association for Aerosol Research (AAAR), the Association of Environmental Engineering and Science Professors (AEESP), the American Society of Civil Engineers (ASCE), and the Syracuse Center of Excellence in Environmental and Energy Systems. He served as President of AAAR in 1999-2000.

Co-sponsors: Department of Civil and Environmental Engineering and Earth Sciences, College of Engineering, Notre Dame Research