The research opportunity presented itself when four existing buildings, identical in size, design and occupant schedules, were re-roofed at the same time. Four different ways of roofing were implemented for the project:
1. Black EPDM membrane with 4 inches of foam insulation
2. Vegetative roof with 4 inches of foam insulation
3. White TPO roof with 4 inches of insulation
4. White TPO roof with 8 inches of insulation
|Photo courtesy of Kellen Technical Services|
The findings that were completed in 2011 showed that the TPO white membranes and the vegetative roof had lower roof surface temperatures, however, they also had increased heat loss during heating months.
But, the findings also showed that the TPO roof with the extra said insulation, along with providing cooler roof surfaces, had lower heating losses than the EDPM roof.
James R. Kirby, AIA and VP of Sustainability for the Center for Environmental Innovation in Roofing, Washington D.C., said this in an article about the study:
"There isn't one answer; however, this study provides a convincing case that insulation is critically important, and the R-values in the building code should be followed as absolute minimums for roof designs."
Closed cell polyurethane foam has a much higher R-value per inch than open-cell foam. Because of its density and glue-like tenacity, it also adds structural strength to a wall, ceiling, or roof.
James Kirby, AIA, vice president of Sustainability for the Center for Environmental Innovation in Roofing, Washington, D.C.