Modeling of Natural Plant Materials to enable performance Evaluation of Environmentally Friendly Buildings

Sponsor: National Science Foundation (NSF)

Dates: 07/2009 - 12/2011


Research has shown that building green roofs have the potential to reduce energy demand on space conditioning, reduce storm water runoff, expand the lifetime of roofing membranes, improve air quality, and reduce the urban heat island effect in cities. Predictive methods to quantify the benefits of green roofs? capabilities to reduce energy consumption and water runoff are needed. The long-term goal of the proposed research is to develop and verify the methods and tools that can be used to calculate heat/mass transfer through a building envelope covered with natural plant material for a given location in the United States. The goal of the present study is to provide tools and calculation methods to quantify summer cooling effects of a green roof, which presently is the most popular natural plant material for buildings.

The performance of green roofs is climate dependent and having a reliable estimate on potential energy savings is vital in evaluating the investment in this technology. The laboratory experimental methodology to be refined in this project can be applied to other natural plant materials to be incorporated into building envelopes in the future. Furthermore, the impact of the GREEN educational component will not be limited to the two participating schools, but rather an entire community of teachers and students interested in exploring environmental issues. In the future, research results of the present study will be transferable to other diverse natural materials to be integrated not only on building roofs, but also on building vertical walls.


The NSF Visit and Document the Green Roof lab Experiments at Penn State


President Obama and Secretary of Energy Chu Visit the Green Roof lab




Commented Code for Engineering Equation Solver

Calculation Procedure

Mingjie Zhao's Calculation procedure

Input into EES

Excel File with measured data: Temperature, radiation, windspeed, albedo h.


EES Code File

Primary Engineering Equation Solver Code file.

EES Code File

Sensitivity Analysis of the previous EES code.


Journal Papers

  • Tabares-Velasco, P.C., and Srebric, J. 2012. “Predictive Green Roof Model for Assessment of Heat Transfer through a Roof Assembly in Summer Weather Conditions,” accepted to appear in Building and Environment.
  • Tabares-Velasco, P.C., and Srebric, J. 2011. “Experimental Quantification of Heat and Mass Transfer Process through a Vegetated Roof Assembly in a new Laboratory Setup,” Int. Journal of Heat and Mass Transfer, 54 (2011): 5149-5162.
  • Ayata, T., Tabares-Velasco, P.C., and Srebric, J. 2011. “An Investigation of Sensible Heat Fluxes at a Green Roof in a Laboratory Setup,” Building and Environment, 46(9): 1851-1861.
  • Tabares-Velasco, P.C. and Srebric, J. 2009. “The Role of Plants in the Reduction of Heat Flux through Green Roofs: Laboratory Experiments” ASHRAE Transactions,115(2): 793-802.

Conference Papers

  • Zhao, M., and Srebric, J. 2011. "Assessment of Green Roof Performance for Sustainable Buildings during Winter Weather Conditions," International Conference of WREC-Asia & SuDBE2011, October 28-31, 2011, Chongqing, China.
  • Tabares-Velasco, P.C., and Srebric, J. 2009. “Heat Fluxes and Water management of a Green and Brown Roof: Laboratory Experiments,” 7th Annual Greening Rooftops for Sustainable Communities Conference, CD ROM, 12 pages, June 3-5, 2009, Atlanta, GA.
  •  Tabares-Velasco, P.C., Srebric, J., and Berghage, R.D. 2007. “Thermal Performance of a Lightweight Tray for the Green Roof Media,” The 5th Annual Greening Rooftops for Sustainable Communities Conference, CD ROM, 12 pages, April 29-May 1, 2007, Minneapolis, MN.

Papers in Preparation for 2012

  • Tabares-Velasco, P.C., Zhao, M., Peterson, N., Srebric, J., and Berghage, R.D. 2012. “Validation of Predictive Heat and Mass Transfer Green Roof Model with Extensive Green Roof Field Data,” in preparations for Ecological Modelling
  • Zhao, M., Srebric, J., Dressler, K.A., and Berghage, R.D. 2012. “An Experimental Study of Green Roof Buildings under Snow Cover,” in preparations for HVAC&R Research
  • Zhao, M., Srebric, J., Berghage, R.D., and Dressler, K. A. 2012. “Snow Effects on Heat Load Calculations for Buildings with Green Roofs,” in preparations for Energy and Buildings
  • Tabares-Velasco, P.C., Zhao, M., and Srebric, J. 2012. “Effects of Different Green Roof Substrate on Spectral Reflectivity and Resultant Heat Flux,” in preparations for Building and Environment