Residential Green Roof Systems

 

November 19, 2009
Our green roof team recently took First Place in the Baiada Center Green to Gold Concepts to Change the World Pitch Competition! Our multidisciplinary student team competed alongside 13 other Drexel teams and was judged by a panel of industry experts. Congrats team!

One of our latest projects, the residential green roof group seeks to develop a green roofing structure and system suitable for integration in residential properties. One of the challenges faced by the team early on was the structural evaluation of the 3425 property. Since an evaluation was recently carried out on the property, design requirements have been set and the team is planning to design a green roofing platform suitable for installation on the original roof structure of a 19th century Victorian twin home.

The most significant challenge the team is faced with is identifying a light weight replacement for the growing medium (most commonly soil or clay) that can be sourced within 500 miles of the installation site. Sourcing perlite, a lightweight volcanic soil, on the east or west coasts is feasible since it is mined on both coasts. Shipping perlite over 500 miles to the midwest incurrs a carbon footprint, since fuel is used for the transport of perlite. LEED outlines how building materials should be sourced, and specifies a 500 mile radius for it's local materials point.

This growing medium must balance high water retention with good drainage properties while supporting plant life. Smart House researchers use several test methods to measure water retention and drainage, as well as freeze stability, density, erosion, and pH.

Further impacts of this research include the potential for sloped green roofing systems and vertical outdoor walls.

Green roofs have the potential to reduce a building's environmental impact by offering water retention, thereby reducing water runoff to surrounding areas. Additionally, the roof vegetation serves to reduce cooling loads by reducing heat gain. Significant implementation of green roofs and cool roofs can in part mitigate the urban heat island effect.