Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.0

Inquiry

Our building has an existing EPDM membrane roof with smooth, river rock type ballast. It is two years old. We would like to capture this credit by coating (painting) the ballast with a reflective coating. We are in contact with a supplier that has several of these coated roofs in place and under scrutiny. One is being monitored by Oak Ridge Labs. While no formal data are yet available, discussion indicates that initial system reflectivity values are between .58 and .62 and that year two values drop to .54 -.56 range. None have 3 year data yet. Our contact estimated that the coated gravel will meet the .9 emissivity criteria but cannot offer data. He noted that Energy Star no longer requires emissivity testing. While we could capture the credit by replacing the roof with a white membrane, we would be taking materials out of service (EPDM and ballast) that have 15-20 years of life yet. Those materials could be recycled but would require energy to remove, transport and reinstall. Secondly, it could be argued that in our climate (Pittsburgh, PA), reflective roofs have only a fraction of the environmental impact that they do in cooling dominated climates such as Florida, therefore, we meet the credit intent even though we are a few percentage points off the target. To make up for the slightly lower values, we could do up to 100% of the roof area and not just 75%. A related question concerns the amount of HVAC equipment on the roof. The Lab functions in our building dictated that we install several RTU\'s, condensing units and exposed ductwork such that approximately 30% of the roof is covered by this equipment. It varies in height from 2\' to 8\'. Should we count this area as "roof" to determine our 75% roof surface? The equipment could be specified to be light colored. We ask the committee to respond ASAP as we are now beginning our construction phase.