New research confirms the conventional wisdom about green roofs: Vegetative roofs can help reduce heat gain and heat losses, resulting in significant energy savings in mixed climates.

New research confirms the conventional wisdom about green roofs: A recent study conducted by Oak Ridge National Laboratory (ORNL) and SPRI shows that vegetative roofs can help reduce heat gain and heat losses, resulting in significant energy savings in mixed climates.

According to SPRI, the association representing sheet membrane and component suppliers to the commercial roofing industry, the reduction in heat gain in cooling dominated periods - and heat losses in heating dominated periods - translates into lower heating and cooling demands for the conditioned space. However, the study notes that the energy savings offered by are dependent on the local climate and are affected by the efficiencies of HVAC equipment.

The results of the ORNL study also show that lower membrane temperatures and temperature fluctuations were experienced by the vegetative roofing system than the control black-EPDM and white-TPO roofing systems.

“As part of the effort to reduce energy use in commercial buildings, energy codes are greatly increasing the required thermal efficiency of roofing systems,” said SPRI Technical Director Mike Ennis. “It is important to understand the energy savings associated with vegetative roofs so that they can be properly credited in these codes.”

A summary of the ORNL/SPRI study written by Andre Desjarlais, Abdi Zaltash and Jerald Atchley of ORNL and Mike Ennis of SPRI was released earlier this year at the RCI Annual Convention.

We’ll publish SPRI’s in-depth analysis of the findings in a future issue of the magazine.