Research Project Information

Research Project Summary Information

Green Roof Demonstration at Manufacturing Facility :Manufacturing Green (ST7523-1)

Pratt Institute Center for Community & E


Green roofs are used extensively on buildings throughout Europe. These roofs have layers of lightweight soil applied to the top surface of a building's roof to support vegetation. U.S. examples of green roofs include the Gap Headquarters, Chicago's City Hall, and the Boston World Trade Center. Gratz Industries, LLC operates a small metal fabrication facility in Long Island City. Gratz is interested in working with the Pratt Institute Center for Community and Environmental Development, a public interest planning, architectural and public policy office, and Balmori Associates, Inc., a New York City landscape design firm, to plan the installation of a green roof on its facility.

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Project Description

Pratt and it team installed a green roof on Gratz Industries Long Island City manufacturing facility. Approximately 25% of the roof was not covered with sedum to serve as a control area. This area had a black tar finish. This work will establish the design and costs for the green roof and quantify its energy savings and storm water runoff benefits.


Green roofs reduce energy usage of buildings by lowering roof temperatures during the summer and retaining heat during the winter. Green roofs can reduce heat island effect in urban areas. Green roofs can also reduce storm water runoff volume.

Project Results

The temperatures of the control section roof membrane fluctuated significantly more than the temperatures of the membrane under the green roof sections. Heat fluxes into the building during summer months were lower for the green roof than the control roof (air conditioning benefit for the green roof). Still, heat fluxes leaving the building during the winter months were higher for the green roof than the control roof (heating penalty for the green roof). The green roof reduced storm water run off by 40%. The storm water run off from the green roof sections contained less suspended solids, organic materials and heavy metals than found in the control roof storm water run off. Nevertheless, the storm water run off from the green roof contained more calcium and magnesium than found in the control roof storm water run off. A preliminary heat transfer analysis was conducted of the roof system on the Gratz Industries building. These results indicate that extensive and intensive green roofs have the potential to significantly reduce the heating requirements and noticeably reduce cooling requirements for this building. Still, comparing these savings to the costs for installing the green roof reveals that the payback period for this technology will exceed 30 years for this building, based on energy savings alone.


Pratt Institute Center for Community & E
200 Willoughby Ave
Brooklyn, NY 11205

Principle Investigator

Bill Riley

Universities Involved

Pratt Institute


Project Type:

Research Study

Technologies Types:

Building Systems
Building Construction Methods

NYSERDA Contact Information

Robert Carver


R&D - Buildings Research

Contract Details

Start Date: 1/11/2010
Project Status: Active
Contract Number: ST7523-1

Last Updated: 1/10/2014